65 files changed, 2429 insertions, 1692 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 36cff6402..eefa9a676 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -89,9 +89,9 @@ dependencies = [
 
 [[package]]
 name = "cargo_metadata"
-version = "0.9.1"
+version = "0.10.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "46e3374c604fb39d1a2f35ed5e4a4e30e60d01fab49446e08f1b3e9a90aef202"
+checksum = "b8de60b887edf6d74370fc8eb177040da4847d971d6234c7b13a6da324ef0caf"
 dependencies = [
  "semver",
  "serde",
@@ -958,14 +958,6 @@ dependencies = [
 ]
 
 [[package]]
-name = "ra_env"
-version = "0.1.0"
-dependencies = [
- "anyhow",
- "home",
-]
-
-[[package]]
 name = "ra_flycheck"
 version = "0.1.0"
 dependencies = [
@@ -975,7 +967,7 @@ dependencies = [
  "jod-thread",
  "log",
  "lsp-types",
- "ra_env",
+ "ra_toolchain",
  "serde_json",
 ]
 
@@ -1180,8 +1172,8 @@ dependencies = [
  "ra_arena",
  "ra_cfg",
  "ra_db",
- "ra_env",
  "ra_proc_macro",
+ "ra_toolchain",
  "rustc-hash",
  "serde",
  "serde_json",
@@ -1214,6 +1206,13 @@ dependencies = [
 ]
 
 [[package]]
+name = "ra_toolchain"
+version = "0.1.0"
+dependencies = [
+ "home",
+]
+
+[[package]]
 name = "ra_tt"
 version = "0.1.0"
 dependencies = [
@@ -1515,18 +1514,18 @@ checksum = "388a1df253eca08550bef6c72392cfe7c30914bf41df5269b68cbd6ff8f570a3"
 
 [[package]]
 name = "serde"
-version = "1.0.106"
+version = "1.0.107"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "36df6ac6412072f67cf767ebbde4133a5b2e88e76dc6187fa7104cd16f783399"
+checksum = "eba7550f2cdf88ffc23ab0f1607133486c390a8c0f89b57e589b9654ee15e04d"
 dependencies = [
  "serde_derive",
 ]
 
 [[package]]
 name = "serde_derive"
-version = "1.0.106"
+version = "1.0.107"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9e549e3abf4fb8621bd1609f11dfc9f5e50320802273b12f3811a67e6716ea6c"
+checksum = "10be45e22e5597d4b88afcc71f9d7bfadcd604bf0c78a3ab4582b8d2b37f39f3"
 dependencies = [
  "proc-macro2",
  "quote",
diff --git a/crates/ra_assists/src/assist_context.rs b/crates/ra_assists/src/assist_context.rs
index 3085c4330..a680f752b 100644
--- a/crates/ra_assists/src/assist_context.rs
+++ b/crates/ra_assists/src/assist_context.rs
@@ -49,7 +49,7 @@ use crate::{Assist, AssistId, GroupLabel, ResolvedAssist};
 /// easier to just compute the edit eagerly :-)
 pub(crate) struct AssistContext<'a> {
     pub(crate) sema: Semantics<'a, RootDatabase>,
-    pub(super) db: &'a RootDatabase,
+    pub(crate) db: &'a RootDatabase,
     pub(crate) frange: FileRange,
     source_file: SourceFile,
 }
diff --git a/crates/ra_assists/src/handlers/add_explicit_type.rs b/crates/ra_assists/src/handlers/add_explicit_type.rs
index 55409e501..7ced00626 100644
--- a/crates/ra_assists/src/handlers/add_explicit_type.rs
+++ b/crates/ra_assists/src/handlers/add_explicit_type.rs
@@ -23,6 +23,7 @@ use crate::{AssistContext, AssistId, Assists};
 // ```
 pub(crate) fn add_explicit_type(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let stmt = ctx.find_node_at_offset::<LetStmt>()?;
+    let module = ctx.sema.scope(stmt.syntax()).module()?;
     let expr = stmt.initializer()?;
     let pat = stmt.pat()?;
     // Must be a binding
@@ -57,17 +58,17 @@ pub(crate) fn add_explicit_type(acc: &mut Assists, ctx: &AssistContext) -> Optio
         return None;
     }
 
-    let db = ctx.db;
-    let new_type_string = ty.display_truncated(db, None).to_string();
+    let inferred_type = ty.display_source_code(ctx.db, module.into()).ok()?;
     acc.add(
         AssistId("add_explicit_type"),
-        format!("Insert explicit type '{}'", new_type_string),
+        format!("Insert explicit type '{}'", inferred_type),
         pat_range,
-        |edit| {
-            if let Some(ascribed_ty) = ascribed_ty {
-                edit.replace(ascribed_ty.syntax().text_range(), new_type_string);
-            } else {
-                edit.insert(name_range.end(), format!(": {}", new_type_string));
+        |builder| match ascribed_ty {
+            Some(ascribed_ty) => {
+                builder.replace(ascribed_ty.syntax().text_range(), inferred_type);
+            }
+            None => {
+                builder.insert(name_range.end(), format!(": {}", inferred_type));
             }
         },
     )
diff --git a/crates/ra_assists/src/handlers/add_from_impl_for_enum.rs b/crates/ra_assists/src/handlers/add_from_impl_for_enum.rs
index 275184e24..6a49b7dbd 100644
--- a/crates/ra_assists/src/handlers/add_from_impl_for_enum.rs
+++ b/crates/ra_assists/src/handlers/add_from_impl_for_enum.rs
@@ -1,8 +1,5 @@
 use ra_ide_db::RootDatabase;
-use ra_syntax::{
-    ast::{self, AstNode, NameOwner},
-    TextSize,
-};
+use ra_syntax::ast::{self, AstNode, NameOwner};
 use stdx::format_to;
 use test_utils::tested_by;
 
@@ -69,7 +66,6 @@ impl From<{0}> for {1} {{
                 variant_name
             );
             edit.insert(start_offset, buf);
-            edit.set_cursor(start_offset + TextSize::of("\n\n"));
         },
     )
 }
@@ -97,19 +93,20 @@ fn existing_from_impl(
 
 #[cfg(test)]
 mod tests {
-    use super::*;
+    use test_utils::covers;
 
     use crate::tests::{check_assist, check_assist_not_applicable};
-    use test_utils::covers;
+
+    use super::*;
 
     #[test]
     fn test_add_from_impl_for_enum() {
         check_assist(
             add_from_impl_for_enum,
             "enum A { <|>One(u32) }",
-            r#"enum A { One(u32) }
+            r#"enum A { <|>One(u32) }
 
-<|>impl From<u32> for A {
+impl From<u32> for A {
     fn from(v: u32) -> Self {
         A::One(v)
     }
@@ -121,10 +118,10 @@ mod tests {
     fn test_add_from_impl_for_enum_complicated_path() {
         check_assist(
             add_from_impl_for_enum,
-            "enum A { <|>One(foo::bar::baz::Boo) }",
-            r#"enum A { One(foo::bar::baz::Boo) }
+            r#"enum A { <|>One(foo::bar::baz::Boo) }"#,
+            r#"enum A { <|>One(foo::bar::baz::Boo) }
 
-<|>impl From<foo::bar::baz::Boo> for A {
+impl From<foo::bar::baz::Boo> for A {
     fn from(v: foo::bar::baz::Boo) -> Self {
         A::One(v)
     }
@@ -184,9 +181,9 @@ impl From<String> for A {
 pub trait From<T> {
     fn from(T) -> Self;
 }"#,
-            r#"enum A { One(u32), Two(String), }
+            r#"enum A { <|>One(u32), Two(String), }
 
-<|>impl From<u32> for A {
+impl From<u32> for A {
     fn from(v: u32) -> Self {
         A::One(v)
     }
diff --git a/crates/ra_assists/src/handlers/add_function.rs b/crates/ra_assists/src/handlers/add_function.rs
index 6b5616aa9..de016ae4e 100644
--- a/crates/ra_assists/src/handlers/add_function.rs
+++ b/crates/ra_assists/src/handlers/add_function.rs
@@ -1,7 +1,11 @@
 use hir::HirDisplay;
 use ra_db::FileId;
 use ra_syntax::{
-    ast::{self, edit::IndentLevel, ArgListOwner, AstNode, ModuleItemOwner},
+    ast::{
+        self,
+        edit::{AstNodeEdit, IndentLevel},
+        ArgListOwner, AstNode, ModuleItemOwner,
+    },
     SyntaxKind, SyntaxNode, TextSize,
 };
 use rustc_hash::{FxHashMap, FxHashSet};
@@ -43,16 +47,12 @@ pub(crate) fn add_function(acc: &mut Assists, ctx: &AssistContext) -> Option<()>
         return None;
     }
 
-    let target_module = if let Some(qualifier) = path.qualifier() {
-        if let Some(hir::PathResolution::Def(hir::ModuleDef::Module(module))) =
-            ctx.sema.resolve_path(&qualifier)
-        {
-            Some(module.definition_source(ctx.sema.db))
-        } else {
-            return None;
-        }
-    } else {
-        None
+    let target_module = match path.qualifier() {
+        Some(qualifier) => match ctx.sema.resolve_path(&qualifier) {
+            Some(hir::PathResolution::Def(hir::ModuleDef::Module(module))) => Some(module),
+            _ => return None,
+        },
+        None => None,
     };
 
     let function_builder = FunctionBuilder::from_call(&ctx, &call, &path, target_module)?;
@@ -83,25 +83,29 @@ struct FunctionBuilder {
 }
 
 impl FunctionBuilder {
-    /// Prepares a generated function that matches `call` in `generate_in`
-    /// (or as close to `call` as possible, if `generate_in` is `None`)
+    /// Prepares a generated function that matches `call`.
+    /// The function is generated in `target_module` or next to `call`
     fn from_call(
         ctx: &AssistContext,
         call: &ast::CallExpr,
         path: &ast::Path,
-        target_module: Option<hir::InFile<hir::ModuleSource>>,
+        target_module: Option<hir::Module>,
     ) -> Option<Self> {
-        let needs_pub = target_module.is_some();
         let mut file = ctx.frange.file_id;
-        let target = if let Some(target_module) = target_module {
-            let (in_file, target) = next_space_for_fn_in_module(ctx.sema.db, target_module)?;
-            file = in_file;
-            target
-        } else {
-            next_space_for_fn_after_call_site(&call)?
+        let target = match &target_module {
+            Some(target_module) => {
+                let module_source = target_module.definition_source(ctx.db);
+                let (in_file, target) = next_space_for_fn_in_module(ctx.sema.db, &module_source)?;
+                file = in_file;
+                target
+            }
+            None => next_space_for_fn_after_call_site(&call)?,
         };
+        let needs_pub = target_module.is_some();
+        let target_module = target_module.or_else(|| ctx.sema.scope(target.syntax()).module())?;
         let fn_name = fn_name(&path)?;
-        let (type_params, params) = fn_args(ctx, &call)?;
+        let (type_params, params) = fn_args(ctx, target_module, &call)?;
+
         Some(Self { target, fn_name, type_params, params, file, needs_pub })
     }
 
@@ -116,17 +120,16 @@ impl FunctionBuilder {
         let (fn_def, insert_offset) = match self.target {
             GeneratedFunctionTarget::BehindItem(it) => {
                 let with_leading_blank_line = ast::make::add_leading_newlines(2, fn_def);
-                let indented = IndentLevel::from_node(&it).increase_indent(with_leading_blank_line);
+                let indented = with_leading_blank_line.indent(IndentLevel::from_node(&it));
                 (indented, it.text_range().end())
             }
             GeneratedFunctionTarget::InEmptyItemList(it) => {
                 let indent_once = IndentLevel(1);
                 let indent = IndentLevel::from_node(it.syntax());
-
                 let fn_def = ast::make::add_leading_newlines(1, fn_def);
-                let fn_def = indent_once.increase_indent(fn_def);
+                let fn_def = fn_def.indent(indent_once);
                 let fn_def = ast::make::add_trailing_newlines(1, fn_def);
-                let fn_def = indent.increase_indent(fn_def);
+                let fn_def = fn_def.indent(indent);
                 (fn_def, it.syntax().text_range().start() + TextSize::of('{'))
             }
         };
@@ -144,6 +147,15 @@ enum GeneratedFunctionTarget {
     InEmptyItemList(ast::ItemList),
 }
 
+impl GeneratedFunctionTarget {
+    fn syntax(&self) -> &SyntaxNode {
+        match self {
+            GeneratedFunctionTarget::BehindItem(it) => it,
+            GeneratedFunctionTarget::InEmptyItemList(it) => it.syntax(),
+        }
+    }
+}
+
 fn fn_name(call: &ast::Path) -> Option<ast::Name> {
     let name = call.segment()?.syntax().to_string();
     Some(ast::make::name(&name))
@@ -152,17 +164,17 @@ fn fn_name(call: &ast::Path) -> Option<ast::Name> {
 /// Computes the type variables and arguments required for the generated function
 fn fn_args(
     ctx: &AssistContext,
+    target_module: hir::Module,
     call: &ast::CallExpr,
 ) -> Option<(Option<ast::TypeParamList>, ast::ParamList)> {
     let mut arg_names = Vec::new();
     let mut arg_types = Vec::new();
     for arg in call.arg_list()?.args() {
-        let arg_name = match fn_arg_name(&arg) {
+        arg_names.push(match fn_arg_name(&arg) {
             Some(name) => name,
             None => String::from("arg"),
-        };
-        arg_names.push(arg_name);
-        arg_types.push(match fn_arg_type(ctx, &arg) {
+        });
+        arg_types.push(match fn_arg_type(ctx, target_module, &arg) {
             Some(ty) => ty,
             None => String::from("()"),
         });
@@ -218,12 +230,21 @@ fn fn_arg_name(fn_arg: &ast::Expr) -> Option<String> {
     }
 }
 
-fn fn_arg_type(ctx: &AssistContext, fn_arg: &ast::Expr) -> Option<String> {
+fn fn_arg_type(
+    ctx: &AssistContext,
+    target_module: hir::Module,
+    fn_arg: &ast::Expr,
+) -> Option<String> {
     let ty = ctx.sema.type_of_expr(fn_arg)?;
     if ty.is_unknown() {
         return None;
     }
-    Some(ty.display(ctx.sema.db).to_string())
+
+    if let Ok(rendered) = ty.display_source_code(ctx.db, target_module.into()) {
+        Some(rendered)
+    } else {
+        None
+    }
 }
 
 /// Returns the position inside the current mod or file
@@ -252,10 +273,10 @@ fn next_space_for_fn_after_call_site(expr: &ast::CallExpr) -> Option<GeneratedFu
 
 fn next_space_for_fn_in_module(
     db: &dyn hir::db::AstDatabase,
-    module: hir::InFile<hir::ModuleSource>,
+    module_source: &hir::InFile<hir::ModuleSource>,
 ) -> Option<(FileId, GeneratedFunctionTarget)> {
-    let file = module.file_id.original_file(db);
-    let assist_item = match module.value {
+    let file = module_source.file_id.original_file(db);
+    let assist_item = match &module_source.value {
         hir::ModuleSource::SourceFile(it) => {
             if let Some(last_item) = it.items().last() {
                 GeneratedFunctionTarget::BehindItem(last_item.syntax().clone())
@@ -599,8 +620,33 @@ fn bar(foo: impl Foo) {
     }
 
     #[test]
-    #[ignore]
-    // FIXME print paths properly to make this test pass
+    fn borrowed_arg() {
+        check_assist(
+            add_function,
+            r"
+struct Baz;
+fn baz() -> Baz { todo!() }
+
+fn foo() {
+    bar<|>(&baz())
+}
+",
+            r"
+struct Baz;
+fn baz() -> Baz { todo!() }
+
+fn foo() {
+    bar(&baz())
+}
+
+fn bar(baz: &Baz) {
+    <|>todo!()
+}
+",
+        )
+    }
+
+    #[test]
     fn add_function_with_qualified_path_arg() {
         check_assist(
             add_function,
@@ -609,10 +655,8 @@ mod Baz {
     pub struct Bof;
     pub fn baz() -> Bof { Bof }
 }
-mod Foo {
-    fn foo() {
-        <|>bar(super::Baz::baz())
-    }
+fn foo() {
+    <|>bar(Baz::baz())
 }
 ",
             r"
@@ -620,14 +664,12 @@ mod Baz {
     pub struct Bof;
     pub fn baz() -> Bof { Bof }
 }
-mod Foo {
-    fn foo() {
-        bar(super::Baz::baz())
-    }
+fn foo() {
+    bar(Baz::baz())
+}
 
-    fn bar(baz: super::Baz::Bof) {
-        <|>todo!()
-    }
+fn bar(baz: Baz::Bof) {
+    <|>todo!()
 }
 ",
         )
@@ -809,6 +851,40 @@ fn foo() {
     }
 
     #[test]
+    #[ignore]
+    // Ignored until local imports are supported.
+    // See https://github.com/rust-analyzer/rust-analyzer/issues/1165
+    fn qualified_path_uses_correct_scope() {
+        check_assist(
+            add_function,
+            "
+mod foo {
+    pub struct Foo;
+}
+fn bar() {
+    use foo::Foo;
+    let foo = Foo;
+    baz<|>(foo)
+}
+",
+            "
+mod foo {
+    pub struct Foo;
+}
+fn bar() {
+    use foo::Foo;
+    let foo = Foo;
+    baz(foo)
+}
+
+fn baz(foo: foo::Foo) {
+    <|>todo!()
+}
+",
+        )
+    }
+
+    #[test]
     fn add_function_in_module_containing_other_items() {
         check_assist(
             add_function,
@@ -920,21 +996,6 @@ fn bar(baz: ()) {}
     }
 
     #[test]
-    fn add_function_not_applicable_if_function_path_not_singleton() {
-        // In the future this assist could be extended to generate functions
-        // if the path is in the same crate (or even the same workspace).
-        // For the beginning, I think this is fine.
-        check_assist_not_applicable(
-            add_function,
-            r"
-fn foo() {
-    other_crate::bar<|>();
-}
-        ",
-        )
-    }
-
-    #[test]
     #[ignore]
     fn create_method_with_no_args() {
         check_assist(
diff --git a/crates/ra_assists/src/handlers/add_missing_impl_members.rs b/crates/ra_assists/src/handlers/add_missing_impl_members.rs
index 3482a75bf..c1ce87914 100644
--- a/crates/ra_assists/src/handlers/add_missing_impl_members.rs
+++ b/crates/ra_assists/src/handlers/add_missing_impl_members.rs
@@ -2,7 +2,7 @@ use hir::HasSource;
 use ra_syntax::{
     ast::{
         self,
-        edit::{self, IndentLevel},
+        edit::{self, AstNodeEdit, IndentLevel},
         make, AstNode, NameOwner,
     },
     SmolStr,
@@ -176,8 +176,7 @@ fn add_body(fn_def: ast::FnDef) -> ast::FnDef {
     if fn_def.body().is_some() {
         return fn_def;
     }
-    let body = make::block_expr(None, Some(make::expr_todo()));
-    let body = IndentLevel(1).increase_indent(body);
+    let body = make::block_expr(None, Some(make::expr_todo())).indent(IndentLevel(1));
     fn_def.with_body(body)
 }
 
diff --git a/crates/ra_assists/src/handlers/early_return.rs b/crates/ra_assists/src/handlers/early_return.rs
index 810784ad5..66b296081 100644
--- a/crates/ra_assists/src/handlers/early_return.rs
+++ b/crates/ra_assists/src/handlers/early_return.rs
@@ -2,7 +2,11 @@ use std::{iter::once, ops::RangeInclusive};
 
 use ra_syntax::{
     algo::replace_children,
-    ast::{self, edit::IndentLevel, make},
+    ast::{
+        self,
+        edit::{AstNodeEdit, IndentLevel},
+        make,
+    },
     AstNode,
     SyntaxKind::{FN_DEF, LOOP_EXPR, L_CURLY, R_CURLY, WHILE_EXPR, WHITESPACE},
     SyntaxNode,
@@ -105,8 +109,7 @@ pub(crate) fn convert_to_guarded_return(acc: &mut Assists, ctx: &AssistContext)
                     let then_branch =
                         make::block_expr(once(make::expr_stmt(early_expression).into()), None);
                     let cond = invert_boolean_expression(cond_expr);
-                    let e = make::expr_if(make::condition(cond, None), then_branch);
-                    if_indent_level.increase_indent(e)
+                    make::expr_if(make::condition(cond, None), then_branch).indent(if_indent_level)
                 };
                 replace(new_expr.syntax(), &then_block, &parent_block, &if_expr)
             }
@@ -140,7 +143,7 @@ pub(crate) fn convert_to_guarded_return(acc: &mut Assists, ctx: &AssistContext)
                     make::bind_pat(make::name(&bound_ident.syntax().to_string())).into(),
                     Some(match_expr),
                 );
-                let let_stmt = if_indent_level.increase_indent(let_stmt);
+                let let_stmt = let_stmt.indent(if_indent_level);
                 replace(let_stmt.syntax(), &then_block, &parent_block, &if_expr)
             }
         };
@@ -153,7 +156,7 @@ pub(crate) fn convert_to_guarded_return(acc: &mut Assists, ctx: &AssistContext)
             parent_block: &ast::BlockExpr,
             if_expr: &ast::IfExpr,
         ) -> SyntaxNode {
-            let then_block_items = IndentLevel::from(1).decrease_indent(then_block.clone());
+            let then_block_items = then_block.dedent(IndentLevel::from(1));
             let end_of_then = then_block_items.syntax().last_child_or_token().unwrap();
             let end_of_then =
                 if end_of_then.prev_sibling_or_token().map(|n| n.kind()) == Some(WHITESPACE) {
diff --git a/crates/ra_assists/src/handlers/replace_if_let_with_match.rs b/crates/ra_assists/src/handlers/replace_if_let_with_match.rs
index a59a06efa..65f5fc6ab 100644
--- a/crates/ra_assists/src/handlers/replace_if_let_with_match.rs
+++ b/crates/ra_assists/src/handlers/replace_if_let_with_match.rs
@@ -1,6 +1,10 @@
 use ra_fmt::unwrap_trivial_block;
 use ra_syntax::{
-    ast::{self, edit::IndentLevel, make},
+    ast::{
+        self,
+        edit::{AstNodeEdit, IndentLevel},
+        make,
+    },
     AstNode,
 };
 
@@ -61,10 +65,9 @@ pub(crate) fn replace_if_let_with_match(acc: &mut Assists, ctx: &AssistContext)
                 make::match_arm(vec![pattern], else_expr)
             };
             make::expr_match(expr, make::match_arm_list(vec![then_arm, else_arm]))
+                .indent(IndentLevel::from_node(if_expr.syntax()))
         };
 
-        let match_expr = IndentLevel::from_node(if_expr.syntax()).increase_indent(match_expr);
-
         edit.set_cursor(if_expr.syntax().text_range().start());
         edit.replace_ast::<ast::Expr>(if_expr.into(), match_expr);
     })
diff --git a/crates/ra_assists/src/handlers/replace_let_with_if_let.rs b/crates/ra_assists/src/handlers/replace_let_with_if_let.rs
index d3f214591..482957dc6 100644
--- a/crates/ra_assists/src/handlers/replace_let_with_if_let.rs
+++ b/crates/ra_assists/src/handlers/replace_let_with_if_let.rs
@@ -53,8 +53,7 @@ pub(crate) fn replace_let_with_if_let(acc: &mut Assists, ctx: &AssistContext) ->
             )
             .into(),
         };
-        let block =
-            IndentLevel::from_node(let_stmt.syntax()).increase_indent(make::block_expr(None, None));
+        let block = make::block_expr(None, None).indent(IndentLevel::from_node(let_stmt.syntax()));
         let if_ = make::expr_if(make::condition(init, Some(with_placeholder)), block);
         let stmt = make::expr_stmt(if_);
 
diff --git a/crates/ra_assists/src/handlers/replace_unwrap_with_match.rs b/crates/ra_assists/src/handlers/replace_unwrap_with_match.rs
index a46998b8e..c4b56f6e9 100644
--- a/crates/ra_assists/src/handlers/replace_unwrap_with_match.rs
+++ b/crates/ra_assists/src/handlers/replace_unwrap_with_match.rs
@@ -1,7 +1,11 @@
 use std::iter;
 
 use ra_syntax::{
-    ast::{self, edit::IndentLevel, make},
+    ast::{
+        self,
+        edit::{AstNodeEdit, IndentLevel},
+        make,
+    },
     AstNode,
 };
 
@@ -51,8 +55,8 @@ pub(crate) fn replace_unwrap_with_match(acc: &mut Assists, ctx: &AssistContext)
         let err_arm = make::match_arm(iter::once(make::placeholder_pat().into()), unreachable_call);
 
         let match_arm_list = make::match_arm_list(vec![ok_arm, err_arm]);
-        let match_expr = make::expr_match(caller.clone(), match_arm_list);
-        let match_expr = IndentLevel::from_node(method_call.syntax()).increase_indent(match_expr);
+        let match_expr = make::expr_match(caller.clone(), match_arm_list)
+            .indent(IndentLevel::from_node(method_call.syntax()));
 
         edit.set_cursor(caller.syntax().text_range().start());
         edit.replace_ast::<ast::Expr>(method_call.into(), match_expr);
diff --git a/crates/ra_assists/src/handlers/unwrap_block.rs b/crates/ra_assists/src/handlers/unwrap_block.rs
index eba0631a4..e52ec557e 100644
--- a/crates/ra_assists/src/handlers/unwrap_block.rs
+++ b/crates/ra_assists/src/handlers/unwrap_block.rs
@@ -1,6 +1,6 @@
 use crate::{AssistContext, AssistId, Assists};
 
-use ast::LoopBodyOwner;
+use ast::{ElseBranch, Expr, LoopBodyOwner};
 use ra_fmt::unwrap_trivial_block;
 use ra_syntax::{ast, match_ast, AstNode, TextRange, T};
 
@@ -25,19 +25,11 @@ pub(crate) fn unwrap_block(acc: &mut Assists, ctx: &AssistContext) -> Option<()>
     let l_curly_token = ctx.find_token_at_offset(T!['{'])?;
     let block = ast::BlockExpr::cast(l_curly_token.parent())?;
     let parent = block.syntax().parent()?;
+    let assist_id = AssistId("unwrap_block");
+    let assist_label = "Unwrap block";
+
     let (expr, expr_to_unwrap) = match_ast! {
         match parent {
-            ast::IfExpr(if_expr) => {
-                let expr_to_unwrap = if_expr.blocks().find_map(|expr| extract_expr(ctx.frange.range, expr));
-                let expr_to_unwrap = expr_to_unwrap?;
-                // Find if we are in a else if block
-                let ancestor = if_expr.syntax().parent().and_then(ast::IfExpr::cast);
-
-                match ancestor {
-                    None => (ast::Expr::IfExpr(if_expr), expr_to_unwrap),
-                    Some(ancestor) => (ast::Expr::IfExpr(ancestor), expr_to_unwrap),
-                }
-            },
             ast::ForExpr(for_expr) => {
                 let block_expr = for_expr.loop_body()?;
                 let expr_to_unwrap = extract_expr(ctx.frange.range, block_expr)?;
@@ -53,27 +45,62 @@ pub(crate) fn unwrap_block(acc: &mut Assists, ctx: &AssistContext) -> Option<()>
                 let expr_to_unwrap = extract_expr(ctx.frange.range, block_expr)?;
                 (ast::Expr::LoopExpr(loop_expr), expr_to_unwrap)
             },
+            ast::IfExpr(if_expr) => {
+                let mut resp = None;
+
+                let then_branch = if_expr.then_branch()?;
+                if then_branch.l_curly_token()?.text_range().contains_range(ctx.frange.range) {
+                    if let Some(ancestor) = if_expr.syntax().parent().and_then(ast::IfExpr::cast) {
+                        // For `else if` blocks
+                        let ancestor_then_branch = ancestor.then_branch()?;
+                        let l_curly_token = then_branch.l_curly_token()?;
+
+                        let target = then_branch.syntax().text_range();
+                        return acc.add(assist_id, assist_label, target, |edit| {
+                            let range_to_del_else_if = TextRange::new(ancestor_then_branch.syntax().text_range().end(), l_curly_token.text_range().start());
+                            let range_to_del_rest = TextRange::new(then_branch.syntax().text_range().end(), if_expr.syntax().text_range().end());
+
+                            edit.set_cursor(ancestor_then_branch.syntax().text_range().end());
+                            edit.delete(range_to_del_rest);
+                            edit.delete(range_to_del_else_if);
+                            edit.replace(target, update_expr_string(then_branch.to_string(), &[' ', '{']));
+                        });
+                    } else {
+                        resp = Some((ast::Expr::IfExpr(if_expr.clone()), Expr::BlockExpr(then_branch)));
+                    }
+                } else if let Some(else_branch) = if_expr.else_branch() {
+                    match else_branch {
+                        ElseBranch::Block(else_block) => {
+                            let l_curly_token = else_block.l_curly_token()?;
+                            if l_curly_token.text_range().contains_range(ctx.frange.range) {
+                                let target = else_block.syntax().text_range();
+                                return acc.add(assist_id, assist_label, target, |edit| {
+                                    let range_to_del = TextRange::new(then_branch.syntax().text_range().end(), l_curly_token.text_range().start());
+
+                                    edit.set_cursor(then_branch.syntax().text_range().end());
+                                    edit.delete(range_to_del);
+                                    edit.replace(target, update_expr_string(else_block.to_string(), &[' ', '{']));
+                                });
+                            }
+                        },
+                        ElseBranch::IfExpr(_) => {},
+                    }
+                }
+
+                resp?
+            },
             _ => return None,
         }
     };
 
     let target = expr_to_unwrap.syntax().text_range();
-    acc.add(AssistId("unwrap_block"), "Unwrap block", target, |edit| {
+    acc.add(assist_id, assist_label, target, |edit| {
         edit.set_cursor(expr.syntax().text_range().start());
 
-        let pat_start: &[_] = &[' ', '{', '\n'];
-        let expr_to_unwrap = expr_to_unwrap.to_string();
-        let expr_string = expr_to_unwrap.trim_start_matches(pat_start);
-        let mut expr_string_lines: Vec<&str> = expr_string.lines().collect();
-        expr_string_lines.pop(); // Delete last line
-
-        let expr_string = expr_string_lines
-            .into_iter()
-            .map(|line| line.replacen("    ", "", 1)) // Delete indentation
-            .collect::<Vec<String>>()
-            .join("\n");
-
-        edit.replace(expr.syntax().text_range(), expr_string);
+        edit.replace(
+            expr.syntax().text_range(),
+            update_expr_string(expr_to_unwrap.to_string(), &[' ', '{', '\n']),
+        );
     })
 }
 
@@ -87,6 +114,18 @@ fn extract_expr(cursor_range: TextRange, block: ast::BlockExpr) -> Option<ast::E
     }
 }
 
+fn update_expr_string(expr_str: String, trim_start_pat: &[char]) -> String {
+    let expr_string = expr_str.trim_start_matches(trim_start_pat);
+    let mut expr_string_lines: Vec<&str> = expr_string.lines().collect();
+    expr_string_lines.pop(); // Delete last line
+
+    expr_string_lines
+        .into_iter()
+        .map(|line| line.replacen("    ", "", 1)) // Delete indentation
+        .collect::<Vec<String>>()
+        .join("\n")
+}
+
 #[cfg(test)]
 mod tests {
     use crate::tests::{check_assist, check_assist_not_applicable};
@@ -142,7 +181,13 @@ mod tests {
             r#"
             fn main() {
                 bar();
-                <|>println!("bar");
+                if true {
+                    foo();
+
+                    //comment
+                    bar();
+                }<|>
+                println!("bar");
             }
             "#,
         );
@@ -170,7 +215,127 @@ mod tests {
             r#"
             fn main() {
                 //bar();
-                <|>println!("bar");
+                if true {
+                    println!("true");
+
+                    //comment
+                    //bar();
+                }<|>
+                println!("bar");
+            }
+            "#,
+        );
+    }
+
+    #[test]
+    fn simple_if_else_if_nested() {
+        check_assist(
+            unwrap_block,
+            r#"
+            fn main() {
+                //bar();
+                if true {
+                    println!("true");
+
+                    //comment
+                    //bar();
+                } else if false {
+                    println!("bar");
+                } else if true {<|>
+                    println!("foo");
+                }
+            }
+            "#,
+            r#"
+            fn main() {
+                //bar();
+                if true {
+                    println!("true");
+
+                    //comment
+                    //bar();
+                } else if false {
+                    println!("bar");
+                }<|>
+                println!("foo");
+            }
+            "#,
+        );
+    }
+
+    #[test]
+    fn simple_if_else_if_nested_else() {
+        check_assist(
+            unwrap_block,
+            r#"
+            fn main() {
+                //bar();
+                if true {
+                    println!("true");
+
+                    //comment
+                    //bar();
+                } else if false {
+                    println!("bar");
+                } else if true {
+                    println!("foo");
+                } else {<|>
+                    println!("else");
+                }
+            }
+            "#,
+            r#"
+            fn main() {
+                //bar();
+                if true {
+                    println!("true");
+
+                    //comment
+                    //bar();
+                } else if false {
+                    println!("bar");
+                } else if true {
+                    println!("foo");
+                }<|>
+                println!("else");
+            }
+            "#,
+        );
+    }
+
+    #[test]
+    fn simple_if_else_if_nested_middle() {
+        check_assist(
+            unwrap_block,
+            r#"
+            fn main() {
+                //bar();
+                if true {
+                    println!("true");
+
+                    //comment
+                    //bar();
+                } else if false {
+                    println!("bar");
+                } else if true {<|>
+                    println!("foo");
+                } else {
+                    println!("else");
+                }
+            }
+            "#,
+            r#"
+            fn main() {
+                //bar();
+                if true {
+                    println!("true");
+
+                    //comment
+                    //bar();
+                } else if false {
+                    println!("bar");
+                }<|>
+                println!("foo");
             }
             "#,
         );
diff --git a/crates/ra_env/src/lib.rs b/crates/ra_env/src/lib.rs
deleted file mode 100644
index 413da1982..000000000
--- a/crates/ra_env/src/lib.rs
+++ /dev/null
@@ -1,66 +0,0 @@
-//! This crate contains a single public function
-//! [`get_path_for_executable`](fn.get_path_for_executable.html).
-//! See docs there for more information.
-
-use anyhow::{bail, Result};
-use std::env;
-use std::path::{Path, PathBuf};
-use std::process::Command;
-
-/// Return a `PathBuf` to use for the given executable.
-///
-/// E.g., `get_path_for_executable("cargo")` may return just `cargo` if that
-/// gives a valid Cargo executable; or it may return a full path to a valid
-/// Cargo.
-pub fn get_path_for_executable(executable_name: impl AsRef<str>) -> Result<PathBuf> {
-    // The current implementation checks three places for an executable to use:
-    // 1) Appropriate environment variable (erroring if this is set but not a usable executable)
-    //      example: for cargo, this checks $CARGO environment variable; for rustc, $RUSTC; etc
-    // 2) `<executable_name>`
-    //      example: for cargo, this tries just `cargo`, which will succeed if `cargo` is on the $PATH
-    // 3) `~/.cargo/bin/<executable_name>`
-    //      example: for cargo, this tries ~/.cargo/bin/cargo
-    //      It seems that this is a reasonable place to try for cargo, rustc, and rustup
-    let executable_name = executable_name.as_ref();
-    let env_var = executable_name.to_ascii_uppercase();
-    if let Ok(path) = env::var(&env_var) {
-        if is_valid_executable(&path) {
-            Ok(path.into())
-        } else {
-            bail!(
-                "`{}` environment variable points to something that's not a valid executable",
-                env_var
-            )
-        }
-    } else {
-        if is_valid_executable(executable_name) {
-            return Ok(executable_name.into());
-        }
-        if let Some(mut path) = ::home::home_dir() {
-            path.push(".cargo");
-            path.push("bin");
-            path.push(executable_name);
-            if is_valid_executable(&path) {
-                return Ok(path);
-            }
-        }
-        // This error message may also be caused by $PATH or $CARGO/$RUSTC/etc not being set correctly
-        // for VSCode, even if they are set correctly in a terminal.
-        // On macOS in particular, launching VSCode from terminal with `code <dirname>` causes VSCode
-        // to inherit environment variables including $PATH, $CARGO, $RUSTC, etc from that terminal;
-        // but launching VSCode from Dock does not inherit environment variables from a terminal.
-        // For more discussion, see #3118.
-        bail!(
-            "Failed to find `{}` executable. Make sure `{}` is in `$PATH`, or set `${}` to point to a valid executable.",
-            executable_name, executable_name, env_var
-        )
-    }
-}
-
-/// Does the given `Path` point to a usable executable?
-///
-/// (assumes the executable takes a `--version` switch and writes to stdout,
-/// which is true for `cargo`, `rustc`, and `rustup`)
-fn is_valid_executable(p: impl AsRef<Path>) -> bool {
-    Command::new(p.as_ref()).arg("--version").output().is_ok()
-}
diff --git a/crates/ra_flycheck/Cargo.toml b/crates/ra_flycheck/Cargo.toml
index d0f7fb2dc..eac502da5 100644
--- a/crates/ra_flycheck/Cargo.toml
+++ b/crates/ra_flycheck/Cargo.toml
@@ -11,10 +11,10 @@ doctest = false
 crossbeam-channel = "0.4.0"
 lsp-types = { version = "0.74.0", features = ["proposed"] }
 log = "0.4.8"
-cargo_metadata = "0.9.1"
+cargo_metadata = "0.10.0"
 serde_json = "1.0.48"
 jod-thread = "0.1.1"
-ra_env = { path = "../ra_env" }
+ra_toolchain = { path = "../ra_toolchain" }
 
 [dev-dependencies]
 insta = "0.16.0"
diff --git a/crates/ra_flycheck/src/lib.rs b/crates/ra_flycheck/src/lib.rs
index d8b727b0e..24af75c95 100644
--- a/crates/ra_flycheck/src/lib.rs
+++ b/crates/ra_flycheck/src/lib.rs
@@ -16,7 +16,6 @@ use lsp_types::{
     CodeAction, CodeActionOrCommand, Diagnostic, Url, WorkDoneProgress, WorkDoneProgressBegin,
     WorkDoneProgressEnd, WorkDoneProgressReport,
 };
-use ra_env::get_path_for_executable;
 
 use crate::conv::{map_rust_diagnostic_to_lsp, MappedRustDiagnostic};
 
@@ -205,6 +204,8 @@ impl FlycheckThread {
             }
 
             CheckEvent::Msg(Message::BuildScriptExecuted(_msg)) => {}
+            CheckEvent::Msg(Message::BuildFinished(_)) => {}
+            CheckEvent::Msg(Message::TextLine(_)) => {}
             CheckEvent::Msg(Message::Unknown) => {}
         }
     }
@@ -216,10 +217,10 @@ impl FlycheckThread {
 
         let mut cmd = match &self.config {
             FlycheckConfig::CargoCommand { command, all_targets, all_features, extra_args } => {
-                let mut cmd = Command::new(get_path_for_executable("cargo").unwrap());
+                let mut cmd = Command::new(ra_toolchain::cargo());
                 cmd.arg(command);
-                cmd.args(&["--workspace", "--message-format=json", "--manifest-path"]);
-                cmd.arg(self.workspace_root.join("Cargo.toml"));
+                cmd.args(&["--workspace", "--message-format=json", "--manifest-path"])
+                    .arg(self.workspace_root.join("Cargo.toml"));
                 if *all_targets {
                     cmd.arg("--all-targets");
                 }
diff --git a/crates/ra_hir/src/code_model.rs b/crates/ra_hir/src/code_model.rs
index 5f480c304..3fc2eccdd 100644
--- a/crates/ra_hir/src/code_model.rs
+++ b/crates/ra_hir/src/code_model.rs
@@ -22,8 +22,11 @@ use hir_expand::{
     MacroDefId, MacroDefKind,
 };
 use hir_ty::{
-    autoderef, display::HirFormatter, expr::ExprValidator, method_resolution, ApplicationTy,
-    Canonical, InEnvironment, Substs, TraitEnvironment, Ty, TyDefId, TypeCtor,
+    autoderef,
+    display::{HirDisplayError, HirFormatter},
+    expr::ExprValidator,
+    method_resolution, ApplicationTy, Canonical, InEnvironment, Substs, TraitEnvironment, Ty,
+    TyDefId, TypeCtor,
 };
 use ra_db::{CrateId, CrateName, Edition, FileId};
 use ra_prof::profile;
@@ -675,6 +678,10 @@ impl Static {
     pub fn name(self, db: &dyn HirDatabase) -> Option<Name> {
         db.static_data(self.id).name.clone()
     }
+
+    pub fn is_mut(self, db: &dyn HirDatabase) -> bool {
+        db.static_data(self.id).mutable
+    }
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
@@ -1319,7 +1326,7 @@ impl Type {
 }
 
 impl HirDisplay for Type {
-    fn hir_fmt(&self, f: &mut HirFormatter) -> std::fmt::Result {
+    fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
         self.ty.value.hir_fmt(f)
     }
 }
diff --git a/crates/ra_hir_def/src/data.rs b/crates/ra_hir_def/src/data.rs
index e7eb2bb11..e2130d931 100644
--- a/crates/ra_hir_def/src/data.rs
+++ b/crates/ra_hir_def/src/data.rs
@@ -251,11 +251,6 @@ impl ConstData {
         Arc::new(ConstData::new(db, vis_default, node))
     }
 
-    pub(crate) fn static_data_query(db: &dyn DefDatabase, konst: StaticId) -> Arc<ConstData> {
-        let node = konst.lookup(db).source(db);
-        Arc::new(ConstData::new(db, RawVisibility::private(), node))
-    }
-
     fn new<N: NameOwner + TypeAscriptionOwner + VisibilityOwner>(
         db: &dyn DefDatabase,
         vis_default: RawVisibility,
@@ -270,6 +265,32 @@ impl ConstData {
     }
 }
 
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct StaticData {
+    pub name: Option<Name>,
+    pub type_ref: TypeRef,
+    pub visibility: RawVisibility,
+    pub mutable: bool,
+}
+
+impl StaticData {
+    pub(crate) fn static_data_query(db: &dyn DefDatabase, konst: StaticId) -> Arc<StaticData> {
+        let node = konst.lookup(db).source(db);
+        let ctx = LowerCtx::new(db, node.file_id);
+
+        let name = node.value.name().map(|n| n.as_name());
+        let type_ref = TypeRef::from_ast_opt(&ctx, node.value.ascribed_type());
+        let mutable = node.value.mut_token().is_some();
+        let visibility = RawVisibility::from_ast_with_default(
+            db,
+            RawVisibility::private(),
+            node.map(|n| n.visibility()),
+        );
+
+        Arc::new(StaticData { name, type_ref, visibility, mutable })
+    }
+}
+
 fn collect_items_in_macros(
     db: &dyn DefDatabase,
     expander: &mut Expander,
diff --git a/crates/ra_hir_def/src/db.rs b/crates/ra_hir_def/src/db.rs
index 5dc7395f5..e665ab45d 100644
--- a/crates/ra_hir_def/src/db.rs
+++ b/crates/ra_hir_def/src/db.rs
@@ -10,7 +10,7 @@ use crate::{
     adt::{EnumData, StructData},
     attr::Attrs,
     body::{scope::ExprScopes, Body, BodySourceMap},
-    data::{ConstData, FunctionData, ImplData, TraitData, TypeAliasData},
+    data::{ConstData, FunctionData, ImplData, StaticData, TraitData, TypeAliasData},
     docs::Documentation,
     generics::GenericParams,
     lang_item::{LangItemTarget, LangItems},
@@ -77,8 +77,8 @@ pub trait DefDatabase: InternDatabase + AstDatabase + Upcast<dyn AstDatabase> {
     #[salsa::invoke(ConstData::const_data_query)]
     fn const_data(&self, konst: ConstId) -> Arc<ConstData>;
 
-    #[salsa::invoke(ConstData::static_data_query)]
-    fn static_data(&self, konst: StaticId) -> Arc<ConstData>;
+    #[salsa::invoke(StaticData::static_data_query)]
+    fn static_data(&self, konst: StaticId) -> Arc<StaticData>;
 
     #[salsa::invoke(Body::body_with_source_map_query)]
     fn body_with_source_map(&self, def: DefWithBodyId) -> (Arc<Body>, Arc<BodySourceMap>);
diff --git a/crates/ra_hir_ty/src/diagnostics.rs b/crates/ra_hir_ty/src/diagnostics.rs
index c8fd54861..41ac70272 100644
--- a/crates/ra_hir_ty/src/diagnostics.rs
+++ b/crates/ra_hir_ty/src/diagnostics.rs
@@ -131,3 +131,31 @@ impl AstDiagnostic for MissingOkInTailExpr {
         ast::Expr::cast(node).unwrap()
     }
 }
+
+#[derive(Debug)]
+pub struct BreakOutsideOfLoop {
+    pub file: HirFileId,
+    pub expr: AstPtr<ast::Expr>,
+}
+
+impl Diagnostic for BreakOutsideOfLoop {
+    fn message(&self) -> String {
+        "break outside of loop".to_string()
+    }
+    fn source(&self) -> InFile<SyntaxNodePtr> {
+        InFile { file_id: self.file, value: self.expr.clone().into() }
+    }
+    fn as_any(&self) -> &(dyn Any + Send + 'static) {
+        self
+    }
+}
+
+impl AstDiagnostic for BreakOutsideOfLoop {
+    type AST = ast::Expr;
+
+    fn ast(&self, db: &impl AstDatabase) -> Self::AST {
+        let root = db.parse_or_expand(self.file).unwrap();
+        let node = self.source().value.to_node(&root);
+        ast::Expr::cast(node).unwrap()
+    }
+}
diff --git a/crates/ra_hir_ty/src/display.rs b/crates/ra_hir_ty/src/display.rs
index d03bbd5a7..b9c4d2e89 100644
--- a/crates/ra_hir_ty/src/display.rs
+++ b/crates/ra_hir_ty/src/display.rs
@@ -6,28 +6,42 @@ use crate::{
     db::HirDatabase, utils::generics, ApplicationTy, CallableDef, FnSig, GenericPredicate,
     Obligation, ProjectionTy, Substs, TraitRef, Ty, TypeCtor,
 };
-use hir_def::{generics::TypeParamProvenance, AdtId, AssocContainerId, Lookup};
+use hir_def::{
+    find_path, generics::TypeParamProvenance, item_scope::ItemInNs, AdtId, AssocContainerId,
+    Lookup, ModuleId,
+};
 use hir_expand::name::Name;
 
-pub struct HirFormatter<'a, 'b> {
+pub struct HirFormatter<'a> {
     pub db: &'a dyn HirDatabase,
-    fmt: &'a mut fmt::Formatter<'b>,
+    fmt: &'a mut dyn fmt::Write,
     buf: String,
     curr_size: usize,
     pub(crate) max_size: Option<usize>,
     omit_verbose_types: bool,
+    display_target: DisplayTarget,
 }
 
 pub trait HirDisplay {
-    fn hir_fmt(&self, f: &mut HirFormatter) -> fmt::Result;
+    fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError>;
 
+    /// Returns a `Display`able type that is human-readable.
+    /// Use this for showing types to the user (e.g. diagnostics)
     fn display<'a>(&'a self, db: &'a dyn HirDatabase) -> HirDisplayWrapper<'a, Self>
     where
         Self: Sized,
     {
-        HirDisplayWrapper(db, self, None, false)
+        HirDisplayWrapper {
+            db,
+            t: self,
+            max_size: None,
+            omit_verbose_types: false,
+            display_target: DisplayTarget::Diagnostics,
+        }
     }
 
+    /// Returns a `Display`able type that is human-readable and tries to be succinct.
+    /// Use this for showing types to the user where space is constrained (e.g. doc popups)
     fn display_truncated<'a>(
         &'a self,
         db: &'a dyn HirDatabase,
@@ -36,16 +50,46 @@ pub trait HirDisplay {
     where
         Self: Sized,
     {
-        HirDisplayWrapper(db, self, max_size, true)
+        HirDisplayWrapper {
+            db,
+            t: self,
+            max_size,
+            omit_verbose_types: true,
+            display_target: DisplayTarget::Diagnostics,
+        }
+    }
+
+    /// Returns a String representation of `self` that can be inserted into the given module.
+    /// Use this when generating code (e.g. assists)
+    fn display_source_code<'a>(
+        &'a self,
+        db: &'a dyn HirDatabase,
+        module_id: ModuleId,
+    ) -> Result<String, DisplaySourceCodeError> {
+        let mut result = String::new();
+        match self.hir_fmt(&mut HirFormatter {
+            db,
+            fmt: &mut result,
+            buf: String::with_capacity(20),
+            curr_size: 0,
+            max_size: None,
+            omit_verbose_types: false,
+            display_target: DisplayTarget::SourceCode { module_id },
+        }) {
+            Ok(()) => {}
+            Err(HirDisplayError::FmtError) => panic!("Writing to String can't fail!"),
+            Err(HirDisplayError::DisplaySourceCodeError(e)) => return Err(e),
+        };
+        Ok(result)
     }
 }
 
-impl<'a, 'b> HirFormatter<'a, 'b> {
+impl<'a> HirFormatter<'a> {
     pub fn write_joined<T: HirDisplay>(
         &mut self,
         iter: impl IntoIterator<Item = T>,
         sep: &str,
-    ) -> fmt::Result {
+    ) -> Result<(), HirDisplayError> {
         let mut first = true;
         for e in iter {
             if !first {
@@ -58,14 +102,14 @@ impl<'a, 'b> HirFormatter<'a, 'b> {
     }
 
     /// This allows using the `write!` macro directly with a `HirFormatter`.
-    pub fn write_fmt(&mut self, args: fmt::Arguments) -> fmt::Result {
+    pub fn write_fmt(&mut self, args: fmt::Arguments) -> Result<(), HirDisplayError> {
         // We write to a buffer first to track output size
         self.buf.clear();
         fmt::write(&mut self.buf, args)?;
         self.curr_size += self.buf.len();
 
         // Then we write to the internal formatter from the buffer
-        self.fmt.write_str(&self.buf)
+        self.fmt.write_str(&self.buf).map_err(HirDisplayError::from)
     }
 
     pub fn should_truncate(&self) -> bool {
@@ -81,34 +125,82 @@ impl<'a, 'b> HirFormatter<'a, 'b> {
     }
 }
 
-pub struct HirDisplayWrapper<'a, T>(&'a dyn HirDatabase, &'a T, Option<usize>, bool);
+#[derive(Clone, Copy)]
+enum DisplayTarget {
+    /// Display types for inlays, doc popups, autocompletion, etc...
+    /// Showing `{unknown}` or not qualifying paths is fine here.
+    /// There's no reason for this to fail.
+    Diagnostics,
+    /// Display types for inserting them in source files.
+    /// The generated code should compile, so paths need to be qualified.
+    SourceCode { module_id: ModuleId },
+}
+
+impl DisplayTarget {
+    fn is_source_code(&self) -> bool {
+        matches!(self, Self::SourceCode {..})
+    }
+}
+
+#[derive(Debug)]
+pub enum DisplaySourceCodeError {
+    PathNotFound,
+}
+
+pub enum HirDisplayError {
+    /// Errors that can occur when generating source code
+    DisplaySourceCodeError(DisplaySourceCodeError),
+    /// `FmtError` is required to be compatible with std::fmt::Display
+    FmtError,
+}
+impl From<fmt::Error> for HirDisplayError {
+    fn from(_: fmt::Error) -> Self {
+        Self::FmtError
+    }
+}
+
+pub struct HirDisplayWrapper<'a, T> {
+    db: &'a dyn HirDatabase,
+    t: &'a T,
+    max_size: Option<usize>,
+    omit_verbose_types: bool,
+    display_target: DisplayTarget,
+}
 
 impl<'a, T> fmt::Display for HirDisplayWrapper<'a, T>
 where
     T: HirDisplay,
 {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        self.1.hir_fmt(&mut HirFormatter {
-            db: self.0,
+        match self.t.hir_fmt(&mut HirFormatter {
+            db: self.db,
             fmt: f,
             buf: String::with_capacity(20),
             curr_size: 0,
-            max_size: self.2,
-            omit_verbose_types: self.3,
-        })
+            max_size: self.max_size,
+            omit_verbose_types: self.omit_verbose_types,
+            display_target: self.display_target,
+        }) {
+            Ok(()) => Ok(()),
+            Err(HirDisplayError::FmtError) => Err(fmt::Error),
+            Err(HirDisplayError::DisplaySourceCodeError(_)) => {
+                // This should never happen
+                panic!("HirDisplay failed when calling Display::fmt!")
+            }
+        }
     }
 }
 
 const TYPE_HINT_TRUNCATION: &str = "…";
 
 impl HirDisplay for &Ty {
-    fn hir_fmt(&self, f: &mut HirFormatter) -> fmt::Result {
+    fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
         HirDisplay::hir_fmt(*self, f)
     }
 }
 
 impl HirDisplay for ApplicationTy {
-    fn hir_fmt(&self, f: &mut HirFormatter) -> fmt::Result {
+    fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
         if f.should_truncate() {
             return write!(f, "{}", TYPE_HINT_TRUNCATION);
         }
@@ -191,45 +283,66 @@ impl HirDisplay for ApplicationTy {
                 }
             }
             TypeCtor::Adt(def_id) => {
-                let name = match def_id {
-                    AdtId::StructId(it) => f.db.struct_data(it).name.clone(),
-                    AdtId::UnionId(it) => f.db.union_data(it).name.clone(),
-                    AdtId::EnumId(it) => f.db.enum_data(it).name.clone(),
-                };
-                write!(f, "{}", name)?;
+                match f.display_target {
+                    DisplayTarget::Diagnostics => {
+                        let name = match def_id {
+                            AdtId::StructId(it) => f.db.struct_data(it).name.clone(),
+                            AdtId::UnionId(it) => f.db.union_data(it).name.clone(),
+                            AdtId::EnumId(it) => f.db.enum_data(it).name.clone(),
+                        };
+                        write!(f, "{}", name)?;
+                    }
+                    DisplayTarget::SourceCode { module_id } => {
+                        if let Some(path) = find_path::find_path(
+                            f.db.upcast(),
+                            ItemInNs::Types(def_id.into()),
+                            module_id,
+                        ) {
+                            write!(f, "{}", path)?;
+                        } else {
+                            return Err(HirDisplayError::DisplaySourceCodeError(
+                                DisplaySourceCodeError::PathNotFound,
+                            ));
+                        }
+                    }
+                }
+
                 if self.parameters.len() > 0 {
                     let mut non_default_parameters = Vec::with_capacity(self.parameters.len());
-                    let parameters_to_write = if f.omit_verbose_types() {
-                        match self
-                            .ctor
-                            .as_generic_def()
-                            .map(|generic_def_id| f.db.generic_defaults(generic_def_id))
-                            .filter(|defaults| !defaults.is_empty())
-                        {
-                            None => self.parameters.0.as_ref(),
-                            Some(default_parameters) => {
-                                for (i, parameter) in self.parameters.iter().enumerate() {
-                                    match (parameter, default_parameters.get(i)) {
-                                        (&Ty::Unknown, _) | (_, None) => {
-                                            non_default_parameters.push(parameter.clone())
+                    let parameters_to_write =
+                        if f.display_target.is_source_code() || f.omit_verbose_types() {
+                            match self
+                                .ctor
+                                .as_generic_def()
+                                .map(|generic_def_id| f.db.generic_defaults(generic_def_id))
+                                .filter(|defaults| !defaults.is_empty())
+                            {
+                                None => self.parameters.0.as_ref(),
+                                Some(default_parameters) => {
+                                    for (i, parameter) in self.parameters.iter().enumerate() {
+                                        match (parameter, default_parameters.get(i)) {
+                                            (&Ty::Unknown, _) | (_, None) => {
+                                                non_default_parameters.push(parameter.clone())
+                                            }
+                                            (_, Some(default_parameter))
+                                                if parameter != default_parameter =>
+                                            {
+                                                non_default_parameters.push(parameter.clone())
+                                            }
+                                            _ => (),
                                         }
-                                        (_, Some(default_parameter))
-                                            if parameter != default_parameter =>
-                                        {
-                                            non_default_parameters.push(parameter.clone())
-                                        }
-                                        _ => (),
                                     }
+                                    &non_default_parameters
                                 }
-                                &non_default_parameters
                             }
-                        }
-                    } else {
-                        self.parameters.0.as_ref()
-                    };
-                    write!(f, "<")?;
-                    f.write_joined(parameters_to_write, ", ")?;
-                    write!(f, ">")?;
+                        } else {
+                            self.parameters.0.as_ref()
+                        };
+                    if !parameters_to_write.is_empty() {
+                        write!(f, "<")?;
+                        f.write_joined(parameters_to_write, ", ")?;
+                        write!(f, ">")?;
+                    }
                 }
             }
             TypeCtor::AssociatedType(type_alias) => {
@@ -269,7 +382,7 @@ impl HirDisplay for ApplicationTy {
 }
 
 impl HirDisplay for ProjectionTy {
-    fn hir_fmt(&self, f: &mut HirFormatter) -> fmt::Result {
+    fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
         if f.should_truncate() {
             return write!(f, "{}", TYPE_HINT_TRUNCATION);
         }
@@ -287,7 +400,7 @@ impl HirDisplay for ProjectionTy {
 }
 
 impl HirDisplay for Ty {
-    fn hir_fmt(&self, f: &mut HirFormatter) -> fmt::Result {
+    fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
         if f.should_truncate() {
             return write!(f, "{}", TYPE_HINT_TRUNCATION);
         }
@@ -332,7 +445,7 @@ impl HirDisplay for Ty {
 fn write_bounds_like_dyn_trait(
     predicates: &[GenericPredicate],
     f: &mut HirFormatter,
-) -> fmt::Result {
+) -> Result<(), HirDisplayError> {
     // Note: This code is written to produce nice results (i.e.
     // corresponding to surface Rust) for types that can occur in
     // actual Rust. It will have weird results if the predicates
@@ -394,7 +507,7 @@ fn write_bounds_like_dyn_trait(
 }
 
 impl TraitRef {
-    fn hir_fmt_ext(&self, f: &mut HirFormatter, use_as: bool) -> fmt::Result {
+    fn hir_fmt_ext(&self, f: &mut HirFormatter, use_as: bool) -> Result<(), HirDisplayError> {
         if f.should_truncate() {
             return write!(f, "{}", TYPE_HINT_TRUNCATION);
         }
@@ -416,19 +529,19 @@ impl TraitRef {
 }
 
 impl HirDisplay for TraitRef {
-    fn hir_fmt(&self, f: &mut HirFormatter) -> fmt::Result {
+    fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
         self.hir_fmt_ext(f, false)
     }
 }
 
 impl HirDisplay for &GenericPredicate {
-    fn hir_fmt(&self, f: &mut HirFormatter) -> fmt::Result {
+    fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
         HirDisplay::hir_fmt(*self, f)
     }
 }
 
 impl HirDisplay for GenericPredicate {
-    fn hir_fmt(&self, f: &mut HirFormatter) -> fmt::Result {
+    fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
         if f.should_truncate() {
             return write!(f, "{}", TYPE_HINT_TRUNCATION);
         }
@@ -452,15 +565,15 @@ impl HirDisplay for GenericPredicate {
 }
 
 impl HirDisplay for Obligation {
-    fn hir_fmt(&self, f: &mut HirFormatter) -> fmt::Result {
-        match self {
-            Obligation::Trait(tr) => write!(f, "Implements({})", tr.display(f.db)),
+    fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
+        Ok(match self {
+            Obligation::Trait(tr) => write!(f, "Implements({})", tr.display(f.db))?,
             Obligation::Projection(proj) => write!(
                 f,
                 "Normalize({} => {})",
                 proj.projection_ty.display(f.db),
                 proj.ty.display(f.db)
-            ),
-        }
+            )?,
+        })
     }
 }
diff --git a/crates/ra_hir_ty/src/infer.rs b/crates/ra_hir_ty/src/infer.rs
index bd4ef69a0..fb7c6cd8c 100644
--- a/crates/ra_hir_ty/src/infer.rs
+++ b/crates/ra_hir_ty/src/infer.rs
@@ -22,7 +22,7 @@ use rustc_hash::FxHashMap;
 
 use hir_def::{
     body::Body,
-    data::{ConstData, FunctionData},
+    data::{ConstData, FunctionData, StaticData},
     expr::{BindingAnnotation, ExprId, PatId},
     lang_item::LangItemTarget,
     path::{path, Path},
@@ -71,7 +71,7 @@ pub(crate) fn infer_query(db: &dyn HirDatabase, def: DefWithBodyId) -> Arc<Infer
     match def {
         DefWithBodyId::ConstId(c) => ctx.collect_const(&db.const_data(c)),
         DefWithBodyId::FunctionId(f) => ctx.collect_fn(&db.function_data(f)),
-        DefWithBodyId::StaticId(s) => ctx.collect_const(&db.static_data(s)),
+        DefWithBodyId::StaticId(s) => ctx.collect_static(&db.static_data(s)),
     }
 
     ctx.infer_body();
@@ -210,6 +210,13 @@ struct InferenceContext<'a> {
     /// closures, but currently this is the only field that will change there,
     /// so it doesn't make sense.
     return_ty: Ty,
+    diverges: Diverges,
+    breakables: Vec<BreakableContext>,
+}
+
+#[derive(Clone, Debug)]
+struct BreakableContext {
+    pub may_break: bool,
 }
 
 impl<'a> InferenceContext<'a> {
@@ -224,6 +231,8 @@ impl<'a> InferenceContext<'a> {
             owner,
             body: db.body(owner),
             resolver,
+            diverges: Diverges::Maybe,
+            breakables: Vec::new(),
         }
     }
 
@@ -476,6 +485,10 @@ impl<'a> InferenceContext<'a> {
         self.return_ty = self.make_ty(&data.type_ref);
     }
 
+    fn collect_static(&mut self, data: &StaticData) {
+        self.return_ty = self.make_ty(&data.type_ref);
+    }
+
     fn collect_fn(&mut self, data: &FunctionData) {
         let body = Arc::clone(&self.body); // avoid borrow checker problem
         let ctx = crate::lower::TyLoweringContext::new(self.db, &self.resolver)
@@ -666,15 +679,57 @@ impl Expectation {
     }
 }
 
+#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
+enum Diverges {
+    Maybe,
+    Always,
+}
+
+impl Diverges {
+    fn is_always(self) -> bool {
+        self == Diverges::Always
+    }
+}
+
+impl std::ops::BitAnd for Diverges {
+    type Output = Self;
+    fn bitand(self, other: Self) -> Self {
+        std::cmp::min(self, other)
+    }
+}
+
+impl std::ops::BitOr for Diverges {
+    type Output = Self;
+    fn bitor(self, other: Self) -> Self {
+        std::cmp::max(self, other)
+    }
+}
+
+impl std::ops::BitAndAssign for Diverges {
+    fn bitand_assign(&mut self, other: Self) {
+        *self = *self & other;
+    }
+}
+
+impl std::ops::BitOrAssign for Diverges {
+    fn bitor_assign(&mut self, other: Self) {
+        *self = *self | other;
+    }
+}
+
 mod diagnostics {
     use hir_def::{expr::ExprId, FunctionId};
     use hir_expand::diagnostics::DiagnosticSink;
 
-    use crate::{db::HirDatabase, diagnostics::NoSuchField};
+    use crate::{
+        db::HirDatabase,
+        diagnostics::{BreakOutsideOfLoop, NoSuchField},
+    };
 
     #[derive(Debug, PartialEq, Eq, Clone)]
     pub(super) enum InferenceDiagnostic {
         NoSuchField { expr: ExprId, field: usize },
+        BreakOutsideOfLoop { expr: ExprId },
     }
 
     impl InferenceDiagnostic {
@@ -690,6 +745,13 @@ mod diagnostics {
                     let field = source_map.field_syntax(*expr, *field);
                     sink.push(NoSuchField { file: field.file_id, field: field.value })
                 }
+                InferenceDiagnostic::BreakOutsideOfLoop { expr } => {
+                    let (_, source_map) = db.body_with_source_map(owner.into());
+                    let ptr = source_map
+                        .expr_syntax(*expr)
+                        .expect("break outside of loop in synthetic syntax");
+                    sink.push(BreakOutsideOfLoop { file: ptr.file_id, expr: ptr.value })
+                }
             }
         }
     }
diff --git a/crates/ra_hir_ty/src/infer/coerce.rs b/crates/ra_hir_ty/src/infer/coerce.rs
index 89200255a..173ec59ed 100644
--- a/crates/ra_hir_ty/src/infer/coerce.rs
+++ b/crates/ra_hir_ty/src/infer/coerce.rs
@@ -20,21 +20,35 @@ impl<'a> InferenceContext<'a> {
         self.coerce_inner(from_ty, &to_ty)
     }
 
-    /// Merge two types from different branches, with possible implicit coerce.
+    /// Merge two types from different branches, with possible coercion.
     ///
-    /// Note that it is only possible that one type are coerced to another.
-    /// Coercing both types to another least upper bound type is not possible in rustc,
-    /// which will simply result in "incompatible types" error.
+    /// Mostly this means trying to coerce one to the other, but
+    ///  - if we have two function types for different functions, we need to
+    ///    coerce both to function pointers;
+    ///  - if we were concerned with lifetime subtyping, we'd need to look for a
+    ///    least upper bound.
     pub(super) fn coerce_merge_branch(&mut self, ty1: &Ty, ty2: &Ty) -> Ty {
         if self.coerce(ty1, ty2) {
             ty2.clone()
         } else if self.coerce(ty2, ty1) {
             ty1.clone()
         } else {
-            tested_by!(coerce_merge_fail_fallback);
-            // For incompatible types, we use the latter one as result
-            // to be better recovery for `if` without `else`.
-            ty2.clone()
+            if let (ty_app!(TypeCtor::FnDef(_)), ty_app!(TypeCtor::FnDef(_))) = (ty1, ty2) {
+                tested_by!(coerce_fn_reification);
+                // Special case: two function types. Try to coerce both to
+                // pointers to have a chance at getting a match. See
+                // https://github.com/rust-lang/rust/blob/7b805396bf46dce972692a6846ce2ad8481c5f85/src/librustc_typeck/check/coercion.rs#L877-L916
+                let sig1 = ty1.callable_sig(self.db).expect("FnDef without callable sig");
+                let sig2 = ty2.callable_sig(self.db).expect("FnDef without callable sig");
+                let ptr_ty1 = Ty::fn_ptr(sig1);
+                let ptr_ty2 = Ty::fn_ptr(sig2);
+                self.coerce_merge_branch(&ptr_ty1, &ptr_ty2)
+            } else {
+                tested_by!(coerce_merge_fail_fallback);
+                // For incompatible types, we use the latter one as result
+                // to be better recovery for `if` without `else`.
+                ty2.clone()
+            }
         }
     }
 
@@ -84,9 +98,7 @@ impl<'a> InferenceContext<'a> {
                 match from_ty.callable_sig(self.db) {
                     None => return false,
                     Some(sig) => {
-                        let num_args = sig.params_and_return.len() as u16 - 1;
-                        from_ty =
-                            Ty::apply(TypeCtor::FnPtr { num_args }, Substs(sig.params_and_return));
+                        from_ty = Ty::fn_ptr(sig);
                     }
                 }
             }
diff --git a/crates/ra_hir_ty/src/infer/expr.rs b/crates/ra_hir_ty/src/infer/expr.rs
index 83f946eee..0b67d216a 100644
--- a/crates/ra_hir_ty/src/infer/expr.rs
+++ b/crates/ra_hir_ty/src/infer/expr.rs
@@ -1,7 +1,7 @@
 //! Type inference for expressions.
 
 use std::iter::{repeat, repeat_with};
-use std::sync::Arc;
+use std::{mem, sync::Arc};
 
 use hir_def::{
     builtin_type::Signedness,
@@ -21,11 +21,18 @@ use crate::{
     Ty, TypeCtor, Uncertain,
 };
 
-use super::{BindingMode, Expectation, InferenceContext, InferenceDiagnostic, TypeMismatch};
+use super::{
+    BindingMode, BreakableContext, Diverges, Expectation, InferenceContext, InferenceDiagnostic,
+    TypeMismatch,
+};
 
 impl<'a> InferenceContext<'a> {
     pub(super) fn infer_expr(&mut self, tgt_expr: ExprId, expected: &Expectation) -> Ty {
         let ty = self.infer_expr_inner(tgt_expr, expected);
+        if ty.is_never() {
+            // Any expression that produces a value of type `!` must have diverged
+            self.diverges = Diverges::Always;
+        }
         let could_unify = self.unify(&ty, &expected.ty);
         if !could_unify {
             self.result.type_mismatches.insert(
@@ -64,11 +71,18 @@ impl<'a> InferenceContext<'a> {
                 // if let is desugared to match, so this is always simple if
                 self.infer_expr(*condition, &Expectation::has_type(Ty::simple(TypeCtor::Bool)));
 
+                let condition_diverges = mem::replace(&mut self.diverges, Diverges::Maybe);
+                let mut both_arms_diverge = Diverges::Always;
+
                 let then_ty = self.infer_expr_inner(*then_branch, &expected);
+                both_arms_diverge &= mem::replace(&mut self.diverges, Diverges::Maybe);
                 let else_ty = match else_branch {
                     Some(else_branch) => self.infer_expr_inner(*else_branch, &expected),
                     None => Ty::unit(),
                 };
+                both_arms_diverge &= self.diverges;
+
+                self.diverges = condition_diverges | both_arms_diverge;
 
                 self.coerce_merge_branch(&then_ty, &else_ty)
             }
@@ -79,24 +93,43 @@ impl<'a> InferenceContext<'a> {
                 Ty::Unknown
             }
             Expr::Loop { body } => {
+                self.breakables.push(BreakableContext { may_break: false });
                 self.infer_expr(*body, &Expectation::has_type(Ty::unit()));
+
+                let ctxt = self.breakables.pop().expect("breakable stack broken");
+                if ctxt.may_break {
+                    self.diverges = Diverges::Maybe;
+                }
                 // FIXME handle break with value
-                Ty::simple(TypeCtor::Never)
+                if ctxt.may_break {
+                    Ty::unit()
+                } else {
+                    Ty::simple(TypeCtor::Never)
+                }
             }
             Expr::While { condition, body } => {
+                self.breakables.push(BreakableContext { may_break: false });
                 // while let is desugared to a match loop, so this is always simple while
                 self.infer_expr(*condition, &Expectation::has_type(Ty::simple(TypeCtor::Bool)));
                 self.infer_expr(*body, &Expectation::has_type(Ty::unit()));
+                let _ctxt = self.breakables.pop().expect("breakable stack broken");
+                // the body may not run, so it diverging doesn't mean we diverge
+                self.diverges = Diverges::Maybe;
                 Ty::unit()
             }
             Expr::For { iterable, body, pat } => {
                 let iterable_ty = self.infer_expr(*iterable, &Expectation::none());
 
+                self.breakables.push(BreakableContext { may_break: false });
                 let pat_ty =
                     self.resolve_associated_type(iterable_ty, self.resolve_into_iter_item());
 
                 self.infer_pat(*pat, &pat_ty, BindingMode::default());
+
                 self.infer_expr(*body, &Expectation::has_type(Ty::unit()));
+                let _ctxt = self.breakables.pop().expect("breakable stack broken");
+                // the body may not run, so it diverging doesn't mean we diverge
+                self.diverges = Diverges::Maybe;
                 Ty::unit()
             }
             Expr::Lambda { body, args, ret_type, arg_types } => {
@@ -132,10 +165,12 @@ impl<'a> InferenceContext<'a> {
                 // infer the body.
                 self.coerce(&closure_ty, &expected.ty);
 
-                let prev_ret_ty = std::mem::replace(&mut self.return_ty, ret_ty.clone());
+                let prev_diverges = mem::replace(&mut self.diverges, Diverges::Maybe);
+                let prev_ret_ty = mem::replace(&mut self.return_ty, ret_ty.clone());
 
                 self.infer_expr_coerce(*body, &Expectation::has_type(ret_ty));
 
+                self.diverges = prev_diverges;
                 self.return_ty = prev_ret_ty;
 
                 closure_ty
@@ -165,7 +200,11 @@ impl<'a> InferenceContext<'a> {
                     self.table.new_type_var()
                 };
 
+                let matchee_diverges = self.diverges;
+                let mut all_arms_diverge = Diverges::Always;
+
                 for arm in arms {
+                    self.diverges = Diverges::Maybe;
                     let _pat_ty = self.infer_pat(arm.pat, &input_ty, BindingMode::default());
                     if let Some(guard_expr) = arm.guard {
                         self.infer_expr(
@@ -175,9 +214,12 @@ impl<'a> InferenceContext<'a> {
                     }
 
                     let arm_ty = self.infer_expr_inner(arm.expr, &expected);
+                    all_arms_diverge &= self.diverges;
                     result_ty = self.coerce_merge_branch(&result_ty, &arm_ty);
                 }
 
+                self.diverges = matchee_diverges | all_arms_diverge;
+
                 result_ty
             }
             Expr::Path(p) => {
@@ -191,6 +233,13 @@ impl<'a> InferenceContext<'a> {
                     // FIXME handle break with value
                     self.infer_expr(*expr, &Expectation::none());
                 }
+                if let Some(ctxt) = self.breakables.last_mut() {
+                    ctxt.may_break = true;
+                } else {
+                    self.push_diagnostic(InferenceDiagnostic::BreakOutsideOfLoop {
+                        expr: tgt_expr,
+                    });
+                }
                 Ty::simple(TypeCtor::Never)
             }
             Expr::Return { expr } => {
@@ -501,8 +550,8 @@ impl<'a> InferenceContext<'a> {
                 }
                 Literal::ByteString(..) => {
                     let byte_type = Ty::simple(TypeCtor::Int(Uncertain::Known(IntTy::u8())));
-                    let slice_type = Ty::apply_one(TypeCtor::Slice, byte_type);
-                    Ty::apply_one(TypeCtor::Ref(Mutability::Shared), slice_type)
+                    let array_type = Ty::apply_one(TypeCtor::Array, byte_type);
+                    Ty::apply_one(TypeCtor::Ref(Mutability::Shared), array_type)
                 }
                 Literal::Char(..) => Ty::simple(TypeCtor::Char),
                 Literal::Int(_v, ty) => Ty::simple(TypeCtor::Int((*ty).into())),
@@ -522,7 +571,6 @@ impl<'a> InferenceContext<'a> {
         tail: Option<ExprId>,
         expected: &Expectation,
     ) -> Ty {
-        let mut diverges = false;
         for stmt in statements {
             match stmt {
                 Statement::Let { pat, type_ref, initializer } => {
@@ -544,9 +592,7 @@ impl<'a> InferenceContext<'a> {
                     self.infer_pat(*pat, &ty, BindingMode::default());
                 }
                 Statement::Expr(expr) => {
-                    if let ty_app!(TypeCtor::Never) = self.infer_expr(*expr, &Expectation::none()) {
-                        diverges = true;
-                    }
+                    self.infer_expr(*expr, &Expectation::none());
                 }
             }
         }
@@ -554,14 +600,22 @@ impl<'a> InferenceContext<'a> {
         let ty = if let Some(expr) = tail {
             self.infer_expr_coerce(expr, expected)
         } else {
-            self.coerce(&Ty::unit(), expected.coercion_target());
-            Ty::unit()
+            // Citing rustc: if there is no explicit tail expression,
+            // that is typically equivalent to a tail expression
+            // of `()` -- except if the block diverges. In that
+            // case, there is no value supplied from the tail
+            // expression (assuming there are no other breaks,
+            // this implies that the type of the block will be
+            // `!`).
+            if self.diverges.is_always() {
+                // we don't even make an attempt at coercion
+                self.table.new_maybe_never_type_var()
+            } else {
+                self.coerce(&Ty::unit(), expected.coercion_target());
+                Ty::unit()
+            }
         };
-        if diverges {
-            Ty::simple(TypeCtor::Never)
-        } else {
-            ty
-        }
+        ty
     }
 
     fn infer_method_call(
diff --git a/crates/ra_hir_ty/src/lib.rs b/crates/ra_hir_ty/src/lib.rs
index a6f56c661..e8f3482fe 100644
--- a/crates/ra_hir_ty/src/lib.rs
+++ b/crates/ra_hir_ty/src/lib.rs
@@ -683,6 +683,12 @@ impl Ty {
     pub fn unit() -> Self {
         Ty::apply(TypeCtor::Tuple { cardinality: 0 }, Substs::empty())
     }
+    pub fn fn_ptr(sig: FnSig) -> Self {
+        Ty::apply(
+            TypeCtor::FnPtr { num_args: sig.params().len() as u16 },
+            Substs(sig.params_and_return),
+        )
+    }
 
     pub fn as_reference(&self) -> Option<(&Ty, Mutability)> {
         match self {
@@ -730,6 +736,10 @@ impl Ty {
         }
     }
 
+    pub fn is_never(&self) -> bool {
+        matches!(self, Ty::Apply(ApplicationTy { ctor: TypeCtor::Never, .. }))
+    }
+
     /// If this is a `dyn Trait` type, this returns the `Trait` part.
     pub fn dyn_trait_ref(&self) -> Option<&TraitRef> {
         match self {
diff --git a/crates/ra_hir_ty/src/marks.rs b/crates/ra_hir_ty/src/marks.rs
index de5cb1d6b..a39740143 100644
--- a/crates/ra_hir_ty/src/marks.rs
+++ b/crates/ra_hir_ty/src/marks.rs
@@ -7,5 +7,6 @@ test_utils::marks!(
     impl_self_type_match_without_receiver
     match_ergonomics_ref
     coerce_merge_fail_fallback
+    coerce_fn_reification
     trait_self_implements_self
 );
diff --git a/crates/ra_hir_ty/src/op.rs b/crates/ra_hir_ty/src/op.rs
index 54e2bd05a..0870874fc 100644
--- a/crates/ra_hir_ty/src/op.rs
+++ b/crates/ra_hir_ty/src/op.rs
@@ -30,7 +30,8 @@ pub(super) fn binary_op_return_ty(op: BinaryOp, lhs_ty: Ty, rhs_ty: Ty) -> Ty {
 pub(super) fn binary_op_rhs_expectation(op: BinaryOp, lhs_ty: Ty) -> Ty {
     match op {
         BinaryOp::LogicOp(..) => Ty::simple(TypeCtor::Bool),
-        BinaryOp::Assignment { op: None } | BinaryOp::CmpOp(CmpOp::Eq { .. }) => match lhs_ty {
+        BinaryOp::Assignment { op: None } => lhs_ty,
+        BinaryOp::CmpOp(CmpOp::Eq { .. }) => match lhs_ty {
             Ty::Apply(ApplicationTy { ctor, .. }) => match ctor {
                 TypeCtor::Int(..)
                 | TypeCtor::Float(..)
diff --git a/crates/ra_hir_ty/src/tests.rs b/crates/ra_hir_ty/src/tests.rs
index d60732e19..1fe05c70c 100644
--- a/crates/ra_hir_ty/src/tests.rs
+++ b/crates/ra_hir_ty/src/tests.rs
@@ -6,6 +6,7 @@ mod patterns;
 mod traits;
 mod method_resolution;
 mod macros;
+mod display_source_code;
 
 use std::sync::Arc;
 
@@ -16,7 +17,7 @@ use hir_def::{
     item_scope::ItemScope,
     keys,
     nameres::CrateDefMap,
-    AssocItemId, DefWithBodyId, LocalModuleId, Lookup, ModuleDefId,
+    AssocItemId, DefWithBodyId, LocalModuleId, Lookup, ModuleDefId, ModuleId,
 };
 use hir_expand::{db::AstDatabase, InFile};
 use insta::assert_snapshot;
@@ -37,6 +38,18 @@ use crate::{
 // update the snapshots.
 
 fn type_at_pos(db: &TestDB, pos: FilePosition) -> String {
+    type_at_pos_displayed(db, pos, |ty, _| ty.display(db).to_string())
+}
+
+fn displayed_source_at_pos(db: &TestDB, pos: FilePosition) -> String {
+    type_at_pos_displayed(db, pos, |ty, module_id| ty.display_source_code(db, module_id).unwrap())
+}
+
+fn type_at_pos_displayed(
+    db: &TestDB,
+    pos: FilePosition,
+    display_fn: impl FnOnce(&Ty, ModuleId) -> String,
+) -> String {
     let file = db.parse(pos.file_id).ok().unwrap();
     let expr = algo::find_node_at_offset::<ast::Expr>(file.syntax(), pos.offset).unwrap();
     let fn_def = expr.syntax().ancestors().find_map(ast::FnDef::cast).unwrap();
@@ -49,7 +62,7 @@ fn type_at_pos(db: &TestDB, pos: FilePosition) -> String {
     if let Some(expr_id) = source_map.node_expr(InFile::new(pos.file_id.into(), &expr)) {
         let infer = db.infer(func.into());
         let ty = &infer[expr_id];
-        return ty.display(db).to_string();
+        return display_fn(ty, module);
     }
     panic!("Can't find expression")
 }
@@ -518,3 +531,21 @@ fn missing_record_pat_field_no_diagnostic_if_not_exhaustive() {
 
     assert_snapshot!(diagnostics, @"");
 }
+
+#[test]
+fn break_outside_of_loop() {
+    let diagnostics = TestDB::with_files(
+        r"
+        //- /lib.rs
+        fn foo() {
+            break;
+        }
+        ",
+    )
+    .diagnostics()
+    .0;
+
+    assert_snapshot!(diagnostics, @r###""break": break outside of loop
+    "###
+    );
+}
diff --git a/crates/ra_hir_ty/src/tests/coercion.rs b/crates/ra_hir_ty/src/tests/coercion.rs
index e6fb3e123..6dc4b2cd1 100644
--- a/crates/ra_hir_ty/src/tests/coercion.rs
+++ b/crates/ra_hir_ty/src/tests/coercion.rs
@@ -384,7 +384,7 @@ fn foo() -> u32 {
 }
 "#, true),
         @r###"
-    17..40 '{     ...own; }': !
+    17..40 '{     ...own; }': u32
     23..37 'return unknown': !
     30..37 'unknown': u32
     "###
@@ -514,7 +514,7 @@ fn foo() {
     27..103 '{     ...     }': &u32
     37..82 'if tru...     }': ()
     40..44 'true': bool
-    45..82 '{     ...     }': !
+    45..82 '{     ...     }': ()
     59..71 'return &1u32': !
     66..71 '&1u32': &u32
     67..71 '1u32': u32
@@ -546,6 +546,48 @@ fn test() {
 }
 
 #[test]
+fn coerce_fn_items_in_match_arms() {
+    covers!(coerce_fn_reification);
+    assert_snapshot!(
+        infer_with_mismatches(r#"
+fn foo1(x: u32) -> isize { 1 }
+fn foo2(x: u32) -> isize { 2 }
+fn foo3(x: u32) -> isize { 3 }
+fn test() {
+    let x = match 1 {
+        1 => foo1,
+        2 => foo2,
+        _ => foo3,
+    };
+}
+"#, true),
+        @r###"
+    9..10 'x': u32
+    26..31 '{ 1 }': isize
+    28..29 '1': isize
+    40..41 'x': u32
+    57..62 '{ 2 }': isize
+    59..60 '2': isize
+    71..72 'x': u32
+    88..93 '{ 3 }': isize
+    90..91 '3': isize
+    104..193 '{     ...  }; }': ()
+    114..115 'x': fn(u32) -> isize
+    118..190 'match ...     }': fn(u32) -> isize
+    124..125 '1': i32
+    136..137 '1': i32
+    136..137 '1': i32
+    141..145 'foo1': fn foo1(u32) -> isize
+    155..156 '2': i32
+    155..156 '2': i32
+    160..164 'foo2': fn foo2(u32) -> isize
+    174..175 '_': i32
+    179..183 'foo3': fn foo3(u32) -> isize
+    "###
+    );
+}
+
+#[test]
 fn coerce_closure_to_fn_ptr() {
     assert_snapshot!(
         infer_with_mismatches(r#"
diff --git a/crates/ra_hir_ty/src/tests/display_source_code.rs b/crates/ra_hir_ty/src/tests/display_source_code.rs
new file mode 100644
index 000000000..4088b1d22
--- /dev/null
+++ b/crates/ra_hir_ty/src/tests/display_source_code.rs
@@ -0,0 +1,50 @@
+use super::displayed_source_at_pos;
+use crate::test_db::TestDB;
+use ra_db::fixture::WithFixture;
+
+#[test]
+fn qualify_path_to_submodule() {
+    let (db, pos) = TestDB::with_position(
+        r#"
+//- /main.rs
+
+mod foo {
+    pub struct Foo;
+}
+
+fn bar() {
+    let foo: foo::Foo = foo::Foo;
+    foo<|>
+}
+
+"#,
+    );
+    assert_eq!("foo::Foo", displayed_source_at_pos(&db, pos));
+}
+
+#[test]
+fn omit_default_type_parameters() {
+    let (db, pos) = TestDB::with_position(
+        r"
+        //- /main.rs
+        struct Foo<T = u8> { t: T }
+        fn main() {
+            let foo = Foo { t: 5 };
+            foo<|>;
+        }
+        ",
+    );
+    assert_eq!("Foo", displayed_source_at_pos(&db, pos));
+
+    let (db, pos) = TestDB::with_position(
+        r"
+        //- /main.rs
+        struct Foo<K, T = u8> { k: K, t: T }
+        fn main() {
+            let foo = Foo { k: 400, t: 5 };
+            foo<|>;
+        }
+        ",
+    );
+    assert_eq!("Foo<i32>", displayed_source_at_pos(&db, pos));
+}
diff --git a/crates/ra_hir_ty/src/tests/macros.rs b/crates/ra_hir_ty/src/tests/macros.rs
index 07398ddcc..4c6099aa2 100644
--- a/crates/ra_hir_ty/src/tests/macros.rs
+++ b/crates/ra_hir_ty/src/tests/macros.rs
@@ -197,7 +197,7 @@ fn spam() {
     !0..6 '1isize': isize
     !0..6 '1isize': isize
     !0..6 '1isize': isize
-    54..457 '{     ...!(); }': !
+    54..457 '{     ...!(); }': ()
     88..109 'spam!(...am!())': {unknown}
     115..134 'for _ ...!() {}': ()
     119..120 '_': {unknown}
diff --git a/crates/ra_hir_ty/src/tests/method_resolution.rs b/crates/ra_hir_ty/src/tests/method_resolution.rs
index ab87f598a..67f964ab5 100644
--- a/crates/ra_hir_ty/src/tests/method_resolution.rs
+++ b/crates/ra_hir_ty/src/tests/method_resolution.rs
@@ -17,8 +17,8 @@ impl<T> [T] {
 #[lang = "slice_alloc"]
 impl<T> [T] {}
 
-fn test() {
-    <[_]>::foo(b"foo");
+fn test(x: &[u8]) {
+    <[_]>::foo(x);
 }
 "#),
         @r###"
@@ -26,10 +26,11 @@ fn test() {
     56..79 '{     ...     }': T
     66..73 'loop {}': !
     71..73 '{}': ()
-    133..160 '{     ...o"); }': ()
-    139..149 '<[_]>::foo': fn foo<u8>(&[u8]) -> u8
-    139..157 '<[_]>:..."foo")': u8
-    150..156 'b"foo"': &[u8]
+    131..132 'x': &[u8]
+    141..163 '{     ...(x); }': ()
+    147..157 '<[_]>::foo': fn foo<u8>(&[u8]) -> u8
+    147..160 '<[_]>::foo(x)': u8
+    158..159 'x': &[u8]
     "###
     );
 }
diff --git a/crates/ra_hir_ty/src/tests/never_type.rs b/crates/ra_hir_ty/src/tests/never_type.rs
index a77209480..082c47208 100644
--- a/crates/ra_hir_ty/src/tests/never_type.rs
+++ b/crates/ra_hir_ty/src/tests/never_type.rs
@@ -1,4 +1,6 @@
-use super::type_at;
+use insta::assert_snapshot;
+
+use super::{infer_with_mismatches, type_at};
 
 #[test]
 fn infer_never1() {
@@ -261,3 +263,176 @@ fn test(a: i32) {
     );
     assert_eq!(t, "f64");
 }
+
+#[test]
+fn diverging_expression_1() {
+    let t = infer_with_mismatches(
+        r#"
+//- /main.rs
+fn test1() {
+    let x: u32 = return;
+}
+fn test2() {
+    let x: u32 = { return; };
+}
+fn test3() {
+    let x: u32 = loop {};
+}
+fn test4() {
+    let x: u32 = { loop {} };
+}
+fn test5() {
+    let x: u32 = { if true { loop {}; } else { loop {}; } };
+}
+fn test6() {
+    let x: u32 = { let y: u32 = { loop {}; }; };
+}
+"#,
+        true,
+    );
+    assert_snapshot!(t, @r###"
+    25..53 '{     ...urn; }': ()
+    35..36 'x': u32
+    44..50 'return': !
+    65..98 '{     ...; }; }': ()
+    75..76 'x': u32
+    84..95 '{ return; }': u32
+    86..92 'return': !
+    110..139 '{     ... {}; }': ()
+    120..121 'x': u32
+    129..136 'loop {}': !
+    134..136 '{}': ()
+    151..184 '{     ...} }; }': ()
+    161..162 'x': u32
+    170..181 '{ loop {} }': u32
+    172..179 'loop {}': !
+    177..179 '{}': ()
+    196..260 '{     ...} }; }': ()
+    206..207 'x': u32
+    215..257 '{ if t...}; } }': u32
+    217..255 'if tru... {}; }': u32
+    220..224 'true': bool
+    225..237 '{ loop {}; }': u32
+    227..234 'loop {}': !
+    232..234 '{}': ()
+    243..255 '{ loop {}; }': u32
+    245..252 'loop {}': !
+    250..252 '{}': ()
+    272..324 '{     ...; }; }': ()
+    282..283 'x': u32
+    291..321 '{ let ...; }; }': u32
+    297..298 'y': u32
+    306..318 '{ loop {}; }': u32
+    308..315 'loop {}': !
+    313..315 '{}': ()
+    "###);
+}
+
+#[test]
+fn diverging_expression_2() {
+    let t = infer_with_mismatches(
+        r#"
+//- /main.rs
+fn test1() {
+    // should give type mismatch
+    let x: u32 = { loop {}; "foo" };
+}
+"#,
+        true,
+    );
+    assert_snapshot!(t, @r###"
+    25..98 '{     ..." }; }': ()
+    68..69 'x': u32
+    77..95 '{ loop...foo" }': &str
+    79..86 'loop {}': !
+    84..86 '{}': ()
+    88..93 '"foo"': &str
+    77..95: expected u32, got &str
+    88..93: expected u32, got &str
+    "###);
+}
+
+#[test]
+fn diverging_expression_3_break() {
+    let t = infer_with_mismatches(
+        r#"
+//- /main.rs
+fn test1() {
+    // should give type mismatch
+    let x: u32 = { loop { break; } };
+}
+fn test2() {
+    // should give type mismatch
+    let x: u32 = { for a in b { break; }; };
+    // should give type mismatch as well
+    let x: u32 = { for a in b {}; };
+    // should give type mismatch as well
+    let x: u32 = { for a in b { return; }; };
+}
+fn test3() {
+    // should give type mismatch
+    let x: u32 = { while true { break; }; };
+    // should give type mismatch as well -- there's an implicit break, even if it's never hit
+    let x: u32 = { while true {}; };
+    // should give type mismatch as well
+    let x: u32 = { while true { return; }; };
+}
+"#,
+        true,
+    );
+    assert_snapshot!(t, @r###"
+    25..99 '{     ...} }; }': ()
+    68..69 'x': u32
+    77..96 '{ loop...k; } }': ()
+    79..94 'loop { break; }': ()
+    84..94 '{ break; }': ()
+    86..91 'break': !
+    77..96: expected u32, got ()
+    79..94: expected u32, got ()
+    111..357 '{     ...; }; }': ()
+    154..155 'x': u32
+    163..189 '{ for ...; }; }': ()
+    165..186 'for a ...eak; }': ()
+    169..170 'a': {unknown}
+    174..175 'b': {unknown}
+    176..186 '{ break; }': ()
+    178..183 'break': !
+    240..241 'x': u32
+    249..267 '{ for ... {}; }': ()
+    251..264 'for a in b {}': ()
+    255..256 'a': {unknown}
+    260..261 'b': {unknown}
+    262..264 '{}': ()
+    318..319 'x': u32
+    327..354 '{ for ...; }; }': ()
+    329..351 'for a ...urn; }': ()
+    333..334 'a': {unknown}
+    338..339 'b': {unknown}
+    340..351 '{ return; }': ()
+    342..348 'return': !
+    163..189: expected u32, got ()
+    249..267: expected u32, got ()
+    327..354: expected u32, got ()
+    369..668 '{     ...; }; }': ()
+    412..413 'x': u32
+    421..447 '{ whil...; }; }': ()
+    423..444 'while ...eak; }': ()
+    429..433 'true': bool
+    434..444 '{ break; }': ()
+    436..441 'break': !
+    551..552 'x': u32
+    560..578 '{ whil... {}; }': ()
+    562..575 'while true {}': ()
+    568..572 'true': bool
+    573..575 '{}': ()
+    629..630 'x': u32
+    638..665 '{ whil...; }; }': ()
+    640..662 'while ...urn; }': ()
+    646..650 'true': bool
+    651..662 '{ return; }': ()
+    653..659 'return': !
+    421..447: expected u32, got ()
+    560..578: expected u32, got ()
+    638..665: expected u32, got ()
+    "###);
+}
diff --git a/crates/ra_hir_ty/src/tests/simple.rs b/crates/ra_hir_ty/src/tests/simple.rs
index 3d3088965..322838f02 100644
--- a/crates/ra_hir_ty/src/tests/simple.rs
+++ b/crates/ra_hir_ty/src/tests/simple.rs
@@ -179,7 +179,7 @@ fn test(a: u32, b: isize, c: !, d: &str) {
     17..18 'b': isize
     27..28 'c': !
     33..34 'd': &str
-    42..121 '{     ...f32; }': !
+    42..121 '{     ...f32; }': ()
     48..49 'a': u32
     55..56 'b': isize
     62..63 'c': !
@@ -414,7 +414,7 @@ fn test() {
     27..31 '5f32': f32
     37..41 '5f64': f64
     47..54 '"hello"': &str
-    60..68 'b"bytes"': &[u8]
+    60..68 'b"bytes"': &[u8; _]
     74..77 ''c'': char
     83..87 'b'b'': u8
     93..97 '3.14': f64
@@ -422,7 +422,7 @@ fn test() {
     113..118 'false': bool
     124..128 'true': bool
     134..202 'r#"   ...    "#': &str
-    208..218 'br#"yolo"#': &[u8]
+    208..218 'br#"yolo"#': &[u8; _]
     "###
     );
 }
@@ -935,7 +935,7 @@ fn foo() {
     29..33 'true': bool
     34..51 '{     ...     }': i32
     44..45 '1': i32
-    57..80 '{     ...     }': !
+    57..80 '{     ...     }': i32
     67..73 'return': !
     90..93 '_x2': i32
     96..149 'if tru...     }': i32
@@ -951,7 +951,7 @@ fn foo() {
     186..190 'true': bool
     194..195 '3': i32
     205..206 '_': bool
-    210..241 '{     ...     }': !
+    210..241 '{     ...     }': i32
     224..230 'return': !
     257..260 '_x4': i32
     263..320 'match ...     }': i32
@@ -1687,7 +1687,7 @@ fn foo() -> u32 {
     17..59 '{     ...; }; }': ()
     27..28 'x': || -> usize
     31..56 '|| -> ...n 1; }': || -> usize
-    43..56 '{ return 1; }': !
+    43..56 '{ return 1; }': usize
     45..53 'return 1': !
     52..53 '1': usize
     "###
@@ -1706,7 +1706,7 @@ fn foo() -> u32 {
     17..48 '{     ...; }; }': ()
     27..28 'x': || -> ()
     31..45 '|| { return; }': || -> ()
-    34..45 '{ return; }': !
+    34..45 '{ return; }': ()
     36..42 'return': !
     "###
     );
@@ -1787,3 +1787,32 @@ fn main() {
     "###
     )
 }
+
+#[test]
+fn infer_generic_from_later_assignment() {
+    assert_snapshot!(
+        infer(r#"
+enum Option<T> { Some(T), None }
+use Option::*;
+
+fn test() {
+    let mut end = None;
+    loop {
+        end = Some(true);
+    }
+}
+"#),
+        @r###"
+    60..130 '{     ...   } }': ()
+    70..77 'mut end': Option<bool>
+    80..84 'None': Option<bool>
+    90..128 'loop {...     }': !
+    95..128 '{     ...     }': ()
+    105..108 'end': Option<bool>
+    105..121 'end = ...(true)': ()
+    111..115 'Some': Some<bool>(bool) -> Option<bool>
+    111..121 'Some(true)': Option<bool>
+    116..120 'true': bool
+    "###
+    );
+}
diff --git a/crates/ra_ide/src/display/function_signature.rs b/crates/ra_ide/src/display/function_signature.rs
index f16d42276..9572debd8 100644
--- a/crates/ra_ide/src/display/function_signature.rs
+++ b/crates/ra_ide/src/display/function_signature.rs
@@ -84,8 +84,8 @@ impl FunctionSignature {
             let ty = field.signature_ty(db);
             let raw_param = format!("{}", ty.display(db));
 
-            if let Some(param_type) = raw_param.split(':').nth(1) {
-                parameter_types.push(param_type[1..].to_string());
+            if let Some(param_type) = raw_param.split(':').nth(1).and_then(|it| it.get(1..)) {
+                parameter_types.push(param_type.to_string());
             } else {
                 // useful when you have tuple struct
                 parameter_types.push(raw_param.clone());
@@ -129,8 +129,8 @@ impl FunctionSignature {
         for field in variant.fields(db).into_iter() {
             let ty = field.signature_ty(db);
             let raw_param = format!("{}", ty.display(db));
-            if let Some(param_type) = raw_param.split(':').nth(1) {
-                parameter_types.push(param_type[1..].to_string());
+            if let Some(param_type) = raw_param.split(':').nth(1).and_then(|it| it.get(1..)) {
+                parameter_types.push(param_type.to_string());
             } else {
                 // The unwrap_or_else is useful when you have tuple
                 parameter_types.push(raw_param);
@@ -197,7 +197,12 @@ impl From<&'_ ast::FnDef> for FunctionSignature {
                     let raw_param = self_param.syntax().text().to_string();
 
                     res_types.push(
-                        raw_param.split(':').nth(1).unwrap_or_else(|| " Self")[1..].to_string(),
+                        raw_param
+                            .split(':')
+                            .nth(1)
+                            .and_then(|it| it.get(1..))
+                            .unwrap_or_else(|| "Self")
+                            .to_string(),
                     );
                     res.push(raw_param);
                 }
@@ -205,8 +210,8 @@ impl From<&'_ ast::FnDef> for FunctionSignature {
                 res.extend(param_list.params().map(|param| param.syntax().text().to_string()));
                 res_types.extend(param_list.params().map(|param| {
                     let param_text = param.syntax().text().to_string();
-                    match param_text.split(':').nth(1) {
-                        Some(it) => it[1..].to_string(),
+                    match param_text.split(':').nth(1).and_then(|it| it.get(1..)) {
+                        Some(it) => it.to_string(),
                         None => param_text,
                     }
                 }));
diff --git a/crates/ra_ide/src/display/navigation_target.rs b/crates/ra_ide/src/display/navigation_target.rs
index de35c6711..5da28edd2 100644
--- a/crates/ra_ide/src/display/navigation_target.rs
+++ b/crates/ra_ide/src/display/navigation_target.rs
@@ -11,7 +11,7 @@ use ra_syntax::{
     TextRange,
 };
 
-use crate::FileSymbol;
+use crate::{FileRange, FileSymbol};
 
 use super::short_label::ShortLabel;
 
@@ -22,10 +22,11 @@ use super::short_label::ShortLabel;
 /// code, like a function or a struct, but this is not strictly required.
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct NavigationTarget {
+    // FIXME: use FileRange?
     file_id: FileId,
+    full_range: TextRange,
     name: SmolStr,
     kind: SyntaxKind,
-    full_range: TextRange,
     focus_range: Option<TextRange>,
     container_name: Option<SmolStr>,
     description: Option<String>,
@@ -63,6 +64,10 @@ impl NavigationTarget {
         self.file_id
     }
 
+    pub fn file_range(&self) -> FileRange {
+        FileRange { file_id: self.file_id, range: self.full_range }
+    }
+
     pub fn full_range(&self) -> TextRange {
         self.full_range
     }
diff --git a/crates/ra_ide/src/snapshots/highlight_strings.html b/crates/ra_ide/src/snapshots/highlight_strings.html
index de06daf72..752b487e8 100644
--- a/crates/ra_ide/src/snapshots/highlight_strings.html
+++ b/crates/ra_ide/src/snapshots/highlight_strings.html
@@ -27,13 +27,13 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
 .keyword.unsafe     { color: #BC8383; font-weight: bold; }
 .control            { font-style: italic; }
 </style>
-<pre><code><span class="macro">macro_rules!</span> println {
+<pre><code><span class="macro">macro_rules!</span> <span class="macro declaration">println</span> {
     ($($arg:tt)*) =&gt; ({
         $<span class="keyword">crate</span>::io::_print($<span class="keyword">crate</span>::format_args_nl!($($arg)*));
     })
 }
 #[rustc_builtin_macro]
-<span class="macro">macro_rules!</span> format_args_nl {
+<span class="macro">macro_rules!</span> <span class="macro declaration">format_args_nl</span> {
     ($fmt:expr) =&gt; {{ <span class="comment">/* compiler built-in */</span> }};
     ($fmt:expr, $($args:tt)*) =&gt; {{ <span class="comment">/* compiler built-in */</span> }};
 }
diff --git a/crates/ra_ide/src/snapshots/highlighting.html b/crates/ra_ide/src/snapshots/highlighting.html
index 4b12fe823..4c27aade4 100644
--- a/crates/ra_ide/src/snapshots/highlighting.html
+++ b/crates/ra_ide/src/snapshots/highlighting.html
@@ -33,11 +33,13 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
     <span class="keyword">pub</span> <span class="field declaration">y</span>: <span class="builtin_type">i32</span>,
 }
 
+<span class="keyword">static</span> <span class="keyword">mut</span> <span class="static declaration mutable">STATIC_MUT</span>: <span class="builtin_type">i32</span> = <span class="numeric_literal">0</span>;
+
 <span class="keyword">fn</span> <span class="function declaration">foo</span>&lt;<span class="lifetime declaration">'a</span>, <span class="type_param declaration">T</span>&gt;() -&gt; <span class="type_param">T</span> {
     <span class="function">foo</span>::&lt;<span class="lifetime">'a</span>, <span class="builtin_type">i32</span>&gt;()
 }
 
-<span class="macro">macro_rules!</span> def_fn {
+<span class="macro">macro_rules!</span> <span class="macro declaration">def_fn</span> {
     ($($tt:tt)*) =&gt; {$($tt)*}
 }
 
@@ -56,7 +58,10 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
         <span class="keyword">let</span> <span class="variable declaration">x</span> = <span class="numeric_literal">92</span>;
         <span class="variable mutable">vec</span>.<span class="unresolved_reference">push</span>(<span class="struct">Foo</span> { <span class="field">x</span>, <span class="field">y</span>: <span class="numeric_literal">1</span> });
     }
-    <span class="keyword unsafe">unsafe</span> { <span class="variable mutable">vec</span>.<span class="unresolved_reference">set_len</span>(<span class="numeric_literal">0</span>); }
+    <span class="keyword unsafe">unsafe</span> {
+        <span class="variable mutable">vec</span>.<span class="unresolved_reference">set_len</span>(<span class="numeric_literal">0</span>);
+        <span class="static mutable">STATIC_MUT</span> = <span class="numeric_literal">1</span>;
+    }
 
     <span class="keyword">let</span> <span class="keyword">mut</span> <span class="variable declaration mutable">x</span> = <span class="numeric_literal">42</span>;
     <span class="keyword">let</span> <span class="variable declaration mutable">y</span> = &<span class="keyword">mut</span> <span class="variable mutable">x</span>;
diff --git a/crates/ra_ide/src/syntax_highlighting.rs b/crates/ra_ide/src/syntax_highlighting.rs
index 6658c7bb2..d53a39f57 100644
--- a/crates/ra_ide/src/syntax_highlighting.rs
+++ b/crates/ra_ide/src/syntax_highlighting.rs
@@ -167,6 +167,19 @@ pub(crate) fn highlight(
                         binding_hash: None,
                     });
                 }
+                if let Some(name) = mc.is_macro_rules() {
+                    if let Some((highlight, binding_hash)) = highlight_element(
+                        &sema,
+                        &mut bindings_shadow_count,
+                        name.syntax().clone().into(),
+                    ) {
+                        stack.add(HighlightedRange {
+                            range: name.syntax().text_range(),
+                            highlight,
+                            binding_hash,
+                        });
+                    }
+                }
                 continue;
             }
             WalkEvent::Leave(Some(mc)) => {
@@ -431,10 +444,16 @@ fn highlight_name(db: &RootDatabase, def: Definition) -> Highlight {
             hir::ModuleDef::Adt(hir::Adt::Union(_)) => HighlightTag::Union,
             hir::ModuleDef::EnumVariant(_) => HighlightTag::EnumVariant,
             hir::ModuleDef::Const(_) => HighlightTag::Constant,
-            hir::ModuleDef::Static(_) => HighlightTag::Static,
             hir::ModuleDef::Trait(_) => HighlightTag::Trait,
             hir::ModuleDef::TypeAlias(_) => HighlightTag::TypeAlias,
             hir::ModuleDef::BuiltinType(_) => HighlightTag::BuiltinType,
+            hir::ModuleDef::Static(s) => {
+                let mut h = Highlight::new(HighlightTag::Static);
+                if s.is_mut(db) {
+                    h |= HighlightModifier::Mutable;
+                }
+                return h;
+            }
         },
         Definition::SelfType(_) => HighlightTag::SelfType,
         Definition::TypeParam(_) => HighlightTag::TypeParam,
diff --git a/crates/ra_ide/src/syntax_highlighting/tests.rs b/crates/ra_ide/src/syntax_highlighting/tests.rs
index d2926ba78..13894869c 100644
--- a/crates/ra_ide/src/syntax_highlighting/tests.rs
+++ b/crates/ra_ide/src/syntax_highlighting/tests.rs
@@ -17,6 +17,8 @@ struct Foo {
     pub y: i32,
 }
 
+static mut STATIC_MUT: i32 = 0;
+
 fn foo<'a, T>() -> T {
     foo::<'a, i32>()
 }
@@ -40,7 +42,10 @@ fn main() {
         let x = 92;
         vec.push(Foo { x, y: 1 });
     }
-    unsafe { vec.set_len(0); }
+    unsafe {
+        vec.set_len(0);
+        STATIC_MUT = 1;
+    }
 
     let mut x = 42;
     let y = &mut x;
diff --git a/crates/ra_proc_macro_srv/Cargo.toml b/crates/ra_proc_macro_srv/Cargo.toml
index 886e14870..bb3003278 100644
--- a/crates/ra_proc_macro_srv/Cargo.toml
+++ b/crates/ra_proc_macro_srv/Cargo.toml
@@ -18,7 +18,7 @@ memmap = "0.7"
 test_utils = { path = "../test_utils" }
 
 [dev-dependencies]
-cargo_metadata = "0.9.1"
+cargo_metadata = "0.10.0"
 difference = "2.0.0"
 # used as proc macro test target
-serde_derive = "=1.0.106"
+serde_derive = "1.0.106"
diff --git a/crates/ra_proc_macro_srv/src/tests/fixtures/test_serialize_proc_macro.txt b/crates/ra_proc_macro_srv/src/tests/fixtures/test_serialize_proc_macro.txt
index 6776f5231..bc010cfe9 100644
--- a/crates/ra_proc_macro_srv/src/tests/fixtures/test_serialize_proc_macro.txt
+++ b/crates/ra_proc_macro_srv/src/tests/fixtures/test_serialize_proc_macro.txt
@@ -23,23 +23,12 @@ SUBTREE $
     SUBTREE [] 4294967295
       IDENT   allow 4294967295
       SUBTREE () 4294967295
-        IDENT   unknown_lints 4294967295
-    PUNCH   # [alone] 4294967295
-    SUBTREE [] 4294967295
-      IDENT   cfg_attr 4294967295
-      SUBTREE () 4294967295
-        IDENT   feature 4294967295
-        PUNCH   = [alone] 4294967295
-        LITERAL "cargo-clippy" 0
-        PUNCH   , [alone] 4294967295
-        IDENT   allow 4294967295
-        SUBTREE () 4294967295
-          IDENT   useless_attribute 4294967295
-    PUNCH   # [alone] 4294967295
-    SUBTREE [] 4294967295
-      IDENT   allow 4294967295
-      SUBTREE () 4294967295
         IDENT   rust_2018_idioms 4294967295
+        PUNCH   , [alone] 4294967295
+        IDENT   clippy 4294967295
+        PUNCH   : [joint] 4294967295
+        PUNCH   : [alone] 4294967295
+        IDENT   useless_attribute 4294967295
     IDENT   extern 4294967295
     IDENT   crate 4294967295
     IDENT   serde 4294967295
diff --git a/crates/ra_proc_macro_srv/src/tests/mod.rs b/crates/ra_proc_macro_srv/src/tests/mod.rs
index 9cf58511c..82cefbb29 100644
--- a/crates/ra_proc_macro_srv/src/tests/mod.rs
+++ b/crates/ra_proc_macro_srv/src/tests/mod.rs
@@ -10,7 +10,7 @@ fn test_derive_serialize_proc_macro() {
     assert_expand(
         "serde_derive",
         "Serialize",
-        "1.0.106",
+        "1.0",
         r##"struct Foo {}"##,
         include_str!("fixtures/test_serialize_proc_macro.txt"),
     );
@@ -21,7 +21,7 @@ fn test_derive_serialize_proc_macro_failed() {
     assert_expand(
         "serde_derive",
         "Serialize",
-        "1.0.106",
+        "1.0",
         r##"
     struct {}
 "##,
@@ -37,7 +37,7 @@ SUBTREE $
 
 #[test]
 fn test_derive_proc_macro_list() {
-    let res = list("serde_derive", "1.0.106").join("\n");
+    let res = list("serde_derive", "1.0").join("\n");
 
     assert_eq_text!(
         &res,
diff --git a/crates/ra_proc_macro_srv/src/tests/utils.rs b/crates/ra_proc_macro_srv/src/tests/utils.rs
index 646a427c5..84348b5de 100644
--- a/crates/ra_proc_macro_srv/src/tests/utils.rs
+++ b/crates/ra_proc_macro_srv/src/tests/utils.rs
@@ -8,7 +8,7 @@ use std::str::FromStr;
 use test_utils::assert_eq_text;
 
 mod fixtures {
-    use cargo_metadata::{parse_messages, Message};
+    use cargo_metadata::Message;
     use std::process::Command;
 
     // Use current project metadata to get the proc-macro dylib path
@@ -19,7 +19,7 @@ mod fixtures {
             .unwrap()
             .stdout;
 
-        for message in parse_messages(command.as_slice()) {
+        for message in Message::parse_stream(command.as_slice()) {
             match message.unwrap() {
                 Message::CompilerArtifact(artifact) => {
                     if artifact.target.kind.contains(&"proc-macro".to_string()) {
diff --git a/crates/ra_project_model/Cargo.toml b/crates/ra_project_model/Cargo.toml
index 626478468..e4a60f4c0 100644
--- a/crates/ra_project_model/Cargo.toml
+++ b/crates/ra_project_model/Cargo.toml
@@ -11,12 +11,12 @@ doctest = false
 log = "0.4.8"
 rustc-hash = "1.1.0"
 
-cargo_metadata = "0.9.1"
+cargo_metadata = "0.10.0"
 
 ra_arena = { path = "../ra_arena" }
 ra_cfg = { path = "../ra_cfg" }
 ra_db = { path = "../ra_db" }
-ra_env = { path = "../ra_env" }
+ra_toolchain = { path = "../ra_toolchain" }
 ra_proc_macro =  { path = "../ra_proc_macro" }
 
 serde = { version = "1.0.106", features = ["derive"] }
diff --git a/crates/ra_project_model/src/cargo_workspace.rs b/crates/ra_project_model/src/cargo_workspace.rs
index eb9f33ee8..a306ce95f 100644
--- a/crates/ra_project_model/src/cargo_workspace.rs
+++ b/crates/ra_project_model/src/cargo_workspace.rs
@@ -11,7 +11,6 @@ use anyhow::{Context, Result};
 use cargo_metadata::{BuildScript, CargoOpt, Message, MetadataCommand, PackageId};
 use ra_arena::{Arena, Idx};
 use ra_db::Edition;
-use ra_env::get_path_for_executable;
 use rustc_hash::FxHashMap;
 
 /// `CargoWorkspace` represents the logical structure of, well, a Cargo
@@ -147,7 +146,7 @@ impl CargoWorkspace {
         cargo_features: &CargoConfig,
     ) -> Result<CargoWorkspace> {
         let mut meta = MetadataCommand::new();
-        meta.cargo_path(get_path_for_executable("cargo")?);
+        meta.cargo_path(ra_toolchain::cargo());
         meta.manifest_path(cargo_toml);
         if cargo_features.all_features {
             meta.features(CargoOpt::AllFeatures);
@@ -162,7 +161,7 @@ impl CargoWorkspace {
             meta.current_dir(parent);
         }
         if let Some(target) = cargo_features.target.as_ref() {
-            meta.other_options(&[String::from("--filter-platform"), target.clone()]);
+            meta.other_options(vec![String::from("--filter-platform"), target.clone()]);
         }
         let meta = meta.exec().with_context(|| {
             format!("Failed to run `cargo metadata --manifest-path {}`", cargo_toml.display())
@@ -289,7 +288,7 @@ pub fn load_extern_resources(
     cargo_toml: &Path,
     cargo_features: &CargoConfig,
 ) -> Result<ExternResources> {
-    let mut cmd = Command::new(get_path_for_executable("cargo")?);
+    let mut cmd = Command::new(ra_toolchain::cargo());
     cmd.args(&["check", "--message-format=json", "--manifest-path"]).arg(cargo_toml);
     if cargo_features.all_features {
         cmd.arg("--all-features");
@@ -305,19 +304,13 @@ pub fn load_extern_resources(
 
     let mut res = ExternResources::default();
 
-    for message in cargo_metadata::parse_messages(output.stdout.as_slice()) {
+    for message in cargo_metadata::Message::parse_stream(output.stdout.as_slice()) {
         if let Ok(message) = message {
             match message {
                 Message::BuildScriptExecuted(BuildScript { package_id, out_dir, cfgs, .. }) => {
                     res.out_dirs.insert(package_id.clone(), out_dir);
-                    res.cfgs.insert(
-                        package_id,
-                        // FIXME: Current `cargo_metadata` uses `PathBuf` instead of `String`,
-                        // change when https://github.com/oli-obk/cargo_metadata/pulls/112 reaches crates.io
-                        cfgs.iter().filter_map(|c| c.to_str().map(|s| s.to_owned())).collect(),
-                    );
+                    res.cfgs.insert(package_id, cfgs);
                 }
-
                 Message::CompilerArtifact(message) => {
                     if message.target.kind.contains(&"proc-macro".to_string()) {
                         let package_id = message.package_id;
@@ -330,6 +323,8 @@ pub fn load_extern_resources(
                 }
                 Message::CompilerMessage(_) => (),
                 Message::Unknown => (),
+                Message::BuildFinished(_) => {}
+                Message::TextLine(_) => {}
             }
         }
     }
diff --git a/crates/ra_project_model/src/lib.rs b/crates/ra_project_model/src/lib.rs
index 88a6ffb2a..4f098b706 100644
--- a/crates/ra_project_model/src/lib.rs
+++ b/crates/ra_project_model/src/lib.rs
@@ -8,13 +8,12 @@ use std::{
     fs::{read_dir, File, ReadDir},
     io::{self, BufReader},
     path::{Path, PathBuf},
-    process::Command,
+    process::{Command, Output},
 };
 
 use anyhow::{bail, Context, Result};
 use ra_cfg::CfgOptions;
 use ra_db::{CrateGraph, CrateName, Edition, Env, ExternSource, ExternSourceId, FileId};
-use ra_env::get_path_for_executable;
 use rustc_hash::FxHashMap;
 use serde_json::from_reader;
 
@@ -89,46 +88,28 @@ impl ProjectRoot {
     }
 
     pub fn discover(path: &Path) -> io::Result<Vec<ProjectRoot>> {
-        if let Some(project_json) = find_rust_project_json(path) {
+        if let Some(project_json) = find_in_parent_dirs(path, "rust-project.json") {
             return Ok(vec![ProjectRoot::ProjectJson(project_json)]);
         }
         return find_cargo_toml(path)
             .map(|paths| paths.into_iter().map(ProjectRoot::CargoToml).collect());
 
-        fn find_rust_project_json(path: &Path) -> Option<PathBuf> {
-            if path.ends_with("rust-project.json") {
-                return Some(path.to_path_buf());
-            }
-
-            let mut curr = Some(path);
-            while let Some(path) = curr {
-                let candidate = path.join("rust-project.json");
-                if candidate.exists() {
-                    return Some(candidate);
-                }
-                curr = path.parent();
-            }
-
-            None
-        }
-
         fn find_cargo_toml(path: &Path) -> io::Result<Vec<PathBuf>> {
-            if path.ends_with("Cargo.toml") {
-                return Ok(vec![path.to_path_buf()]);
+            match find_in_parent_dirs(path, "Cargo.toml") {
+                Some(it) => Ok(vec![it]),
+                None => Ok(find_cargo_toml_in_child_dir(read_dir(path)?)),
             }
+        }
 
-            if let Some(p) = find_cargo_toml_in_parent_dir(path) {
-                return Ok(vec![p]);
+        fn find_in_parent_dirs(path: &Path, target_file_name: &str) -> Option<PathBuf> {
+            if path.ends_with(target_file_name) {
+                return Some(path.to_owned());
             }
 
-            let entities = read_dir(path)?;
-            Ok(find_cargo_toml_in_child_dir(entities))
-        }
-
-        fn find_cargo_toml_in_parent_dir(path: &Path) -> Option<PathBuf> {
             let mut curr = Some(path);
+
             while let Some(path) = curr {
-                let candidate = path.join("Cargo.toml");
+                let candidate = path.join(target_file_name);
                 if candidate.exists() {
                     return Some(candidate);
                 }
@@ -140,14 +121,11 @@ impl ProjectRoot {
 
         fn find_cargo_toml_in_child_dir(entities: ReadDir) -> Vec<PathBuf> {
             // Only one level down to avoid cycles the easy way and stop a runaway scan with large projects
-            let mut valid_canditates = vec![];
-            for entity in entities.filter_map(Result::ok) {
-                let candidate = entity.path().join("Cargo.toml");
-                if candidate.exists() {
-                    valid_canditates.push(candidate)
-                }
-            }
-            valid_canditates
+            entities
+                .filter_map(Result::ok)
+                .map(|it| it.path().join("Cargo.toml"))
+                .filter(|it| it.exists())
+                .collect()
         }
     }
 }
@@ -568,25 +546,18 @@ pub fn get_rustc_cfg_options(target: Option<&String>) -> CfgOptions {
         }
     }
 
-    match (|| -> Result<String> {
+    let rustc_cfgs = || -> Result<String> {
         // `cfg(test)` and `cfg(debug_assertion)` are handled outside, so we suppress them here.
-        let mut cmd = Command::new(get_path_for_executable("rustc")?);
+        let mut cmd = Command::new(ra_toolchain::rustc());
         cmd.args(&["--print", "cfg", "-O"]);
         if let Some(target) = target {
             cmd.args(&["--target", target.as_str()]);
         }
-        let output = cmd.output().context("Failed to get output from rustc --print cfg -O")?;
-        if !output.status.success() {
-            bail!(
-                "rustc --print cfg -O exited with exit code ({})",
-                output
-                    .status
-                    .code()
-                    .map_or(String::from("no exit code"), |code| format!("{}", code))
-            );
-        }
+        let output = output(cmd)?;
         Ok(String::from_utf8(output.stdout)?)
-    })() {
+    }();
+
+    match rustc_cfgs {
         Ok(rustc_cfgs) => {
             for line in rustc_cfgs.lines() {
                 match line.find('=') {
@@ -599,8 +570,21 @@ pub fn get_rustc_cfg_options(target: Option<&String>) -> CfgOptions {
                 }
             }
         }
-        Err(e) => log::error!("failed to get rustc cfgs: {}", e),
+        Err(e) => log::error!("failed to get rustc cfgs: {:#}", e),
     }
 
     cfg_options
 }
+
+fn output(mut cmd: Command) -> Result<Output> {
+    let output = cmd.output().with_context(|| format!("{:?} failed", cmd))?;
+    if !output.status.success() {
+        match String::from_utf8(output.stderr) {
+            Ok(stderr) if !stderr.is_empty() => {
+                bail!("{:?} failed, {}\nstderr:\n{}", cmd, output.status, stderr)
+            }
+            _ => bail!("{:?} failed, {}", cmd, output.status),
+        }
+    }
+    Ok(output)
+}
diff --git a/crates/ra_project_model/src/sysroot.rs b/crates/ra_project_model/src/sysroot.rs
index 11c26ad89..a8a196e64 100644
--- a/crates/ra_project_model/src/sysroot.rs
+++ b/crates/ra_project_model/src/sysroot.rs
@@ -1,14 +1,15 @@
 //! FIXME: write short doc here
 
-use anyhow::{bail, Context, Result};
 use std::{
     env, ops,
     path::{Path, PathBuf},
-    process::{Command, Output},
+    process::Command,
 };
 
+use anyhow::{bail, Result};
 use ra_arena::{Arena, Idx};
-use ra_env::get_path_for_executable;
+
+use crate::output;
 
 #[derive(Default, Debug, Clone)]
 pub struct Sysroot {
@@ -85,50 +86,22 @@ impl Sysroot {
     }
 }
 
-fn create_command_text(program: &str, args: &[&str]) -> String {
-    format!("{} {}", program, args.join(" "))
-}
-
-fn run_command_in_cargo_dir(
-    cargo_toml: impl AsRef<Path>,
-    program: impl AsRef<Path>,
-    args: &[&str],
-) -> Result<Output> {
-    let program = program.as_ref().as_os_str().to_str().expect("Invalid Unicode in path");
-    let output = Command::new(program)
-        .current_dir(cargo_toml.as_ref().parent().unwrap())
-        .args(args)
-        .output()
-        .context(format!("{} failed", create_command_text(program, args)))?;
-    if !output.status.success() {
-        match output.status.code() {
-            Some(code) => bail!(
-                "failed to run the command: '{}' exited with code {}",
-                create_command_text(program, args),
-                code
-            ),
-            None => bail!(
-                "failed to run the command: '{}' terminated by signal",
-                create_command_text(program, args)
-            ),
-        };
-    }
-    Ok(output)
-}
-
 fn get_or_install_rust_src(cargo_toml: &Path) -> Result<PathBuf> {
     if let Ok(path) = env::var("RUST_SRC_PATH") {
         return Ok(path.into());
     }
-    let rustc = get_path_for_executable("rustc")?;
-    let rustc_output = run_command_in_cargo_dir(cargo_toml, &rustc, &["--print", "sysroot"])?;
+    let current_dir = cargo_toml.parent().unwrap();
+    let mut rustc = Command::new(ra_toolchain::rustc());
+    rustc.current_dir(current_dir).args(&["--print", "sysroot"]);
+    let rustc_output = output(rustc)?;
     let stdout = String::from_utf8(rustc_output.stdout)?;
     let sysroot_path = Path::new(stdout.trim());
     let src_path = sysroot_path.join("lib/rustlib/src/rust/src");
 
     if !src_path.exists() {
-        let rustup = get_path_for_executable("rustup")?;
-        run_command_in_cargo_dir(cargo_toml, &rustup, &["component", "add", "rust-src"])?;
+        let mut rustup = Command::new(ra_toolchain::rustup());
+        rustup.current_dir(current_dir).args(&["component", "add", "rust-src"]);
+        let _output = output(rustup)?;
     }
     if !src_path.exists() {
         bail!(
diff --git a/crates/ra_syntax/src/ast/edit.rs b/crates/ra_syntax/src/ast/edit.rs
index 3e6dd6061..24a1e1d91 100644
--- a/crates/ra_syntax/src/ast/edit.rs
+++ b/crates/ra_syntax/src/ast/edit.rs
@@ -453,11 +453,7 @@ impl IndentLevel {
         IndentLevel(0)
     }
 
-    pub fn increase_indent<N: AstNode>(self, node: N) -> N {
-        N::cast(self._increase_indent(node.syntax().clone())).unwrap()
-    }
-
-    fn _increase_indent(self, node: SyntaxNode) -> SyntaxNode {
+    fn increase_indent(self, node: SyntaxNode) -> SyntaxNode {
         let mut rewriter = SyntaxRewriter::default();
         node.descendants_with_tokens()
             .filter_map(|el| el.into_token())
@@ -478,11 +474,7 @@ impl IndentLevel {
         rewriter.rewrite(&node)
     }
 
-    pub fn decrease_indent<N: AstNode>(self, node: N) -> N {
-        N::cast(self._decrease_indent(node.syntax().clone())).unwrap()
-    }
-
-    fn _decrease_indent(self, node: SyntaxNode) -> SyntaxNode {
+    fn decrease_indent(self, node: SyntaxNode) -> SyntaxNode {
         let mut rewriter = SyntaxRewriter::default();
         node.descendants_with_tokens()
             .filter_map(|el| el.into_token())
@@ -521,7 +513,7 @@ fn prev_tokens(token: SyntaxToken) -> impl Iterator<Item = SyntaxToken> {
     iter::successors(Some(token), |token| token.prev_token())
 }
 
-pub trait AstNodeEdit: AstNode + Sized {
+pub trait AstNodeEdit: AstNode + Clone + Sized {
     #[must_use]
     fn insert_children(
         &self,
@@ -558,9 +550,17 @@ pub trait AstNodeEdit: AstNode + Sized {
         }
         rewriter.rewrite_ast(self)
     }
+    #[must_use]
+    fn indent(&self, indent: IndentLevel) -> Self {
+        Self::cast(indent.increase_indent(self.syntax().clone())).unwrap()
+    }
+    #[must_use]
+    fn dedent(&self, indent: IndentLevel) -> Self {
+        Self::cast(indent.decrease_indent(self.syntax().clone())).unwrap()
+    }
 }
 
-impl<N: AstNode> AstNodeEdit for N {}
+impl<N: AstNode + Clone> AstNodeEdit for N {}
 
 fn single_node(element: impl Into<SyntaxElement>) -> RangeInclusive<SyntaxElement> {
     let element = element.into();
@@ -580,7 +580,7 @@ fn test_increase_indent() {
     _ => (),
 }"
     );
-    let indented = IndentLevel(2).increase_indent(arm_list);
+    let indented = arm_list.indent(IndentLevel(2));
     assert_eq!(
         indented.syntax().to_string(),
         "{
diff --git a/crates/ra_text_edit/src/lib.rs b/crates/ra_text_edit/src/lib.rs
index 3409713ff..37f77cc47 100644
--- a/crates/ra_text_edit/src/lib.rs
+++ b/crates/ra_text_edit/src/lib.rs
@@ -75,6 +75,7 @@ impl TextEdit {
         self.indels.is_empty()
     }
 
+    // FXME: impl IntoIter instead
     pub fn as_indels(&self) -> &[Indel] {
         &self.indels
     }
diff --git a/crates/ra_env/Cargo.toml b/crates/ra_toolchain/Cargo.toml
index f0a401be5..1873fbe16 100644
--- a/crates/ra_env/Cargo.toml
+++ b/crates/ra_toolchain/Cargo.toml
@@ -1,9 +1,8 @@
 [package]
 edition = "2018"
-name = "ra_env"
+name = "ra_toolchain"
 version = "0.1.0"
 authors = ["rust-analyzer developers"]
 
 [dependencies]
-anyhow = "1.0.26"
 home = "0.5.3"
diff --git a/crates/ra_toolchain/src/lib.rs b/crates/ra_toolchain/src/lib.rs
new file mode 100644
index 000000000..3d2865e09
--- /dev/null
+++ b/crates/ra_toolchain/src/lib.rs
@@ -0,0 +1,63 @@
+//! This crate contains a single public function
+//! [`get_path_for_executable`](fn.get_path_for_executable.html).
+//! See docs there for more information.
+use std::{env, iter, path::PathBuf};
+
+pub fn cargo() -> PathBuf {
+    get_path_for_executable("cargo")
+}
+
+pub fn rustc() -> PathBuf {
+    get_path_for_executable("rustc")
+}
+
+pub fn rustup() -> PathBuf {
+    get_path_for_executable("rustup")
+}
+
+/// Return a `PathBuf` to use for the given executable.
+///
+/// E.g., `get_path_for_executable("cargo")` may return just `cargo` if that
+/// gives a valid Cargo executable; or it may return a full path to a valid
+/// Cargo.
+fn get_path_for_executable(executable_name: &'static str) -> PathBuf {
+    // The current implementation checks three places for an executable to use:
+    // 1) Appropriate environment variable (erroring if this is set but not a usable executable)
+    //      example: for cargo, this checks $CARGO environment variable; for rustc, $RUSTC; etc
+    // 2) `<executable_name>`
+    //      example: for cargo, this tries just `cargo`, which will succeed if `cargo` is on the $PATH
+    // 3) `~/.cargo/bin/<executable_name>`
+    //      example: for cargo, this tries ~/.cargo/bin/cargo
+    //      It seems that this is a reasonable place to try for cargo, rustc, and rustup
+    let env_var = executable_name.to_ascii_uppercase();
+    if let Some(path) = env::var_os(&env_var) {
+        return path.into();
+    }
+
+    if lookup_in_path(executable_name) {
+        return executable_name.into();
+    }
+
+    if let Some(mut path) = home::home_dir() {
+        path.push(".cargo");
+        path.push("bin");
+        path.push(executable_name);
+        if path.is_file() {
+            return path;
+        }
+    }
+    executable_name.into()
+}
+
+fn lookup_in_path(exec: &str) -> bool {
+    let paths = env::var_os("PATH").unwrap_or_default();
+    let mut candidates = env::split_paths(&paths).flat_map(|path| {
+        let candidate = path.join(&exec);
+        let with_exe = match env::consts::EXE_EXTENSION {
+            "" => None,
+            it => Some(candidate.with_extension(it)),
+        };
+        iter::once(candidate).chain(with_exe)
+    });
+    candidates.any(|it| it.is_file())
+}
diff --git a/crates/rust-analyzer/src/conv.rs b/crates/rust-analyzer/src/conv.rs
deleted file mode 100644
index f64c90b5b..000000000
--- a/crates/rust-analyzer/src/conv.rs
+++ /dev/null
@@ -1,726 +0,0 @@
-//! Convenience module responsible for translating between rust-analyzer's types
-//! and LSP types.
-
-use lsp_types::{
-    self, CreateFile, DiagnosticSeverity, DocumentChangeOperation, DocumentChanges, Documentation,
-    Location, LocationLink, MarkupContent, MarkupKind, ParameterInformation, ParameterLabel,
-    Position, Range, RenameFile, ResourceOp, SemanticTokenModifier, SemanticTokenType,
-    SignatureInformation, SymbolKind, TextDocumentEdit, TextDocumentIdentifier, TextDocumentItem,
-    TextDocumentPositionParams, Url, VersionedTextDocumentIdentifier, WorkspaceEdit,
-};
-use ra_ide::{
-    translate_offset_with_edit, CompletionItem, CompletionItemKind, FileId, FilePosition,
-    FileRange, FileSystemEdit, Fold, FoldKind, Highlight, HighlightModifier, HighlightTag,
-    InlayHint, InlayKind, InsertTextFormat, LineCol, LineIndex, NavigationTarget, RangeInfo,
-    ReferenceAccess, Severity, SourceChange, SourceFileEdit,
-};
-use ra_syntax::{SyntaxKind, TextRange, TextSize};
-use ra_text_edit::{Indel, TextEdit};
-use ra_vfs::LineEndings;
-
-use crate::{
-    req,
-    semantic_tokens::{self, ModifierSet, CONSTANT, CONTROL_FLOW, MUTABLE, UNSAFE},
-    world::WorldSnapshot,
-    Result,
-};
-use semantic_tokens::{
-    ATTRIBUTE, BUILTIN_TYPE, ENUM_MEMBER, FORMAT_SPECIFIER, LIFETIME, TYPE_ALIAS, UNION,
-    UNRESOLVED_REFERENCE,
-};
-
-pub trait Conv {
-    type Output;
-    fn conv(self) -> Self::Output;
-}
-
-pub trait ConvWith<CTX> {
-    type Output;
-    fn conv_with(self, ctx: CTX) -> Self::Output;
-}
-
-pub trait TryConvWith<CTX> {
-    type Output;
-    fn try_conv_with(self, ctx: CTX) -> Result<Self::Output>;
-}
-
-impl Conv for SyntaxKind {
-    type Output = SymbolKind;
-
-    fn conv(self) -> <Self as Conv>::Output {
-        match self {
-            SyntaxKind::FN_DEF => SymbolKind::Function,
-            SyntaxKind::STRUCT_DEF => SymbolKind::Struct,
-            SyntaxKind::ENUM_DEF => SymbolKind::Enum,
-            SyntaxKind::ENUM_VARIANT => SymbolKind::EnumMember,
-            SyntaxKind::TRAIT_DEF => SymbolKind::Interface,
-            SyntaxKind::MACRO_CALL => SymbolKind::Function,
-            SyntaxKind::MODULE => SymbolKind::Module,
-            SyntaxKind::TYPE_ALIAS_DEF => SymbolKind::TypeParameter,
-            SyntaxKind::RECORD_FIELD_DEF => SymbolKind::Field,
-            SyntaxKind::STATIC_DEF => SymbolKind::Constant,
-            SyntaxKind::CONST_DEF => SymbolKind::Constant,
-            SyntaxKind::IMPL_DEF => SymbolKind::Object,
-            _ => SymbolKind::Variable,
-        }
-    }
-}
-
-impl Conv for ReferenceAccess {
-    type Output = ::lsp_types::DocumentHighlightKind;
-
-    fn conv(self) -> Self::Output {
-        use lsp_types::DocumentHighlightKind;
-        match self {
-            ReferenceAccess::Read => DocumentHighlightKind::Read,
-            ReferenceAccess::Write => DocumentHighlightKind::Write,
-        }
-    }
-}
-
-impl Conv for CompletionItemKind {
-    type Output = ::lsp_types::CompletionItemKind;
-
-    fn conv(self) -> <Self as Conv>::Output {
-        use lsp_types::CompletionItemKind::*;
-        match self {
-            CompletionItemKind::Keyword => Keyword,
-            CompletionItemKind::Snippet => Snippet,
-            CompletionItemKind::Module => Module,
-            CompletionItemKind::Function => Function,
-            CompletionItemKind::Struct => Struct,
-            CompletionItemKind::Enum => Enum,
-            CompletionItemKind::EnumVariant => EnumMember,
-            CompletionItemKind::BuiltinType => Struct,
-            CompletionItemKind::Binding => Variable,
-            CompletionItemKind::Field => Field,
-            CompletionItemKind::Trait => Interface,
-            CompletionItemKind::TypeAlias => Struct,
-            CompletionItemKind::Const => Constant,
-            CompletionItemKind::Static => Value,
-            CompletionItemKind::Method => Method,
-            CompletionItemKind::TypeParam => TypeParameter,
-            CompletionItemKind::Macro => Method,
-            CompletionItemKind::Attribute => EnumMember,
-        }
-    }
-}
-
-impl Conv for Severity {
-    type Output = DiagnosticSeverity;
-    fn conv(self) -> DiagnosticSeverity {
-        match self {
-            Severity::Error => DiagnosticSeverity::Error,
-            Severity::WeakWarning => DiagnosticSeverity::Hint,
-        }
-    }
-}
-
-impl ConvWith<(&LineIndex, LineEndings)> for CompletionItem {
-    type Output = ::lsp_types::CompletionItem;
-
-    fn conv_with(self, ctx: (&LineIndex, LineEndings)) -> ::lsp_types::CompletionItem {
-        let mut additional_text_edits = Vec::new();
-        let mut text_edit = None;
-        // LSP does not allow arbitrary edits in completion, so we have to do a
-        // non-trivial mapping here.
-        for indel in self.text_edit().as_indels() {
-            if indel.delete.contains_range(self.source_range()) {
-                text_edit = Some(if indel.delete == self.source_range() {
-                    indel.conv_with((ctx.0, ctx.1))
-                } else {
-                    assert!(self.source_range().end() == indel.delete.end());
-                    let range1 = TextRange::new(indel.delete.start(), self.source_range().start());
-                    let range2 = self.source_range();
-                    let edit1 = Indel::replace(range1, String::new());
-                    let edit2 = Indel::replace(range2, indel.insert.clone());
-                    additional_text_edits.push(edit1.conv_with((ctx.0, ctx.1)));
-                    edit2.conv_with((ctx.0, ctx.1))
-                })
-            } else {
-                assert!(self.source_range().intersect(indel.delete).is_none());
-                additional_text_edits.push(indel.conv_with((ctx.0, ctx.1)));
-            }
-        }
-        let text_edit = text_edit.unwrap();
-
-        let mut res = lsp_types::CompletionItem {
-            label: self.label().to_string(),
-            detail: self.detail().map(|it| it.to_string()),
-            filter_text: Some(self.lookup().to_string()),
-            kind: self.kind().map(|it| it.conv()),
-            text_edit: Some(text_edit.into()),
-            additional_text_edits: Some(additional_text_edits),
-            documentation: self.documentation().map(|it| it.conv()),
-            deprecated: Some(self.deprecated()),
-            command: if self.trigger_call_info() {
-                let cmd = lsp_types::Command {
-                    title: "triggerParameterHints".into(),
-                    command: "editor.action.triggerParameterHints".into(),
-                    arguments: None,
-                };
-                Some(cmd)
-            } else {
-                None
-            },
-            ..Default::default()
-        };
-
-        if self.score().is_some() {
-            res.preselect = Some(true)
-        }
-
-        if self.deprecated() {
-            res.tags = Some(vec![lsp_types::CompletionItemTag::Deprecated])
-        }
-
-        res.insert_text_format = Some(match self.insert_text_format() {
-            InsertTextFormat::Snippet => lsp_types::InsertTextFormat::Snippet,
-            InsertTextFormat::PlainText => lsp_types::InsertTextFormat::PlainText,
-        });
-
-        res
-    }
-}
-
-impl ConvWith<&LineIndex> for Position {
-    type Output = TextSize;
-
-    fn conv_with(self, line_index: &LineIndex) -> TextSize {
-        let line_col = LineCol { line: self.line as u32, col_utf16: self.character as u32 };
-        line_index.offset(line_col)
-    }
-}
-
-impl ConvWith<&LineIndex> for TextSize {
-    type Output = Position;
-
-    fn conv_with(self, line_index: &LineIndex) -> Position {
-        let line_col = line_index.line_col(self);
-        Position::new(u64::from(line_col.line), u64::from(line_col.col_utf16))
-    }
-}
-
-impl ConvWith<&LineIndex> for TextRange {
-    type Output = Range;
-
-    fn conv_with(self, line_index: &LineIndex) -> Range {
-        Range::new(self.start().conv_with(line_index), self.end().conv_with(line_index))
-    }
-}
-
-impl ConvWith<&LineIndex> for Range {
-    type Output = TextRange;
-
-    fn conv_with(self, line_index: &LineIndex) -> TextRange {
-        TextRange::new(self.start.conv_with(line_index), self.end.conv_with(line_index))
-    }
-}
-
-impl Conv for ra_ide::Documentation {
-    type Output = lsp_types::Documentation;
-    fn conv(self) -> Documentation {
-        Documentation::MarkupContent(MarkupContent {
-            kind: MarkupKind::Markdown,
-            value: crate::markdown::format_docs(self.as_str()),
-        })
-    }
-}
-
-impl ConvWith<bool> for ra_ide::FunctionSignature {
-    type Output = lsp_types::SignatureInformation;
-    fn conv_with(self, concise: bool) -> Self::Output {
-        let (label, documentation, params) = if concise {
-            let mut params = self.parameters;
-            if self.has_self_param {
-                params.remove(0);
-            }
-            (params.join(", "), None, params)
-        } else {
-            (self.to_string(), self.doc.map(|it| it.conv()), self.parameters)
-        };
-
-        let parameters: Vec<ParameterInformation> = params
-            .into_iter()
-            .map(|param| ParameterInformation {
-                label: ParameterLabel::Simple(param),
-                documentation: None,
-            })
-            .collect();
-
-        SignatureInformation { label, documentation, parameters: Some(parameters) }
-    }
-}
-
-impl ConvWith<(&LineIndex, LineEndings)> for TextEdit {
-    type Output = Vec<lsp_types::TextEdit>;
-
-    fn conv_with(self, ctx: (&LineIndex, LineEndings)) -> Vec<lsp_types::TextEdit> {
-        self.as_indels().iter().map_conv_with(ctx).collect()
-    }
-}
-
-impl ConvWith<(&LineIndex, LineEndings)> for &Indel {
-    type Output = lsp_types::TextEdit;
-
-    fn conv_with(
-        self,
-        (line_index, line_endings): (&LineIndex, LineEndings),
-    ) -> lsp_types::TextEdit {
-        let mut new_text = self.insert.clone();
-        if line_endings == LineEndings::Dos {
-            new_text = new_text.replace('\n', "\r\n");
-        }
-        lsp_types::TextEdit { range: self.delete.conv_with(line_index), new_text }
-    }
-}
-
-pub(crate) struct FoldConvCtx<'a> {
-    pub(crate) text: &'a str,
-    pub(crate) line_index: &'a LineIndex,
-    pub(crate) line_folding_only: bool,
-}
-
-impl ConvWith<&FoldConvCtx<'_>> for Fold {
-    type Output = lsp_types::FoldingRange;
-
-    fn conv_with(self, ctx: &FoldConvCtx) -> lsp_types::FoldingRange {
-        let kind = match self.kind {
-            FoldKind::Comment => Some(lsp_types::FoldingRangeKind::Comment),
-            FoldKind::Imports => Some(lsp_types::FoldingRangeKind::Imports),
-            FoldKind::Mods => None,
-            FoldKind::Block => None,
-        };
-
-        let range = self.range.conv_with(&ctx.line_index);
-
-        if ctx.line_folding_only {
-            // Clients with line_folding_only == true (such as VSCode) will fold the whole end line
-            // even if it contains text not in the folding range. To prevent that we exclude
-            // range.end.line from the folding region if there is more text after range.end
-            // on the same line.
-            let has_more_text_on_end_line = ctx.text
-                [TextRange::new(self.range.end(), TextSize::of(ctx.text))]
-            .chars()
-            .take_while(|it| *it != '\n')
-            .any(|it| !it.is_whitespace());
-
-            let end_line = if has_more_text_on_end_line {
-                range.end.line.saturating_sub(1)
-            } else {
-                range.end.line
-            };
-
-            lsp_types::FoldingRange {
-                start_line: range.start.line,
-                start_character: None,
-                end_line,
-                end_character: None,
-                kind,
-            }
-        } else {
-            lsp_types::FoldingRange {
-                start_line: range.start.line,
-                start_character: Some(range.start.character),
-                end_line: range.end.line,
-                end_character: Some(range.end.character),
-                kind,
-            }
-        }
-    }
-}
-
-impl ConvWith<&LineIndex> for InlayHint {
-    type Output = req::InlayHint;
-    fn conv_with(self, line_index: &LineIndex) -> Self::Output {
-        req::InlayHint {
-            label: self.label.to_string(),
-            range: self.range.conv_with(line_index),
-            kind: match self.kind {
-                InlayKind::ParameterHint => req::InlayKind::ParameterHint,
-                InlayKind::TypeHint => req::InlayKind::TypeHint,
-                InlayKind::ChainingHint => req::InlayKind::ChainingHint,
-            },
-        }
-    }
-}
-
-impl Conv for Highlight {
-    type Output = (u32, u32);
-
-    fn conv(self) -> Self::Output {
-        let mut mods = ModifierSet::default();
-        let type_ = match self.tag {
-            HighlightTag::Struct => SemanticTokenType::STRUCT,
-            HighlightTag::Enum => SemanticTokenType::ENUM,
-            HighlightTag::Union => UNION,
-            HighlightTag::TypeAlias => TYPE_ALIAS,
-            HighlightTag::Trait => SemanticTokenType::INTERFACE,
-            HighlightTag::BuiltinType => BUILTIN_TYPE,
-            HighlightTag::SelfType => SemanticTokenType::TYPE,
-            HighlightTag::Field => SemanticTokenType::MEMBER,
-            HighlightTag::Function => SemanticTokenType::FUNCTION,
-            HighlightTag::Module => SemanticTokenType::NAMESPACE,
-            HighlightTag::Constant => {
-                mods |= CONSTANT;
-                mods |= SemanticTokenModifier::STATIC;
-                SemanticTokenType::VARIABLE
-            }
-            HighlightTag::Static => {
-                mods |= SemanticTokenModifier::STATIC;
-                SemanticTokenType::VARIABLE
-            }
-            HighlightTag::EnumVariant => ENUM_MEMBER,
-            HighlightTag::Macro => SemanticTokenType::MACRO,
-            HighlightTag::Local => SemanticTokenType::VARIABLE,
-            HighlightTag::TypeParam => SemanticTokenType::TYPE_PARAMETER,
-            HighlightTag::Lifetime => LIFETIME,
-            HighlightTag::ByteLiteral | HighlightTag::NumericLiteral => SemanticTokenType::NUMBER,
-            HighlightTag::CharLiteral | HighlightTag::StringLiteral => SemanticTokenType::STRING,
-            HighlightTag::Comment => SemanticTokenType::COMMENT,
-            HighlightTag::Attribute => ATTRIBUTE,
-            HighlightTag::Keyword => SemanticTokenType::KEYWORD,
-            HighlightTag::UnresolvedReference => UNRESOLVED_REFERENCE,
-            HighlightTag::FormatSpecifier => FORMAT_SPECIFIER,
-        };
-
-        for modifier in self.modifiers.iter() {
-            let modifier = match modifier {
-                HighlightModifier::Definition => SemanticTokenModifier::DECLARATION,
-                HighlightModifier::ControlFlow => CONTROL_FLOW,
-                HighlightModifier::Mutable => MUTABLE,
-                HighlightModifier::Unsafe => UNSAFE,
-            };
-            mods |= modifier;
-        }
-
-        (semantic_tokens::type_index(type_), mods.0)
-    }
-}
-
-impl<T: ConvWith<CTX>, CTX> ConvWith<CTX> for Option<T> {
-    type Output = Option<T::Output>;
-
-    fn conv_with(self, ctx: CTX) -> Self::Output {
-        self.map(|x| ConvWith::conv_with(x, ctx))
-    }
-}
-
-impl TryConvWith<&WorldSnapshot> for &Url {
-    type Output = FileId;
-    fn try_conv_with(self, world: &WorldSnapshot) -> Result<FileId> {
-        world.uri_to_file_id(self)
-    }
-}
-
-impl TryConvWith<&WorldSnapshot> for FileId {
-    type Output = Url;
-    fn try_conv_with(self, world: &WorldSnapshot) -> Result<Url> {
-        world.file_id_to_uri(self)
-    }
-}
-
-impl TryConvWith<&WorldSnapshot> for &TextDocumentItem {
-    type Output = FileId;
-    fn try_conv_with(self, world: &WorldSnapshot) -> Result<FileId> {
-        self.uri.try_conv_with(world)
-    }
-}
-
-impl TryConvWith<&WorldSnapshot> for &VersionedTextDocumentIdentifier {
-    type Output = FileId;
-    fn try_conv_with(self, world: &WorldSnapshot) -> Result<FileId> {
-        self.uri.try_conv_with(world)
-    }
-}
-
-impl TryConvWith<&WorldSnapshot> for &TextDocumentIdentifier {
-    type Output = FileId;
-    fn try_conv_with(self, world: &WorldSnapshot) -> Result<FileId> {
-        world.uri_to_file_id(&self.uri)
-    }
-}
-
-impl TryConvWith<&WorldSnapshot> for &TextDocumentPositionParams {
-    type Output = FilePosition;
-    fn try_conv_with(self, world: &WorldSnapshot) -> Result<FilePosition> {
-        let file_id = self.text_document.try_conv_with(world)?;
-        let line_index = world.analysis().file_line_index(file_id)?;
-        let offset = self.position.conv_with(&line_index);
-        Ok(FilePosition { file_id, offset })
-    }
-}
-
-impl TryConvWith<&WorldSnapshot> for (&TextDocumentIdentifier, Range) {
-    type Output = FileRange;
-    fn try_conv_with(self, world: &WorldSnapshot) -> Result<FileRange> {
-        let file_id = self.0.try_conv_with(world)?;
-        let line_index = world.analysis().file_line_index(file_id)?;
-        let range = self.1.conv_with(&line_index);
-        Ok(FileRange { file_id, range })
-    }
-}
-
-impl<T: TryConvWith<CTX>, CTX: Copy> TryConvWith<CTX> for Vec<T> {
-    type Output = Vec<<T as TryConvWith<CTX>>::Output>;
-    fn try_conv_with(self, ctx: CTX) -> Result<Self::Output> {
-        let mut res = Vec::with_capacity(self.len());
-        for item in self {
-            res.push(item.try_conv_with(ctx)?);
-        }
-        Ok(res)
-    }
-}
-
-impl TryConvWith<&WorldSnapshot> for SourceChange {
-    type Output = req::SourceChange;
-    fn try_conv_with(self, world: &WorldSnapshot) -> Result<req::SourceChange> {
-        let cursor_position = match self.cursor_position {
-            None => None,
-            Some(pos) => {
-                let line_index = world.analysis().file_line_index(pos.file_id)?;
-                let edit = self
-                    .source_file_edits
-                    .iter()
-                    .find(|it| it.file_id == pos.file_id)
-                    .map(|it| &it.edit);
-                let line_col = match edit {
-                    Some(edit) => translate_offset_with_edit(&*line_index, pos.offset, edit),
-                    None => line_index.line_col(pos.offset),
-                };
-                let position =
-                    Position::new(u64::from(line_col.line), u64::from(line_col.col_utf16));
-                Some(TextDocumentPositionParams {
-                    text_document: TextDocumentIdentifier::new(pos.file_id.try_conv_with(world)?),
-                    position,
-                })
-            }
-        };
-        let mut document_changes: Vec<DocumentChangeOperation> = Vec::new();
-        for resource_op in self.file_system_edits.try_conv_with(world)? {
-            document_changes.push(DocumentChangeOperation::Op(resource_op));
-        }
-        for text_document_edit in self.source_file_edits.try_conv_with(world)? {
-            document_changes.push(DocumentChangeOperation::Edit(text_document_edit));
-        }
-        let workspace_edit = WorkspaceEdit {
-            changes: None,
-            document_changes: Some(DocumentChanges::Operations(document_changes)),
-        };
-        Ok(req::SourceChange { label: self.label, workspace_edit, cursor_position })
-    }
-}
-
-impl TryConvWith<&WorldSnapshot> for SourceFileEdit {
-    type Output = TextDocumentEdit;
-    fn try_conv_with(self, world: &WorldSnapshot) -> Result<TextDocumentEdit> {
-        let text_document = VersionedTextDocumentIdentifier {
-            uri: self.file_id.try_conv_with(world)?,
-            version: None,
-        };
-        let line_index = world.analysis().file_line_index(self.file_id)?;
-        let line_endings = world.file_line_endings(self.file_id);
-        let edits =
-            self.edit.as_indels().iter().map_conv_with((&line_index, line_endings)).collect();
-        Ok(TextDocumentEdit { text_document, edits })
-    }
-}
-
-impl TryConvWith<&WorldSnapshot> for FileSystemEdit {
-    type Output = ResourceOp;
-    fn try_conv_with(self, world: &WorldSnapshot) -> Result<ResourceOp> {
-        let res = match self {
-            FileSystemEdit::CreateFile { source_root, path } => {
-                let uri = world.path_to_uri(source_root, &path)?;
-                ResourceOp::Create(CreateFile { uri, options: None })
-            }
-            FileSystemEdit::MoveFile { src, dst_source_root, dst_path } => {
-                let old_uri = world.file_id_to_uri(src)?;
-                let new_uri = world.path_to_uri(dst_source_root, &dst_path)?;
-                ResourceOp::Rename(RenameFile { old_uri, new_uri, options: None })
-            }
-        };
-        Ok(res)
-    }
-}
-
-impl TryConvWith<&WorldSnapshot> for &NavigationTarget {
-    type Output = Location;
-    fn try_conv_with(self, world: &WorldSnapshot) -> Result<Location> {
-        let line_index = world.analysis().file_line_index(self.file_id())?;
-        let range = self.range();
-        to_location(self.file_id(), range, &world, &line_index)
-    }
-}
-
-impl TryConvWith<&WorldSnapshot> for (FileId, RangeInfo<NavigationTarget>) {
-    type Output = LocationLink;
-    fn try_conv_with(self, world: &WorldSnapshot) -> Result<LocationLink> {
-        let (src_file_id, target) = self;
-
-        let target_uri = target.info.file_id().try_conv_with(world)?;
-        let src_line_index = world.analysis().file_line_index(src_file_id)?;
-        let tgt_line_index = world.analysis().file_line_index(target.info.file_id())?;
-
-        let target_range = target.info.full_range().conv_with(&tgt_line_index);
-
-        let target_selection_range = target
-            .info
-            .focus_range()
-            .map(|it| it.conv_with(&tgt_line_index))
-            .unwrap_or(target_range);
-
-        let res = LocationLink {
-            origin_selection_range: Some(target.range.conv_with(&src_line_index)),
-            target_uri,
-            target_range,
-            target_selection_range,
-        };
-        Ok(res)
-    }
-}
-
-impl TryConvWith<&WorldSnapshot> for (FileId, RangeInfo<Vec<NavigationTarget>>) {
-    type Output = req::GotoDefinitionResponse;
-    fn try_conv_with(self, world: &WorldSnapshot) -> Result<req::GotoTypeDefinitionResponse> {
-        let (file_id, RangeInfo { range, info: navs }) = self;
-        let links = navs
-            .into_iter()
-            .map(|nav| (file_id, RangeInfo::new(range, nav)))
-            .try_conv_with_to_vec(world)?;
-        if world.config.client_caps.location_link {
-            Ok(links.into())
-        } else {
-            let locations: Vec<Location> = links
-                .into_iter()
-                .map(|link| Location { uri: link.target_uri, range: link.target_selection_range })
-                .collect();
-            Ok(locations.into())
-        }
-    }
-}
-
-pub fn to_call_hierarchy_item(
-    file_id: FileId,
-    range: TextRange,
-    world: &WorldSnapshot,
-    line_index: &LineIndex,
-    nav: NavigationTarget,
-) -> Result<lsp_types::CallHierarchyItem> {
-    Ok(lsp_types::CallHierarchyItem {
-        name: nav.name().to_string(),
-        kind: nav.kind().conv(),
-        tags: None,
-        detail: nav.description().map(|it| it.to_string()),
-        uri: file_id.try_conv_with(&world)?,
-        range: nav.range().conv_with(&line_index),
-        selection_range: range.conv_with(&line_index),
-    })
-}
-
-pub fn to_location(
-    file_id: FileId,
-    range: TextRange,
-    world: &WorldSnapshot,
-    line_index: &LineIndex,
-) -> Result<Location> {
-    let url = file_id.try_conv_with(world)?;
-    let loc = Location::new(url, range.conv_with(line_index));
-    Ok(loc)
-}
-
-pub trait MapConvWith<CTX>: Sized {
-    type Output;
-
-    fn map_conv_with(self, ctx: CTX) -> ConvWithIter<Self, CTX> {
-        ConvWithIter { iter: self, ctx }
-    }
-}
-
-impl<CTX, I> MapConvWith<CTX> for I
-where
-    I: Iterator,
-    I::Item: ConvWith<CTX>,
-{
-    type Output = <I::Item as ConvWith<CTX>>::Output;
-}
-
-pub struct ConvWithIter<I, CTX> {
-    iter: I,
-    ctx: CTX,
-}
-
-impl<I, CTX> Iterator for ConvWithIter<I, CTX>
-where
-    I: Iterator,
-    I::Item: ConvWith<CTX>,
-    CTX: Copy,
-{
-    type Item = <I::Item as ConvWith<CTX>>::Output;
-
-    fn next(&mut self) -> Option<Self::Item> {
-        self.iter.next().map(|item| item.conv_with(self.ctx))
-    }
-}
-
-pub trait TryConvWithToVec<CTX>: Sized {
-    type Output;
-
-    fn try_conv_with_to_vec(self, ctx: CTX) -> Result<Vec<Self::Output>>;
-}
-
-impl<I, CTX> TryConvWithToVec<CTX> for I
-where
-    I: Iterator,
-    I::Item: TryConvWith<CTX>,
-    CTX: Copy,
-{
-    type Output = <I::Item as TryConvWith<CTX>>::Output;
-
-    fn try_conv_with_to_vec(self, ctx: CTX) -> Result<Vec<Self::Output>> {
-        self.map(|it| it.try_conv_with(ctx)).collect()
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use test_utils::extract_ranges;
-
-    #[test]
-    fn conv_fold_line_folding_only_fixup() {
-        let text = r#"<fold>mod a;
-mod b;
-mod c;</fold>
-
-fn main() <fold>{
-    if cond <fold>{
-        a::do_a();
-    }</fold> else <fold>{
-        b::do_b();
-    }</fold>
-}</fold>"#;
-
-        let (ranges, text) = extract_ranges(text, "fold");
-        assert_eq!(ranges.len(), 4);
-        let folds = vec![
-            Fold { range: ranges[0], kind: FoldKind::Mods },
-            Fold { range: ranges[1], kind: FoldKind::Block },
-            Fold { range: ranges[2], kind: FoldKind::Block },
-            Fold { range: ranges[3], kind: FoldKind::Block },
-        ];
-
-        let line_index = LineIndex::new(&text);
-        let ctx = FoldConvCtx { text: &text, line_index: &line_index, line_folding_only: true };
-        let converted: Vec<_> = folds.into_iter().map_conv_with(&ctx).collect();
-
-        let expected_lines = [(0, 2), (4, 10), (5, 6), (7, 9)];
-        assert_eq!(converted.len(), expected_lines.len());
-        for (folding_range, (start_line, end_line)) in converted.iter().zip(expected_lines.iter()) {
-            assert_eq!(folding_range.start_line, *start_line);
-            assert_eq!(folding_range.start_character, None);
-            assert_eq!(folding_range.end_line, *end_line);
-            assert_eq!(folding_range.end_character, None);
-        }
-    }
-}
diff --git a/crates/rust-analyzer/src/from_proto.rs b/crates/rust-analyzer/src/from_proto.rs
new file mode 100644
index 000000000..4bb16a496
--- /dev/null
+++ b/crates/rust-analyzer/src/from_proto.rs
@@ -0,0 +1,42 @@
+//! Conversion lsp_types types to rust-analyzer specific ones.
+use ra_db::{FileId, FilePosition, FileRange};
+use ra_ide::{LineCol, LineIndex};
+use ra_syntax::{TextRange, TextSize};
+
+use crate::{world::WorldSnapshot, Result};
+
+pub(crate) fn offset(line_index: &LineIndex, position: lsp_types::Position) -> TextSize {
+    let line_col = LineCol { line: position.line as u32, col_utf16: position.character as u32 };
+    line_index.offset(line_col)
+}
+
+pub(crate) fn text_range(line_index: &LineIndex, range: lsp_types::Range) -> TextRange {
+    let start = offset(line_index, range.start);
+    let end = offset(line_index, range.end);
+    TextRange::new(start, end)
+}
+
+pub(crate) fn file_id(world: &WorldSnapshot, url: &lsp_types::Url) -> Result<FileId> {
+    world.uri_to_file_id(url)
+}
+
+pub(crate) fn file_position(
+    world: &WorldSnapshot,
+    tdpp: lsp_types::TextDocumentPositionParams,
+) -> Result<FilePosition> {
+    let file_id = file_id(world, &tdpp.text_document.uri)?;
+    let line_index = world.analysis().file_line_index(file_id)?;
+    let offset = offset(&*line_index, tdpp.position);
+    Ok(FilePosition { file_id, offset })
+}
+
+pub(crate) fn file_range(
+    world: &WorldSnapshot,
+    text_document_identifier: lsp_types::TextDocumentIdentifier,
+    range: lsp_types::Range,
+) -> Result<FileRange> {
+    let file_id = file_id(world, &text_document_identifier.uri)?;
+    let line_index = world.analysis().file_line_index(file_id)?;
+    let range = text_range(&line_index, range);
+    Ok(FileRange { file_id, range })
+}
diff --git a/crates/rust-analyzer/src/lib.rs b/crates/rust-analyzer/src/lib.rs
index 036bf62a7..57d0e9218 100644
--- a/crates/rust-analyzer/src/lib.rs
+++ b/crates/rust-analyzer/src/lib.rs
@@ -20,10 +20,11 @@ macro_rules! eprintln {
 mod vfs_glob;
 mod caps;
 mod cargo_target_spec;
-mod conv;
+mod to_proto;
+mod from_proto;
 mod main_loop;
 mod markdown;
-pub mod req;
+pub mod lsp_ext;
 pub mod config;
 mod world;
 mod diagnostics;
diff --git a/crates/rust-analyzer/src/req.rs b/crates/rust-analyzer/src/lsp_ext.rs
index 0dae6bad4..313a8c769 100644
--- a/crates/rust-analyzer/src/req.rs
+++ b/crates/rust-analyzer/src/lsp_ext.rs
@@ -1,25 +1,12 @@
-//! Defines `rust-analyzer` specific custom messages.
+//! rust-analyzer extensions to the LSP.
 
+use std::path::PathBuf;
+
+use lsp_types::request::Request;
 use lsp_types::{Location, Position, Range, TextDocumentIdentifier};
 use rustc_hash::FxHashMap;
 use serde::{Deserialize, Serialize};
 
-pub use lsp_types::{
-    notification::*, request::*, ApplyWorkspaceEditParams, CodeActionParams, CodeLens,
-    CodeLensParams, CompletionParams, CompletionResponse, ConfigurationItem, ConfigurationParams,
-    DiagnosticTag, DidChangeConfigurationParams, DidChangeWatchedFilesParams,
-    DidChangeWatchedFilesRegistrationOptions, DocumentHighlightParams,
-    DocumentOnTypeFormattingParams, DocumentSymbolParams, DocumentSymbolResponse,
-    FileSystemWatcher, GotoDefinitionParams, GotoDefinitionResponse, Hover, HoverParams,
-    InitializeResult, MessageType, PartialResultParams, ProgressParams, ProgressParamsValue,
-    ProgressToken, PublishDiagnosticsParams, ReferenceParams, Registration, RegistrationParams,
-    SelectionRange, SelectionRangeParams, SemanticTokensParams, SemanticTokensRangeParams,
-    SemanticTokensRangeResult, SemanticTokensResult, ServerCapabilities, ShowMessageParams,
-    SignatureHelp, SignatureHelpParams, SymbolKind, TextDocumentEdit, TextDocumentPositionParams,
-    TextEdit, WorkDoneProgressParams, WorkspaceEdit, WorkspaceSymbolParams,
-};
-use std::path::PathBuf;
-
 pub enum AnalyzerStatus {}
 
 impl Request for AnalyzerStatus {
@@ -91,7 +78,7 @@ pub struct FindMatchingBraceParams {
 pub enum ParentModule {}
 
 impl Request for ParentModule {
-    type Params = TextDocumentPositionParams;
+    type Params = lsp_types::TextDocumentPositionParams;
     type Result = Vec<Location>;
     const METHOD: &'static str = "rust-analyzer/parentModule";
 }
@@ -114,7 +101,7 @@ pub struct JoinLinesParams {
 pub enum OnEnter {}
 
 impl Request for OnEnter {
-    type Params = TextDocumentPositionParams;
+    type Params = lsp_types::TextDocumentPositionParams;
     type Result = Option<SourceChange>;
     const METHOD: &'static str = "rust-analyzer/onEnter";
 }
@@ -150,8 +137,8 @@ pub struct Runnable {
 #[serde(rename_all = "camelCase")]
 pub struct SourceChange {
     pub label: String,
-    pub workspace_edit: WorkspaceEdit,
-    pub cursor_position: Option<TextDocumentPositionParams>,
+    pub workspace_edit: lsp_types::WorkspaceEdit,
+    pub cursor_position: Option<lsp_types::TextDocumentPositionParams>,
 }
 
 pub enum InlayHints {}
diff --git a/crates/rust-analyzer/src/main_loop.rs b/crates/rust-analyzer/src/main_loop.rs
index b77f0c5a9..3f12dd718 100644
--- a/crates/rust-analyzer/src/main_loop.rs
+++ b/crates/rust-analyzer/src/main_loop.rs
@@ -37,13 +37,12 @@ use threadpool::ThreadPool;
 
 use crate::{
     config::{Config, FilesWatcher},
-    conv::{ConvWith, TryConvWith},
     diagnostics::DiagnosticTask,
+    from_proto, lsp_ext,
     main_loop::{
         pending_requests::{PendingRequest, PendingRequests},
         subscriptions::Subscriptions,
     },
-    req,
     world::{WorldSnapshot, WorldState},
     Result,
 };
@@ -96,23 +95,21 @@ pub fn main_loop(ws_roots: Vec<PathBuf>, config: Config, connection: Connection)
     let mut world_state = {
         let workspaces = {
             // FIXME: support dynamic workspace loading.
-            let mut visited = FxHashSet::default();
-            let project_roots = ws_roots
+            let project_roots: FxHashSet<_> = ws_roots
                 .iter()
                 .filter_map(|it| ra_project_model::ProjectRoot::discover(it).ok())
                 .flatten()
-                .filter(|it| visited.insert(it.clone()))
-                .collect::<Vec<_>>();
+                .collect();
 
             if project_roots.is_empty() && config.notifications.cargo_toml_not_found {
                 show_message(
-                        req::MessageType::Error,
-                        format!(
-                            "rust-analyzer failed to discover workspace, no Cargo.toml found, dirs searched: {}",
-                            ws_roots.iter().format_with(", ", |it, f| f(&it.display()))
-                        ),
-                        &connection.sender,
-                    );
+                    lsp_types::MessageType::Error,
+                    format!(
+                        "rust-analyzer failed to discover workspace, no Cargo.toml found, dirs searched: {}",
+                        ws_roots.iter().format_with(", ", |it, f| f(&it.display()))
+                    ),
+                    &connection.sender,
+                );
             };
 
             project_roots
@@ -126,7 +123,7 @@ pub fn main_loop(ws_roots: Vec<PathBuf>, config: Config, connection: Connection)
                     .map_err(|err| {
                         log::error!("failed to load workspace: {:#}", err);
                         show_message(
-                            req::MessageType::Error,
+                            lsp_types::MessageType::Error,
                             format!("rust-analyzer failed to load workspace: {:#}", err),
                             &connection.sender,
                         );
@@ -144,23 +141,25 @@ pub fn main_loop(ws_roots: Vec<PathBuf>, config: Config, connection: Connection)
             .collect::<std::result::Result<Vec<_>, _>>()?;
 
         if let FilesWatcher::Client = config.files.watcher {
-            let registration_options = req::DidChangeWatchedFilesRegistrationOptions {
+            let registration_options = lsp_types::DidChangeWatchedFilesRegistrationOptions {
                 watchers: workspaces
                     .iter()
                     .flat_map(ProjectWorkspace::to_roots)
                     .filter(PackageRoot::is_member)
                     .map(|root| format!("{}/**/*.rs", root.path().display()))
-                    .map(|glob_pattern| req::FileSystemWatcher { glob_pattern, kind: None })
+                    .map(|glob_pattern| lsp_types::FileSystemWatcher { glob_pattern, kind: None })
                     .collect(),
             };
-            let registration = req::Registration {
+            let registration = lsp_types::Registration {
                 id: "file-watcher".to_string(),
                 method: "workspace/didChangeWatchedFiles".to_string(),
                 register_options: Some(serde_json::to_value(registration_options).unwrap()),
             };
-            let params = req::RegistrationParams { registrations: vec![registration] };
-            let request =
-                request_new::<req::RegisterCapability>(loop_state.next_request_id(), params);
+            let params = lsp_types::RegistrationParams { registrations: vec![registration] };
+            let request = request_new::<lsp_types::request::RegisterCapability>(
+                loop_state.next_request_id(),
+                params,
+            );
             connection.sender.send(request.into()).unwrap();
         }
 
@@ -175,7 +174,6 @@ pub fn main_loop(ws_roots: Vec<PathBuf>, config: Config, connection: Connection)
     };
 
     loop_state.roots_total = world_state.vfs.read().n_roots();
-    loop_state.roots_scanned = 0;
 
     let pool = ThreadPool::default();
     let (task_sender, task_receiver) = unbounded::<Task>();
@@ -260,14 +258,14 @@ impl fmt::Debug for Event {
 
         match self {
             Event::Msg(Message::Notification(not)) => {
-                if notification_is::<req::DidOpenTextDocument>(not)
-                    || notification_is::<req::DidChangeTextDocument>(not)
+                if notification_is::<lsp_types::notification::DidOpenTextDocument>(not)
+                    || notification_is::<lsp_types::notification::DidChangeTextDocument>(not)
                 {
                     return debug_verbose_not(not, f);
                 }
             }
             Event::Task(Task::Notify(not)) => {
-                if notification_is::<req::PublishDiagnostics>(not) {
+                if notification_is::<lsp_types::notification::PublishDiagnostics>(not) {
                     return debug_verbose_not(not, f);
                 }
             }
@@ -402,10 +400,12 @@ fn loop_turn(
     }
 
     let max_in_flight_libs = pool.max_count().saturating_sub(2).max(1);
-    while loop_state.in_flight_libraries < max_in_flight_libs
-        && !loop_state.pending_libraries.is_empty()
-    {
-        let (root, files) = loop_state.pending_libraries.pop().unwrap();
+    while loop_state.in_flight_libraries < max_in_flight_libs {
+        let (root, files) = match loop_state.pending_libraries.pop() {
+            Some(it) => it,
+            None => break,
+        };
+
         loop_state.in_flight_libraries += 1;
         let sender = libdata_sender.clone();
         pool.execute(move || {
@@ -452,7 +452,7 @@ fn loop_turn(
         log::error!("overly long loop turn: {:?}", loop_duration);
         if env::var("RA_PROFILE").is_ok() {
             show_message(
-                req::MessageType::Error,
+                lsp_types::MessageType::Error,
                 format!("overly long loop turn: {:?}", loop_duration),
                 &connection.sender,
             );
@@ -502,45 +502,51 @@ fn on_request(
         request_received,
     };
     pool_dispatcher
-        .on_sync::<req::CollectGarbage>(|s, ()| Ok(s.collect_garbage()))?
-        .on_sync::<req::JoinLines>(|s, p| handlers::handle_join_lines(s.snapshot(), p))?
-        .on_sync::<req::OnEnter>(|s, p| handlers::handle_on_enter(s.snapshot(), p))?
-        .on_sync::<req::SelectionRangeRequest>(|s, p| {
+        .on_sync::<lsp_ext::CollectGarbage>(|s, ()| Ok(s.collect_garbage()))?
+        .on_sync::<lsp_ext::JoinLines>(|s, p| handlers::handle_join_lines(s.snapshot(), p))?
+        .on_sync::<lsp_ext::OnEnter>(|s, p| handlers::handle_on_enter(s.snapshot(), p))?
+        .on_sync::<lsp_types::request::SelectionRangeRequest>(|s, p| {
             handlers::handle_selection_range(s.snapshot(), p)
         })?
-        .on_sync::<req::FindMatchingBrace>(|s, p| {
+        .on_sync::<lsp_ext::FindMatchingBrace>(|s, p| {
             handlers::handle_find_matching_brace(s.snapshot(), p)
         })?
-        .on::<req::AnalyzerStatus>(handlers::handle_analyzer_status)?
-        .on::<req::SyntaxTree>(handlers::handle_syntax_tree)?
-        .on::<req::ExpandMacro>(handlers::handle_expand_macro)?
-        .on::<req::OnTypeFormatting>(handlers::handle_on_type_formatting)?
-        .on::<req::DocumentSymbolRequest>(handlers::handle_document_symbol)?
-        .on::<req::WorkspaceSymbol>(handlers::handle_workspace_symbol)?
-        .on::<req::GotoDefinition>(handlers::handle_goto_definition)?
-        .on::<req::GotoImplementation>(handlers::handle_goto_implementation)?
-        .on::<req::GotoTypeDefinition>(handlers::handle_goto_type_definition)?
-        .on::<req::ParentModule>(handlers::handle_parent_module)?
-        .on::<req::Runnables>(handlers::handle_runnables)?
-        .on::<req::Completion>(handlers::handle_completion)?
-        .on::<req::CodeActionRequest>(handlers::handle_code_action)?
-        .on::<req::CodeLensRequest>(handlers::handle_code_lens)?
-        .on::<req::CodeLensResolve>(handlers::handle_code_lens_resolve)?
-        .on::<req::FoldingRangeRequest>(handlers::handle_folding_range)?
-        .on::<req::SignatureHelpRequest>(handlers::handle_signature_help)?
-        .on::<req::HoverRequest>(handlers::handle_hover)?
-        .on::<req::PrepareRenameRequest>(handlers::handle_prepare_rename)?
-        .on::<req::Rename>(handlers::handle_rename)?
-        .on::<req::References>(handlers::handle_references)?
-        .on::<req::Formatting>(handlers::handle_formatting)?
-        .on::<req::DocumentHighlightRequest>(handlers::handle_document_highlight)?
-        .on::<req::InlayHints>(handlers::handle_inlay_hints)?
-        .on::<req::CallHierarchyPrepare>(handlers::handle_call_hierarchy_prepare)?
-        .on::<req::CallHierarchyIncomingCalls>(handlers::handle_call_hierarchy_incoming)?
-        .on::<req::CallHierarchyOutgoingCalls>(handlers::handle_call_hierarchy_outgoing)?
-        .on::<req::SemanticTokensRequest>(handlers::handle_semantic_tokens)?
-        .on::<req::SemanticTokensRangeRequest>(handlers::handle_semantic_tokens_range)?
-        .on::<req::Ssr>(handlers::handle_ssr)?
+        .on::<lsp_ext::AnalyzerStatus>(handlers::handle_analyzer_status)?
+        .on::<lsp_ext::SyntaxTree>(handlers::handle_syntax_tree)?
+        .on::<lsp_ext::ExpandMacro>(handlers::handle_expand_macro)?
+        .on::<lsp_ext::ParentModule>(handlers::handle_parent_module)?
+        .on::<lsp_ext::Runnables>(handlers::handle_runnables)?
+        .on::<lsp_ext::InlayHints>(handlers::handle_inlay_hints)?
+        .on::<lsp_types::request::OnTypeFormatting>(handlers::handle_on_type_formatting)?
+        .on::<lsp_types::request::DocumentSymbolRequest>(handlers::handle_document_symbol)?
+        .on::<lsp_types::request::WorkspaceSymbol>(handlers::handle_workspace_symbol)?
+        .on::<lsp_types::request::GotoDefinition>(handlers::handle_goto_definition)?
+        .on::<lsp_types::request::GotoImplementation>(handlers::handle_goto_implementation)?
+        .on::<lsp_types::request::GotoTypeDefinition>(handlers::handle_goto_type_definition)?
+        .on::<lsp_types::request::Completion>(handlers::handle_completion)?
+        .on::<lsp_types::request::CodeActionRequest>(handlers::handle_code_action)?
+        .on::<lsp_types::request::CodeLensRequest>(handlers::handle_code_lens)?
+        .on::<lsp_types::request::CodeLensResolve>(handlers::handle_code_lens_resolve)?
+        .on::<lsp_types::request::FoldingRangeRequest>(handlers::handle_folding_range)?
+        .on::<lsp_types::request::SignatureHelpRequest>(handlers::handle_signature_help)?
+        .on::<lsp_types::request::HoverRequest>(handlers::handle_hover)?
+        .on::<lsp_types::request::PrepareRenameRequest>(handlers::handle_prepare_rename)?
+        .on::<lsp_types::request::Rename>(handlers::handle_rename)?
+        .on::<lsp_types::request::References>(handlers::handle_references)?
+        .on::<lsp_types::request::Formatting>(handlers::handle_formatting)?
+        .on::<lsp_types::request::DocumentHighlightRequest>(handlers::handle_document_highlight)?
+        .on::<lsp_types::request::CallHierarchyPrepare>(handlers::handle_call_hierarchy_prepare)?
+        .on::<lsp_types::request::CallHierarchyIncomingCalls>(
+            handlers::handle_call_hierarchy_incoming,
+        )?
+        .on::<lsp_types::request::CallHierarchyOutgoingCalls>(
+            handlers::handle_call_hierarchy_outgoing,
+        )?
+        .on::<lsp_types::request::SemanticTokensRequest>(handlers::handle_semantic_tokens)?
+        .on::<lsp_types::request::SemanticTokensRangeRequest>(
+            handlers::handle_semantic_tokens_range,
+        )?
+        .on::<lsp_ext::Ssr>(handlers::handle_ssr)?
         .finish();
     Ok(())
 }
@@ -551,7 +557,7 @@ fn on_notification(
     loop_state: &mut LoopState,
     not: Notification,
 ) -> Result<()> {
-    let not = match notification_cast::<req::Cancel>(not) {
+    let not = match notification_cast::<lsp_types::notification::Cancel>(not) {
         Ok(params) => {
             let id: RequestId = match params.id {
                 NumberOrString::Number(id) => id.into(),
@@ -569,7 +575,7 @@ fn on_notification(
         }
         Err(not) => not,
     };
-    let not = match notification_cast::<req::DidOpenTextDocument>(not) {
+    let not = match notification_cast::<lsp_types::notification::DidOpenTextDocument>(not) {
         Ok(params) => {
             let uri = params.text_document.uri;
             let path = uri.to_file_path().map_err(|()| format!("invalid uri: {}", uri))?;
@@ -582,11 +588,11 @@ fn on_notification(
         }
         Err(not) => not,
     };
-    let not = match notification_cast::<req::DidChangeTextDocument>(not) {
+    let not = match notification_cast::<lsp_types::notification::DidChangeTextDocument>(not) {
         Ok(params) => {
             let DidChangeTextDocumentParams { text_document, content_changes } = params;
             let world = state.snapshot();
-            let file_id = text_document.try_conv_with(&world)?;
+            let file_id = from_proto::file_id(&world, &text_document.uri)?;
             let line_index = world.analysis().file_line_index(file_id)?;
             let uri = text_document.uri;
             let path = uri.to_file_path().map_err(|()| format!("invalid uri: {}", uri))?;
@@ -597,7 +603,7 @@ fn on_notification(
         }
         Err(not) => not,
     };
-    let not = match notification_cast::<req::DidSaveTextDocument>(not) {
+    let not = match notification_cast::<lsp_types::notification::DidSaveTextDocument>(not) {
         Ok(_params) => {
             if let Some(flycheck) = &state.flycheck {
                 flycheck.update();
@@ -606,7 +612,7 @@ fn on_notification(
         }
         Err(not) => not,
     };
-    let not = match notification_cast::<req::DidCloseTextDocument>(not) {
+    let not = match notification_cast::<lsp_types::notification::DidCloseTextDocument>(not) {
         Ok(params) => {
             let uri = params.text_document.uri;
             let path = uri.to_file_path().map_err(|()| format!("invalid uri: {}", uri))?;
@@ -614,22 +620,22 @@ fn on_notification(
                 loop_state.subscriptions.remove_sub(FileId(file_id.0));
             }
             let params =
-                req::PublishDiagnosticsParams { uri, diagnostics: Vec::new(), version: None };
-            let not = notification_new::<req::PublishDiagnostics>(params);
+                lsp_types::PublishDiagnosticsParams { uri, diagnostics: Vec::new(), version: None };
+            let not = notification_new::<lsp_types::notification::PublishDiagnostics>(params);
             msg_sender.send(not.into()).unwrap();
             return Ok(());
         }
         Err(not) => not,
     };
-    let not = match notification_cast::<req::DidChangeConfiguration>(not) {
+    let not = match notification_cast::<lsp_types::notification::DidChangeConfiguration>(not) {
         Ok(_) => {
             // As stated in https://github.com/microsoft/language-server-protocol/issues/676,
             // this notification's parameters should be ignored and the actual config queried separately.
             let request_id = loop_state.next_request_id();
-            let request = request_new::<req::WorkspaceConfiguration>(
+            let request = request_new::<lsp_types::request::WorkspaceConfiguration>(
                 request_id.clone(),
-                req::ConfigurationParams {
-                    items: vec![req::ConfigurationItem {
+                lsp_types::ConfigurationParams {
+                    items: vec![lsp_types::ConfigurationItem {
                         scope_uri: None,
                         section: Some("rust-analyzer".to_string()),
                     }],
@@ -642,7 +648,7 @@ fn on_notification(
         }
         Err(not) => not,
     };
-    let not = match notification_cast::<req::DidChangeWatchedFiles>(not) {
+    let not = match notification_cast::<lsp_types::notification::DidChangeWatchedFiles>(not) {
         Ok(params) => {
             let mut vfs = state.vfs.write();
             for change in params.changes {
@@ -696,7 +702,7 @@ fn apply_document_changes(
                     line_index = Cow::Owned(LineIndex::new(&old_text));
                 }
                 index_valid = IndexValid::UpToLineExclusive(range.start.line);
-                let range = range.conv_with(&line_index);
+                let range = from_proto::text_range(&line_index, range);
                 let mut text = old_text.to_owned();
                 match std::panic::catch_unwind(move || {
                     text.replace_range(Range::<usize>::from(range), &change.text);
@@ -744,11 +750,11 @@ fn on_check_task(
         }
 
         CheckTask::Status(progress) => {
-            let params = req::ProgressParams {
-                token: req::ProgressToken::String("rustAnalyzer/cargoWatcher".to_string()),
-                value: req::ProgressParamsValue::WorkDone(progress),
+            let params = lsp_types::ProgressParams {
+                token: lsp_types::ProgressToken::String("rustAnalyzer/cargoWatcher".to_string()),
+                value: lsp_types::ProgressParamsValue::WorkDone(progress),
             };
-            let not = notification_new::<req::Progress>(params);
+            let not = notification_new::<lsp_types::notification::Progress>(params);
             task_sender.send(Task::Notify(not)).unwrap();
         }
     };
@@ -770,8 +776,8 @@ fn on_diagnostic_task(task: DiagnosticTask, msg_sender: &Sender<Message>, state:
         };
 
         let diagnostics = state.diagnostics.diagnostics_for(file_id).cloned().collect();
-        let params = req::PublishDiagnosticsParams { uri, diagnostics, version: None };
-        let not = notification_new::<req::PublishDiagnostics>(params);
+        let params = lsp_types::PublishDiagnosticsParams { uri, diagnostics, version: None };
+        let not = notification_new::<lsp_types::notification::PublishDiagnostics>(params);
         msg_sender.send(not.into()).unwrap();
     }
 }
@@ -784,10 +790,10 @@ fn send_startup_progress(sender: &Sender<Message>, loop_state: &mut LoopState) {
 
     match (prev, loop_state.workspace_loaded) {
         (None, false) => {
-            let work_done_progress_create = request_new::<req::WorkDoneProgressCreate>(
+            let work_done_progress_create = request_new::<lsp_types::request::WorkDoneProgressCreate>(
                 loop_state.next_request_id(),
                 WorkDoneProgressCreateParams {
-                    token: req::ProgressToken::String("rustAnalyzer/startup".into()),
+                    token: lsp_types::ProgressToken::String("rustAnalyzer/startup".into()),
                 },
             );
             sender.send(work_done_progress_create.into()).unwrap();
@@ -819,10 +825,11 @@ fn send_startup_progress(sender: &Sender<Message>, loop_state: &mut LoopState) {
     }
 
     fn send_startup_progress_notif(sender: &Sender<Message>, work_done_progress: WorkDoneProgress) {
-        let notif = notification_new::<req::Progress>(req::ProgressParams {
-            token: req::ProgressToken::String("rustAnalyzer/startup".into()),
-            value: req::ProgressParamsValue::WorkDone(work_done_progress),
-        });
+        let notif =
+            notification_new::<lsp_types::notification::Progress>(lsp_types::ProgressParams {
+                token: lsp_types::ProgressToken::String("rustAnalyzer/startup".into()),
+                value: lsp_types::ProgressParamsValue::WorkDone(work_done_progress),
+            });
         sender.send(notif.into()).unwrap();
     }
 }
@@ -844,7 +851,7 @@ impl<'a> PoolDispatcher<'a> {
         f: fn(&mut WorldState, R::Params) -> Result<R::Result>,
     ) -> Result<&mut Self>
     where
-        R: req::Request + 'static,
+        R: lsp_types::request::Request + 'static,
         R::Params: DeserializeOwned + panic::UnwindSafe + 'static,
         R::Result: Serialize + 'static,
     {
@@ -867,7 +874,7 @@ impl<'a> PoolDispatcher<'a> {
     /// Dispatches the request onto thread pool
     fn on<R>(&mut self, f: fn(WorldSnapshot, R::Params) -> Result<R::Result>) -> Result<&mut Self>
     where
-        R: req::Request + 'static,
+        R: lsp_types::request::Request + 'static,
         R::Params: DeserializeOwned + Send + 'static,
         R::Result: Serialize + 'static,
     {
@@ -893,7 +900,7 @@ impl<'a> PoolDispatcher<'a> {
 
     fn parse<R>(&mut self) -> Option<(RequestId, R::Params)>
     where
-        R: req::Request + 'static,
+        R: lsp_types::request::Request + 'static,
         R::Params: DeserializeOwned + 'static,
     {
         let req = self.req.take()?;
@@ -930,7 +937,7 @@ impl<'a> PoolDispatcher<'a> {
 
 fn result_to_task<R>(id: RequestId, result: Result<R::Result>) -> Task
 where
-    R: req::Request + 'static,
+    R: lsp_types::request::Request + 'static,
     R::Params: DeserializeOwned + 'static,
     R::Result: Serialize + 'static,
 {
@@ -986,10 +993,14 @@ fn update_file_notifications_on_threadpool(
     }
 }
 
-pub fn show_message(typ: req::MessageType, message: impl Into<String>, sender: &Sender<Message>) {
+pub fn show_message(
+    typ: lsp_types::MessageType,
+    message: impl Into<String>,
+    sender: &Sender<Message>,
+) {
     let message = message.into();
-    let params = req::ShowMessageParams { typ, message };
-    let not = notification_new::<req::ShowMessage>(params);
+    let params = lsp_types::ShowMessageParams { typ, message };
+    let not = notification_new::<lsp_types::notification::ShowMessage>(params);
     sender.send(not.into()).unwrap();
 }
 
diff --git a/crates/rust-analyzer/src/main_loop/handlers.rs b/crates/rust-analyzer/src/main_loop/handlers.rs
index f4353af64..be8688bc3 100644
--- a/crates/rust-analyzer/src/main_loop/handlers.rs
+++ b/crates/rust-analyzer/src/main_loop/handlers.rs
@@ -22,6 +22,7 @@ use ra_ide::{
     Assist, FileId, FilePosition, FileRange, Query, RangeInfo, Runnable, RunnableKind, SearchScope,
 };
 use ra_prof::profile;
+use ra_project_model::TargetKind;
 use ra_syntax::{AstNode, SyntaxKind, TextRange, TextSize};
 use rustc_hash::FxHashMap;
 use serde::{Deserialize, Serialize};
@@ -31,18 +32,13 @@ use stdx::format_to;
 use crate::{
     cargo_target_spec::CargoTargetSpec,
     config::RustfmtConfig,
-    conv::{
-        to_call_hierarchy_item, to_location, Conv, ConvWith, FoldConvCtx, MapConvWith, TryConvWith,
-        TryConvWithToVec,
-    },
     diagnostics::DiagnosticTask,
-    from_json,
-    req::{self, InlayHint, InlayHintsParams},
-    semantic_tokens::SemanticTokensBuilder,
+    from_json, from_proto,
+    lsp_ext::{self, InlayHint, InlayHintsParams},
+    to_proto,
     world::WorldSnapshot,
     LspError, Result,
 };
-use ra_project_model::TargetKind;
 
 pub fn handle_analyzer_status(world: WorldSnapshot, _: ()) -> Result<String> {
     let _p = profile("handle_analyzer_status");
@@ -56,48 +52,51 @@ pub fn handle_analyzer_status(world: WorldSnapshot, _: ()) -> Result<String> {
     Ok(buf)
 }
 
-pub fn handle_syntax_tree(world: WorldSnapshot, params: req::SyntaxTreeParams) -> Result<String> {
+pub fn handle_syntax_tree(
+    world: WorldSnapshot,
+    params: lsp_ext::SyntaxTreeParams,
+) -> Result<String> {
     let _p = profile("handle_syntax_tree");
-    let id = params.text_document.try_conv_with(&world)?;
+    let id = from_proto::file_id(&world, &params.text_document.uri)?;
     let line_index = world.analysis().file_line_index(id)?;
-    let text_range = params.range.map(|p| p.conv_with(&line_index));
+    let text_range = params.range.map(|r| from_proto::text_range(&line_index, r));
     let res = world.analysis().syntax_tree(id, text_range)?;
     Ok(res)
 }
 
 pub fn handle_expand_macro(
     world: WorldSnapshot,
-    params: req::ExpandMacroParams,
-) -> Result<Option<req::ExpandedMacro>> {
+    params: lsp_ext::ExpandMacroParams,
+) -> Result<Option<lsp_ext::ExpandedMacro>> {
     let _p = profile("handle_expand_macro");
-    let file_id = params.text_document.try_conv_with(&world)?;
+    let file_id = from_proto::file_id(&world, &params.text_document.uri)?;
     let line_index = world.analysis().file_line_index(file_id)?;
-    let offset = params.position.map(|p| p.conv_with(&line_index));
+    let offset = params.position.map(|p| from_proto::offset(&line_index, p));
 
     match offset {
         None => Ok(None),
         Some(offset) => {
             let res = world.analysis().expand_macro(FilePosition { file_id, offset })?;
-            Ok(res.map(|it| req::ExpandedMacro { name: it.name, expansion: it.expansion }))
+            Ok(res.map(|it| lsp_ext::ExpandedMacro { name: it.name, expansion: it.expansion }))
         }
     }
 }
 
 pub fn handle_selection_range(
     world: WorldSnapshot,
-    params: req::SelectionRangeParams,
-) -> Result<Option<Vec<req::SelectionRange>>> {
+    params: lsp_types::SelectionRangeParams,
+) -> Result<Option<Vec<lsp_types::SelectionRange>>> {
     let _p = profile("handle_selection_range");
-    let file_id = params.text_document.try_conv_with(&world)?;
+    let file_id = from_proto::file_id(&world, &params.text_document.uri)?;
     let line_index = world.analysis().file_line_index(file_id)?;
-    let res: Result<Vec<req::SelectionRange>> = params
+    let res: Result<Vec<lsp_types::SelectionRange>> = params
         .positions
         .into_iter()
-        .map_conv_with(&line_index)
         .map(|position| {
+            let offset = from_proto::offset(&line_index, position);
             let mut ranges = Vec::new();
             {
-                let mut range = TextRange::new(position, position);
+                let mut range = TextRange::new(offset, offset);
                 loop {
                     ranges.push(range);
                     let frange = FileRange { file_id, range };
@@ -109,13 +108,13 @@ pub fn handle_selection_range(
                     }
                 }
             }
-            let mut range = req::SelectionRange {
-                range: ranges.last().unwrap().conv_with(&line_index),
+            let mut range = lsp_types::SelectionRange {
+                range: to_proto::range(&line_index, *ranges.last().unwrap()),
                 parent: None,
             };
-            for r in ranges.iter().rev().skip(1) {
-                range = req::SelectionRange {
-                    range: r.conv_with(&line_index),
+            for &r in ranges.iter().rev().skip(1) {
+                range = lsp_types::SelectionRange {
+                    range: to_proto::range(&line_index, r),
                     parent: Some(Box::new(range)),
                 }
             }
@@ -128,57 +127,55 @@ pub fn handle_selection_range(
 
 pub fn handle_find_matching_brace(
     world: WorldSnapshot,
-    params: req::FindMatchingBraceParams,
+    params: lsp_ext::FindMatchingBraceParams,
 ) -> Result<Vec<Position>> {
     let _p = profile("handle_find_matching_brace");
-    let file_id = params.text_document.try_conv_with(&world)?;
+    let file_id = from_proto::file_id(&world, &params.text_document.uri)?;
     let line_index = world.analysis().file_line_index(file_id)?;
     let res = params
         .offsets
         .into_iter()
-        .map_conv_with(&line_index)
-        .map(|offset| {
-            if let Ok(Some(matching_brace_offset)) =
-                world.analysis().matching_brace(FilePosition { file_id, offset })
-            {
-                matching_brace_offset
-            } else {
-                offset
-            }
+        .map(|position| {
+            let offset = from_proto::offset(&line_index, position);
+            let offset = match world.analysis().matching_brace(FilePosition { file_id, offset }) {
+                Ok(Some(matching_brace_offset)) => matching_brace_offset,
+                Err(_) | Ok(None) => offset,
+            };
+            to_proto::position(&line_index, offset)
         })
-        .map_conv_with(&line_index)
         .collect();
     Ok(res)
 }
 
 pub fn handle_join_lines(
     world: WorldSnapshot,
-    params: req::JoinLinesParams,
-) -> Result<req::SourceChange> {
+    params: lsp_ext::JoinLinesParams,
+) -> Result<lsp_ext::SourceChange> {
     let _p = profile("handle_join_lines");
-    let frange = (&params.text_document, params.range).try_conv_with(&world)?;
-    world.analysis().join_lines(frange)?.try_conv_with(&world)
+    let frange = from_proto::file_range(&world, params.text_document, params.range)?;
+    let source_change = world.analysis().join_lines(frange)?;
+    to_proto::source_change(&world, source_change)
 }
 
 pub fn handle_on_enter(
     world: WorldSnapshot,
-    params: req::TextDocumentPositionParams,
-) -> Result<Option<req::SourceChange>> {
+    params: lsp_types::TextDocumentPositionParams,
+) -> Result<Option<lsp_ext::SourceChange>> {
     let _p = profile("handle_on_enter");
-    let position = params.try_conv_with(&world)?;
+    let position = from_proto::file_position(&world, params)?;
     match world.analysis().on_enter(position)? {
         None => Ok(None),
-        Some(edit) => Ok(Some(edit.try_conv_with(&world)?)),
+        Some(source_change) => to_proto::source_change(&world, source_change).map(Some),
     }
 }
 
 // Don't forget to add new trigger characters to `ServerCapabilities` in `caps.rs`.
 pub fn handle_on_type_formatting(
     world: WorldSnapshot,
-    params: req::DocumentOnTypeFormattingParams,
+    params: lsp_types::DocumentOnTypeFormattingParams,
 ) -> Result<Option<Vec<TextEdit>>> {
     let _p = profile("handle_on_type_formatting");
-    let mut position = params.text_document_position.try_conv_with(&world)?;
+    let mut position = from_proto::file_position(&world, params.text_document_position)?;
     let line_index = world.analysis().file_line_index(position.file_id)?;
     let line_endings = world.file_line_endings(position.file_id);
 
@@ -208,18 +205,17 @@ pub fn handle_on_type_formatting(
     // This should be a single-file edit
     let edit = edit.source_file_edits.pop().unwrap();
 
-    let change: Vec<TextEdit> = edit.edit.conv_with((&line_index, line_endings));
+    let change = to_proto::text_edit_vec(&line_index, line_endings, edit.edit);
     Ok(Some(change))
 }
 
 pub fn handle_document_symbol(
     world: WorldSnapshot,
-    params: req::DocumentSymbolParams,
-) -> Result<Option<req::DocumentSymbolResponse>> {
+    params: lsp_types::DocumentSymbolParams,
+) -> Result<Option<lsp_types::DocumentSymbolResponse>> {
     let _p = profile("handle_document_symbol");
-    let file_id = params.text_document.try_conv_with(&world)?;
+    let file_id = from_proto::file_id(&world, &params.text_document.uri)?;
     let line_index = world.analysis().file_line_index(file_id)?;
-    let url = file_id.try_conv_with(&world)?;
 
     let mut parents: Vec<(DocumentSymbol, Option<usize>)> = Vec::new();
 
@@ -227,10 +223,10 @@ pub fn handle_document_symbol(
         let doc_symbol = DocumentSymbol {
             name: symbol.label,
             detail: symbol.detail,
-            kind: symbol.kind.conv(),
+            kind: to_proto::symbol_kind(symbol.kind),
             deprecated: Some(symbol.deprecated),
-            range: symbol.node_range.conv_with(&line_index),
-            selection_range: symbol.navigation_range.conv_with(&line_index),
+            range: to_proto::range(&line_index, symbol.node_range),
+            selection_range: to_proto::range(&line_index, symbol.navigation_range),
             children: None,
         };
         parents.push((doc_symbol, symbol.parent));
@@ -249,40 +245,41 @@ pub fn handle_document_symbol(
         }
     }
 
-    if world.config.client_caps.hierarchical_symbols {
-        Ok(Some(document_symbols.into()))
+    let res = if world.config.client_caps.hierarchical_symbols {
+        document_symbols.into()
     } else {
+        let url = to_proto::url(&world, file_id)?;
         let mut symbol_information = Vec::<SymbolInformation>::new();
         for symbol in document_symbols {
             flatten_document_symbol(&symbol, None, &url, &mut symbol_information);
         }
+        symbol_information.into()
+    };
+    return Ok(Some(res));
 
-        Ok(Some(symbol_information.into()))
-    }
-}
-
-fn flatten_document_symbol(
-    symbol: &DocumentSymbol,
-    container_name: Option<String>,
-    url: &Url,
-    res: &mut Vec<SymbolInformation>,
-) {
-    res.push(SymbolInformation {
-        name: symbol.name.clone(),
-        kind: symbol.kind,
-        deprecated: symbol.deprecated,
-        location: Location::new(url.clone(), symbol.range),
-        container_name: container_name,
-    });
+    fn flatten_document_symbol(
+        symbol: &DocumentSymbol,
+        container_name: Option<String>,
+        url: &Url,
+        res: &mut Vec<SymbolInformation>,
+    ) {
+        res.push(SymbolInformation {
+            name: symbol.name.clone(),
+            kind: symbol.kind,
+            deprecated: symbol.deprecated,
+            location: Location::new(url.clone(), symbol.range),
+            container_name: container_name,
+        });
 
-    for child in symbol.children.iter().flatten() {
-        flatten_document_symbol(child, Some(symbol.name.clone()), url, res);
+        for child in symbol.children.iter().flatten() {
+            flatten_document_symbol(child, Some(symbol.name.clone()), url, res);
+        }
     }
 }
 
 pub fn handle_workspace_symbol(
     world: WorldSnapshot,
-    params: req::WorkspaceSymbolParams,
+    params: lsp_types::WorkspaceSymbolParams,
 ) -> Result<Option<Vec<SymbolInformation>>> {
     let _p = profile("handle_workspace_symbol");
     let all_symbols = params.query.contains('#');
@@ -313,8 +310,8 @@ pub fn handle_workspace_symbol(
         for nav in world.analysis().symbol_search(query)? {
             let info = SymbolInformation {
                 name: nav.name().to_string(),
-                kind: nav.kind().conv(),
-                location: nav.try_conv_with(world)?,
+                kind: to_proto::symbol_kind(nav.kind()),
+                location: to_proto::location(world, nav.file_range())?,
                 container_name: nav.container_name().map(|v| v.to_string()),
                 deprecated: None,
             };
@@ -326,63 +323,80 @@ pub fn handle_workspace_symbol(
 
 pub fn handle_goto_definition(
     world: WorldSnapshot,
-    params: req::GotoDefinitionParams,
-) -> Result<Option<req::GotoDefinitionResponse>> {
+    params: lsp_types::GotoDefinitionParams,
+) -> Result<Option<lsp_types::GotoDefinitionResponse>> {
     let _p = profile("handle_goto_definition");
-    let position = params.text_document_position_params.try_conv_with(&world)?;
+    let position = from_proto::file_position(&world, params.text_document_position_params)?;
     let nav_info = match world.analysis().goto_definition(position)? {
         None => return Ok(None),
         Some(it) => it,
     };
-    let res = (position.file_id, nav_info).try_conv_with(&world)?;
+    let res = to_proto::goto_definition_response(
+        &world,
+        FileRange { file_id: position.file_id, range: nav_info.range },
+        nav_info.info,
+    )?;
     Ok(Some(res))
 }
 
 pub fn handle_goto_implementation(
     world: WorldSnapshot,
-    params: req::GotoImplementationParams,
-) -> Result<Option<req::GotoImplementationResponse>> {
+    params: lsp_types::request::GotoImplementationParams,
+) -> Result<Option<lsp_types::request::GotoImplementationResponse>> {
     let _p = profile("handle_goto_implementation");
-    let position = params.text_document_position_params.try_conv_with(&world)?;
+    let position = from_proto::file_position(&world, params.text_document_position_params)?;
     let nav_info = match world.analysis().goto_implementation(position)? {
         None => return Ok(None),
         Some(it) => it,
     };
-    let res = (position.file_id, nav_info).try_conv_with(&world)?;
+    let res = to_proto::goto_definition_response(
+        &world,
+        FileRange { file_id: position.file_id, range: nav_info.range },
+        nav_info.info,
+    )?;
     Ok(Some(res))
 }
 
 pub fn handle_goto_type_definition(
     world: WorldSnapshot,
-    params: req::GotoTypeDefinitionParams,
-) -> Result<Option<req::GotoTypeDefinitionResponse>> {
+    params: lsp_types::request::GotoTypeDefinitionParams,
+) -> Result<Option<lsp_types::request::GotoTypeDefinitionResponse>> {
     let _p = profile("handle_goto_type_definition");
-    let position = params.text_document_position_params.try_conv_with(&world)?;
+    let position = from_proto::file_position(&world, params.text_document_position_params)?;
     let nav_info = match world.analysis().goto_type_definition(position)? {
         None => return Ok(None),
         Some(it) => it,
     };
-    let res = (position.file_id, nav_info).try_conv_with(&world)?;
+    let res = to_proto::goto_definition_response(
+        &world,
+        FileRange { file_id: position.file_id, range: nav_info.range },
+        nav_info.info,
+    )?;
     Ok(Some(res))
 }
 
 pub fn handle_parent_module(
     world: WorldSnapshot,
-    params: req::TextDocumentPositionParams,
+    params: lsp_types::TextDocumentPositionParams,
 ) -> Result<Vec<Location>> {
     let _p = profile("handle_parent_module");
-    let position = params.try_conv_with(&world)?;
-    world.analysis().parent_module(position)?.iter().try_conv_with_to_vec(&world)
+    let position = from_proto::file_position(&world, params)?;
+    world
+        .analysis()
+        .parent_module(position)?
+        .into_iter()
+        .map(|it| to_proto::location(&world, it.file_range()))
+        .collect::<Result<Vec<_>>>()
 }
 
 pub fn handle_runnables(
     world: WorldSnapshot,
-    params: req::RunnablesParams,
-) -> Result<Vec<req::Runnable>> {
+    params: lsp_ext::RunnablesParams,
+) -> Result<Vec<lsp_ext::Runnable>> {
     let _p = profile("handle_runnables");
-    let file_id = params.text_document.try_conv_with(&world)?;
+    let file_id = from_proto::file_id(&world, &params.text_document.uri)?;
     let line_index = world.analysis().file_line_index(file_id)?;
-    let offset = params.position.map(|it| it.conv_with(&line_index));
+    let offset = params.position.map(|it| from_proto::offset(&line_index, it));
     let mut res = Vec::new();
     let workspace_root = world.workspace_root_for(file_id);
     let cargo_spec = CargoTargetSpec::for_file(&world, file_id)?;
@@ -408,7 +422,7 @@ pub fn handle_runnables(
     match cargo_spec {
         Some(spec) => {
             for &cmd in ["check", "test"].iter() {
-                res.push(req::Runnable {
+                res.push(lsp_ext::Runnable {
                     range: Default::default(),
                     label: format!("cargo {} -p {}", cmd, spec.package),
                     bin: "cargo".to_string(),
@@ -420,7 +434,7 @@ pub fn handle_runnables(
             }
         }
         None => {
-            res.push(req::Runnable {
+            res.push(lsp_ext::Runnable {
                 range: Default::default(),
                 label: "cargo check --workspace".to_string(),
                 bin: "cargo".to_string(),
@@ -436,10 +450,10 @@ pub fn handle_runnables(
 
 pub fn handle_completion(
     world: WorldSnapshot,
-    params: req::CompletionParams,
-) -> Result<Option<req::CompletionResponse>> {
+    params: lsp_types::CompletionParams,
+) -> Result<Option<lsp_types::CompletionResponse>> {
     let _p = profile("handle_completion");
-    let position = params.text_document_position.try_conv_with(&world)?;
+    let position = from_proto::file_position(&world, params.text_document_position)?;
     let completion_triggered_after_single_colon = {
         let mut res = false;
         if let Some(ctx) = params.context {
@@ -468,8 +482,10 @@ pub fn handle_completion(
     };
     let line_index = world.analysis().file_line_index(position.file_id)?;
     let line_endings = world.file_line_endings(position.file_id);
-    let items: Vec<CompletionItem> =
-        items.into_iter().map(|item| item.conv_with((&line_index, line_endings))).collect();
+    let items: Vec<CompletionItem> = items
+        .into_iter()
+        .map(|item| to_proto::completion_item(&line_index, line_endings, item))
+        .collect();
 
     Ok(Some(items.into()))
 }
@@ -479,52 +495,51 @@ pub fn handle_folding_range(
     params: FoldingRangeParams,
 ) -> Result<Option<Vec<FoldingRange>>> {
     let _p = profile("handle_folding_range");
-    let file_id = params.text_document.try_conv_with(&world)?;
+    let file_id = from_proto::file_id(&world, &params.text_document.uri)?;
     let folds = world.analysis().folding_ranges(file_id)?;
     let text = world.analysis().file_text(file_id)?;
     let line_index = world.analysis().file_line_index(file_id)?;
-    let ctx = FoldConvCtx {
-        text: &text,
-        line_index: &line_index,
-        line_folding_only: world.config.client_caps.line_folding_only,
-    };
-    let res = Some(folds.into_iter().map_conv_with(&ctx).collect());
-    Ok(res)
+    let line_folding_only = world.config.client_caps.line_folding_only;
+    let res = folds
+        .into_iter()
+        .map(|it| to_proto::folding_range(&*text, &line_index, line_folding_only, it))
+        .collect();
+    Ok(Some(res))
 }
 
 pub fn handle_signature_help(
     world: WorldSnapshot,
-    params: req::SignatureHelpParams,
-) -> Result<Option<req::SignatureHelp>> {
+    params: lsp_types::SignatureHelpParams,
+) -> Result<Option<lsp_types::SignatureHelp>> {
     let _p = profile("handle_signature_help");
-    let position = params.text_document_position_params.try_conv_with(&world)?;
-    if let Some(call_info) = world.analysis().call_info(position)? {
-        let concise = !world.config.call_info_full;
-        let mut active_parameter = call_info.active_parameter.map(|it| it as i64);
-        if concise && call_info.signature.has_self_param {
-            active_parameter = active_parameter.map(|it| it.saturating_sub(1));
-        }
-        let sig_info = call_info.signature.conv_with(concise);
-
-        Ok(Some(req::SignatureHelp {
-            signatures: vec![sig_info],
-            active_signature: Some(0),
-            active_parameter,
-        }))
-    } else {
-        Ok(None)
+    let position = from_proto::file_position(&world, params.text_document_position_params)?;
+    let call_info = match world.analysis().call_info(position)? {
+        None => return Ok(None),
+        Some(it) => it,
+    };
+    let concise = !world.config.call_info_full;
+    let mut active_parameter = call_info.active_parameter.map(|it| it as i64);
+    if concise && call_info.signature.has_self_param {
+        active_parameter = active_parameter.map(|it| it.saturating_sub(1));
     }
+    let sig_info = to_proto::signature_information(call_info.signature, concise);
+
+    Ok(Some(lsp_types::SignatureHelp {
+        signatures: vec![sig_info],
+        active_signature: Some(0),
+        active_parameter,
+    }))
 }
 
-pub fn handle_hover(world: WorldSnapshot, params: req::HoverParams) -> Result<Option<Hover>> {
+pub fn handle_hover(world: WorldSnapshot, params: lsp_types::HoverParams) -> Result<Option<Hover>> {
     let _p = profile("handle_hover");
-    let position = params.text_document_position_params.try_conv_with(&world)?;
+    let position = from_proto::file_position(&world, params.text_document_position_params)?;
     let info = match world.analysis().hover(position)? {
         None => return Ok(None),
         Some(info) => info,
     };
     let line_index = world.analysis.file_line_index(position.file_id)?;
-    let range = info.range.conv_with(&line_index);
+    let range = to_proto::range(&line_index, info.range);
     let res = Hover {
         contents: HoverContents::Markup(MarkupContent {
             kind: MarkupKind::Markdown,
@@ -537,10 +552,10 @@ pub fn handle_hover(world: WorldSnapshot, params: req::HoverParams) -> Result<Op
 
 pub fn handle_prepare_rename(
     world: WorldSnapshot,
-    params: req::TextDocumentPositionParams,
+    params: lsp_types::TextDocumentPositionParams,
 ) -> Result<Option<PrepareRenameResponse>> {
     let _p = profile("handle_prepare_rename");
-    let position = params.try_conv_with(&world)?;
+    let position = from_proto::file_position(&world, params)?;
 
     let optional_change = world.analysis().rename(position, "dummy")?;
     let range = match optional_change {
@@ -548,15 +563,14 @@ pub fn handle_prepare_rename(
         Some(it) => it.range,
     };
 
-    let file_id = params.text_document.try_conv_with(&world)?;
-    let line_index = world.analysis().file_line_index(file_id)?;
-    let range = range.conv_with(&line_index);
+    let line_index = world.analysis().file_line_index(position.file_id)?;
+    let range = to_proto::range(&line_index, range);
     Ok(Some(PrepareRenameResponse::Range(range)))
 }
 
 pub fn handle_rename(world: WorldSnapshot, params: RenameParams) -> Result<Option<WorkspaceEdit>> {
     let _p = profile("handle_rename");
-    let position = params.text_document_position.try_conv_with(&world)?;
+    let position = from_proto::file_position(&world, params.text_document_position)?;
 
     if params.new_name.is_empty() {
         return Err(LspError::new(
@@ -567,22 +581,21 @@ pub fn handle_rename(world: WorldSnapshot, params: RenameParams) -> Result<Optio
     }
 
     let optional_change = world.analysis().rename(position, &*params.new_name)?;
-    let change = match optional_change {
+    let source_change = match optional_change {
         None => return Ok(None),
         Some(it) => it.info,
     };
 
-    let source_change_req = change.try_conv_with(&world)?;
-
-    Ok(Some(source_change_req.workspace_edit))
+    let source_change = to_proto::source_change(&world, source_change)?;
+    Ok(Some(source_change.workspace_edit))
 }
 
 pub fn handle_references(
     world: WorldSnapshot,
-    params: req::ReferenceParams,
+    params: lsp_types::ReferenceParams,
 ) -> Result<Option<Vec<Location>>> {
     let _p = profile("handle_references");
-    let position = params.text_document_position.try_conv_with(&world)?;
+    let position = from_proto::file_position(&world, params.text_document_position)?;
 
     let refs = match world.analysis().find_all_refs(position, None)? {
         None => return Ok(None),
@@ -591,33 +604,13 @@ pub fn handle_references(
 
     let locations = if params.context.include_declaration {
         refs.into_iter()
-            .filter_map(|reference| {
-                let line_index =
-                    world.analysis().file_line_index(reference.file_range.file_id).ok()?;
-                to_location(
-                    reference.file_range.file_id,
-                    reference.file_range.range,
-                    &world,
-                    &line_index,
-                )
-                .ok()
-            })
+            .filter_map(|reference| to_proto::location(&world, reference.file_range).ok())
             .collect()
     } else {
         // Only iterate over the references if include_declaration was false
         refs.references()
             .iter()
-            .filter_map(|reference| {
-                let line_index =
-                    world.analysis().file_line_index(reference.file_range.file_id).ok()?;
-                to_location(
-                    reference.file_range.file_id,
-                    reference.file_range.range,
-                    &world,
-                    &line_index,
-                )
-                .ok()
-            })
+            .filter_map(|reference| to_proto::location(&world, reference.file_range).ok())
             .collect()
     };
 
@@ -629,12 +622,12 @@ pub fn handle_formatting(
     params: DocumentFormattingParams,
 ) -> Result<Option<Vec<TextEdit>>> {
     let _p = profile("handle_formatting");
-    let file_id = params.text_document.try_conv_with(&world)?;
+    let file_id = from_proto::file_id(&world, &params.text_document.uri)?;
     let file = world.analysis().file_text(file_id)?;
     let crate_ids = world.analysis().crate_for(file_id)?;
 
     let file_line_index = world.analysis().file_line_index(file_id)?;
-    let end_position = TextSize::of(file.as_str()).conv_with(&file_line_index);
+    let end_position = to_proto::position(&file_line_index, TextSize::of(file.as_str()));
 
     let mut rustfmt = match &world.config.rustfmt {
         RustfmtConfig::Rustfmt { extra_args } => {
@@ -700,33 +693,14 @@ pub fn handle_formatting(
     }]))
 }
 
-fn create_single_code_action(assist: Assist, world: &WorldSnapshot) -> Result<CodeAction> {
-    let arg = to_value(assist.source_change.try_conv_with(world)?)?;
-    let title = assist.label;
-    let command = Command {
-        title: title.clone(),
-        command: "rust-analyzer.applySourceChange".to_string(),
-        arguments: Some(vec![arg]),
-    };
-
-    Ok(CodeAction {
-        title,
-        kind: Some(String::new()),
-        diagnostics: None,
-        edit: None,
-        command: Some(command),
-        is_preferred: None,
-    })
-}
-
 pub fn handle_code_action(
     world: WorldSnapshot,
-    params: req::CodeActionParams,
+    params: lsp_types::CodeActionParams,
 ) -> Result<Option<CodeActionResponse>> {
     let _p = profile("handle_code_action");
-    let file_id = params.text_document.try_conv_with(&world)?;
+    let file_id = from_proto::file_id(&world, &params.text_document.uri)?;
     let line_index = world.analysis().file_line_index(file_id)?;
-    let range = params.range.conv_with(&line_index);
+    let range = from_proto::text_range(&line_index, params.range);
 
     let diagnostics = world.analysis().diagnostics(file_id)?;
     let mut res = CodeActionResponse::default();
@@ -739,7 +713,7 @@ pub fn handle_code_action(
 
     for source_edit in fixes_from_diagnostics {
         let title = source_edit.label.clone();
-        let edit = source_edit.try_conv_with(&world)?;
+        let edit = to_proto::source_change(&world, source_edit)?;
 
         let command = Command {
             title,
@@ -758,7 +732,7 @@ pub fn handle_code_action(
     }
 
     for fix in world.check_fixes.get(&file_id).into_iter().flatten() {
-        let fix_range = fix.range.conv_with(&line_index);
+        let fix_range = from_proto::text_range(&line_index, fix.range);
         if fix_range.intersect(range).is_none() {
             continue;
         }
@@ -779,21 +753,21 @@ pub fn handle_code_action(
                 .1
                 .push(assist),
             None => {
-                res.push(create_single_code_action(assist, &world)?.into());
+                res.push(to_proto::code_action(&world, assist)?.into());
             }
         }
     }
 
     for (group_label, (idx, assists)) in grouped_assists {
         if assists.len() == 1 {
-            res[idx] =
-                create_single_code_action(assists.into_iter().next().unwrap(), &world)?.into();
+            res[idx] = to_proto::code_action(&world, assists.into_iter().next().unwrap())?.into();
         } else {
             let title = group_label;
 
             let mut arguments = Vec::with_capacity(assists.len());
             for assist in assists {
-                arguments.push(to_value(assist.source_change.try_conv_with(&world)?)?);
+                let source_change = to_proto::source_change(&world, assist.source_change)?;
+                arguments.push(to_value(source_change)?);
             }
 
             let command = Some(Command {
@@ -835,10 +809,10 @@ pub fn handle_code_action(
 
 pub fn handle_code_lens(
     world: WorldSnapshot,
-    params: req::CodeLensParams,
+    params: lsp_types::CodeLensParams,
 ) -> Result<Option<Vec<CodeLens>>> {
     let _p = profile("handle_code_lens");
-    let file_id = params.text_document.try_conv_with(&world)?;
+    let file_id = from_proto::file_id(&world, &params.text_document.uri)?;
     let line_index = world.analysis().file_line_index(file_id)?;
 
     let mut lenses: Vec<CodeLens> = Default::default();
@@ -902,10 +876,10 @@ pub fn handle_code_lens(
                 _ => false,
             })
             .map(|it| {
-                let range = it.node_range.conv_with(&line_index);
+                let range = to_proto::range(&line_index, it.node_range);
                 let pos = range.start;
-                let lens_params = req::GotoImplementationParams {
-                    text_document_position_params: req::TextDocumentPositionParams::new(
+                let lens_params = lsp_types::request::GotoImplementationParams {
+                    text_document_position_params: lsp_types::TextDocumentPositionParams::new(
                         params.text_document.clone(),
                         pos,
                     ),
@@ -926,7 +900,7 @@ pub fn handle_code_lens(
 #[derive(Debug, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
 enum CodeLensResolveData {
-    Impls(req::GotoImplementationParams),
+    Impls(lsp_types::request::GotoImplementationParams),
 }
 
 pub fn handle_code_lens_resolve(world: WorldSnapshot, code_lens: CodeLens) -> Result<CodeLens> {
@@ -937,9 +911,9 @@ pub fn handle_code_lens_resolve(world: WorldSnapshot, code_lens: CodeLens) -> Re
         Some(CodeLensResolveData::Impls(lens_params)) => {
             let locations: Vec<Location> =
                 match handle_goto_implementation(world, lens_params.clone())? {
-                    Some(req::GotoDefinitionResponse::Scalar(loc)) => vec![loc],
-                    Some(req::GotoDefinitionResponse::Array(locs)) => locs,
-                    Some(req::GotoDefinitionResponse::Link(links)) => links
+                    Some(lsp_types::GotoDefinitionResponse::Scalar(loc)) => vec![loc],
+                    Some(lsp_types::GotoDefinitionResponse::Array(locs)) => locs,
+                    Some(lsp_types::GotoDefinitionResponse::Link(links)) => links
                         .into_iter()
                         .map(|link| Location::new(link.target_uri, link.target_selection_range))
                         .collect(),
@@ -976,37 +950,39 @@ pub fn handle_code_lens_resolve(world: WorldSnapshot, code_lens: CodeLens) -> Re
 
 pub fn handle_document_highlight(
     world: WorldSnapshot,
-    params: req::DocumentHighlightParams,
+    params: lsp_types::DocumentHighlightParams,
 ) -> Result<Option<Vec<DocumentHighlight>>> {
     let _p = profile("handle_document_highlight");
-    let file_id = params.text_document_position_params.text_document.try_conv_with(&world)?;
-    let line_index = world.analysis().file_line_index(file_id)?;
+    let position = from_proto::file_position(&world, params.text_document_position_params)?;
+    let line_index = world.analysis().file_line_index(position.file_id)?;
 
-    let refs = match world.analysis().find_all_refs(
-        params.text_document_position_params.try_conv_with(&world)?,
-        Some(SearchScope::single_file(file_id)),
-    )? {
+    let refs = match world
+        .analysis()
+        .find_all_refs(position, Some(SearchScope::single_file(position.file_id)))?
+    {
         None => return Ok(None),
         Some(refs) => refs,
     };
 
-    Ok(Some(
-        refs.into_iter()
-            .filter(|reference| reference.file_range.file_id == file_id)
-            .map(|reference| DocumentHighlight {
-                range: reference.file_range.range.conv_with(&line_index),
-                kind: reference.access.map(|it| it.conv()),
-            })
-            .collect(),
-    ))
+    let res = refs
+        .into_iter()
+        .filter(|reference| reference.file_range.file_id == position.file_id)
+        .map(|reference| DocumentHighlight {
+            range: to_proto::range(&line_index, reference.file_range.range),
+            kind: reference.access.map(to_proto::document_highlight_kind),
+        })
+        .collect();
+    Ok(Some(res))
 }
 
-pub fn handle_ssr(world: WorldSnapshot, params: req::SsrParams) -> Result<req::SourceChange> {
+pub fn handle_ssr(
+    world: WorldSnapshot,
+    params: lsp_ext::SsrParams,
+) -> Result<lsp_ext::SourceChange> {
     let _p = profile("handle_ssr");
-    world
-        .analysis()
-        .structural_search_replace(&params.query, params.parse_only)??
-        .try_conv_with(&world)
+    let source_change =
+        world.analysis().structural_search_replace(&params.query, params.parse_only)??;
+    to_proto::source_change(&world, source_change)
 }
 
 pub fn publish_diagnostics(world: &WorldSnapshot, file_id: FileId) -> Result<DiagnosticTask> {
@@ -1017,8 +993,8 @@ pub fn publish_diagnostics(world: &WorldSnapshot, file_id: FileId) -> Result<Dia
         .diagnostics(file_id)?
         .into_iter()
         .map(|d| Diagnostic {
-            range: d.range.conv_with(&line_index),
-            severity: Some(d.severity.conv()),
+            range: to_proto::range(&line_index, d.range),
+            severity: Some(to_proto::diagnostic_severity(d.severity)),
             code: None,
             source: Some("rust-analyzer".to_string()),
             message: d.message,
@@ -1033,7 +1009,7 @@ fn to_lsp_runnable(
     world: &WorldSnapshot,
     file_id: FileId,
     runnable: Runnable,
-) -> Result<req::Runnable> {
+) -> Result<lsp_ext::Runnable> {
     let spec = CargoTargetSpec::for_file(world, file_id)?;
     let (args, extra_args) = CargoTargetSpec::runnable_args(spec, &runnable.kind)?;
     let line_index = world.analysis().file_line_index(file_id)?;
@@ -1044,8 +1020,8 @@ fn to_lsp_runnable(
         RunnableKind::DocTest { test_id, .. } => format!("doctest {}", test_id),
         RunnableKind::Bin => "run binary".to_string(),
     };
-    Ok(req::Runnable {
-        range: runnable.range.conv_with(&line_index),
+    Ok(lsp_ext::Runnable {
+        range: to_proto::range(&line_index, runnable.range),
         label,
         bin: "cargo".to_string(),
         args,
@@ -1064,13 +1040,13 @@ pub fn handle_inlay_hints(
     params: InlayHintsParams,
 ) -> Result<Vec<InlayHint>> {
     let _p = profile("handle_inlay_hints");
-    let file_id = params.text_document.try_conv_with(&world)?;
+    let file_id = from_proto::file_id(&world, &params.text_document.uri)?;
     let analysis = world.analysis();
     let line_index = analysis.file_line_index(file_id)?;
     Ok(analysis
         .inlay_hints(file_id, &world.config.inlay_hints)?
         .into_iter()
-        .map_conv_with(&line_index)
+        .map(|it| to_proto::inlay_int(&line_index, it))
         .collect())
 }
 
@@ -1079,21 +1055,19 @@ pub fn handle_call_hierarchy_prepare(
     params: CallHierarchyPrepareParams,
 ) -> Result<Option<Vec<CallHierarchyItem>>> {
     let _p = profile("handle_call_hierarchy_prepare");
-    let position = params.text_document_position_params.try_conv_with(&world)?;
-    let file_id = position.file_id;
+    let position = from_proto::file_position(&world, params.text_document_position_params)?;
 
     let nav_info = match world.analysis().call_hierarchy(position)? {
         None => return Ok(None),
         Some(it) => it,
     };
 
-    let line_index = world.analysis().file_line_index(file_id)?;
-    let RangeInfo { range, info: navs } = nav_info;
+    let RangeInfo { range: _, info: navs } = nav_info;
     let res = navs
         .into_iter()
         .filter(|it| it.kind() == SyntaxKind::FN_DEF)
-        .filter_map(|it| to_call_hierarchy_item(file_id, range, &world, &line_index, it).ok())
-        .collect();
+        .map(|it| to_proto::call_hierarchy_item(&world, it))
+        .collect::<Result<Vec<_>>>()?;
 
     Ok(Some(res))
 }
@@ -1106,7 +1080,7 @@ pub fn handle_call_hierarchy_incoming(
     let item = params.item;
 
     let doc = TextDocumentIdentifier::new(item.uri);
-    let frange: FileRange = (&doc, item.range).try_conv_with(&world)?;
+    let frange = from_proto::file_range(&world, doc, item.range)?;
     let fpos = FilePosition { file_id: frange.file_id, offset: frange.range.start() };
 
     let call_items = match world.analysis().incoming_calls(fpos)? {
@@ -1119,11 +1093,14 @@ pub fn handle_call_hierarchy_incoming(
     for call_item in call_items.into_iter() {
         let file_id = call_item.target.file_id();
         let line_index = world.analysis().file_line_index(file_id)?;
-        let range = call_item.target.range();
-        let item = to_call_hierarchy_item(file_id, range, &world, &line_index, call_item.target)?;
+        let item = to_proto::call_hierarchy_item(&world, call_item.target)?;
         res.push(CallHierarchyIncomingCall {
             from: item,
-            from_ranges: call_item.ranges.iter().map(|it| it.conv_with(&line_index)).collect(),
+            from_ranges: call_item
+                .ranges
+                .into_iter()
+                .map(|it| to_proto::range(&line_index, it))
+                .collect(),
         });
     }
 
@@ -1138,7 +1115,7 @@ pub fn handle_call_hierarchy_outgoing(
     let item = params.item;
 
     let doc = TextDocumentIdentifier::new(item.uri);
-    let frange: FileRange = (&doc, item.range).try_conv_with(&world)?;
+    let frange = from_proto::file_range(&world, doc, item.range)?;
     let fpos = FilePosition { file_id: frange.file_id, offset: frange.range.start() };
 
     let call_items = match world.analysis().outgoing_calls(fpos)? {
@@ -1151,11 +1128,14 @@ pub fn handle_call_hierarchy_outgoing(
     for call_item in call_items.into_iter() {
         let file_id = call_item.target.file_id();
         let line_index = world.analysis().file_line_index(file_id)?;
-        let range = call_item.target.range();
-        let item = to_call_hierarchy_item(file_id, range, &world, &line_index, call_item.target)?;
+        let item = to_proto::call_hierarchy_item(&world, call_item.target)?;
         res.push(CallHierarchyOutgoingCall {
             to: item,
-            from_ranges: call_item.ranges.iter().map(|it| it.conv_with(&line_index)).collect(),
+            from_ranges: call_item
+                .ranges
+                .into_iter()
+                .map(|it| to_proto::range(&line_index, it))
+                .collect(),
         });
     }
 
@@ -1168,26 +1148,13 @@ pub fn handle_semantic_tokens(
 ) -> Result<Option<SemanticTokensResult>> {
     let _p = profile("handle_semantic_tokens");
 
-    let file_id = params.text_document.try_conv_with(&world)?;
+    let file_id = from_proto::file_id(&world, &params.text_document.uri)?;
     let text = world.analysis().file_text(file_id)?;
     let line_index = world.analysis().file_line_index(file_id)?;
 
-    let mut builder = SemanticTokensBuilder::default();
-
-    for highlight_range in world.analysis().highlight(file_id)?.into_iter() {
-        let (token_index, modifier_bitset) = highlight_range.highlight.conv();
-        for mut range in line_index.lines(highlight_range.range) {
-            if text[range].ends_with('\n') {
-                range = TextRange::new(range.start(), range.end() - TextSize::of('\n'));
-            }
-            let range = range.conv_with(&line_index);
-            builder.push(range, token_index, modifier_bitset);
-        }
-    }
-
-    let tokens = builder.build();
-
-    Ok(Some(tokens.into()))
+    let highlights = world.analysis().highlight(file_id)?;
+    let semantic_tokens = to_proto::semantic_tokens(&text, &line_index, highlights);
+    Ok(Some(semantic_tokens.into()))
 }
 
 pub fn handle_semantic_tokens_range(
@@ -1196,17 +1163,11 @@ pub fn handle_semantic_tokens_range(
 ) -> Result<Option<SemanticTokensRangeResult>> {
     let _p = profile("handle_semantic_tokens_range");
 
-    let frange = (&params.text_document, params.range).try_conv_with(&world)?;
+    let frange = from_proto::file_range(&world, params.text_document, params.range)?;
+    let text = world.analysis().file_text(frange.file_id)?;
     let line_index = world.analysis().file_line_index(frange.file_id)?;
 
-    let mut builder = SemanticTokensBuilder::default();
-
-    for highlight_range in world.analysis().highlight_range(frange)?.into_iter() {
-        let (token_type, token_modifiers) = highlight_range.highlight.conv();
-        builder.push(highlight_range.range.conv_with(&line_index), token_type, token_modifiers);
-    }
-
-    let tokens = builder.build();
-
-    Ok(Some(tokens.into()))
+    let highlights = world.analysis().highlight_range(frange)?;
+    let semantic_tokens = to_proto::semantic_tokens(&text, &line_index, highlights);
+    Ok(Some(semantic_tokens.into()))
 }
diff --git a/crates/rust-analyzer/src/to_proto.rs b/crates/rust-analyzer/src/to_proto.rs
new file mode 100644
index 000000000..4500d4982
--- /dev/null
+++ b/crates/rust-analyzer/src/to_proto.rs
@@ -0,0 +1,592 @@
+//! Conversion of rust-analyzer specific types to lsp_types equivalents.
+use ra_db::{FileId, FileRange};
+use ra_ide::{
+    translate_offset_with_edit, Assist, CompletionItem, CompletionItemKind, Documentation,
+    FileSystemEdit, Fold, FoldKind, FunctionSignature, Highlight, HighlightModifier, HighlightTag,
+    HighlightedRange, InlayHint, InlayKind, InsertTextFormat, LineIndex, NavigationTarget,
+    ReferenceAccess, Severity, SourceChange, SourceFileEdit,
+};
+use ra_syntax::{SyntaxKind, TextRange, TextSize};
+use ra_text_edit::{Indel, TextEdit};
+use ra_vfs::LineEndings;
+
+use crate::{lsp_ext, semantic_tokens, world::WorldSnapshot, Result};
+
+pub(crate) fn position(line_index: &LineIndex, offset: TextSize) -> lsp_types::Position {
+    let line_col = line_index.line_col(offset);
+    let line = u64::from(line_col.line);
+    let character = u64::from(line_col.col_utf16);
+    lsp_types::Position::new(line, character)
+}
+
+pub(crate) fn range(line_index: &LineIndex, range: TextRange) -> lsp_types::Range {
+    let start = position(line_index, range.start());
+    let end = position(line_index, range.end());
+    lsp_types::Range::new(start, end)
+}
+
+pub(crate) fn symbol_kind(syntax_kind: SyntaxKind) -> lsp_types::SymbolKind {
+    match syntax_kind {
+        SyntaxKind::FN_DEF => lsp_types::SymbolKind::Function,
+        SyntaxKind::STRUCT_DEF => lsp_types::SymbolKind::Struct,
+        SyntaxKind::ENUM_DEF => lsp_types::SymbolKind::Enum,
+        SyntaxKind::ENUM_VARIANT => lsp_types::SymbolKind::EnumMember,
+        SyntaxKind::TRAIT_DEF => lsp_types::SymbolKind::Interface,
+        SyntaxKind::MACRO_CALL => lsp_types::SymbolKind::Function,
+        SyntaxKind::MODULE => lsp_types::SymbolKind::Module,
+        SyntaxKind::TYPE_ALIAS_DEF => lsp_types::SymbolKind::TypeParameter,
+        SyntaxKind::RECORD_FIELD_DEF => lsp_types::SymbolKind::Field,
+        SyntaxKind::STATIC_DEF => lsp_types::SymbolKind::Constant,
+        SyntaxKind::CONST_DEF => lsp_types::SymbolKind::Constant,
+        SyntaxKind::IMPL_DEF => lsp_types::SymbolKind::Object,
+        _ => lsp_types::SymbolKind::Variable,
+    }
+}
+
+pub(crate) fn document_highlight_kind(
+    reference_access: ReferenceAccess,
+) -> lsp_types::DocumentHighlightKind {
+    match reference_access {
+        ReferenceAccess::Read => lsp_types::DocumentHighlightKind::Read,
+        ReferenceAccess::Write => lsp_types::DocumentHighlightKind::Write,
+    }
+}
+
+pub(crate) fn diagnostic_severity(severity: Severity) -> lsp_types::DiagnosticSeverity {
+    match severity {
+        Severity::Error => lsp_types::DiagnosticSeverity::Error,
+        Severity::WeakWarning => lsp_types::DiagnosticSeverity::Hint,
+    }
+}
+
+pub(crate) fn documentation(documentation: Documentation) -> lsp_types::Documentation {
+    let value = crate::markdown::format_docs(documentation.as_str());
+    let markup_content = lsp_types::MarkupContent { kind: lsp_types::MarkupKind::Markdown, value };
+    lsp_types::Documentation::MarkupContent(markup_content)
+}
+
+pub(crate) fn insert_text_format(
+    insert_text_format: InsertTextFormat,
+) -> lsp_types::InsertTextFormat {
+    match insert_text_format {
+        InsertTextFormat::Snippet => lsp_types::InsertTextFormat::Snippet,
+        InsertTextFormat::PlainText => lsp_types::InsertTextFormat::PlainText,
+    }
+}
+
+pub(crate) fn completion_item_kind(
+    completion_item_kind: CompletionItemKind,
+) -> lsp_types::CompletionItemKind {
+    match completion_item_kind {
+        CompletionItemKind::Keyword => lsp_types::CompletionItemKind::Keyword,
+        CompletionItemKind::Snippet => lsp_types::CompletionItemKind::Snippet,
+        CompletionItemKind::Module => lsp_types::CompletionItemKind::Module,
+        CompletionItemKind::Function => lsp_types::CompletionItemKind::Function,
+        CompletionItemKind::Struct => lsp_types::CompletionItemKind::Struct,
+        CompletionItemKind::Enum => lsp_types::CompletionItemKind::Enum,
+        CompletionItemKind::EnumVariant => lsp_types::CompletionItemKind::EnumMember,
+        CompletionItemKind::BuiltinType => lsp_types::CompletionItemKind::Struct,
+        CompletionItemKind::Binding => lsp_types::CompletionItemKind::Variable,
+        CompletionItemKind::Field => lsp_types::CompletionItemKind::Field,
+        CompletionItemKind::Trait => lsp_types::CompletionItemKind::Interface,
+        CompletionItemKind::TypeAlias => lsp_types::CompletionItemKind::Struct,
+        CompletionItemKind::Const => lsp_types::CompletionItemKind::Constant,
+        CompletionItemKind::Static => lsp_types::CompletionItemKind::Value,
+        CompletionItemKind::Method => lsp_types::CompletionItemKind::Method,
+        CompletionItemKind::TypeParam => lsp_types::CompletionItemKind::TypeParameter,
+        CompletionItemKind::Macro => lsp_types::CompletionItemKind::Method,
+        CompletionItemKind::Attribute => lsp_types::CompletionItemKind::EnumMember,
+    }
+}
+
+pub(crate) fn text_edit(
+    line_index: &LineIndex,
+    line_endings: LineEndings,
+    indel: Indel,
+) -> lsp_types::TextEdit {
+    let range = range(line_index, indel.delete);
+    let new_text = match line_endings {
+        LineEndings::Unix => indel.insert,
+        LineEndings::Dos => indel.insert.replace('\n', "\r\n"),
+    };
+    lsp_types::TextEdit { range, new_text }
+}
+
+pub(crate) fn text_edit_vec(
+    line_index: &LineIndex,
+    line_endings: LineEndings,
+    text_edit: TextEdit,
+) -> Vec<lsp_types::TextEdit> {
+    text_edit
+        .as_indels()
+        .iter()
+        .map(|it| self::text_edit(line_index, line_endings, it.clone()))
+        .collect()
+}
+
+pub(crate) fn completion_item(
+    line_index: &LineIndex,
+    line_endings: LineEndings,
+    completion_item: CompletionItem,
+) -> lsp_types::CompletionItem {
+    let mut additional_text_edits = Vec::new();
+    let mut text_edit = None;
+    // LSP does not allow arbitrary edits in completion, so we have to do a
+    // non-trivial mapping here.
+    let source_range = completion_item.source_range();
+    for indel in completion_item.text_edit().as_indels() {
+        if indel.delete.contains_range(source_range) {
+            text_edit = Some(if indel.delete == source_range {
+                self::text_edit(line_index, line_endings, indel.clone())
+            } else {
+                assert!(source_range.end() == indel.delete.end());
+                let range1 = TextRange::new(indel.delete.start(), source_range.start());
+                let range2 = source_range;
+                let indel1 = Indel::replace(range1, String::new());
+                let indel2 = Indel::replace(range2, indel.insert.clone());
+                additional_text_edits.push(self::text_edit(line_index, line_endings, indel1));
+                self::text_edit(line_index, line_endings, indel2)
+            })
+        } else {
+            assert!(source_range.intersect(indel.delete).is_none());
+            let text_edit = self::text_edit(line_index, line_endings, indel.clone());
+            additional_text_edits.push(text_edit);
+        }
+    }
+    let text_edit = text_edit.unwrap();
+
+    let mut res = lsp_types::CompletionItem {
+        label: completion_item.label().to_string(),
+        detail: completion_item.detail().map(|it| it.to_string()),
+        filter_text: Some(completion_item.lookup().to_string()),
+        kind: completion_item.kind().map(completion_item_kind),
+        text_edit: Some(text_edit.into()),
+        additional_text_edits: Some(additional_text_edits),
+        documentation: completion_item.documentation().map(documentation),
+        deprecated: Some(completion_item.deprecated()),
+        command: if completion_item.trigger_call_info() {
+            let cmd = lsp_types::Command {
+                title: "triggerParameterHints".into(),
+                command: "editor.action.triggerParameterHints".into(),
+                arguments: None,
+            };
+            Some(cmd)
+        } else {
+            None
+        },
+        ..Default::default()
+    };
+
+    if completion_item.score().is_some() {
+        res.preselect = Some(true)
+    }
+
+    if completion_item.deprecated() {
+        res.tags = Some(vec![lsp_types::CompletionItemTag::Deprecated])
+    }
+
+    res.insert_text_format = Some(insert_text_format(completion_item.insert_text_format()));
+
+    res
+}
+
+pub(crate) fn signature_information(
+    signature: FunctionSignature,
+    concise: bool,
+) -> lsp_types::SignatureInformation {
+    let (label, documentation, params) = if concise {
+        let mut params = signature.parameters;
+        if signature.has_self_param {
+            params.remove(0);
+        }
+        (params.join(", "), None, params)
+    } else {
+        (signature.to_string(), signature.doc.map(documentation), signature.parameters)
+    };
+
+    let parameters: Vec<lsp_types::ParameterInformation> = params
+        .into_iter()
+        .map(|param| lsp_types::ParameterInformation {
+            label: lsp_types::ParameterLabel::Simple(param),
+            documentation: None,
+        })
+        .collect();
+
+    lsp_types::SignatureInformation { label, documentation, parameters: Some(parameters) }
+}
+
+pub(crate) fn inlay_int(line_index: &LineIndex, inlay_hint: InlayHint) -> lsp_ext::InlayHint {
+    lsp_ext::InlayHint {
+        label: inlay_hint.label.to_string(),
+        range: range(line_index, inlay_hint.range),
+        kind: match inlay_hint.kind {
+            InlayKind::ParameterHint => lsp_ext::InlayKind::ParameterHint,
+            InlayKind::TypeHint => lsp_ext::InlayKind::TypeHint,
+            InlayKind::ChainingHint => lsp_ext::InlayKind::ChainingHint,
+        },
+    }
+}
+
+pub(crate) fn semantic_tokens(
+    text: &str,
+    line_index: &LineIndex,
+    highlights: Vec<HighlightedRange>,
+) -> lsp_types::SemanticTokens {
+    let mut builder = semantic_tokens::SemanticTokensBuilder::default();
+
+    for highlight_range in highlights {
+        let (type_, mods) = semantic_token_type_and_modifiers(highlight_range.highlight);
+        let token_index = semantic_tokens::type_index(type_);
+        let modifier_bitset = mods.0;
+
+        for mut text_range in line_index.lines(highlight_range.range) {
+            if text[text_range].ends_with('\n') {
+                text_range =
+                    TextRange::new(text_range.start(), text_range.end() - TextSize::of('\n'));
+            }
+            let range = range(&line_index, text_range);
+            builder.push(range, token_index, modifier_bitset);
+        }
+    }
+
+    builder.build()
+}
+
+fn semantic_token_type_and_modifiers(
+    highlight: Highlight,
+) -> (lsp_types::SemanticTokenType, semantic_tokens::ModifierSet) {
+    let mut mods = semantic_tokens::ModifierSet::default();
+    let type_ = match highlight.tag {
+        HighlightTag::Struct => lsp_types::SemanticTokenType::STRUCT,
+        HighlightTag::Enum => lsp_types::SemanticTokenType::ENUM,
+        HighlightTag::Union => semantic_tokens::UNION,
+        HighlightTag::TypeAlias => semantic_tokens::TYPE_ALIAS,
+        HighlightTag::Trait => lsp_types::SemanticTokenType::INTERFACE,
+        HighlightTag::BuiltinType => semantic_tokens::BUILTIN_TYPE,
+        HighlightTag::SelfType => lsp_types::SemanticTokenType::TYPE,
+        HighlightTag::Field => lsp_types::SemanticTokenType::MEMBER,
+        HighlightTag::Function => lsp_types::SemanticTokenType::FUNCTION,
+        HighlightTag::Module => lsp_types::SemanticTokenType::NAMESPACE,
+        HighlightTag::Constant => {
+            mods |= semantic_tokens::CONSTANT;
+            mods |= lsp_types::SemanticTokenModifier::STATIC;
+            lsp_types::SemanticTokenType::VARIABLE
+        }
+        HighlightTag::Static => {
+            mods |= lsp_types::SemanticTokenModifier::STATIC;
+            lsp_types::SemanticTokenType::VARIABLE
+        }
+        HighlightTag::EnumVariant => semantic_tokens::ENUM_MEMBER,
+        HighlightTag::Macro => lsp_types::SemanticTokenType::MACRO,
+        HighlightTag::Local => lsp_types::SemanticTokenType::VARIABLE,
+        HighlightTag::TypeParam => lsp_types::SemanticTokenType::TYPE_PARAMETER,
+        HighlightTag::Lifetime => semantic_tokens::LIFETIME,
+        HighlightTag::ByteLiteral | HighlightTag::NumericLiteral => {
+            lsp_types::SemanticTokenType::NUMBER
+        }
+        HighlightTag::CharLiteral | HighlightTag::StringLiteral => {
+            lsp_types::SemanticTokenType::STRING
+        }
+        HighlightTag::Comment => lsp_types::SemanticTokenType::COMMENT,
+        HighlightTag::Attribute => semantic_tokens::ATTRIBUTE,
+        HighlightTag::Keyword => lsp_types::SemanticTokenType::KEYWORD,
+        HighlightTag::UnresolvedReference => semantic_tokens::UNRESOLVED_REFERENCE,
+        HighlightTag::FormatSpecifier => semantic_tokens::FORMAT_SPECIFIER,
+    };
+
+    for modifier in highlight.modifiers.iter() {
+        let modifier = match modifier {
+            HighlightModifier::Definition => lsp_types::SemanticTokenModifier::DECLARATION,
+            HighlightModifier::ControlFlow => semantic_tokens::CONTROL_FLOW,
+            HighlightModifier::Mutable => semantic_tokens::MUTABLE,
+            HighlightModifier::Unsafe => semantic_tokens::UNSAFE,
+        };
+        mods |= modifier;
+    }
+
+    (type_, mods)
+}
+
+pub(crate) fn folding_range(
+    text: &str,
+    line_index: &LineIndex,
+    line_folding_only: bool,
+    fold: Fold,
+) -> lsp_types::FoldingRange {
+    let kind = match fold.kind {
+        FoldKind::Comment => Some(lsp_types::FoldingRangeKind::Comment),
+        FoldKind::Imports => Some(lsp_types::FoldingRangeKind::Imports),
+        FoldKind::Mods | FoldKind::Block => None,
+    };
+
+    let range = range(line_index, fold.range);
+
+    if line_folding_only {
+        // Clients with line_folding_only == true (such as VSCode) will fold the whole end line
+        // even if it contains text not in the folding range. To prevent that we exclude
+        // range.end.line from the folding region if there is more text after range.end
+        // on the same line.
+        let has_more_text_on_end_line = text[TextRange::new(fold.range.end(), TextSize::of(text))]
+            .chars()
+            .take_while(|it| *it != '\n')
+            .any(|it| !it.is_whitespace());
+
+        let end_line = if has_more_text_on_end_line {
+            range.end.line.saturating_sub(1)
+        } else {
+            range.end.line
+        };
+
+        lsp_types::FoldingRange {
+            start_line: range.start.line,
+            start_character: None,
+            end_line,
+            end_character: None,
+            kind,
+        }
+    } else {
+        lsp_types::FoldingRange {
+            start_line: range.start.line,
+            start_character: Some(range.start.character),
+            end_line: range.end.line,
+            end_character: Some(range.end.character),
+            kind,
+        }
+    }
+}
+
+pub(crate) fn url(world: &WorldSnapshot, file_id: FileId) -> Result<lsp_types::Url> {
+    world.file_id_to_uri(file_id)
+}
+
+pub(crate) fn text_document_identifier(
+    world: &WorldSnapshot,
+    file_id: FileId,
+) -> Result<lsp_types::TextDocumentIdentifier> {
+    let res = lsp_types::TextDocumentIdentifier { uri: url(world, file_id)? };
+    Ok(res)
+}
+
+pub(crate) fn versioned_text_document_identifier(
+    world: &WorldSnapshot,
+    file_id: FileId,
+    version: Option<i64>,
+) -> Result<lsp_types::VersionedTextDocumentIdentifier> {
+    let res = lsp_types::VersionedTextDocumentIdentifier { uri: url(world, file_id)?, version };
+    Ok(res)
+}
+
+pub(crate) fn location(world: &WorldSnapshot, frange: FileRange) -> Result<lsp_types::Location> {
+    let url = url(world, frange.file_id)?;
+    let line_index = world.analysis().file_line_index(frange.file_id)?;
+    let range = range(&line_index, frange.range);
+    let loc = lsp_types::Location::new(url, range);
+    Ok(loc)
+}
+
+pub(crate) fn location_link(
+    world: &WorldSnapshot,
+    src: FileRange,
+    target: NavigationTarget,
+) -> Result<lsp_types::LocationLink> {
+    let src_location = location(world, src)?;
+    let (target_uri, target_range, target_selection_range) = location_info(world, target)?;
+    let res = lsp_types::LocationLink {
+        origin_selection_range: Some(src_location.range),
+        target_uri,
+        target_range,
+        target_selection_range,
+    };
+    Ok(res)
+}
+
+fn location_info(
+    world: &WorldSnapshot,
+    target: NavigationTarget,
+) -> Result<(lsp_types::Url, lsp_types::Range, lsp_types::Range)> {
+    let line_index = world.analysis().file_line_index(target.file_id())?;
+
+    let target_uri = url(world, target.file_id())?;
+    let target_range = range(&line_index, target.full_range());
+    let target_selection_range =
+        target.focus_range().map(|it| range(&line_index, it)).unwrap_or(target_range);
+    Ok((target_uri, target_range, target_selection_range))
+}
+
+pub(crate) fn goto_definition_response(
+    world: &WorldSnapshot,
+    src: FileRange,
+    targets: Vec<NavigationTarget>,
+) -> Result<lsp_types::GotoDefinitionResponse> {
+    if world.config.client_caps.location_link {
+        let links = targets
+            .into_iter()
+            .map(|nav| location_link(world, src, nav))
+            .collect::<Result<Vec<_>>>()?;
+        Ok(links.into())
+    } else {
+        let locations = targets
+            .into_iter()
+            .map(|nav| {
+                location(
+                    world,
+                    FileRange {
+                        file_id: nav.file_id(),
+                        range: nav.focus_range().unwrap_or(nav.range()),
+                    },
+                )
+            })
+            .collect::<Result<Vec<_>>>()?;
+        Ok(locations.into())
+    }
+}
+
+pub(crate) fn text_document_edit(
+    world: &WorldSnapshot,
+    source_file_edit: SourceFileEdit,
+) -> Result<lsp_types::TextDocumentEdit> {
+    let text_document = versioned_text_document_identifier(world, source_file_edit.file_id, None)?;
+    let line_index = world.analysis().file_line_index(source_file_edit.file_id)?;
+    let line_endings = world.file_line_endings(source_file_edit.file_id);
+    let edits = source_file_edit
+        .edit
+        .as_indels()
+        .iter()
+        .map(|it| text_edit(&line_index, line_endings, it.clone()))
+        .collect();
+    Ok(lsp_types::TextDocumentEdit { text_document, edits })
+}
+
+pub(crate) fn resource_op(
+    world: &WorldSnapshot,
+    file_system_edit: FileSystemEdit,
+) -> Result<lsp_types::ResourceOp> {
+    let res = match file_system_edit {
+        FileSystemEdit::CreateFile { source_root, path } => {
+            let uri = world.path_to_uri(source_root, &path)?;
+            lsp_types::ResourceOp::Create(lsp_types::CreateFile { uri, options: None })
+        }
+        FileSystemEdit::MoveFile { src, dst_source_root, dst_path } => {
+            let old_uri = world.file_id_to_uri(src)?;
+            let new_uri = world.path_to_uri(dst_source_root, &dst_path)?;
+            lsp_types::ResourceOp::Rename(lsp_types::RenameFile { old_uri, new_uri, options: None })
+        }
+    };
+    Ok(res)
+}
+
+pub(crate) fn source_change(
+    world: &WorldSnapshot,
+    source_change: SourceChange,
+) -> Result<lsp_ext::SourceChange> {
+    let cursor_position = match source_change.cursor_position {
+        None => None,
+        Some(pos) => {
+            let line_index = world.analysis().file_line_index(pos.file_id)?;
+            let edit = source_change
+                .source_file_edits
+                .iter()
+                .find(|it| it.file_id == pos.file_id)
+                .map(|it| &it.edit);
+            let line_col = match edit {
+                Some(edit) => translate_offset_with_edit(&*line_index, pos.offset, edit),
+                None => line_index.line_col(pos.offset),
+            };
+            let position =
+                lsp_types::Position::new(u64::from(line_col.line), u64::from(line_col.col_utf16));
+            Some(lsp_types::TextDocumentPositionParams {
+                text_document: text_document_identifier(world, pos.file_id)?,
+                position,
+            })
+        }
+    };
+    let mut document_changes: Vec<lsp_types::DocumentChangeOperation> = Vec::new();
+    for op in source_change.file_system_edits {
+        let op = resource_op(&world, op)?;
+        document_changes.push(lsp_types::DocumentChangeOperation::Op(op));
+    }
+    for edit in source_change.source_file_edits {
+        let edit = text_document_edit(&world, edit)?;
+        document_changes.push(lsp_types::DocumentChangeOperation::Edit(edit));
+    }
+    let workspace_edit = lsp_types::WorkspaceEdit {
+        changes: None,
+        document_changes: Some(lsp_types::DocumentChanges::Operations(document_changes)),
+    };
+    Ok(lsp_ext::SourceChange { label: source_change.label, workspace_edit, cursor_position })
+}
+
+pub fn call_hierarchy_item(
+    world: &WorldSnapshot,
+    target: NavigationTarget,
+) -> Result<lsp_types::CallHierarchyItem> {
+    let name = target.name().to_string();
+    let detail = target.description().map(|it| it.to_string());
+    let kind = symbol_kind(target.kind());
+    let (uri, range, selection_range) = location_info(world, target)?;
+    Ok(lsp_types::CallHierarchyItem { name, kind, tags: None, detail, uri, range, selection_range })
+}
+
+#[cfg(test)]
+mod tests {
+    use test_utils::extract_ranges;
+
+    use super::*;
+
+    #[test]
+    fn conv_fold_line_folding_only_fixup() {
+        let text = r#"<fold>mod a;
+mod b;
+mod c;</fold>
+
+fn main() <fold>{
+    if cond <fold>{
+        a::do_a();
+    }</fold> else <fold>{
+        b::do_b();
+    }</fold>
+}</fold>"#;
+
+        let (ranges, text) = extract_ranges(text, "fold");
+        assert_eq!(ranges.len(), 4);
+        let folds = vec![
+            Fold { range: ranges[0], kind: FoldKind::Mods },
+            Fold { range: ranges[1], kind: FoldKind::Block },
+            Fold { range: ranges[2], kind: FoldKind::Block },
+            Fold { range: ranges[3], kind: FoldKind::Block },
+        ];
+
+        let line_index = LineIndex::new(&text);
+        let converted: Vec<lsp_types::FoldingRange> =
+            folds.into_iter().map(|it| folding_range(&text, &line_index, true, it)).collect();
+
+        let expected_lines = [(0, 2), (4, 10), (5, 6), (7, 9)];
+        assert_eq!(converted.len(), expected_lines.len());
+        for (folding_range, (start_line, end_line)) in converted.iter().zip(expected_lines.iter()) {
+            assert_eq!(folding_range.start_line, *start_line);
+            assert_eq!(folding_range.start_character, None);
+            assert_eq!(folding_range.end_line, *end_line);
+            assert_eq!(folding_range.end_character, None);
+        }
+    }
+}
+
+pub(crate) fn code_action(world: &WorldSnapshot, assist: Assist) -> Result<lsp_types::CodeAction> {
+    let source_change = source_change(&world, assist.source_change)?;
+    let arg = serde_json::to_value(source_change)?;
+    let title = assist.label;
+    let command = lsp_types::Command {
+        title: title.clone(),
+        command: "rust-analyzer.applySourceChange".to_string(),
+        arguments: Some(vec![arg]),
+    };
+
+    Ok(lsp_types::CodeAction {
+        title,
+        kind: Some(String::new()),
+        diagnostics: None,
+        edit: None,
+        command: Some(command),
+        is_preferred: None,
+    })
+}
diff --git a/crates/rust-analyzer/src/world.rs b/crates/rust-analyzer/src/world.rs
index 16020648d..6333c15b2 100644
--- a/crates/rust-analyzer/src/world.rs
+++ b/crates/rust-analyzer/src/world.rs
@@ -137,15 +137,6 @@ impl WorldState {
             opts
         };
 
-        // Create crate graph from all the workspaces
-        let mut crate_graph = CrateGraph::default();
-        let mut load = |path: &std::path::Path| {
-            // Some path from metadata will be non canonicalized, e.g. /foo/../bar/lib.rs
-            let path = path.canonicalize().ok()?;
-            let vfs_file = vfs.load(&path);
-            vfs_file.map(|f| FileId(f.0))
-        };
-
         let proc_macro_client = match &config.proc_macro_srv {
             None => ProcMacroClient::dummy(),
             Some((path, args)) => match ProcMacroClient::extern_process(path.into(), args) {
@@ -161,19 +152,22 @@ impl WorldState {
             },
         };
 
-        workspaces
-            .iter()
-            .map(|ws| {
-                ws.to_crate_graph(
-                    &default_cfg_options,
-                    &extern_source_roots,
-                    &proc_macro_client,
-                    &mut load,
-                )
-            })
-            .for_each(|graph| {
-                crate_graph.extend(graph);
-            });
+        // Create crate graph from all the workspaces
+        let mut crate_graph = CrateGraph::default();
+        let mut load = |path: &Path| {
+            // Some path from metadata will be non canonicalized, e.g. /foo/../bar/lib.rs
+            let path = path.canonicalize().ok()?;
+            let vfs_file = vfs.load(&path);
+            vfs_file.map(|f| FileId(f.0))
+        };
+        for ws in workspaces.iter() {
+            crate_graph.extend(ws.to_crate_graph(
+                &default_cfg_options,
+                &extern_source_roots,
+                &proc_macro_client,
+                &mut load,
+            ));
+        }
         change.set_crate_graph(crate_graph);
 
         let flycheck = config.check.as_ref().and_then(|c| create_flycheck(&workspaces, c));
diff --git a/crates/rust-analyzer/tests/heavy_tests/main.rs b/crates/rust-analyzer/tests/heavy_tests/main.rs
index e459e3a3c..5011cc273 100644
--- a/crates/rust-analyzer/tests/heavy_tests/main.rs
+++ b/crates/rust-analyzer/tests/heavy_tests/main.rs
@@ -3,15 +3,16 @@ mod support;
 use std::{collections::HashMap, path::PathBuf, time::Instant};
 
 use lsp_types::{
-    CodeActionContext, DidOpenTextDocumentParams, DocumentFormattingParams, FormattingOptions,
-    GotoDefinitionParams, HoverParams, PartialResultParams, Position, Range, TextDocumentItem,
-    TextDocumentPositionParams, WorkDoneProgressParams,
-};
-use rust_analyzer::req::{
-    CodeActionParams, CodeActionRequest, Completion, CompletionParams, DidOpenTextDocument,
-    Formatting, GotoDefinition, GotoTypeDefinition, HoverRequest, OnEnter, Runnables,
-    RunnablesParams,
+    notification::DidOpenTextDocument,
+    request::{
+        CodeActionRequest, Completion, Formatting, GotoDefinition, GotoTypeDefinition, HoverRequest,
+    },
+    CodeActionContext, CodeActionParams, CompletionParams, DidOpenTextDocumentParams,
+    DocumentFormattingParams, FormattingOptions, GotoDefinitionParams, HoverParams,
+    PartialResultParams, Position, Range, TextDocumentItem, TextDocumentPositionParams,
+    WorkDoneProgressParams,
 };
+use rust_analyzer::lsp_ext::{OnEnter, Runnables, RunnablesParams};
 use serde_json::json;
 use tempfile::TempDir;
 use test_utils::skip_slow_tests;
diff --git a/crates/rust-analyzer/tests/heavy_tests/support.rs b/crates/rust-analyzer/tests/heavy_tests/support.rs
index 8d47ee4f6..8756ad4a3 100644
--- a/crates/rust-analyzer/tests/heavy_tests/support.rs
+++ b/crates/rust-analyzer/tests/heavy_tests/support.rs
@@ -13,15 +13,15 @@ use lsp_types::{
     request::Shutdown,
     DidOpenTextDocumentParams, TextDocumentIdentifier, TextDocumentItem, Url, WorkDoneProgress,
 };
+use lsp_types::{ProgressParams, ProgressParamsValue};
 use serde::Serialize;
 use serde_json::{to_string_pretty, Value};
 use tempfile::TempDir;
 use test_utils::{find_mismatch, parse_fixture};
 
-use req::{ProgressParams, ProgressParamsValue};
 use rust_analyzer::{
     config::{ClientCapsConfig, Config},
-    main_loop, req,
+    main_loop,
 };
 
 pub struct Project<'a> {
@@ -206,7 +206,7 @@ impl Server {
             Message::Notification(n) if n.method == "$/progress" => {
                 match n.clone().extract::<ProgressParams>("$/progress").unwrap() {
                     ProgressParams {
-                        token: req::ProgressToken::String(ref token),
+                        token: lsp_types::ProgressToken::String(ref token),
                         value: ProgressParamsValue::WorkDone(WorkDoneProgress::End(_)),
                     } if token == "rustAnalyzer/startup" => true,
                     _ => false,
diff --git a/crates/test_utils/src/lib.rs b/crates/test_utils/src/lib.rs
index b13e13af2..b1e3c328f 100644
--- a/crates/test_utils/src/lib.rs
+++ b/crates/test_utils/src/lib.rs
@@ -270,7 +270,7 @@ fn parse_fixture_checks_further_indented_metadata() {
 }
 
 #[test]
-fn parse_fixture_can_handle_unindented_first_line() {
+fn parse_fixture_can_handle_dedented_first_line() {
     let fixture = "//- /lib.rs
                    mod foo;
                    //- /foo.rs
diff --git a/editors/code/package.json b/editors/code/package.json
index 853fc513b..c6fc13519 100644
--- a/editors/code/package.json
+++ b/editors/code/package.json
@@ -423,6 +423,16 @@
                     "default": {
                         "/rustc/<id>": "${env:USERPROFILE}/.rustup/toolchains/<toolchain-id>/lib/rustlib/src/rust"
                     }
+                },
+                "rust-analyzer.debug.openDebugPane": {
+                    "description": "Whether to open up the Debug Pane on debugging start.",
+                    "type": "boolean",
+                    "default": false
+                },
+                "rust-analyzer.debug.engineSettings": {
+                    "type": "object",
+                    "default": {},
+                    "description": "Optional settings passed to the debug engine. Example:\n{ \"lldb\": { \"terminal\":\"external\"} }"
                 }
             }
         },
diff --git a/editors/code/src/commands/runnables.ts b/editors/code/src/commands/runnables.ts
index 2ed150e25..ae328d2a4 100644
--- a/editors/code/src/commands/runnables.ts
+++ b/editors/code/src/commands/runnables.ts
@@ -64,29 +64,20 @@ export function runSingle(ctx: Ctx): Cmd {
     };
 }
 
-function getLldbDebugConfig(config: ra.Runnable, sourceFileMap: Record<string, string>): vscode.DebugConfiguration {
+function getLldbDebugConfig(config: ra.Runnable, executable: string, sourceFileMap?: Record<string, string>): vscode.DebugConfiguration {
     return {
         type: "lldb",
         request: "launch",
         name: config.label,
-        cargo: {
-            args: config.args,
-        },
+        program: executable,
         args: config.extraArgs,
         cwd: config.cwd,
-        sourceMap: sourceFileMap
+        sourceMap: sourceFileMap,
+        sourceLanguages: ["rust"]
     };
 }
 
-const debugOutput = vscode.window.createOutputChannel("Debug");
-
-async function getCppvsDebugConfig(config: ra.Runnable, sourceFileMap: Record<string, string>): Promise<vscode.DebugConfiguration> {
-    debugOutput.clear();
-
-    const cargo = new Cargo(config.cwd || '.', debugOutput);
-    const executable = await cargo.executableFromArgs(config.args);
-
-    // if we are here, there were no compilation errors.
+function getCppvsDebugConfig(config: ra.Runnable, executable: string, sourceFileMap?: Record<string, string>): vscode.DebugConfiguration {
     return {
         type: (os.platform() === "win32") ? "cppvsdbg" : 'cppdbg',
         request: "launch",
@@ -98,39 +89,62 @@ async function getCppvsDebugConfig(config: ra.Runnable, sourceFileMap: Record<st
     };
 }
 
+const debugOutput = vscode.window.createOutputChannel("Debug");
+
+async function getDebugExecutable(config: ra.Runnable): Promise<string> {
+    const cargo = new Cargo(config.cwd || '.', debugOutput);
+    const executable = await cargo.executableFromArgs(config.args);
+
+    // if we are here, there were no compilation errors.
+    return executable;
+}
+
+type DebugConfigProvider = (config: ra.Runnable, executable: string, sourceFileMap?: Record<string, string>) => vscode.DebugConfiguration;
+
 export function debugSingle(ctx: Ctx): Cmd {
     return async (config: ra.Runnable) => {
         const editor = ctx.activeRustEditor;
         if (!editor) return;
 
-        const lldbId = "vadimcn.vscode-lldb";
-        const cpptoolsId = "ms-vscode.cpptools";
+        const knownEngines: Record<string, DebugConfigProvider> = {
+            "vadimcn.vscode-lldb": getLldbDebugConfig,
+            "ms-vscode.cpptools": getCppvsDebugConfig
+        };
+        const debugOptions = ctx.config.debug;
 
-        const debugEngineId = ctx.config.debug.engine;
         let debugEngine = null;
-        if (debugEngineId === "auto") {
-            debugEngine = vscode.extensions.getExtension(lldbId);
-            if (!debugEngine) {
-                debugEngine = vscode.extensions.getExtension(cpptoolsId);
+        if (debugOptions.engine === "auto") {
+            for (var engineId in knownEngines) {
+                debugEngine = vscode.extensions.getExtension(engineId);
+                if (debugEngine) break;
             }
         }
         else {
-            debugEngine = vscode.extensions.getExtension(debugEngineId);
+            debugEngine = vscode.extensions.getExtension(debugOptions.engine);
         }
 
         if (!debugEngine) {
-            vscode.window.showErrorMessage(
-                `Install [CodeLLDB](https://marketplace.visualstudio.com/items?itemName=${lldbId}) ` +
-                `or [MS C++ tools](https://marketplace.visualstudio.com/items?itemName=${cpptoolsId}) ` +
-                `extension for debugging.`
-            );
+            vscode.window.showErrorMessage(`Install [CodeLLDB](https://marketplace.visualstudio.com/items?itemName=vadimcn.vscode-lldb)`
+                + ` or [MS C++ tools](https://marketplace.visualstudio.com/items?itemName=ms-vscode.cpptools) extension for debugging.`);
             return;
         }
 
-        const debugConfig = lldbId === debugEngine.id
-            ? getLldbDebugConfig(config, ctx.config.debug.sourceFileMap)
-            : await getCppvsDebugConfig(config, ctx.config.debug.sourceFileMap);
+        debugOutput.clear();
+        if (ctx.config.debug.openUpDebugPane) {
+            debugOutput.show(true);
+        }
+
+        const executable = await getDebugExecutable(config);
+        const debugConfig = knownEngines[debugEngine.id](config, executable, debugOptions.sourceFileMap);
+        if (debugConfig.type in debugOptions.engineSettings) {
+            const settingsMap = (debugOptions.engineSettings as any)[debugConfig.type];
+            for (var key in settingsMap) {
+                debugConfig[key] = settingsMap[key];
+            }
+        }
 
+        debugOutput.appendLine("Launching debug configuration:");
+        debugOutput.appendLine(JSON.stringify(debugConfig, null, 2));
         return vscode.debug.startDebugging(undefined, debugConfig);
     };
 }
diff --git a/editors/code/src/commands/syntax_tree.ts b/editors/code/src/commands/syntax_tree.ts
index cfcf47b2f..b80a18a47 100644
--- a/editors/code/src/commands/syntax_tree.ts
+++ b/editors/code/src/commands/syntax_tree.ts
@@ -225,7 +225,7 @@ class AstInspector implements vscode.HoverProvider, vscode.DefinitionProvider, D
             return doc.positionAt(targetOffset);
         }
 
-        // Shitty workaround for crlf line endings
+        // Dirty workaround for crlf line endings
         // We are still in this prehistoric era of carriage returns here...
 
         let line = 0;
diff --git a/editors/code/src/config.ts b/editors/code/src/config.ts
index 46de922f3..be2e27aec 100644
--- a/editors/code/src/config.ts
+++ b/editors/code/src/config.ts
@@ -109,10 +109,14 @@ export class Config {
     }
 
     get debug() {
+        // "/rustc/<id>" used by suggestions only.
+        const { ["/rustc/<id>"]: _, ...sourceFileMap } = this.get<Record<string, string>>("debug.sourceFileMap");
+
         return {
             engine: this.get<string>("debug.engine"),
-            sourceFileMap: this.get<Record<string, string>>("debug.sourceFileMap"),
+            engineSettings: this.get<object>("debug.engineSettings"),
+            openUpDebugPane: this.get<boolean>("debug.openUpDebugPane"),
+            sourceFileMap: sourceFileMap,
         };
     }
-
 }