Merge branch 'master' of https://github.com/rust-analyzer/rust-analyzer into feature/themes

30 files changed, 835 insertions, 712 deletions

diff --git a/crates/ra_assists/src/assists/early_return.rs b/crates/ra_assists/src/assists/early_return.rs
index 570a07a20..264412526 100644
--- a/crates/ra_assists/src/assists/early_return.rs
+++ b/crates/ra_assists/src/assists/early_return.rs
@@ -1,4 +1,4 @@
-use std::ops::RangeInclusive;
+use std::{iter::once, ops::RangeInclusive};
 
 use hir::db::HirDatabase;
 use ra_syntax::{
@@ -38,27 +38,30 @@ use crate::{
 // ```
 pub(crate) fn convert_to_guarded_return(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
     let if_expr: ast::IfExpr = ctx.find_node_at_offset()?;
+    if if_expr.else_branch().is_some() {
+        return None;
+    }
+
     let cond = if_expr.condition()?;
-    let mut if_let_ident: Option<String> = None;
 
     // Check if there is an IfLet that we can handle.
-    match cond.pat() {
-        None => {} // No IfLet, supported.
-        Some(TupleStructPat(ref pat)) if pat.args().count() == 1usize => match &pat.path() {
-            Some(p) => match p.qualifier() {
-                None => if_let_ident = Some(p.syntax().text().to_string()),
-                _ => return None,
-            },
-            _ => return None,
-        },
-        _ => return None, // Unsupported IfLet.
+    let if_let_pat = match cond.pat() {
+        None => None, // No IfLet, supported.
+        Some(TupleStructPat(pat)) if pat.args().count() == 1 => {
+            let path = pat.path()?;
+            match path.qualifier() {
+                None => {
+                    let bound_ident = pat.args().next().unwrap();
+                    Some((path, bound_ident))
+                }
+                Some(_) => return None,
+            }
+        }
+        Some(_) => return None, // Unsupported IfLet.
     };
 
-    let expr = cond.expr()?;
+    let cond_expr = cond.expr()?;
     let then_block = if_expr.then_branch()?.block()?;
-    if if_expr.else_branch().is_some() {
-        return None;
-    }
 
     let parent_block = if_expr.syntax().parent()?.ancestors().find_map(ast::Block::cast)?;
 
@@ -79,11 +82,11 @@ pub(crate) fn convert_to_guarded_return(ctx: AssistCtx<impl HirDatabase>) -> Opt
 
     let parent_container = parent_block.syntax().parent()?.parent()?;
 
-    let early_expression = match parent_container.kind() {
-        WHILE_EXPR | LOOP_EXPR => Some("continue"),
-        FN_DEF => Some("return"),
-        _ => None,
-    }?;
+    let early_expression: ast::Expr = match parent_container.kind() {
+        WHILE_EXPR | LOOP_EXPR => make::expr_continue().into(),
+        FN_DEF => make::expr_return().into(),
+        _ => return None,
+    };
 
     if then_block.syntax().first_child_or_token().map(|t| t.kind() == L_CURLY).is_none() {
         return None;
@@ -94,22 +97,43 @@ pub(crate) fn convert_to_guarded_return(ctx: AssistCtx<impl HirDatabase>) -> Opt
 
     ctx.add_assist(AssistId("convert_to_guarded_return"), "convert to guarded return", |edit| {
         let if_indent_level = IndentLevel::from_node(&if_expr.syntax());
-        let new_block = match if_let_ident {
+        let new_block = match if_let_pat {
             None => {
                 // If.
-                let early_expression = &(early_expression.to_owned() + ";");
-                let new_expr =
-                    if_indent_level.increase_indent(make::if_expression(&expr, early_expression));
-                replace(new_expr, &then_block, &parent_block, &if_expr)
+                let early_expression = &(early_expression.syntax().to_string() + ";");
+                let new_expr = if_indent_level
+                    .increase_indent(make::if_expression(&cond_expr, early_expression));
+                replace(new_expr.syntax(), &then_block, &parent_block, &if_expr)
             }
-            Some(if_let_ident) => {
+            Some((path, bound_ident)) => {
                 // If-let.
-                let new_expr = if_indent_level.increase_indent(make::let_match_early(
-                    expr,
-                    &if_let_ident,
-                    early_expression,
-                ));
-                replace(new_expr, &then_block, &parent_block, &if_expr)
+                let match_expr = {
+                    let happy_arm = make::match_arm(
+                        once(
+                            make::tuple_struct_pat(
+                                path,
+                                once(make::bind_pat(make::name("it")).into()),
+                            )
+                            .into(),
+                        ),
+                        make::expr_path(make::path_from_name_ref(make::name_ref("it"))).into(),
+                    );
+
+                    let sad_arm = make::match_arm(
+                        // FIXME: would be cool to use `None` or `Err(_)` if appropriate
+                        once(make::placeholder_pat().into()),
+                        early_expression.into(),
+                    );
+
+                    make::expr_match(cond_expr, make::match_arm_list(vec![happy_arm, sad_arm]))
+                };
+
+                let let_stmt = make::let_stmt(
+                    make::bind_pat(make::name(&bound_ident.syntax().to_string())).into(),
+                    Some(match_expr.into()),
+                );
+                let let_stmt = if_indent_level.increase_indent(let_stmt);
+                replace(let_stmt.syntax(), &then_block, &parent_block, &if_expr)
             }
         };
         edit.target(if_expr.syntax().text_range());
@@ -117,7 +141,7 @@ pub(crate) fn convert_to_guarded_return(ctx: AssistCtx<impl HirDatabase>) -> Opt
         edit.set_cursor(cursor_position);
 
         fn replace(
-            new_expr: impl AstNode,
+            new_expr: &SyntaxNode,
             then_block: &Block,
             parent_block: &Block,
             if_expr: &ast::IfExpr,
@@ -130,7 +154,7 @@ pub(crate) fn convert_to_guarded_return(ctx: AssistCtx<impl HirDatabase>) -> Opt
                 } else {
                     end_of_then
                 };
-            let mut then_statements = new_expr.syntax().children_with_tokens().chain(
+            let mut then_statements = new_expr.children_with_tokens().chain(
                 then_block_items
                     .syntax()
                     .children_with_tokens()
@@ -151,9 +175,10 @@ pub(crate) fn convert_to_guarded_return(ctx: AssistCtx<impl HirDatabase>) -> Opt
 
 #[cfg(test)]
 mod tests {
-    use super::*;
     use crate::helpers::{check_assist, check_assist_not_applicable};
 
+    use super::*;
+
     #[test]
     fn convert_inside_fn() {
         check_assist(
@@ -204,7 +229,7 @@ mod tests {
                 bar();
                 le<|>t n = match n {
                     Some(it) => it,
-                    None => return,
+                    _ => return,
                 };
                 foo(n);
 
@@ -216,6 +241,29 @@ mod tests {
     }
 
     #[test]
+    fn convert_if_let_result() {
+        check_assist(
+            convert_to_guarded_return,
+            r#"
+            fn main() {
+                if<|> let Ok(x) = Err(92) {
+                    foo(x);
+                }
+            }
+            "#,
+            r#"
+            fn main() {
+                le<|>t x = match Err(92) {
+                    Ok(it) => it,
+                    _ => return,
+                };
+                foo(x);
+            }
+            "#,
+        );
+    }
+
+    #[test]
     fn convert_let_ok_inside_fn() {
         check_assist(
             convert_to_guarded_return,
@@ -235,7 +283,7 @@ mod tests {
                 bar();
                 le<|>t n = match n {
                     Ok(it) => it,
-                    None => return,
+                    _ => return,
                 };
                 foo(n);
 
@@ -293,7 +341,7 @@ mod tests {
                 while true {
                     le<|>t n = match n {
                         Some(it) => it,
-                        None => continue,
+                        _ => continue,
                     };
                     foo(n);
                     bar();
@@ -350,7 +398,7 @@ mod tests {
                 loop {
                     le<|>t n = match n {
                         Some(it) => it,
-                        None => continue,
+                        _ => continue,
                     };
                     foo(n);
                     bar();
diff --git a/crates/ra_hir/src/code_model.rs b/crates/ra_hir/src/code_model.rs
index 2fd4ccb10..962d5a8c1 100644
--- a/crates/ra_hir/src/code_model.rs
+++ b/crates/ra_hir/src/code_model.rs
@@ -8,6 +8,7 @@ use std::sync::Arc;
 
 use hir_def::{
     adt::VariantData,
+    body::scope::ExprScopes,
     builtin_type::BuiltinType,
     type_ref::{Mutability, TypeRef},
     CrateModuleId, LocalEnumVariantId, LocalStructFieldId, ModuleId, UnionId,
@@ -539,6 +540,7 @@ pub trait HasBody: Copy {
     fn infer(self, db: &impl HirDatabase) -> Arc<InferenceResult>;
     fn body(self, db: &impl HirDatabase) -> Arc<Body>;
     fn body_source_map(self, db: &impl HirDatabase) -> Arc<BodySourceMap>;
+    fn expr_scopes(self, db: &impl HirDatabase) -> Arc<ExprScopes>;
 }
 
 impl<T> HasBody for T
@@ -550,11 +552,15 @@ where
     }
 
     fn body(self, db: &impl HirDatabase) -> Arc<Body> {
-        db.body(self.into())
+        self.into().body(db)
     }
 
     fn body_source_map(self, db: &impl HirDatabase) -> Arc<BodySourceMap> {
-        db.body_with_source_map(self.into()).1
+        self.into().body_source_map(db)
+    }
+
+    fn expr_scopes(self, db: &impl HirDatabase) -> Arc<ExprScopes> {
+        self.into().expr_scopes(db)
     }
 }
 
@@ -564,11 +570,15 @@ impl HasBody for DefWithBody {
     }
 
     fn body(self, db: &impl HirDatabase) -> Arc<Body> {
-        db.body(self)
+        db.body(self.into())
     }
 
     fn body_source_map(self, db: &impl HirDatabase) -> Arc<BodySourceMap> {
-        db.body_with_source_map(self).1
+        db.body_with_source_map(self.into()).1
+    }
+
+    fn expr_scopes(self, db: &impl HirDatabase) -> Arc<ExprScopes> {
+        db.expr_scopes(self.into())
     }
 }
 
@@ -662,11 +672,11 @@ impl Function {
     }
 
     pub(crate) fn body_source_map(self, db: &impl HirDatabase) -> Arc<BodySourceMap> {
-        db.body_with_source_map(self.into()).1
+        db.body_with_source_map(self.id.into()).1
     }
 
     pub fn body(self, db: &impl HirDatabase) -> Arc<Body> {
-        db.body(self.into())
+        db.body(self.id.into())
     }
 
     pub fn ty(self, db: &impl HirDatabase) -> Ty {
@@ -1079,7 +1089,7 @@ pub struct Local {
 
 impl Local {
     pub fn name(self, db: &impl HirDatabase) -> Option<Name> {
-        let body = db.body(self.parent);
+        let body = self.parent.body(db);
         match &body[self.pat_id] {
             Pat::Bind { name, .. } => Some(name.clone()),
             _ => None,
@@ -1091,7 +1101,7 @@ impl Local {
     }
 
     pub fn is_mut(self, db: &impl HirDatabase) -> bool {
-        let body = db.body(self.parent);
+        let body = self.parent.body(db);
         match &body[self.pat_id] {
             Pat::Bind { mode, .. } => match mode {
                 BindingAnnotation::Mutable | BindingAnnotation::RefMut => true,
@@ -1115,7 +1125,7 @@ impl Local {
     }
 
     pub fn source(self, db: &impl HirDatabase) -> Source<Either<ast::BindPat, ast::SelfParam>> {
-        let (_body, source_map) = db.body_with_source_map(self.parent);
+        let source_map = self.parent.body_source_map(db);
         let src = source_map.pat_syntax(self.pat_id).unwrap(); // Hmm...
         let root = src.file_syntax(db);
         src.map(|ast| ast.map(|it| it.cast().unwrap().to_node(&root), |it| it.to_node(&root)))
diff --git a/crates/ra_hir/src/db.rs b/crates/ra_hir/src/db.rs
index 9ac811232..c60029c01 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -8,7 +8,6 @@ use ra_syntax::SmolStr;
 
 use crate::{
     debug::HirDebugDatabase,
-    expr::{Body, BodySourceMap},
     generics::{GenericDef, GenericParams},
     ids,
     impl_block::{ImplBlock, ImplSourceMap, ModuleImplBlocks},
@@ -19,13 +18,14 @@ use crate::{
         InferenceResult, Namespace, Substs, Ty, TypableDef, TypeCtor,
     },
     type_alias::TypeAliasData,
-    Const, ConstData, Crate, DefWithBody, ExprScopes, FnData, Function, Module, Static,
-    StructField, Trait, TypeAlias,
+    Const, ConstData, Crate, DefWithBody, FnData, Function, Module, Static, StructField, Trait,
+    TypeAlias,
 };
 
 pub use hir_def::db::{
-    CrateDefMapQuery, DefDatabase2, DefDatabase2Storage, EnumDataQuery, InternDatabase,
-    InternDatabaseStorage, RawItemsQuery, RawItemsWithSourceMapQuery, StructDataQuery,
+    BodyQuery, BodyWithSourceMapQuery, CrateDefMapQuery, DefDatabase2, DefDatabase2Storage,
+    EnumDataQuery, ExprScopesQuery, InternDatabase, InternDatabaseStorage, RawItemsQuery,
+    RawItemsWithSourceMapQuery, StructDataQuery,
 };
 pub use hir_expand::db::{
     AstDatabase, AstDatabaseStorage, AstIdMapQuery, MacroArgQuery, MacroDefQuery, MacroExpandQuery,
@@ -85,9 +85,6 @@ pub trait DefDatabase: HirDebugDatabase + DefDatabase2 {
 #[salsa::query_group(HirDatabaseStorage)]
 #[salsa::requires(salsa::Database)]
 pub trait HirDatabase: DefDatabase + AstDatabase {
-    #[salsa::invoke(ExprScopes::expr_scopes_query)]
-    fn expr_scopes(&self, def: DefWithBody) -> Arc<ExprScopes>;
-
     #[salsa::invoke(crate::ty::infer_query)]
     fn infer(&self, def: DefWithBody) -> Arc<InferenceResult>;
 
@@ -113,12 +110,6 @@ pub trait HirDatabase: DefDatabase + AstDatabase {
     #[salsa::invoke(crate::ty::generic_defaults_query)]
     fn generic_defaults(&self, def: GenericDef) -> Substs;
 
-    #[salsa::invoke(crate::expr::body_with_source_map_query)]
-    fn body_with_source_map(&self, def: DefWithBody) -> (Arc<Body>, Arc<BodySourceMap>);
-
-    #[salsa::invoke(crate::expr::body_query)]
-    fn body(&self, def: DefWithBody) -> Arc<Body>;
-
     #[salsa::invoke(crate::ty::method_resolution::CrateImplBlocks::impls_in_crate_query)]
     fn impls_in_crate(&self, krate: Crate) -> Arc<CrateImplBlocks>;
 
diff --git a/crates/ra_hir/src/expr.rs b/crates/ra_hir/src/expr.rs
index 82955fa55..9262325f2 100644
--- a/crates/ra_hir/src/expr.rs
+++ b/crates/ra_hir/src/expr.rs
@@ -1,74 +1,233 @@
 //! FIXME: write short doc here
 
-pub(crate) mod scope;
 pub(crate) mod validation;
 
 use std::sync::Arc;
 
-use ra_syntax::{ast, AstPtr};
+use ra_syntax::AstPtr;
 
-use crate::{db::HirDatabase, DefWithBody, HasSource, Resolver};
-
-pub use self::scope::ExprScopes;
+use crate::{db::HirDatabase, DefWithBody, HasBody, Resolver};
 
 pub use hir_def::{
-    body::{Body, BodySourceMap, ExprPtr, ExprSource, PatPtr, PatSource},
+    body::{
+        scope::{ExprScopes, ScopeEntry, ScopeId},
+        Body, BodySourceMap, ExprPtr, ExprSource, PatPtr, PatSource,
+    },
     expr::{
         ArithOp, Array, BinaryOp, BindingAnnotation, CmpOp, Expr, ExprId, Literal, LogicOp,
         MatchArm, Ordering, Pat, PatId, RecordFieldPat, RecordLitField, Statement, UnaryOp,
     },
 };
 
-pub(crate) fn body_with_source_map_query(
-    db: &impl HirDatabase,
-    def: DefWithBody,
-) -> (Arc<Body>, Arc<BodySourceMap>) {
-    let mut params = None;
-
-    let (file_id, body) = match def {
-        DefWithBody::Function(f) => {
-            let src = f.source(db);
-            params = src.ast.param_list();
-            (src.file_id, src.ast.body().map(ast::Expr::from))
-        }
-        DefWithBody::Const(c) => {
-            let src = c.source(db);
-            (src.file_id, src.ast.body())
-        }
-        DefWithBody::Static(s) => {
-            let src = s.source(db);
-            (src.file_id, src.ast.body())
-        }
-    };
-    let resolver = hir_def::body::MacroResolver::new(db, def.module(db).id);
-    let (body, source_map) = Body::new(db, resolver, file_id, params, body);
-    (Arc::new(body), Arc::new(source_map))
-}
-
-pub(crate) fn body_query(db: &impl HirDatabase, def: DefWithBody) -> Arc<Body> {
-    db.body_with_source_map(def).0
-}
-
 // needs arbitrary_self_types to be a method... or maybe move to the def?
 pub(crate) fn resolver_for_expr(
     db: &impl HirDatabase,
     owner: DefWithBody,
     expr_id: ExprId,
 ) -> Resolver {
-    let scopes = db.expr_scopes(owner);
+    let scopes = owner.expr_scopes(db);
     resolver_for_scope(db, owner, scopes.scope_for(expr_id))
 }
 
 pub(crate) fn resolver_for_scope(
     db: &impl HirDatabase,
     owner: DefWithBody,
-    scope_id: Option<scope::ScopeId>,
+    scope_id: Option<ScopeId>,
 ) -> Resolver {
     let mut r = owner.resolver(db);
-    let scopes = db.expr_scopes(owner);
+    let scopes = owner.expr_scopes(db);
     let scope_chain = scopes.scope_chain(scope_id).collect::<Vec<_>>();
     for scope in scope_chain.into_iter().rev() {
         r = r.push_expr_scope(Arc::clone(&scopes), scope);
     }
     r
 }
+
+#[cfg(test)]
+mod tests {
+    use hir_expand::Source;
+    use ra_db::{fixture::WithFixture, SourceDatabase};
+    use ra_syntax::{algo::find_node_at_offset, ast, AstNode};
+    use test_utils::{assert_eq_text, extract_offset};
+
+    use crate::{source_binder::SourceAnalyzer, test_db::TestDB};
+
+    fn do_check(code: &str, expected: &[&str]) {
+        let (off, code) = extract_offset(code);
+        let code = {
+            let mut buf = String::new();
+            let off = u32::from(off) as usize;
+            buf.push_str(&code[..off]);
+            buf.push_str("marker");
+            buf.push_str(&code[off..]);
+            buf
+        };
+
+        let (db, file_id) = TestDB::with_single_file(&code);
+
+        let file = db.parse(file_id).ok().unwrap();
+        let marker: ast::PathExpr = find_node_at_offset(file.syntax(), off).unwrap();
+        let analyzer = SourceAnalyzer::new(&db, file_id, marker.syntax(), None);
+
+        let scopes = analyzer.scopes();
+        let expr_id = analyzer
+            .body_source_map()
+            .node_expr(Source { file_id: file_id.into(), ast: &marker.into() })
+            .unwrap();
+        let scope = scopes.scope_for(expr_id);
+
+        let actual = scopes
+            .scope_chain(scope)
+            .flat_map(|scope| scopes.entries(scope))
+            .map(|it| it.name().to_string())
+            .collect::<Vec<_>>()
+            .join("\n");
+        let expected = expected.join("\n");
+        assert_eq_text!(&expected, &actual);
+    }
+
+    #[test]
+    fn test_lambda_scope() {
+        do_check(
+            r"
+            fn quux(foo: i32) {
+                let f = |bar, baz: i32| {
+                    <|>
+                };
+            }",
+            &["bar", "baz", "foo"],
+        );
+    }
+
+    #[test]
+    fn test_call_scope() {
+        do_check(
+            r"
+            fn quux() {
+                f(|x| <|> );
+            }",
+            &["x"],
+        );
+    }
+
+    #[test]
+    fn test_method_call_scope() {
+        do_check(
+            r"
+            fn quux() {
+                z.f(|x| <|> );
+            }",
+            &["x"],
+        );
+    }
+
+    #[test]
+    fn test_loop_scope() {
+        do_check(
+            r"
+            fn quux() {
+                loop {
+                    let x = ();
+                    <|>
+                };
+            }",
+            &["x"],
+        );
+    }
+
+    #[test]
+    fn test_match() {
+        do_check(
+            r"
+            fn quux() {
+                match () {
+                    Some(x) => {
+                        <|>
+                    }
+                };
+            }",
+            &["x"],
+        );
+    }
+
+    #[test]
+    fn test_shadow_variable() {
+        do_check(
+            r"
+            fn foo(x: String) {
+                let x : &str = &x<|>;
+            }",
+            &["x"],
+        );
+    }
+
+    fn do_check_local_name(code: &str, expected_offset: u32) {
+        let (off, code) = extract_offset(code);
+
+        let (db, file_id) = TestDB::with_single_file(&code);
+        let file = db.parse(file_id).ok().unwrap();
+        let expected_name = find_node_at_offset::<ast::Name>(file.syntax(), expected_offset.into())
+            .expect("failed to find a name at the target offset");
+        let name_ref: ast::NameRef = find_node_at_offset(file.syntax(), off).unwrap();
+        let analyzer = SourceAnalyzer::new(&db, file_id, name_ref.syntax(), None);
+
+        let local_name_entry = analyzer.resolve_local_name(&name_ref).unwrap();
+        let local_name =
+            local_name_entry.ptr().either(|it| it.syntax_node_ptr(), |it| it.syntax_node_ptr());
+        assert_eq!(local_name.range(), expected_name.syntax().text_range());
+    }
+
+    #[test]
+    fn test_resolve_local_name() {
+        do_check_local_name(
+            r#"
+            fn foo(x: i32, y: u32) {
+                {
+                    let z = x * 2;
+                }
+                {
+                    let t = x<|> * 3;
+                }
+            }"#,
+            21,
+        );
+    }
+
+    #[test]
+    fn test_resolve_local_name_declaration() {
+        do_check_local_name(
+            r#"
+            fn foo(x: String) {
+                let x : &str = &x<|>;
+            }"#,
+            21,
+        );
+    }
+
+    #[test]
+    fn test_resolve_local_name_shadow() {
+        do_check_local_name(
+            r"
+            fn foo(x: String) {
+                let x : &str = &x;
+                x<|>
+            }
+            ",
+            53,
+        );
+    }
+
+    #[test]
+    fn ref_patterns_contribute_bindings() {
+        do_check_local_name(
+            r"
+            fn foo() {
+                if let Some(&from) = bar() {
+                    from<|>;
+                }
+            }
+            ",
+            53,
+        );
+    }
+}
diff --git a/crates/ra_hir/src/expr/scope.rs b/crates/ra_hir/src/expr/scope.rs
deleted file mode 100644
index 0e49a28d6..000000000
--- a/crates/ra_hir/src/expr/scope.rs
+++ /dev/null
@@ -1,354 +0,0 @@
-//! FIXME: write short doc here
-
-use std::sync::Arc;
-
-use ra_arena::{impl_arena_id, Arena, RawId};
-use rustc_hash::FxHashMap;
-
-use crate::{
-    db::HirDatabase,
-    expr::{Body, Expr, ExprId, Pat, PatId, Statement},
-    DefWithBody, Name,
-};
-
-#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
-pub struct ScopeId(RawId);
-impl_arena_id!(ScopeId);
-
-#[derive(Debug, PartialEq, Eq)]
-pub struct ExprScopes {
-    pub(crate) body: Arc<Body>,
-    scopes: Arena<ScopeId, ScopeData>,
-    scope_by_expr: FxHashMap<ExprId, ScopeId>,
-}
-
-#[derive(Debug, PartialEq, Eq)]
-pub(crate) struct ScopeEntry {
-    name: Name,
-    pat: PatId,
-}
-
-impl ScopeEntry {
-    pub(crate) fn name(&self) -> &Name {
-        &self.name
-    }
-
-    pub(crate) fn pat(&self) -> PatId {
-        self.pat
-    }
-}
-
-#[derive(Debug, PartialEq, Eq)]
-pub(crate) struct ScopeData {
-    parent: Option<ScopeId>,
-    entries: Vec<ScopeEntry>,
-}
-
-impl ExprScopes {
-    pub(crate) fn expr_scopes_query(db: &impl HirDatabase, def: DefWithBody) -> Arc<ExprScopes> {
-        let body = db.body(def);
-        let res = ExprScopes::new(body);
-        Arc::new(res)
-    }
-
-    fn new(body: Arc<Body>) -> ExprScopes {
-        let mut scopes = ExprScopes {
-            body: body.clone(),
-            scopes: Arena::default(),
-            scope_by_expr: FxHashMap::default(),
-        };
-        let root = scopes.root_scope();
-        scopes.add_params_bindings(root, body.params());
-        compute_expr_scopes(body.body_expr(), &body, &mut scopes, root);
-        scopes
-    }
-
-    pub(crate) fn entries(&self, scope: ScopeId) -> &[ScopeEntry] {
-        &self.scopes[scope].entries
-    }
-
-    pub(crate) fn scope_chain(&self, scope: Option<ScopeId>) -> impl Iterator<Item = ScopeId> + '_ {
-        std::iter::successors(scope, move |&scope| self.scopes[scope].parent)
-    }
-
-    pub(crate) fn scope_for(&self, expr: ExprId) -> Option<ScopeId> {
-        self.scope_by_expr.get(&expr).copied()
-    }
-
-    pub(crate) fn scope_by_expr(&self) -> &FxHashMap<ExprId, ScopeId> {
-        &self.scope_by_expr
-    }
-
-    fn root_scope(&mut self) -> ScopeId {
-        self.scopes.alloc(ScopeData { parent: None, entries: vec![] })
-    }
-
-    fn new_scope(&mut self, parent: ScopeId) -> ScopeId {
-        self.scopes.alloc(ScopeData { parent: Some(parent), entries: vec![] })
-    }
-
-    fn add_bindings(&mut self, body: &Body, scope: ScopeId, pat: PatId) {
-        match &body[pat] {
-            Pat::Bind { name, .. } => {
-                // bind can have a sub pattern, but it's actually not allowed
-                // to bind to things in there
-                let entry = ScopeEntry { name: name.clone(), pat };
-                self.scopes[scope].entries.push(entry)
-            }
-            p => p.walk_child_pats(|pat| self.add_bindings(body, scope, pat)),
-        }
-    }
-
-    fn add_params_bindings(&mut self, scope: ScopeId, params: &[PatId]) {
-        let body = Arc::clone(&self.body);
-        params.iter().for_each(|pat| self.add_bindings(&body, scope, *pat));
-    }
-
-    fn set_scope(&mut self, node: ExprId, scope: ScopeId) {
-        self.scope_by_expr.insert(node, scope);
-    }
-}
-
-fn compute_block_scopes(
-    statements: &[Statement],
-    tail: Option<ExprId>,
-    body: &Body,
-    scopes: &mut ExprScopes,
-    mut scope: ScopeId,
-) {
-    for stmt in statements {
-        match stmt {
-            Statement::Let { pat, initializer, .. } => {
-                if let Some(expr) = initializer {
-                    scopes.set_scope(*expr, scope);
-                    compute_expr_scopes(*expr, body, scopes, scope);
-                }
-                scope = scopes.new_scope(scope);
-                scopes.add_bindings(body, scope, *pat);
-            }
-            Statement::Expr(expr) => {
-                scopes.set_scope(*expr, scope);
-                compute_expr_scopes(*expr, body, scopes, scope);
-            }
-        }
-    }
-    if let Some(expr) = tail {
-        compute_expr_scopes(expr, body, scopes, scope);
-    }
-}
-
-fn compute_expr_scopes(expr: ExprId, body: &Body, scopes: &mut ExprScopes, scope: ScopeId) {
-    scopes.set_scope(expr, scope);
-    match &body[expr] {
-        Expr::Block { statements, tail } => {
-            compute_block_scopes(&statements, *tail, body, scopes, scope);
-        }
-        Expr::For { iterable, pat, body: body_expr } => {
-            compute_expr_scopes(*iterable, body, scopes, scope);
-            let scope = scopes.new_scope(scope);
-            scopes.add_bindings(body, scope, *pat);
-            compute_expr_scopes(*body_expr, body, scopes, scope);
-        }
-        Expr::Lambda { args, body: body_expr, .. } => {
-            let scope = scopes.new_scope(scope);
-            scopes.add_params_bindings(scope, &args);
-            compute_expr_scopes(*body_expr, body, scopes, scope);
-        }
-        Expr::Match { expr, arms } => {
-            compute_expr_scopes(*expr, body, scopes, scope);
-            for arm in arms {
-                let scope = scopes.new_scope(scope);
-                for pat in &arm.pats {
-                    scopes.add_bindings(body, scope, *pat);
-                }
-                scopes.set_scope(arm.expr, scope);
-                compute_expr_scopes(arm.expr, body, scopes, scope);
-            }
-        }
-        e => e.walk_child_exprs(|e| compute_expr_scopes(e, body, scopes, scope)),
-    };
-}
-
-#[cfg(test)]
-mod tests {
-    use ra_db::{fixture::WithFixture, SourceDatabase};
-    use ra_syntax::{algo::find_node_at_offset, ast, AstNode};
-    use test_utils::{assert_eq_text, extract_offset};
-
-    use crate::{source_binder::SourceAnalyzer, test_db::TestDB};
-
-    fn do_check(code: &str, expected: &[&str]) {
-        let (off, code) = extract_offset(code);
-        let code = {
-            let mut buf = String::new();
-            let off = u32::from(off) as usize;
-            buf.push_str(&code[..off]);
-            buf.push_str("marker");
-            buf.push_str(&code[off..]);
-            buf
-        };
-
-        let (db, file_id) = TestDB::with_single_file(&code);
-        let file = db.parse(file_id).ok().unwrap();
-        let marker: ast::PathExpr = find_node_at_offset(file.syntax(), off).unwrap();
-        let analyzer = SourceAnalyzer::new(&db, file_id, marker.syntax(), None);
-
-        let scopes = analyzer.scopes();
-        let expr_id = analyzer.body_source_map().node_expr(&marker.into()).unwrap();
-        let scope = scopes.scope_for(expr_id);
-
-        let actual = scopes
-            .scope_chain(scope)
-            .flat_map(|scope| scopes.entries(scope))
-            .map(|it| it.name().to_string())
-            .collect::<Vec<_>>()
-            .join("\n");
-        let expected = expected.join("\n");
-        assert_eq_text!(&expected, &actual);
-    }
-
-    #[test]
-    fn test_lambda_scope() {
-        do_check(
-            r"
-            fn quux(foo: i32) {
-                let f = |bar, baz: i32| {
-                    <|>
-                };
-            }",
-            &["bar", "baz", "foo"],
-        );
-    }
-
-    #[test]
-    fn test_call_scope() {
-        do_check(
-            r"
-            fn quux() {
-                f(|x| <|> );
-            }",
-            &["x"],
-        );
-    }
-
-    #[test]
-    fn test_method_call_scope() {
-        do_check(
-            r"
-            fn quux() {
-                z.f(|x| <|> );
-            }",
-            &["x"],
-        );
-    }
-
-    #[test]
-    fn test_loop_scope() {
-        do_check(
-            r"
-            fn quux() {
-                loop {
-                    let x = ();
-                    <|>
-                };
-            }",
-            &["x"],
-        );
-    }
-
-    #[test]
-    fn test_match() {
-        do_check(
-            r"
-            fn quux() {
-                match () {
-                    Some(x) => {
-                        <|>
-                    }
-                };
-            }",
-            &["x"],
-        );
-    }
-
-    #[test]
-    fn test_shadow_variable() {
-        do_check(
-            r"
-            fn foo(x: String) {
-                let x : &str = &x<|>;
-            }",
-            &["x"],
-        );
-    }
-
-    fn do_check_local_name(code: &str, expected_offset: u32) {
-        let (off, code) = extract_offset(code);
-
-        let (db, file_id) = TestDB::with_single_file(&code);
-        let file = db.parse(file_id).ok().unwrap();
-        let expected_name = find_node_at_offset::<ast::Name>(file.syntax(), expected_offset.into())
-            .expect("failed to find a name at the target offset");
-        let name_ref: ast::NameRef = find_node_at_offset(file.syntax(), off).unwrap();
-        let analyzer = SourceAnalyzer::new(&db, file_id, name_ref.syntax(), None);
-
-        let local_name_entry = analyzer.resolve_local_name(&name_ref).unwrap();
-        let local_name =
-            local_name_entry.ptr().either(|it| it.syntax_node_ptr(), |it| it.syntax_node_ptr());
-        assert_eq!(local_name.range(), expected_name.syntax().text_range());
-    }
-
-    #[test]
-    fn test_resolve_local_name() {
-        do_check_local_name(
-            r#"
-            fn foo(x: i32, y: u32) {
-                {
-                    let z = x * 2;
-                }
-                {
-                    let t = x<|> * 3;
-                }
-            }"#,
-            21,
-        );
-    }
-
-    #[test]
-    fn test_resolve_local_name_declaration() {
-        do_check_local_name(
-            r#"
-            fn foo(x: String) {
-                let x : &str = &x<|>;
-            }"#,
-            21,
-        );
-    }
-
-    #[test]
-    fn test_resolve_local_name_shadow() {
-        do_check_local_name(
-            r"
-            fn foo(x: String) {
-                let x : &str = &x;
-                x<|>
-            }
-            ",
-            53,
-        );
-    }
-
-    #[test]
-    fn ref_patterns_contribute_bindings() {
-        do_check_local_name(
-            r"
-            fn foo() {
-                if let Some(&from) = bar() {
-                    from<|>;
-                }
-            }
-            ",
-            53,
-        );
-    }
-}
diff --git a/crates/ra_hir/src/from_id.rs b/crates/ra_hir/src/from_id.rs
index 089dbc908..9633ef586 100644
--- a/crates/ra_hir/src/from_id.rs
+++ b/crates/ra_hir/src/from_id.rs
@@ -3,9 +3,9 @@
 //! It's unclear if we need this long-term, but it's definitelly useful while we
 //! are splitting the hir.
 
-use hir_def::{AdtId, EnumVariantId, ModuleDefId};
+use hir_def::{AdtId, DefWithBodyId, EnumVariantId, ModuleDefId};
 
-use crate::{Adt, EnumVariant, ModuleDef};
+use crate::{Adt, DefWithBody, EnumVariant, ModuleDef};
 
 macro_rules! from_id {
     ($(($id:path, $ty:path)),*) => {$(
@@ -61,3 +61,13 @@ impl From<ModuleDefId> for ModuleDef {
         }
     }
 }
+
+impl From<DefWithBody> for DefWithBodyId {
+    fn from(def: DefWithBody) -> Self {
+        match def {
+            DefWithBody::Function(it) => DefWithBodyId::FunctionId(it.id),
+            DefWithBody::Static(it) => DefWithBodyId::StaticId(it.id),
+            DefWithBody::Const(it) => DefWithBodyId::ConstId(it.id),
+        }
+    }
+}
diff --git a/crates/ra_hir/src/from_source.rs b/crates/ra_hir/src/from_source.rs
index 2c441b0f4..9793af858 100644
--- a/crates/ra_hir/src/from_source.rs
+++ b/crates/ra_hir/src/from_source.rs
@@ -10,7 +10,7 @@ use ra_syntax::{
 use crate::{
     db::{AstDatabase, DefDatabase, HirDatabase},
     ids::{AstItemDef, LocationCtx},
-    AstId, Const, Crate, DefWithBody, Enum, EnumVariant, FieldSource, Function, HasSource,
+    AstId, Const, Crate, DefWithBody, Enum, EnumVariant, FieldSource, Function, HasBody, HasSource,
     ImplBlock, Local, Module, ModuleSource, Source, Static, Struct, StructField, Trait, TypeAlias,
     Union, VariantDef,
 };
@@ -144,8 +144,9 @@ impl Local {
             };
             Some(res)
         })?;
-        let (_body, source_map) = db.body_with_source_map(parent);
-        let pat_id = source_map.node_pat(&src.ast.into())?;
+        let source_map = parent.body_source_map(db);
+        let src = src.map(ast::Pat::from);
+        let pat_id = source_map.node_pat(src.as_ref())?;
         Some(Local { parent, pat_id })
     }
 }
diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index 92d71b9e8..5ba847d35 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -77,9 +77,7 @@ pub use crate::{
     source_binder::{PathResolution, ScopeEntryWithSyntax, SourceAnalyzer},
     ty::{
         display::HirDisplay,
-        primitive::{
-            FloatBitness, FloatTy, IntBitness, IntTy, Signedness, UncertainFloatTy, UncertainIntTy,
-        },
+        primitive::{FloatBitness, FloatTy, IntBitness, IntTy, Signedness, Uncertain},
         ApplicationTy, CallableDef, Substs, TraitRef, Ty, TypeCtor, TypeWalk,
     },
 };
diff --git a/crates/ra_hir/src/resolve.rs b/crates/ra_hir/src/resolve.rs
index b932b0c8c..2f3e12eb8 100644
--- a/crates/ra_hir/src/resolve.rs
+++ b/crates/ra_hir/src/resolve.rs
@@ -13,10 +13,7 @@ use rustc_hash::FxHashSet;
 use crate::{
     code_model::Crate,
     db::{DefDatabase, HirDatabase},
-    expr::{
-        scope::{ExprScopes, ScopeId},
-        PatId,
-    },
+    expr::{ExprScopes, PatId, ScopeId},
     generics::GenericParams,
     impl_block::ImplBlock,
     Adt, Const, Enum, EnumVariant, Function, MacroDef, ModuleDef, PerNs, Static, Struct, Trait,
diff --git a/crates/ra_hir/src/source_binder.rs b/crates/ra_hir/src/source_binder.rs
index f28e9c931..ca40e3b54 100644
--- a/crates/ra_hir/src/source_binder.rs
+++ b/crates/ra_hir/src/source_binder.rs
@@ -7,8 +7,11 @@
 //! purely for "IDE needs".
 use std::sync::Arc;
 
-use hir_def::path::known;
-use hir_expand::name::AsName;
+use hir_def::{
+    expr::{ExprId, PatId},
+    path::known,
+};
+use hir_expand::{name::AsName, Source};
 use ra_db::FileId;
 use ra_syntax::{
     ast::{self, AstNode},
@@ -20,11 +23,7 @@ use rustc_hash::FxHashSet;
 
 use crate::{
     db::HirDatabase,
-    expr::{
-        self,
-        scope::{ExprScopes, ScopeId},
-        BodySourceMap,
-    },
+    expr::{self, BodySourceMap, ExprScopes, ScopeId},
     ids::LocationCtx,
     resolve::{ScopeDef, TypeNs, ValueNs},
     ty::method_resolution::{self, implements_trait},
@@ -93,6 +92,8 @@ fn def_with_body_from_child_node(
 /// original source files. It should not be used inside the HIR itself.
 #[derive(Debug)]
 pub struct SourceAnalyzer {
+    // FIXME: this doesn't handle macros at all
+    file_id: FileId,
     resolver: Resolver,
     body_owner: Option<DefWithBody>,
     body_source_map: Option<Arc<BodySourceMap>>,
@@ -145,9 +146,9 @@ impl SourceAnalyzer {
         let def_with_body = def_with_body_from_child_node(db, file_id, node);
         if let Some(def) = def_with_body {
             let source_map = def.body_source_map(db);
-            let scopes = db.expr_scopes(def);
+            let scopes = def.expr_scopes(db);
             let scope = match offset {
-                None => scope_for(&scopes, &source_map, &node),
+                None => scope_for(&scopes, &source_map, file_id.into(), &node),
                 Some(offset) => scope_for_offset(&scopes, &source_map, file_id.into(), offset),
             };
             let resolver = expr::resolver_for_scope(db, def, scope);
@@ -157,6 +158,7 @@ impl SourceAnalyzer {
                 body_source_map: Some(source_map),
                 infer: Some(def.infer(db)),
                 scopes: Some(scopes),
+                file_id,
             }
         } else {
             SourceAnalyzer {
@@ -168,17 +170,28 @@ impl SourceAnalyzer {
                 body_source_map: None,
                 infer: None,
                 scopes: None,
+                file_id,
             }
         }
     }
 
+    fn expr_id(&self, expr: &ast::Expr) -> Option<ExprId> {
+        let src = Source { file_id: self.file_id.into(), ast: expr };
+        self.body_source_map.as_ref()?.node_expr(src)
+    }
+
+    fn pat_id(&self, pat: &ast::Pat) -> Option<PatId> {
+        let src = Source { file_id: self.file_id.into(), ast: pat };
+        self.body_source_map.as_ref()?.node_pat(src)
+    }
+
     pub fn type_of(&self, _db: &impl HirDatabase, expr: &ast::Expr) -> Option<crate::Ty> {
-        let expr_id = self.body_source_map.as_ref()?.node_expr(expr)?;
+        let expr_id = self.expr_id(expr)?;
         Some(self.infer.as_ref()?[expr_id].clone())
     }
 
     pub fn type_of_pat(&self, _db: &impl HirDatabase, pat: &ast::Pat) -> Option<crate::Ty> {
-        let pat_id = self.body_source_map.as_ref()?.node_pat(pat)?;
+        let pat_id = self.pat_id(pat)?;
         Some(self.infer.as_ref()?[pat_id].clone())
     }
 
@@ -191,22 +204,22 @@ impl SourceAnalyzer {
     }
 
     pub fn resolve_method_call(&self, call: &ast::MethodCallExpr) -> Option<Function> {
-        let expr_id = self.body_source_map.as_ref()?.node_expr(&call.clone().into())?;
+        let expr_id = self.expr_id(&call.clone().into())?;
         self.infer.as_ref()?.method_resolution(expr_id)
     }
 
     pub fn resolve_field(&self, field: &ast::FieldExpr) -> Option<crate::StructField> {
-        let expr_id = self.body_source_map.as_ref()?.node_expr(&field.clone().into())?;
+        let expr_id = self.expr_id(&field.clone().into())?;
         self.infer.as_ref()?.field_resolution(expr_id)
     }
 
     pub fn resolve_record_literal(&self, record_lit: &ast::RecordLit) -> Option<crate::VariantDef> {
-        let expr_id = self.body_source_map.as_ref()?.node_expr(&record_lit.clone().into())?;
+        let expr_id = self.expr_id(&record_lit.clone().into())?;
         self.infer.as_ref()?.variant_resolution_for_expr(expr_id)
     }
 
     pub fn resolve_record_pattern(&self, record_pat: &ast::RecordPat) -> Option<crate::VariantDef> {
-        let pat_id = self.body_source_map.as_ref()?.node_pat(&record_pat.clone().into())?;
+        let pat_id = self.pat_id(&record_pat.clone().into())?;
         self.infer.as_ref()?.variant_resolution_for_pat(pat_id)
     }
 
@@ -264,13 +277,13 @@ impl SourceAnalyzer {
 
     pub fn resolve_path(&self, db: &impl HirDatabase, path: &ast::Path) -> Option<PathResolution> {
         if let Some(path_expr) = path.syntax().parent().and_then(ast::PathExpr::cast) {
-            let expr_id = self.body_source_map.as_ref()?.node_expr(&path_expr.into())?;
+            let expr_id = self.expr_id(&path_expr.into())?;
             if let Some(assoc) = self.infer.as_ref()?.assoc_resolutions_for_expr(expr_id) {
                 return Some(PathResolution::AssocItem(assoc));
             }
         }
         if let Some(path_pat) = path.syntax().parent().and_then(ast::PathPat::cast) {
-            let pat_id = self.body_source_map.as_ref()?.node_pat(&path_pat.into())?;
+            let pat_id = self.pat_id(&path_pat.into())?;
             if let Some(assoc) = self.infer.as_ref()?.assoc_resolutions_for_pat(pat_id) {
                 return Some(PathResolution::AssocItem(assoc));
             }
@@ -285,7 +298,7 @@ impl SourceAnalyzer {
         let name = name_ref.as_name();
         let source_map = self.body_source_map.as_ref()?;
         let scopes = self.scopes.as_ref()?;
-        let scope = scope_for(scopes, source_map, name_ref.syntax());
+        let scope = scope_for(scopes, source_map, self.file_id.into(), name_ref.syntax());
         let ret = scopes
             .scope_chain(scope)
             .flat_map(|scope| scopes.entries(scope).iter())
@@ -418,11 +431,12 @@ impl SourceAnalyzer {
 fn scope_for(
     scopes: &ExprScopes,
     source_map: &BodySourceMap,
+    file_id: HirFileId,
     node: &SyntaxNode,
 ) -> Option<ScopeId> {
     node.ancestors()
         .filter_map(ast::Expr::cast)
-        .filter_map(|it| source_map.node_expr(&it))
+        .filter_map(|it| source_map.node_expr(Source { file_id, ast: &it }))
         .find_map(|it| scopes.scope_for(it))
 }
 
diff --git a/crates/ra_hir/src/ty.rs b/crates/ra_hir/src/ty.rs
index 6f24cfad6..ff6030ac4 100644
--- a/crates/ra_hir/src/ty.rs
+++ b/crates/ra_hir/src/ty.rs
@@ -21,7 +21,7 @@ use crate::{
     expr::ExprId,
     generics::{GenericParams, HasGenericParams},
     util::make_mut_slice,
-    Adt, Crate, DefWithBody, Mutability, Name, Trait, TypeAlias,
+    Adt, Crate, DefWithBody, FloatTy, IntTy, Mutability, Name, Trait, TypeAlias, Uncertain,
 };
 use display::{HirDisplay, HirFormatter};
 
@@ -47,10 +47,10 @@ pub enum TypeCtor {
     Char,
 
     /// A primitive integer type. For example, `i32`.
-    Int(primitive::UncertainIntTy),
+    Int(Uncertain<IntTy>),
 
     /// A primitive floating-point type. For example, `f64`.
-    Float(primitive::UncertainFloatTy),
+    Float(Uncertain<FloatTy>),
 
     /// Structures, enumerations and unions.
     Adt(Adt),
diff --git a/crates/ra_hir/src/ty/infer.rs b/crates/ra_hir/src/ty/infer.rs
index f17c6c614..c35378cc4 100644
--- a/crates/ra_hir/src/ty/infer.rs
+++ b/crates/ra_hir/src/ty/infer.rs
@@ -31,10 +31,10 @@ use ra_prof::profile;
 use test_utils::tested_by;
 
 use super::{
-    lower, primitive,
+    lower,
     traits::{Guidance, Obligation, ProjectionPredicate, Solution},
     ApplicationTy, InEnvironment, ProjectionTy, Substs, TraitEnvironment, TraitRef, Ty, TypableDef,
-    TypeCtor, TypeWalk,
+    TypeCtor, TypeWalk, Uncertain,
 };
 use crate::{
     adt::VariantDef,
@@ -43,7 +43,8 @@ use crate::{
     expr::{BindingAnnotation, Body, ExprId, PatId},
     resolve::{Resolver, TypeNs},
     ty::infer::diagnostics::InferenceDiagnostic,
-    Adt, AssocItem, ConstData, DefWithBody, FnData, Function, Path, StructField,
+    Adt, AssocItem, ConstData, DefWithBody, FloatTy, FnData, Function, HasBody, IntTy, Path,
+    StructField,
 };
 
 macro_rules! ty_app {
@@ -214,7 +215,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
             coerce_unsized_map: Self::init_coerce_unsized_map(db, &resolver),
             db,
             owner,
-            body: db.body(owner),
+            body: owner.body(db),
             resolver,
         }
     }
@@ -358,14 +359,12 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
     fn insert_type_vars_shallow(&mut self, ty: Ty) -> Ty {
         match ty {
             Ty::Unknown => self.new_type_var(),
-            Ty::Apply(ApplicationTy {
-                ctor: TypeCtor::Int(primitive::UncertainIntTy::Unknown),
-                ..
-            }) => self.new_integer_var(),
-            Ty::Apply(ApplicationTy {
-                ctor: TypeCtor::Float(primitive::UncertainFloatTy::Unknown),
-                ..
-            }) => self.new_float_var(),
+            Ty::Apply(ApplicationTy { ctor: TypeCtor::Int(Uncertain::Unknown), .. }) => {
+                self.new_integer_var()
+            }
+            Ty::Apply(ApplicationTy { ctor: TypeCtor::Float(Uncertain::Unknown), .. }) => {
+                self.new_float_var()
+            }
             _ => ty,
         }
     }
@@ -684,12 +683,8 @@ impl InferTy {
     fn fallback_value(self) -> Ty {
         match self {
             InferTy::TypeVar(..) => Ty::Unknown,
-            InferTy::IntVar(..) => {
-                Ty::simple(TypeCtor::Int(primitive::UncertainIntTy::Known(primitive::IntTy::i32())))
-            }
-            InferTy::FloatVar(..) => Ty::simple(TypeCtor::Float(
-                primitive::UncertainFloatTy::Known(primitive::FloatTy::f64()),
-            )),
+            InferTy::IntVar(..) => Ty::simple(TypeCtor::Int(Uncertain::Known(IntTy::i32()))),
+            InferTy::FloatVar(..) => Ty::simple(TypeCtor::Float(Uncertain::Known(FloatTy::f64()))),
             InferTy::MaybeNeverTypeVar(..) => Ty::simple(TypeCtor::Never),
         }
     }
diff --git a/crates/ra_hir/src/ty/infer/expr.rs b/crates/ra_hir/src/ty/infer/expr.rs
index c6802487a..5e68a1678 100644
--- a/crates/ra_hir/src/ty/infer/expr.rs
+++ b/crates/ra_hir/src/ty/infer/expr.rs
@@ -3,7 +3,10 @@
 use std::iter::{repeat, repeat_with};
 use std::sync::Arc;
 
-use hir_def::path::{GenericArg, GenericArgs};
+use hir_def::{
+    builtin_type::Signedness,
+    path::{GenericArg, GenericArgs},
+};
 use hir_expand::name;
 
 use super::{BindingMode, Expectation, InferenceContext, InferenceDiagnostic, TypeMismatch};
@@ -12,8 +15,9 @@ use crate::{
     expr::{self, Array, BinaryOp, Expr, ExprId, Literal, Statement, UnaryOp},
     generics::{GenericParams, HasGenericParams},
     ty::{
-        autoderef, method_resolution, op, primitive, CallableDef, InferTy, Mutability, Namespace,
+        autoderef, method_resolution, op, CallableDef, InferTy, IntTy, Mutability, Namespace,
         Obligation, ProjectionPredicate, ProjectionTy, Substs, TraitRef, Ty, TypeCtor, TypeWalk,
+        Uncertain,
     },
     Adt, Name,
 };
@@ -337,13 +341,11 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                     UnaryOp::Neg => {
                         match &inner_ty {
                             Ty::Apply(a_ty) => match a_ty.ctor {
-                                TypeCtor::Int(primitive::UncertainIntTy::Unknown)
-                                | TypeCtor::Int(primitive::UncertainIntTy::Known(
-                                    primitive::IntTy {
-                                        signedness: primitive::Signedness::Signed,
-                                        ..
-                                    },
-                                ))
+                                TypeCtor::Int(Uncertain::Unknown)
+                                | TypeCtor::Int(Uncertain::Known(IntTy {
+                                    signedness: Signedness::Signed,
+                                    ..
+                                }))
                                 | TypeCtor::Float(..) => inner_ty,
                                 _ => Ty::Unknown,
                             },
@@ -428,9 +430,9 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                         );
                         self.infer_expr(
                             *repeat,
-                            &Expectation::has_type(Ty::simple(TypeCtor::Int(
-                                primitive::UncertainIntTy::Known(primitive::IntTy::usize()),
-                            ))),
+                            &Expectation::has_type(Ty::simple(TypeCtor::Int(Uncertain::Known(
+                                IntTy::usize(),
+                            )))),
                         );
                     }
                 }
@@ -443,9 +445,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                     Ty::apply_one(TypeCtor::Ref(Mutability::Shared), Ty::simple(TypeCtor::Str))
                 }
                 Literal::ByteString(..) => {
-                    let byte_type = Ty::simple(TypeCtor::Int(primitive::UncertainIntTy::Known(
-                        primitive::IntTy::u8(),
-                    )));
+                    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)
                 }
diff --git a/crates/ra_hir/src/ty/lower.rs b/crates/ra_hir/src/ty/lower.rs
index 1832fcf50..de3c56097 100644
--- a/crates/ra_hir/src/ty/lower.rs
+++ b/crates/ra_hir/src/ty/lower.rs
@@ -25,7 +25,7 @@ use crate::{
     generics::{GenericDef, WherePredicate},
     resolve::{Resolver, TypeNs},
     ty::{
-        primitive::{FloatTy, IntTy, UncertainFloatTy, UncertainIntTy},
+        primitive::{FloatTy, IntTy, Uncertain},
         Adt,
     },
     util::make_mut_slice,
@@ -674,20 +674,20 @@ impl From<BuiltinFloat> for FloatTy {
     }
 }
 
-impl From<Option<BuiltinInt>> for UncertainIntTy {
+impl From<Option<BuiltinInt>> for Uncertain<IntTy> {
     fn from(t: Option<BuiltinInt>) -> Self {
         match t {
-            None => UncertainIntTy::Unknown,
-            Some(t) => UncertainIntTy::Known(t.into()),
+            None => Uncertain::Unknown,
+            Some(t) => Uncertain::Known(t.into()),
         }
     }
 }
 
-impl From<Option<BuiltinFloat>> for UncertainFloatTy {
+impl From<Option<BuiltinFloat>> for Uncertain<FloatTy> {
     fn from(t: Option<BuiltinFloat>) -> Self {
         match t {
-            None => UncertainFloatTy::Unknown,
-            Some(t) => UncertainFloatTy::Known(t.into()),
+            None => Uncertain::Unknown,
+            Some(t) => Uncertain::Known(t.into()),
         }
     }
 }
diff --git a/crates/ra_hir/src/ty/method_resolution.rs b/crates/ra_hir/src/ty/method_resolution.rs
index 8c3d32d09..eb5ca6769 100644
--- a/crates/ra_hir/src/ty/method_resolution.rs
+++ b/crates/ra_hir/src/ty/method_resolution.rs
@@ -8,16 +8,17 @@ use arrayvec::ArrayVec;
 use hir_def::CrateModuleId;
 use rustc_hash::FxHashMap;
 
-use super::{autoderef, lower, Canonical, InEnvironment, TraitEnvironment, TraitRef};
 use crate::{
     db::HirDatabase,
     impl_block::{ImplBlock, ImplId},
     resolve::Resolver,
-    ty::primitive::{FloatBitness, UncertainFloatTy, UncertainIntTy},
+    ty::primitive::{FloatBitness, Uncertain},
     ty::{Ty, TypeCtor},
     AssocItem, Crate, Function, Module, Mutability, Name, Trait,
 };
 
+use super::{autoderef, lower, Canonical, InEnvironment, TraitEnvironment, TraitRef};
+
 /// This is used as a key for indexing impls.
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
 pub enum TyFingerprint {
@@ -140,14 +141,12 @@ fn def_crates(db: &impl HirDatabase, cur_crate: Crate, ty: &Ty) -> Option<ArrayV
             TypeCtor::Adt(def_id) => Some(std::iter::once(def_id.krate(db)?).collect()),
             TypeCtor::Bool => lang_item_crate!(db, cur_crate, "bool"),
             TypeCtor::Char => lang_item_crate!(db, cur_crate, "char"),
-            TypeCtor::Float(UncertainFloatTy::Known(f)) => match f.bitness {
+            TypeCtor::Float(Uncertain::Known(f)) => match f.bitness {
                 // There are two lang items: one in libcore (fXX) and one in libstd (fXX_runtime)
                 FloatBitness::X32 => lang_item_crate!(db, cur_crate, "f32", "f32_runtime"),
                 FloatBitness::X64 => lang_item_crate!(db, cur_crate, "f64", "f64_runtime"),
             },
-            TypeCtor::Int(UncertainIntTy::Known(i)) => {
-                lang_item_crate!(db, cur_crate, i.ty_to_string())
-            }
+            TypeCtor::Int(Uncertain::Known(i)) => lang_item_crate!(db, cur_crate, i.ty_to_string()),
             TypeCtor::Str => lang_item_crate!(db, cur_crate, "str_alloc", "str"),
             TypeCtor::Slice => lang_item_crate!(db, cur_crate, "slice_alloc", "slice"),
             TypeCtor::RawPtr(Mutability::Shared) => lang_item_crate!(db, cur_crate, "const_ptr"),
diff --git a/crates/ra_hir/src/ty/primitive.rs b/crates/ra_hir/src/ty/primitive.rs
index 7362de4c3..47789db87 100644
--- a/crates/ra_hir/src/ty/primitive.rs
+++ b/crates/ra_hir/src/ty/primitive.rs
@@ -4,44 +4,38 @@ use std::fmt;
 
 pub use hir_def::builtin_type::{FloatBitness, IntBitness, Signedness};
 
-#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
-pub enum UncertainIntTy {
+#[derive(Clone, Copy, Eq, PartialEq, Hash, Debug)]
+pub enum Uncertain<T> {
     Unknown,
-    Known(IntTy),
+    Known(T),
 }
 
-impl From<IntTy> for UncertainIntTy {
+impl From<IntTy> for Uncertain<IntTy> {
     fn from(ty: IntTy) -> Self {
-        UncertainIntTy::Known(ty)
+        Uncertain::Known(ty)
     }
 }
 
-impl fmt::Display for UncertainIntTy {
+impl fmt::Display for Uncertain<IntTy> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match *self {
-            UncertainIntTy::Unknown => write!(f, "{{integer}}"),
-            UncertainIntTy::Known(ty) => write!(f, "{}", ty),
+            Uncertain::Unknown => write!(f, "{{integer}}"),
+            Uncertain::Known(ty) => write!(f, "{}", ty),
         }
     }
 }
 
-#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
-pub enum UncertainFloatTy {
-    Unknown,
-    Known(FloatTy),
-}
-
-impl From<FloatTy> for UncertainFloatTy {
+impl From<FloatTy> for Uncertain<FloatTy> {
     fn from(ty: FloatTy) -> Self {
-        UncertainFloatTy::Known(ty)
+        Uncertain::Known(ty)
     }
 }
 
-impl fmt::Display for UncertainFloatTy {
+impl fmt::Display for Uncertain<FloatTy> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match *self {
-            UncertainFloatTy::Unknown => write!(f, "{{float}}"),
-            UncertainFloatTy::Known(ty) => write!(f, "{}", ty),
+            Uncertain::Unknown => write!(f, "{{float}}"),
+            Uncertain::Known(ty) => write!(f, "{}", ty),
         }
     }
 }
diff --git a/crates/ra_hir/src/ty/traits/chalk.rs b/crates/ra_hir/src/ty/traits/chalk.rs
index de322dd52..75351c17d 100644
--- a/crates/ra_hir/src/ty/traits/chalk.rs
+++ b/crates/ra_hir/src/ty/traits/chalk.rs
@@ -22,7 +22,7 @@ use crate::{
         ApplicationTy, GenericPredicate, Namespace, ProjectionTy, Substs, TraitRef, Ty, TypeCtor,
         TypeWalk,
     },
-    AssocItem, Crate, ImplBlock, Trait, TypeAlias,
+    AssocItem, Crate, HasBody, ImplBlock, Trait, TypeAlias,
 };
 
 /// This represents a trait whose name we could not resolve.
@@ -714,7 +714,7 @@ fn closure_fn_trait_impl_datum(
     let fn_once_trait = get_fn_trait(db, krate, super::FnTrait::FnOnce)?;
     let trait_ = get_fn_trait(db, krate, data.fn_trait)?; // get corresponding fn trait
 
-    let num_args: u16 = match &db.body(data.def)[data.expr] {
+    let num_args: u16 = match &data.def.body(db)[data.expr] {
         crate::expr::Expr::Lambda { args, .. } => args.len() as u16,
         _ => {
             log::warn!("closure for closure type {:?} not found", data);
diff --git a/crates/ra_hir_def/src/body.rs b/crates/ra_hir_def/src/body.rs
index ac8f8261b..85dc4feb0 100644
--- a/crates/ra_hir_def/src/body.rs
+++ b/crates/ra_hir_def/src/body.rs
@@ -1,11 +1,15 @@
 //! FIXME: write short doc here
 mod lower;
+pub mod scope;
 
 use std::{ops::Index, sync::Arc};
 
-use hir_expand::{either::Either, HirFileId, MacroDefId, Source};
+use hir_expand::{
+    either::Either, hygiene::Hygiene, AstId, HirFileId, MacroCallLoc, MacroDefId, MacroFileKind,
+    Source,
+};
 use ra_arena::{map::ArenaMap, Arena};
-use ra_syntax::{ast, AstPtr};
+use ra_syntax::{ast, AstNode, AstPtr};
 use rustc_hash::FxHashMap;
 
 use crate::{
@@ -13,28 +17,87 @@ use crate::{
     expr::{Expr, ExprId, Pat, PatId},
     nameres::CrateDefMap,
     path::Path,
-    ModuleId,
+    AstItemDef, DefWithBodyId, ModuleId,
 };
 
-pub struct MacroResolver {
+pub struct Expander {
     crate_def_map: Arc<CrateDefMap>,
+    current_file_id: HirFileId,
+    hygiene: Hygiene,
     module: ModuleId,
 }
 
-impl MacroResolver {
-    pub fn new(db: &impl DefDatabase2, module: ModuleId) -> MacroResolver {
-        MacroResolver { crate_def_map: db.crate_def_map(module.krate), module }
+impl Expander {
+    pub fn new(db: &impl DefDatabase2, current_file_id: HirFileId, module: ModuleId) -> Expander {
+        let crate_def_map = db.crate_def_map(module.krate);
+        let hygiene = Hygiene::new(db, current_file_id);
+        Expander { crate_def_map, current_file_id, hygiene, module }
     }
 
-    pub(crate) fn resolve_path_as_macro(
-        &self,
+    fn enter_expand(
+        &mut self,
         db: &impl DefDatabase2,
-        path: &Path,
-    ) -> Option<MacroDefId> {
+        macro_call: ast::MacroCall,
+    ) -> Option<(Mark, ast::Expr)> {
+        let ast_id = AstId::new(
+            self.current_file_id,
+            db.ast_id_map(self.current_file_id).ast_id(&macro_call),
+        );
+
+        if let Some(path) = macro_call.path().and_then(|path| self.parse_path(path)) {
+            if let Some(def) = self.resolve_path_as_macro(db, &path) {
+                let call_id = db.intern_macro(MacroCallLoc { def, ast_id });
+                let file_id = call_id.as_file(MacroFileKind::Expr);
+                if let Some(node) = db.parse_or_expand(file_id) {
+                    if let Some(expr) = ast::Expr::cast(node) {
+                        log::debug!("macro expansion {:#?}", expr.syntax());
+
+                        let mark = Mark { file_id: self.current_file_id };
+                        self.hygiene = Hygiene::new(db, file_id);
+                        self.current_file_id = file_id;
+
+                        return Some((mark, expr));
+                    }
+                }
+            }
+        }
+
+        // FIXME: Instead of just dropping the error from expansion
+        // report it
+        None
+    }
+
+    fn exit(&mut self, db: &impl DefDatabase2, mark: Mark) {
+        self.hygiene = Hygiene::new(db, mark.file_id);
+        self.current_file_id = mark.file_id;
+        std::mem::forget(mark);
+    }
+
+    fn to_source<T>(&self, ast: T) -> Source<T> {
+        Source { file_id: self.current_file_id, ast }
+    }
+
+    fn parse_path(&mut self, path: ast::Path) -> Option<Path> {
+        Path::from_src(path, &self.hygiene)
+    }
+
+    fn resolve_path_as_macro(&self, db: &impl DefDatabase2, path: &Path) -> Option<MacroDefId> {
         self.crate_def_map.resolve_path(db, self.module.module_id, path).0.get_macros()
     }
 }
 
+struct Mark {
+    file_id: HirFileId,
+}
+
+impl Drop for Mark {
+    fn drop(&mut self) {
+        if !std::thread::panicking() {
+            panic!("dropped mark")
+        }
+    }
+}
+
 /// The body of an item (function, const etc.).
 #[derive(Debug, Eq, PartialEq)]
 pub struct Body {
@@ -70,22 +133,51 @@ pub type PatSource = Source<PatPtr>;
 /// this properly for macros.
 #[derive(Default, Debug, Eq, PartialEq)]
 pub struct BodySourceMap {
-    expr_map: FxHashMap<ExprPtr, ExprId>,
+    expr_map: FxHashMap<ExprSource, ExprId>,
     expr_map_back: ArenaMap<ExprId, ExprSource>,
-    pat_map: FxHashMap<PatPtr, PatId>,
+    pat_map: FxHashMap<PatSource, PatId>,
     pat_map_back: ArenaMap<PatId, PatSource>,
     field_map: FxHashMap<(ExprId, usize), AstPtr<ast::RecordField>>,
 }
 
 impl Body {
-    pub fn new(
+    pub(crate) fn body_with_source_map_query(
+        db: &impl DefDatabase2,
+        def: DefWithBodyId,
+    ) -> (Arc<Body>, Arc<BodySourceMap>) {
+        let mut params = None;
+
+        let (file_id, module, body) = match def {
+            DefWithBodyId::FunctionId(f) => {
+                let src = f.source(db);
+                params = src.ast.param_list();
+                (src.file_id, f.module(db), src.ast.body().map(ast::Expr::from))
+            }
+            DefWithBodyId::ConstId(c) => {
+                let src = c.source(db);
+                (src.file_id, c.module(db), src.ast.body())
+            }
+            DefWithBodyId::StaticId(s) => {
+                let src = s.source(db);
+                (src.file_id, s.module(db), src.ast.body())
+            }
+        };
+        let expander = Expander::new(db, file_id, module);
+        let (body, source_map) = Body::new(db, expander, params, body);
+        (Arc::new(body), Arc::new(source_map))
+    }
+
+    pub(crate) fn body_query(db: &impl DefDatabase2, def: DefWithBodyId) -> Arc<Body> {
+        db.body_with_source_map(def).0
+    }
+
+    fn new(
         db: &impl DefDatabase2,
-        resolver: MacroResolver,
-        file_id: HirFileId,
+        expander: Expander,
         params: Option<ast::ParamList>,
         body: Option<ast::Expr>,
     ) -> (Body, BodySourceMap) {
-        lower::lower(db, resolver, file_id, params, body)
+        lower::lower(db, expander, params, body)
     }
 
     pub fn params(&self) -> &[PatId] {
@@ -126,16 +218,18 @@ impl BodySourceMap {
         self.expr_map_back.get(expr).copied()
     }
 
-    pub fn node_expr(&self, node: &ast::Expr) -> Option<ExprId> {
-        self.expr_map.get(&Either::A(AstPtr::new(node))).cloned()
+    pub fn node_expr(&self, node: Source<&ast::Expr>) -> Option<ExprId> {
+        let src = node.map(|it| Either::A(AstPtr::new(it)));
+        self.expr_map.get(&src).cloned()
     }
 
     pub fn pat_syntax(&self, pat: PatId) -> Option<PatSource> {
         self.pat_map_back.get(pat).copied()
     }
 
-    pub fn node_pat(&self, node: &ast::Pat) -> Option<PatId> {
-        self.pat_map.get(&Either::A(AstPtr::new(node))).cloned()
+    pub fn node_pat(&self, node: Source<&ast::Pat>) -> Option<PatId> {
+        let src = node.map(|it| Either::A(AstPtr::new(it)));
+        self.pat_map.get(&src).cloned()
     }
 
     pub fn field_syntax(&self, expr: ExprId, field: usize) -> AstPtr<ast::RecordField> {
diff --git a/crates/ra_hir_def/src/body/lower.rs b/crates/ra_hir_def/src/body/lower.rs
index 2aa863c9e..a5bb60e85 100644
--- a/crates/ra_hir_def/src/body/lower.rs
+++ b/crates/ra_hir_def/src/body/lower.rs
@@ -2,9 +2,7 @@
 
 use hir_expand::{
     either::Either,
-    hygiene::Hygiene,
     name::{self, AsName, Name},
-    AstId, HirFileId, MacroCallLoc, MacroFileKind, Source,
 };
 use ra_arena::Arena;
 use ra_syntax::{
@@ -16,7 +14,7 @@ use ra_syntax::{
 };
 
 use crate::{
-    body::{Body, BodySourceMap, MacroResolver, PatPtr},
+    body::{Body, BodySourceMap, Expander, PatPtr},
     builtin_type::{BuiltinFloat, BuiltinInt},
     db::DefDatabase2,
     expr::{
@@ -30,16 +28,13 @@ use crate::{
 
 pub(super) fn lower(
     db: &impl DefDatabase2,
-    resolver: MacroResolver,
-    file_id: HirFileId,
+    expander: Expander,
     params: Option<ast::ParamList>,
     body: Option<ast::Expr>,
 ) -> (Body, BodySourceMap) {
     ExprCollector {
-        resolver,
+        expander,
         db,
-        original_file_id: file_id,
-        current_file_id: file_id,
         source_map: BodySourceMap::default(),
         body: Body {
             exprs: Arena::default(),
@@ -53,9 +48,7 @@ pub(super) fn lower(
 
 struct ExprCollector<DB> {
     db: DB,
-    resolver: MacroResolver,
-    original_file_id: HirFileId,
-    current_file_id: HirFileId,
+    expander: Expander,
 
     body: Body,
     source_map: BodySourceMap,
@@ -101,12 +94,9 @@ where
     fn alloc_expr(&mut self, expr: Expr, ptr: AstPtr<ast::Expr>) -> ExprId {
         let ptr = Either::A(ptr);
         let id = self.body.exprs.alloc(expr);
-        if self.current_file_id == self.original_file_id {
-            self.source_map.expr_map.insert(ptr, id);
-        }
-        self.source_map
-            .expr_map_back
-            .insert(id, Source { file_id: self.current_file_id, ast: ptr });
+        let src = self.expander.to_source(ptr);
+        self.source_map.expr_map.insert(src, id);
+        self.source_map.expr_map_back.insert(id, src);
         id
     }
     // desugared exprs don't have ptr, that's wrong and should be fixed
@@ -117,20 +107,16 @@ where
     fn alloc_expr_field_shorthand(&mut self, expr: Expr, ptr: AstPtr<ast::RecordField>) -> ExprId {
         let ptr = Either::B(ptr);
         let id = self.body.exprs.alloc(expr);
-        if self.current_file_id == self.original_file_id {
-            self.source_map.expr_map.insert(ptr, id);
-        }
-        self.source_map
-            .expr_map_back
-            .insert(id, Source { file_id: self.current_file_id, ast: ptr });
+        let src = self.expander.to_source(ptr);
+        self.source_map.expr_map.insert(src, id);
+        self.source_map.expr_map_back.insert(id, src);
         id
     }
     fn alloc_pat(&mut self, pat: Pat, ptr: PatPtr) -> PatId {
         let id = self.body.pats.alloc(pat);
-        if self.current_file_id == self.original_file_id {
-            self.source_map.pat_map.insert(ptr, id);
-        }
-        self.source_map.pat_map_back.insert(id, Source { file_id: self.current_file_id, ast: ptr });
+        let src = self.expander.to_source(ptr);
+        self.source_map.pat_map.insert(src, id);
+        self.source_map.pat_map_back.insert(id, src);
         id
     }
 
@@ -272,7 +258,7 @@ where
             ast::Expr::PathExpr(e) => {
                 let path = e
                     .path()
-                    .and_then(|path| self.parse_path(path))
+                    .and_then(|path| self.expander.parse_path(path))
                     .map(Expr::Path)
                     .unwrap_or(Expr::Missing);
                 self.alloc_expr(path, syntax_ptr)
@@ -288,7 +274,8 @@ where
             ast::Expr::ParenExpr(e) => {
                 let inner = self.collect_expr_opt(e.expr());
                 // make the paren expr point to the inner expression as well
-                self.source_map.expr_map.insert(Either::A(syntax_ptr), inner);
+                let src = self.expander.to_source(Either::A(syntax_ptr));
+                self.source_map.expr_map.insert(src, inner);
                 inner
             }
             ast::Expr::ReturnExpr(e) => {
@@ -296,7 +283,7 @@ where
                 self.alloc_expr(Expr::Return { expr }, syntax_ptr)
             }
             ast::Expr::RecordLit(e) => {
-                let path = e.path().and_then(|path| self.parse_path(path));
+                let path = e.path().and_then(|path| self.expander.parse_path(path));
                 let mut field_ptrs = Vec::new();
                 let record_lit = if let Some(nfl) = e.record_field_list() {
                     let fields = nfl
@@ -443,32 +430,14 @@ where
             // FIXME implement HIR for these:
             ast::Expr::Label(_e) => self.alloc_expr(Expr::Missing, syntax_ptr),
             ast::Expr::RangeExpr(_e) => self.alloc_expr(Expr::Missing, syntax_ptr),
-            ast::Expr::MacroCall(e) => {
-                let ast_id = AstId::new(
-                    self.current_file_id,
-                    self.db.ast_id_map(self.current_file_id).ast_id(&e),
-                );
-
-                if let Some(path) = e.path().and_then(|path| self.parse_path(path)) {
-                    if let Some(def) = self.resolver.resolve_path_as_macro(self.db, &path) {
-                        let call_id = self.db.intern_macro(MacroCallLoc { def, ast_id });
-                        let file_id = call_id.as_file(MacroFileKind::Expr);
-                        if let Some(node) = self.db.parse_or_expand(file_id) {
-                            if let Some(expr) = ast::Expr::cast(node) {
-                                log::debug!("macro expansion {:#?}", expr.syntax());
-                                let old_file_id =
-                                    std::mem::replace(&mut self.current_file_id, file_id);
-                                let id = self.collect_expr(expr);
-                                self.current_file_id = old_file_id;
-                                return id;
-                            }
-                        }
-                    }
+            ast::Expr::MacroCall(e) => match self.expander.enter_expand(self.db, e) {
+                Some((mark, expansion)) => {
+                    let id = self.collect_expr(expansion);
+                    self.expander.exit(self.db, mark);
+                    id
                 }
-                // FIXME: Instead of just dropping the error from expansion
-                // report it
-                self.alloc_expr(Expr::Missing, syntax_ptr)
-            }
+                None => self.alloc_expr(Expr::Missing, syntax_ptr),
+            },
         }
     }
 
@@ -519,7 +488,7 @@ where
                 Pat::Bind { name, mode: annotation, subpat }
             }
             ast::Pat::TupleStructPat(p) => {
-                let path = p.path().and_then(|path| self.parse_path(path));
+                let path = p.path().and_then(|path| self.expander.parse_path(path));
                 let args = p.args().map(|p| self.collect_pat(p)).collect();
                 Pat::TupleStruct { path, args }
             }
@@ -529,7 +498,7 @@ where
                 Pat::Ref { pat, mutability }
             }
             ast::Pat::PathPat(p) => {
-                let path = p.path().and_then(|path| self.parse_path(path));
+                let path = p.path().and_then(|path| self.expander.parse_path(path));
                 path.map(Pat::Path).unwrap_or(Pat::Missing)
             }
             ast::Pat::TuplePat(p) => {
@@ -538,7 +507,7 @@ where
             }
             ast::Pat::PlaceholderPat(_) => Pat::Wild,
             ast::Pat::RecordPat(p) => {
-                let path = p.path().and_then(|path| self.parse_path(path));
+                let path = p.path().and_then(|path| self.expander.parse_path(path));
                 let record_field_pat_list =
                     p.record_field_pat_list().expect("every struct should have a field list");
                 let mut fields: Vec<_> = record_field_pat_list
@@ -579,11 +548,6 @@ where
             self.missing_pat()
         }
     }
-
-    fn parse_path(&mut self, path: ast::Path) -> Option<Path> {
-        let hygiene = Hygiene::new(self.db, self.current_file_id);
-        Path::from_src(path, &hygiene)
-    }
 }
 
 impl From<ast::BinOp> for BinaryOp {
diff --git a/crates/ra_hir_def/src/body/scope.rs b/crates/ra_hir_def/src/body/scope.rs
new file mode 100644
index 000000000..09a39e721
--- /dev/null
+++ b/crates/ra_hir_def/src/body/scope.rs
@@ -0,0 +1,165 @@
+//! FIXME: write short doc here
+use std::sync::Arc;
+
+use hir_expand::name::Name;
+use ra_arena::{impl_arena_id, Arena, RawId};
+use rustc_hash::FxHashMap;
+
+use crate::{
+    body::Body,
+    db::DefDatabase2,
+    expr::{Expr, ExprId, Pat, PatId, Statement},
+    DefWithBodyId,
+};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct ScopeId(RawId);
+impl_arena_id!(ScopeId);
+
+#[derive(Debug, PartialEq, Eq)]
+pub struct ExprScopes {
+    scopes: Arena<ScopeId, ScopeData>,
+    scope_by_expr: FxHashMap<ExprId, ScopeId>,
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub struct ScopeEntry {
+    name: Name,
+    pat: PatId,
+}
+
+impl ScopeEntry {
+    pub fn name(&self) -> &Name {
+        &self.name
+    }
+
+    pub fn pat(&self) -> PatId {
+        self.pat
+    }
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub struct ScopeData {
+    parent: Option<ScopeId>,
+    entries: Vec<ScopeEntry>,
+}
+
+impl ExprScopes {
+    pub(crate) fn expr_scopes_query(db: &impl DefDatabase2, def: DefWithBodyId) -> Arc<ExprScopes> {
+        let body = db.body(def);
+        Arc::new(ExprScopes::new(&*body))
+    }
+
+    fn new(body: &Body) -> ExprScopes {
+        let mut scopes =
+            ExprScopes { scopes: Arena::default(), scope_by_expr: FxHashMap::default() };
+        let root = scopes.root_scope();
+        scopes.add_params_bindings(body, root, body.params());
+        compute_expr_scopes(body.body_expr(), body, &mut scopes, root);
+        scopes
+    }
+
+    pub fn entries(&self, scope: ScopeId) -> &[ScopeEntry] {
+        &self.scopes[scope].entries
+    }
+
+    pub fn scope_chain(&self, scope: Option<ScopeId>) -> impl Iterator<Item = ScopeId> + '_ {
+        std::iter::successors(scope, move |&scope| self.scopes[scope].parent)
+    }
+
+    pub fn scope_for(&self, expr: ExprId) -> Option<ScopeId> {
+        self.scope_by_expr.get(&expr).copied()
+    }
+
+    pub fn scope_by_expr(&self) -> &FxHashMap<ExprId, ScopeId> {
+        &self.scope_by_expr
+    }
+
+    fn root_scope(&mut self) -> ScopeId {
+        self.scopes.alloc(ScopeData { parent: None, entries: vec![] })
+    }
+
+    fn new_scope(&mut self, parent: ScopeId) -> ScopeId {
+        self.scopes.alloc(ScopeData { parent: Some(parent), entries: vec![] })
+    }
+
+    fn add_bindings(&mut self, body: &Body, scope: ScopeId, pat: PatId) {
+        match &body[pat] {
+            Pat::Bind { name, .. } => {
+                // bind can have a sub pattern, but it's actually not allowed
+                // to bind to things in there
+                let entry = ScopeEntry { name: name.clone(), pat };
+                self.scopes[scope].entries.push(entry)
+            }
+            p => p.walk_child_pats(|pat| self.add_bindings(body, scope, pat)),
+        }
+    }
+
+    fn add_params_bindings(&mut self, body: &Body, scope: ScopeId, params: &[PatId]) {
+        params.iter().for_each(|pat| self.add_bindings(body, scope, *pat));
+    }
+
+    fn set_scope(&mut self, node: ExprId, scope: ScopeId) {
+        self.scope_by_expr.insert(node, scope);
+    }
+}
+
+fn compute_block_scopes(
+    statements: &[Statement],
+    tail: Option<ExprId>,
+    body: &Body,
+    scopes: &mut ExprScopes,
+    mut scope: ScopeId,
+) {
+    for stmt in statements {
+        match stmt {
+            Statement::Let { pat, initializer, .. } => {
+                if let Some(expr) = initializer {
+                    scopes.set_scope(*expr, scope);
+                    compute_expr_scopes(*expr, body, scopes, scope);
+                }
+                scope = scopes.new_scope(scope);
+                scopes.add_bindings(body, scope, *pat);
+            }
+            Statement::Expr(expr) => {
+                scopes.set_scope(*expr, scope);
+                compute_expr_scopes(*expr, body, scopes, scope);
+            }
+        }
+    }
+    if let Some(expr) = tail {
+        compute_expr_scopes(expr, body, scopes, scope);
+    }
+}
+
+fn compute_expr_scopes(expr: ExprId, body: &Body, scopes: &mut ExprScopes, scope: ScopeId) {
+    scopes.set_scope(expr, scope);
+    match &body[expr] {
+        Expr::Block { statements, tail } => {
+            compute_block_scopes(&statements, *tail, body, scopes, scope);
+        }
+        Expr::For { iterable, pat, body: body_expr } => {
+            compute_expr_scopes(*iterable, body, scopes, scope);
+            let scope = scopes.new_scope(scope);
+            scopes.add_bindings(body, scope, *pat);
+            compute_expr_scopes(*body_expr, body, scopes, scope);
+        }
+        Expr::Lambda { args, body: body_expr, .. } => {
+            let scope = scopes.new_scope(scope);
+            scopes.add_params_bindings(body, scope, &args);
+            compute_expr_scopes(*body_expr, body, scopes, scope);
+        }
+        Expr::Match { expr, arms } => {
+            compute_expr_scopes(*expr, body, scopes, scope);
+            for arm in arms {
+                let scope = scopes.new_scope(scope);
+                for pat in &arm.pats {
+                    scopes.add_bindings(body, scope, *pat);
+                }
+                scopes.set_scope(arm.expr, scope);
+                compute_expr_scopes(arm.expr, body, scopes, scope);
+            }
+        }
+        e => e.walk_child_exprs(|e| compute_expr_scopes(e, body, scopes, scope)),
+    };
+}
diff --git a/crates/ra_hir_def/src/db.rs b/crates/ra_hir_def/src/db.rs
index 29cf71a59..40b5920d9 100644
--- a/crates/ra_hir_def/src/db.rs
+++ b/crates/ra_hir_def/src/db.rs
@@ -7,11 +7,12 @@ use ra_syntax::ast;
 
 use crate::{
     adt::{EnumData, StructData},
+    body::{scope::ExprScopes, Body, BodySourceMap},
     nameres::{
         raw::{ImportSourceMap, RawItems},
         CrateDefMap,
     },
-    EnumId, StructOrUnionId,
+    DefWithBodyId, EnumId, StructOrUnionId,
 };
 
 #[salsa::query_group(InternDatabaseStorage)]
@@ -52,4 +53,13 @@ pub trait DefDatabase2: InternDatabase + AstDatabase {
 
     #[salsa::invoke(EnumData::enum_data_query)]
     fn enum_data(&self, e: EnumId) -> Arc<EnumData>;
+
+    #[salsa::invoke(Body::body_with_source_map_query)]
+    fn body_with_source_map(&self, def: DefWithBodyId) -> (Arc<Body>, Arc<BodySourceMap>);
+
+    #[salsa::invoke(Body::body_query)]
+    fn body(&self, def: DefWithBodyId) -> Arc<Body>;
+
+    #[salsa::invoke(ExprScopes::expr_scopes_query)]
+    fn expr_scopes(&self, def: DefWithBodyId) -> Arc<ExprScopes>;
 }
diff --git a/crates/ra_hir_def/src/lib.rs b/crates/ra_hir_def/src/lib.rs
index 4a758bb83..3fab7965c 100644
--- a/crates/ra_hir_def/src/lib.rs
+++ b/crates/ra_hir_def/src/lib.rs
@@ -374,3 +374,13 @@ impl_froms!(
     TypeAliasId,
     BuiltinType
 );
+
+/// The defs which have a body.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum DefWithBodyId {
+    FunctionId(FunctionId),
+    StaticId(StaticId),
+    ConstId(ConstId),
+}
+
+impl_froms!(DefWithBodyId: FunctionId, ConstId, StaticId);
diff --git a/crates/ra_hir_expand/src/lib.rs b/crates/ra_hir_expand/src/lib.rs
index c6ffa2c6f..930789b0f 100644
--- a/crates/ra_hir_expand/src/lib.rs
+++ b/crates/ra_hir_expand/src/lib.rs
@@ -223,7 +223,7 @@ impl<N: AstNode> AstId<N> {
     }
 }
 
-#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+#[derive(Debug, PartialEq, Eq, Clone, Copy, Hash)]
 pub struct Source<T> {
     pub file_id: HirFileId,
     pub ast: T,
@@ -233,6 +233,9 @@ impl<T> Source<T> {
     pub fn map<F: FnOnce(T) -> U, U>(self, f: F) -> Source<U> {
         Source { file_id: self.file_id, ast: f(self.ast) }
     }
+    pub fn as_ref(&self) -> Source<&T> {
+        Source { file_id: self.file_id, ast: &self.ast }
+    }
     pub fn file_syntax(&self, db: &impl db::AstDatabase) -> SyntaxNode {
         db.parse_or_expand(self.file_id).expect("source created from invalid file")
     }
diff --git a/crates/ra_parser/src/grammar/expressions/atom.rs b/crates/ra_parser/src/grammar/expressions/atom.rs
index 4952bd189..f06191963 100644
--- a/crates/ra_parser/src/grammar/expressions/atom.rs
+++ b/crates/ra_parser/src/grammar/expressions/atom.rs
@@ -40,24 +40,24 @@ pub(crate) fn literal(p: &mut Parser) -> Option<CompletedMarker> {
 // E.g. for after the break in `if break {}`, this should not match
 pub(super) const ATOM_EXPR_FIRST: TokenSet =
     LITERAL_FIRST.union(paths::PATH_FIRST).union(token_set![
-        L_PAREN,
-        L_CURLY,
-        L_BRACK,
-        PIPE,
-        MOVE_KW,
-        BOX_KW,
-        IF_KW,
-        WHILE_KW,
-        MATCH_KW,
-        UNSAFE_KW,
-        RETURN_KW,
-        BREAK_KW,
-        CONTINUE_KW,
+        T!['('],
+        T!['{'],
+        T!['['],
+        T![|],
+        T![move],
+        T![box],
+        T![if],
+        T![while],
+        T![match],
+        T![unsafe],
+        T![return],
+        T![break],
+        T![continue],
+        T![async],
+        T![try],
+        T![loop],
+        T![for],
         LIFETIME,
-        ASYNC_KW,
-        TRY_KW,
-        LOOP_KW,
-        FOR_KW,
     ]);
 
 const EXPR_RECOVERY_SET: TokenSet = token_set![LET_KW];
diff --git a/crates/ra_parser/src/token_set.rs b/crates/ra_parser/src/token_set.rs
index 6dc061889..2a6952c01 100644
--- a/crates/ra_parser/src/token_set.rs
+++ b/crates/ra_parser/src/token_set.rs
@@ -30,8 +30,8 @@ const fn mask(kind: SyntaxKind) -> u128 {
 
 #[macro_export]
 macro_rules! token_set {
-    ($($t:ident),*) => { TokenSet::empty()$(.union(TokenSet::singleton($t)))* };
-    ($($t:ident),* ,) => { token_set!($($t),*) };
+    ($($t:expr),*) => { TokenSet::empty()$(.union(TokenSet::singleton($t)))* };
+    ($($t:expr),* ,) => { token_set!($($t),*) };
 }
 
 #[test]
diff --git a/crates/ra_prof/Cargo.toml b/crates/ra_prof/Cargo.toml
index 7db4498c3..bb241258c 100644
--- a/crates/ra_prof/Cargo.toml
+++ b/crates/ra_prof/Cargo.toml
@@ -1,17 +1,19 @@
-[package]
-edition = "2018"
-name = "ra_prof"
-version = "0.1.0"
-authors = ["rust-analyzer developers"]
-publish = false
-
-[dependencies]
-once_cell = "1.0.1"
-itertools = "0.8.0"
-backtrace = "0.3.28"
-jemallocator = { version = "0.3.2", optional = true }
-jemalloc-ctl = { version = "0.3.2", optional = true }
-
-[features]
-jemalloc = [ "jemallocator", "jemalloc-ctl" ]
-cpu_profiler = []
+[package]

+edition = "2018"

+name = "ra_prof"

+version = "0.1.0"

+authors = ["rust-analyzer developers"]

+publish = false

+

+[dependencies]

+once_cell = "1.0.1"

+itertools = "0.8.0"

+backtrace = "0.3.28"

+

+[target.'cfg(not(target_env = "msvc"))'.dependencies]

+jemallocator = { version = "0.3.2", optional = true }

+jemalloc-ctl = { version = "0.3.2", optional = true }

+

+[features]

+jemalloc = [ "jemallocator", "jemalloc-ctl" ]

+cpu_profiler = []

diff --git a/crates/ra_prof/src/lib.rs b/crates/ra_prof/src/lib.rs
index e5385f51b..845b2221c 100644
--- a/crates/ra_prof/src/lib.rs
+++ b/crates/ra_prof/src/lib.rs
@@ -24,7 +24,7 @@ pub use crate::memory_usage::{Bytes, MemoryUsage};
 
 // We use jemalloc mainly to get heap usage statistics, actual performance
 // difference is not measures.
-#[cfg(feature = "jemalloc")]
+#[cfg(all(feature = "jemalloc", not(target_env = "msvc")))]
 #[global_allocator]
 static ALLOC: jemallocator::Jemalloc = jemallocator::Jemalloc;
 
diff --git a/crates/ra_prof/src/memory_usage.rs b/crates/ra_prof/src/memory_usage.rs
index ad005ea14..9768f656c 100644
--- a/crates/ra_prof/src/memory_usage.rs
+++ b/crates/ra_prof/src/memory_usage.rs
@@ -8,7 +8,7 @@ pub struct MemoryUsage {
 }
 
 impl MemoryUsage {
-    #[cfg(feature = "jemalloc")]
+    #[cfg(all(feature = "jemalloc", not(target_env = "msvc")))]
     pub fn current() -> MemoryUsage {
         jemalloc_ctl::epoch::advance().unwrap();
         MemoryUsage {
@@ -17,7 +17,7 @@ impl MemoryUsage {
         }
     }
 
-    #[cfg(not(feature = "jemalloc"))]
+    #[cfg(any(not(feature = "jemalloc"), target_env = "msvc"))]
     pub fn current() -> MemoryUsage {
         MemoryUsage { allocated: Bytes(0), resident: Bytes(0) }
     }
diff --git a/crates/ra_syntax/src/ast/edit.rs b/crates/ra_syntax/src/ast/edit.rs
index 47bdbb81a..6f005a2d8 100644
--- a/crates/ra_syntax/src/ast/edit.rs
+++ b/crates/ra_syntax/src/ast/edit.rs
@@ -358,7 +358,7 @@ fn replace_children<N: AstNode>(
 fn test_increase_indent() {
     let arm_list = {
         let arm = make::match_arm(iter::once(make::placeholder_pat().into()), make::expr_unit());
-        make::match_arm_list(vec![arm.clone(), arm].into_iter())
+        make::match_arm_list(vec![arm.clone(), arm])
     };
     assert_eq!(
         arm_list.syntax().to_string(),
diff --git a/crates/ra_syntax/src/ast/make.rs b/crates/ra_syntax/src/ast/make.rs
index 95062ef6c..9749327fa 100644
--- a/crates/ra_syntax/src/ast/make.rs
+++ b/crates/ra_syntax/src/ast/make.rs
@@ -4,6 +4,10 @@ use itertools::Itertools;
 
 use crate::{ast, AstNode, SourceFile};
 
+pub fn name(text: &str) -> ast::Name {
+    ast_from_text(&format!("mod {};", text))
+}
+
 pub fn name_ref(text: &str) -> ast::NameRef {
     ast_from_text(&format!("fn f() {{ {}; }}", text))
 }
@@ -43,6 +47,21 @@ pub fn expr_unit() -> ast::Expr {
 pub fn expr_unimplemented() -> ast::Expr {
     expr_from_text("unimplemented!()")
 }
+pub fn expr_path(path: ast::Path) -> ast::Expr {
+    expr_from_text(&path.syntax().to_string())
+}
+pub fn expr_continue() -> ast::Expr {
+    expr_from_text("continue")
+}
+pub fn expr_break() -> ast::Expr {
+    expr_from_text("break")
+}
+pub fn expr_return() -> ast::Expr {
+    expr_from_text("return")
+}
+pub fn expr_match(expr: ast::Expr, match_arm_list: ast::MatchArmList) -> ast::Expr {
+    expr_from_text(&format!("match {} {}", expr.syntax(), match_arm_list.syntax()))
+}
 fn expr_from_text(text: &str) -> ast::Expr {
     ast_from_text(&format!("const C: () = {};", text))
 }
@@ -65,9 +84,9 @@ pub fn placeholder_pat() -> ast::PlaceholderPat {
 
 pub fn tuple_struct_pat(
     path: ast::Path,
-    pats: impl Iterator<Item = ast::Pat>,
+    pats: impl IntoIterator<Item = ast::Pat>,
 ) -> ast::TupleStructPat {
-    let pats_str = pats.map(|p| p.syntax().to_string()).join(", ");
+    let pats_str = pats.into_iter().map(|p| p.syntax().to_string()).join(", ");
     return from_text(&format!("{}({})", path.syntax(), pats_str));
 
     fn from_text(text: &str) -> ast::TupleStructPat {
@@ -75,8 +94,8 @@ pub fn tuple_struct_pat(
     }
 }
 
-pub fn record_pat(path: ast::Path, pats: impl Iterator<Item = ast::Pat>) -> ast::RecordPat {
-    let pats_str = pats.map(|p| p.syntax().to_string()).join(", ");
+pub fn record_pat(path: ast::Path, pats: impl IntoIterator<Item = ast::Pat>) -> ast::RecordPat {
+    let pats_str = pats.into_iter().map(|p| p.syntax().to_string()).join(", ");
     return from_text(&format!("{} {{ {} }}", path.syntax(), pats_str));
 
     fn from_text(text: &str) -> ast::RecordPat {
@@ -92,8 +111,8 @@ pub fn path_pat(path: ast::Path) -> ast::PathPat {
     }
 }
 
-pub fn match_arm(pats: impl Iterator<Item = ast::Pat>, expr: ast::Expr) -> ast::MatchArm {
-    let pats_str = pats.map(|p| p.syntax().to_string()).join(" | ");
+pub fn match_arm(pats: impl IntoIterator<Item = ast::Pat>, expr: ast::Expr) -> ast::MatchArm {
+    let pats_str = pats.into_iter().map(|p| p.syntax().to_string()).join(" | ");
     return from_text(&format!("{} => {}", pats_str, expr.syntax()));
 
     fn from_text(text: &str) -> ast::MatchArm {
@@ -101,8 +120,8 @@ pub fn match_arm(pats: impl Iterator<Item = ast::Pat>, expr: ast::Expr) -> ast::
     }
 }
 
-pub fn match_arm_list(arms: impl Iterator<Item = ast::MatchArm>) -> ast::MatchArmList {
-    let arms_str = arms.map(|arm| format!("\n    {}", arm.syntax())).join(",");
+pub fn match_arm_list(arms: impl IntoIterator<Item = ast::MatchArm>) -> ast::MatchArmList {
+    let arms_str = arms.into_iter().map(|arm| format!("\n    {}", arm.syntax())).join(",");
     return from_text(&format!("{},\n", arms_str));
 
     fn from_text(text: &str) -> ast::MatchArmList {
@@ -110,25 +129,11 @@ pub fn match_arm_list(arms: impl Iterator<Item = ast::MatchArm>) -> ast::MatchAr
     }
 }
 
-pub fn let_match_early(expr: ast::Expr, path: &str, early_expression: &str) -> ast::LetStmt {
-    return from_text(&format!(
-        r#"let {} = match {} {{
-    {}(it) => it,
-    None => {},
-}};"#,
-        expr.syntax().text(),
-        expr.syntax().text(),
-        path,
-        early_expression
-    ));
-
-    fn from_text(text: &str) -> ast::LetStmt {
-        ast_from_text(&format!("fn f() {{ {} }}", text))
-    }
-}
-
-pub fn where_pred(path: ast::Path, bounds: impl Iterator<Item = ast::TypeBound>) -> ast::WherePred {
-    let bounds = bounds.map(|b| b.syntax().to_string()).join(" + ");
+pub fn where_pred(
+    path: ast::Path,
+    bounds: impl IntoIterator<Item = ast::TypeBound>,
+) -> ast::WherePred {
+    let bounds = bounds.into_iter().map(|b| b.syntax().to_string()).join(" + ");
     return from_text(&format!("{}: {}", path.syntax(), bounds));
 
     fn from_text(text: &str) -> ast::WherePred {
@@ -136,8 +141,8 @@ pub fn where_pred(path: ast::Path, bounds: impl Iterator<Item = ast::TypeBound>)
     }
 }
 
-pub fn where_clause(preds: impl Iterator<Item = ast::WherePred>) -> ast::WhereClause {
-    let preds = preds.map(|p| p.syntax().to_string()).join(", ");
+pub fn where_clause(preds: impl IntoIterator<Item = ast::WherePred>) -> ast::WhereClause {
+    let preds = preds.into_iter().map(|p| p.syntax().to_string()).join(", ");
     return from_text(preds.as_str());
 
     fn from_text(text: &str) -> ast::WhereClause {
@@ -153,6 +158,14 @@ pub fn if_expression(condition: &ast::Expr, statement: &str) -> ast::IfExpr {
     ))
 }
 
+pub fn let_stmt(pattern: ast::Pat, initializer: Option<ast::Expr>) -> ast::LetStmt {
+    let text = match initializer {
+        Some(it) => format!("let {} = {};", pattern.syntax(), it.syntax()),
+        None => format!("let {};", pattern.syntax()),
+    };
+    ast_from_text(&format!("fn f() {{ {} }}", text))
+}
+
 fn ast_from_text<N: AstNode>(text: &str) -> N {
     let parse = SourceFile::parse(text);
     let res = parse.tree().syntax().descendants().find_map(N::cast).unwrap();