Merge branch 'master' of github.com:rust-analyzer/rust-analyzer into feat_4348

79 files changed, 1920 insertions, 1058 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 5d50a766f..41855f22e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -68,9 +68,9 @@ dependencies = [
 
 [[package]]
 name = "base64"
-version = "0.12.0"
+version = "0.12.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7d5ca2cd0adc3f48f9e9ea5a6bbdf9ccc0bfade884847e484d452414c7ccffb3"
+checksum = "53d1ccbaf7d9ec9537465a97bf19edc1a4e158ecb49fc16178202238c569cc42"
 
 [[package]]
 name = "bitflags"
@@ -342,9 +342,9 @@ dependencies = [
 
 [[package]]
 name = "filetime"
-version = "0.2.9"
+version = "0.2.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f59efc38004c988e4201d11d263b8171f49a2e7ec0bdbb71773433f271504a5e"
+checksum = "affc17579b132fc2461adf7c575cc6e8b134ebca52c51f5411388965227dc695"
 dependencies = [
  "cfg-if",
  "libc",
@@ -465,6 +465,15 @@ dependencies = [
 ]
 
 [[package]]
+name = "home"
+version = "0.5.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2456aef2e6b6a9784192ae780c0f15bc57df0e918585282325e8c8ac27737654"
+dependencies = [
+ "winapi 0.3.8",
+]
+
+[[package]]
 name = "idna"
 version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -610,18 +619,18 @@ checksum = "99e85c08494b21a9054e7fe1374a732aeadaff3980b6990b94bfd3a70f690005"
 
 [[package]]
 name = "libloading"
-version = "0.6.1"
+version = "0.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3c4f51b790f5bdb65acb4cc94bb81d7b2ee60348a5431ac1467d390b017600b0"
+checksum = "2cadb8e769f070c45df05c78c7520eb4cd17061d4ab262e43cfc68b4d00ac71c"
 dependencies = [
  "winapi 0.3.8",
 ]
 
 [[package]]
 name = "linked-hash-map"
-version = "0.5.2"
+version = "0.5.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ae91b68aebc4ddb91978b11a1b02ddd8602a05ec19002801c5666000e05e0f83"
+checksum = "8dd5a6d5999d9907cda8ed67bbd137d3af8085216c2ac62de5be860bd41f304a"
 
 [[package]]
 name = "lock_api"
@@ -824,9 +833,9 @@ dependencies = [
 
 [[package]]
 name = "paste"
-version = "0.1.11"
+version = "0.1.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a3c897744f63f34f7ae3a024d9162bb5001f4ad661dd24bea0dc9f075d2de1c6"
+checksum = "0a229b1c58c692edcaa5b9b0948084f130f55d2dcc15b02fcc5340b2b4521476"
 dependencies = [
  "paste-impl",
  "proc-macro-hack",
@@ -834,9 +843,9 @@ dependencies = [
 
 [[package]]
 name = "paste-impl"
-version = "0.1.11"
+version = "0.1.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "66fd6f92e3594f2dd7b3fc23e42d82e292f7bcda6d8e5dcd167072327234ab89"
+checksum = "2e0bf239e447e67ff6d16a8bb5e4d4bd2343acf5066061c0e8e06ac5ba8ca68c"
 dependencies = [
  "proc-macro-hack",
  "proc-macro2",
@@ -886,9 +895,9 @@ checksum = "0d659fe7c6d27f25e9d80a1a094c223f5246f6a6596453e09d7229bf42750b63"
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.10"
+version = "1.0.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "df246d292ff63439fea9bc8c0a270bed0e390d5ebd4db4ba15aba81111b5abe3"
+checksum = "8872cf6f48eee44265156c111456a700ab3483686b3f96df4cf5481c89157319"
 dependencies = [
  "unicode-xid",
 ]
@@ -958,6 +967,7 @@ dependencies = [
  "jod-thread",
  "log",
  "lsp-types",
+ "ra_toolchain",
  "serde_json",
 ]
 
@@ -1163,6 +1173,7 @@ dependencies = [
  "ra_cfg",
  "ra_db",
  "ra_proc_macro",
+ "ra_toolchain",
  "rustc-hash",
  "serde",
  "serde_json",
@@ -1195,6 +1206,13 @@ dependencies = [
 ]
 
 [[package]]
+name = "ra_toolchain"
+version = "0.1.0"
+dependencies = [
+ "home",
+]
+
+[[package]]
 name = "ra_tt"
 version = "0.1.0"
 dependencies = [
@@ -1581,9 +1599,9 @@ checksum = "ab16ced94dbd8a46c82fd81e3ed9a8727dac2977ea869d217bcc4ea1f122e81f"
 
 [[package]]
 name = "syn"
-version = "1.0.18"
+version = "1.0.19"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "410a7488c0a728c7ceb4ad59b9567eb4053d02e8cc7f5c0e0eeeb39518369213"
+checksum = "e8e5aa70697bb26ee62214ae3288465ecec0000f05182f039b477001f08f5ae7"
 dependencies = [
  "proc-macro2",
  "quote",
diff --git a/crates/ra_assists/src/assist_ctx.rs b/crates/ra_assists/src/assist_context.rs
index 871671de2..a680f752b 100644
--- a/crates/ra_assists/src/assist_ctx.rs
+++ b/crates/ra_assists/src/assist_context.rs
@@ -1,4 +1,6 @@
-//! This module defines `AssistCtx` -- the API surface that is exposed to assists.
+//! See `AssistContext`
+
+use algo::find_covering_element;
 use hir::Semantics;
 use ra_db::{FileId, FileRange};
 use ra_fmt::{leading_indent, reindent};
@@ -7,54 +9,25 @@ use ra_ide_db::{
     RootDatabase,
 };
 use ra_syntax::{
-    algo::{self, find_covering_element, find_node_at_offset, SyntaxRewriter},
+    algo::{self, find_node_at_offset, SyntaxRewriter},
     AstNode, SourceFile, SyntaxElement, SyntaxKind, SyntaxNode, SyntaxToken, TextRange, TextSize,
     TokenAtOffset,
 };
 use ra_text_edit::TextEditBuilder;
 
-use crate::{AssistId, AssistLabel, GroupLabel, ResolvedAssist};
-
-#[derive(Clone, Debug)]
-pub(crate) struct Assist(pub(crate) Vec<AssistInfo>);
-
-#[derive(Clone, Debug)]
-pub(crate) struct AssistInfo {
-    pub(crate) label: AssistLabel,
-    pub(crate) group_label: Option<GroupLabel>,
-    pub(crate) source_change: Option<SourceChange>,
-}
-
-impl AssistInfo {
-    fn new(label: AssistLabel) -> AssistInfo {
-        AssistInfo { label, group_label: None, source_change: None }
-    }
-
-    fn resolved(self, source_change: SourceChange) -> AssistInfo {
-        AssistInfo { source_change: Some(source_change), ..self }
-    }
-
-    fn with_group(self, group_label: GroupLabel) -> AssistInfo {
-        AssistInfo { group_label: Some(group_label), ..self }
-    }
-
-    pub(crate) fn into_resolved(self) -> Option<ResolvedAssist> {
-        let label = self.label;
-        self.source_change.map(|source_change| ResolvedAssist { label, source_change })
-    }
-}
+use crate::{Assist, AssistId, GroupLabel, ResolvedAssist};
 
-/// `AssistCtx` allows to apply an assist or check if it could be applied.
+/// `AssistContext` allows to apply an assist or check if it could be applied.
 ///
-/// Assists use a somewhat over-engineered approach, given the current needs. The
-/// assists workflow consists of two phases. In the first phase, a user asks for
-/// the list of available assists. In the second phase, the user picks a
+/// Assists use a somewhat over-engineered approach, given the current needs.
+/// The assists workflow consists of two phases. In the first phase, a user asks
+/// for the list of available assists. In the second phase, the user picks a
 /// particular assist and it gets applied.
 ///
 /// There are two peculiarities here:
 ///
-/// * first, we ideally avoid computing more things then necessary to answer
-///   "is assist applicable" in the first phase.
+/// * first, we ideally avoid computing more things then necessary to answer "is
+///   assist applicable" in the first phase.
 /// * second, when we are applying assist, we don't have a guarantee that there
 ///   weren't any changes between the point when user asked for assists and when
 ///   they applied a particular assist. So, when applying assist, we need to do
@@ -63,152 +36,157 @@ impl AssistInfo {
 /// To avoid repeating the same code twice for both "check" and "apply"
 /// functions, we use an approach reminiscent of that of Django's function based
 /// views dealing with forms. Each assist receives a runtime parameter,
-/// `should_compute_edit`. It first check if an edit is applicable (potentially
-/// computing info required to compute the actual edit). If it is applicable,
-/// and `should_compute_edit` is `true`, it then computes the actual edit.
+/// `resolve`. It first check if an edit is applicable (potentially computing
+/// info required to compute the actual edit). If it is applicable, and
+/// `resolve` is `true`, it then computes the actual edit.
 ///
 /// So, to implement the original assists workflow, we can first apply each edit
-/// with `should_compute_edit = false`, and then applying the selected edit
-/// again, with `should_compute_edit = true` this time.
+/// with `resolve = false`, and then applying the selected edit again, with
+/// `resolve = true` this time.
 ///
 /// Note, however, that we don't actually use such two-phase logic at the
 /// moment, because the LSP API is pretty awkward in this place, and it's much
 /// easier to just compute the edit eagerly :-)
-#[derive(Clone)]
-pub(crate) struct AssistCtx<'a> {
-    pub(crate) sema: &'a Semantics<'a, RootDatabase>,
+pub(crate) struct AssistContext<'a> {
+    pub(crate) sema: Semantics<'a, RootDatabase>,
     pub(crate) db: &'a RootDatabase,
     pub(crate) frange: FileRange,
     source_file: SourceFile,
-    should_compute_edit: bool,
 }
 
-impl<'a> AssistCtx<'a> {
-    pub fn new(
-        sema: &'a Semantics<'a, RootDatabase>,
-        frange: FileRange,
-        should_compute_edit: bool,
-    ) -> AssistCtx<'a> {
+impl<'a> AssistContext<'a> {
+    pub fn new(sema: Semantics<'a, RootDatabase>, frange: FileRange) -> AssistContext<'a> {
         let source_file = sema.parse(frange.file_id);
-        AssistCtx { sema, db: sema.db, frange, source_file, should_compute_edit }
+        let db = sema.db;
+        AssistContext { sema, db, frange, source_file }
     }
 
-    pub(crate) fn add_assist(
-        self,
-        id: AssistId,
-        label: impl Into<String>,
-        target: TextRange,
-        f: impl FnOnce(&mut ActionBuilder),
-    ) -> Option<Assist> {
-        let label = AssistLabel::new(id, label.into(), None, target);
-        let change_label = label.label.clone();
-        let mut info = AssistInfo::new(label);
-        if self.should_compute_edit {
-            let source_change = {
-                let mut edit = ActionBuilder::new(&self);
-                f(&mut edit);
-                edit.build(change_label)
-            };
-            info = info.resolved(source_change)
-        };
-
-        Some(Assist(vec![info]))
-    }
-
-    pub(crate) fn add_assist_group(self, group_name: impl Into<String>) -> AssistGroup<'a> {
-        let group = GroupLabel(group_name.into());
-        AssistGroup { ctx: self, group, assists: Vec::new() }
+    // NB, this ignores active selection.
+    pub(crate) fn offset(&self) -> TextSize {
+        self.frange.range.start()
     }
 
     pub(crate) fn token_at_offset(&self) -> TokenAtOffset<SyntaxToken> {
-        self.source_file.syntax().token_at_offset(self.frange.range.start())
+        self.source_file.syntax().token_at_offset(self.offset())
     }
-
     pub(crate) fn find_token_at_offset(&self, kind: SyntaxKind) -> Option<SyntaxToken> {
         self.token_at_offset().find(|it| it.kind() == kind)
     }
-
     pub(crate) fn find_node_at_offset<N: AstNode>(&self) -> Option<N> {
-        find_node_at_offset(self.source_file.syntax(), self.frange.range.start())
+        find_node_at_offset(self.source_file.syntax(), self.offset())
     }
-
     pub(crate) fn find_node_at_offset_with_descend<N: AstNode>(&self) -> Option<N> {
-        self.sema
-            .find_node_at_offset_with_descend(self.source_file.syntax(), self.frange.range.start())
+        self.sema.find_node_at_offset_with_descend(self.source_file.syntax(), self.offset())
     }
-
     pub(crate) fn covering_element(&self) -> SyntaxElement {
         find_covering_element(self.source_file.syntax(), self.frange.range)
     }
+    // FIXME: remove
     pub(crate) fn covering_node_for_range(&self, range: TextRange) -> SyntaxElement {
         find_covering_element(self.source_file.syntax(), range)
     }
 }
 
-pub(crate) struct AssistGroup<'a> {
-    ctx: AssistCtx<'a>,
-    group: GroupLabel,
-    assists: Vec<AssistInfo>,
+pub(crate) struct Assists {
+    resolve: bool,
+    file: FileId,
+    buf: Vec<(Assist, Option<SourceChange>)>,
 }
 
-impl<'a> AssistGroup<'a> {
-    pub(crate) fn add_assist(
+impl Assists {
+    pub(crate) fn new_resolved(ctx: &AssistContext) -> Assists {
+        Assists { resolve: true, file: ctx.frange.file_id, buf: Vec::new() }
+    }
+    pub(crate) fn new_unresolved(ctx: &AssistContext) -> Assists {
+        Assists { resolve: false, file: ctx.frange.file_id, buf: Vec::new() }
+    }
+
+    pub(crate) fn finish_unresolved(self) -> Vec<Assist> {
+        assert!(!self.resolve);
+        self.finish()
+            .into_iter()
+            .map(|(label, edit)| {
+                assert!(edit.is_none());
+                label
+            })
+            .collect()
+    }
+
+    pub(crate) fn finish_resolved(self) -> Vec<ResolvedAssist> {
+        assert!(self.resolve);
+        self.finish()
+            .into_iter()
+            .map(|(label, edit)| ResolvedAssist { assist: label, source_change: edit.unwrap() })
+            .collect()
+    }
+
+    pub(crate) fn add(
         &mut self,
         id: AssistId,
         label: impl Into<String>,
         target: TextRange,
-        f: impl FnOnce(&mut ActionBuilder),
-    ) {
-        let label = AssistLabel::new(id, label.into(), Some(self.group.clone()), target);
+        f: impl FnOnce(&mut AssistBuilder),
+    ) -> Option<()> {
+        let label = Assist::new(id, label.into(), None, target);
+        self.add_impl(label, f)
+    }
+    pub(crate) fn add_group(
+        &mut self,
+        group: &GroupLabel,
+        id: AssistId,
+        label: impl Into<String>,
+        target: TextRange,
+        f: impl FnOnce(&mut AssistBuilder),
+    ) -> Option<()> {
+        let label = Assist::new(id, label.into(), Some(group.clone()), target);
+        self.add_impl(label, f)
+    }
+    fn add_impl(&mut self, label: Assist, f: impl FnOnce(&mut AssistBuilder)) -> Option<()> {
         let change_label = label.label.clone();
-        let mut info = AssistInfo::new(label).with_group(self.group.clone());
-        if self.ctx.should_compute_edit {
-            let source_change = {
-                let mut edit = ActionBuilder::new(&self.ctx);
-                f(&mut edit);
-                edit.build(change_label)
-            };
-            info = info.resolved(source_change)
+        let source_change = if self.resolve {
+            let mut builder = AssistBuilder::new(self.file);
+            f(&mut builder);
+            Some(builder.finish(change_label))
+        } else {
+            None
         };
 
-        self.assists.push(info)
+        self.buf.push((label, source_change));
+        Some(())
     }
 
-    pub(crate) fn finish(self) -> Option<Assist> {
-        if self.assists.is_empty() {
-            None
-        } else {
-            Some(Assist(self.assists))
-        }
+    fn finish(mut self) -> Vec<(Assist, Option<SourceChange>)> {
+        self.buf.sort_by_key(|(label, _edit)| label.target.len());
+        self.buf
     }
 }
 
-pub(crate) struct ActionBuilder<'a, 'b> {
+pub(crate) struct AssistBuilder {
     edit: TextEditBuilder,
     cursor_position: Option<TextSize>,
     file: FileId,
-    ctx: &'a AssistCtx<'b>,
 }
 
-impl<'a, 'b> ActionBuilder<'a, 'b> {
-    fn new(ctx: &'a AssistCtx<'b>) -> Self {
-        Self {
-            edit: TextEditBuilder::default(),
-            cursor_position: None,
-            file: ctx.frange.file_id,
-            ctx,
-        }
+impl AssistBuilder {
+    pub(crate) fn new(file: FileId) -> AssistBuilder {
+        AssistBuilder { edit: TextEditBuilder::default(), cursor_position: None, file }
     }
 
-    pub(crate) fn ctx(&self) -> &AssistCtx<'b> {
-        &self.ctx
+    /// Remove specified `range` of text.
+    pub(crate) fn delete(&mut self, range: TextRange) {
+        self.edit.delete(range)
+    }
+    /// Append specified `text` at the given `offset`
+    pub(crate) fn insert(&mut self, offset: TextSize, text: impl Into<String>) {
+        self.edit.insert(offset, text.into())
     }
-
     /// Replaces specified `range` of text with a given string.
     pub(crate) fn replace(&mut self, range: TextRange, replace_with: impl Into<String>) {
         self.edit.replace(range, replace_with.into())
     }
-
+    pub(crate) fn replace_ast<N: AstNode>(&mut self, old: N, new: N) {
+        algo::diff(old.syntax(), new.syntax()).into_text_edit(&mut self.edit)
+    }
     /// Replaces specified `node` of text with a given string, reindenting the
     /// string to maintain `node`'s existing indent.
     // FIXME: remove in favor of ra_syntax::edit::IndentLevel::increase_indent
@@ -223,42 +201,28 @@ impl<'a, 'b> ActionBuilder<'a, 'b> {
         }
         self.replace(node.text_range(), replace_with)
     }
-
-    /// Remove specified `range` of text.
-    #[allow(unused)]
-    pub(crate) fn delete(&mut self, range: TextRange) {
-        self.edit.delete(range)
-    }
-
-    /// Append specified `text` at the given `offset`
-    pub(crate) fn insert(&mut self, offset: TextSize, text: impl Into<String>) {
-        self.edit.insert(offset, text.into())
+    pub(crate) fn rewrite(&mut self, rewriter: SyntaxRewriter) {
+        let node = rewriter.rewrite_root().unwrap();
+        let new = rewriter.rewrite(&node);
+        algo::diff(&node, &new).into_text_edit(&mut self.edit)
     }
 
     /// Specify desired position of the cursor after the assist is applied.
     pub(crate) fn set_cursor(&mut self, offset: TextSize) {
         self.cursor_position = Some(offset)
     }
+    // FIXME: better API
+    pub(crate) fn set_file(&mut self, assist_file: FileId) {
+        self.file = assist_file;
+    }
 
+    // FIXME: kill this API
     /// Get access to the raw `TextEditBuilder`.
     pub(crate) fn text_edit_builder(&mut self) -> &mut TextEditBuilder {
         &mut self.edit
     }
 
-    pub(crate) fn replace_ast<N: AstNode>(&mut self, old: N, new: N) {
-        algo::diff(old.syntax(), new.syntax()).into_text_edit(&mut self.edit)
-    }
-    pub(crate) fn rewrite(&mut self, rewriter: SyntaxRewriter) {
-        let node = rewriter.rewrite_root().unwrap();
-        let new = rewriter.rewrite(&node);
-        algo::diff(&node, &new).into_text_edit(&mut self.edit)
-    }
-
-    pub(crate) fn set_file(&mut self, assist_file: FileId) {
-        self.file = assist_file;
-    }
-
-    fn build(self, change_label: String) -> SourceChange {
+    fn finish(self, change_label: String) -> SourceChange {
         let edit = self.edit.finish();
         if edit.is_empty() && self.cursor_position.is_none() {
             panic!("Only call `add_assist` if the assist can be applied")
diff --git a/crates/ra_assists/src/handlers/add_custom_impl.rs b/crates/ra_assists/src/handlers/add_custom_impl.rs
index 869d4dc04..795a225a4 100644
--- a/crates/ra_assists/src/handlers/add_custom_impl.rs
+++ b/crates/ra_assists/src/handlers/add_custom_impl.rs
@@ -6,7 +6,10 @@ use ra_syntax::{
 };
 use stdx::SepBy;
 
-use crate::{Assist, AssistCtx, AssistId};
+use crate::{
+    assist_context::{AssistContext, Assists},
+    AssistId,
+};
 
 // Assist: add_custom_impl
 //
@@ -25,7 +28,7 @@ use crate::{Assist, AssistCtx, AssistId};
 //
 // }
 // ```
-pub(crate) fn add_custom_impl(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn add_custom_impl(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let input = ctx.find_node_at_offset::<ast::AttrInput>()?;
     let attr = input.syntax().parent().and_then(ast::Attr::cast)?;
 
@@ -49,7 +52,7 @@ pub(crate) fn add_custom_impl(ctx: AssistCtx) -> Option<Assist> {
         format!("Add custom impl '{}' for '{}'", trait_token.text().as_str(), annotated_name);
 
     let target = attr.syntax().text_range();
-    ctx.add_assist(AssistId("add_custom_impl"), label, target, |edit| {
+    acc.add(AssistId("add_custom_impl"), label, target, |edit| {
         let new_attr_input = input
             .syntax()
             .descendants_with_tokens()
diff --git a/crates/ra_assists/src/handlers/add_derive.rs b/crates/ra_assists/src/handlers/add_derive.rs
index 2a6bb1cae..fb08c19e9 100644
--- a/crates/ra_assists/src/handlers/add_derive.rs
+++ b/crates/ra_assists/src/handlers/add_derive.rs
@@ -4,7 +4,7 @@ use ra_syntax::{
     TextSize,
 };
 
-use crate::{Assist, AssistCtx, AssistId};
+use crate::{AssistContext, AssistId, Assists};
 
 // Assist: add_derive
 //
@@ -24,11 +24,11 @@ use crate::{Assist, AssistCtx, AssistId};
 //     y: u32,
 // }
 // ```
-pub(crate) fn add_derive(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn add_derive(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let nominal = ctx.find_node_at_offset::<ast::NominalDef>()?;
     let node_start = derive_insertion_offset(&nominal)?;
     let target = nominal.syntax().text_range();
-    ctx.add_assist(AssistId("add_derive"), "Add `#[derive]`", target, |edit| {
+    acc.add(AssistId("add_derive"), "Add `#[derive]`", target, |edit| {
         let derive_attr = nominal
             .attrs()
             .filter_map(|x| x.as_simple_call())
@@ -57,9 +57,10 @@ fn derive_insertion_offset(nominal: &ast::NominalDef) -> Option<TextSize> {
 
 #[cfg(test)]
 mod tests {
-    use super::*;
     use crate::tests::{check_assist, check_assist_target};
 
+    use super::*;
+
     #[test]
     fn add_derive_new() {
         check_assist(
diff --git a/crates/ra_assists/src/handlers/add_explicit_type.rs b/crates/ra_assists/src/handlers/add_explicit_type.rs
index a59ec16b2..146cc75df 100644
--- a/crates/ra_assists/src/handlers/add_explicit_type.rs
+++ b/crates/ra_assists/src/handlers/add_explicit_type.rs
@@ -4,7 +4,7 @@ use ra_syntax::{
     TextRange,
 };
 
-use crate::{Assist, AssistCtx, AssistId};
+use crate::{AssistContext, AssistId, Assists};
 
 // Assist: add_explicit_type
 //
@@ -21,8 +21,9 @@ use crate::{Assist, AssistCtx, AssistId};
 //     let x: i32 = 92;
 // }
 // ```
-pub(crate) fn add_explicit_type(ctx: AssistCtx) -> Option<Assist> {
+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(ctx: AssistCtx) -> Option<Assist> {
         return None;
     }
 
-    let db = ctx.db;
-    let new_type_string = ty.display_truncated(db, None).to_string();
-    ctx.add_assist(
+    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));
             }
         },
     )
@@ -208,7 +209,7 @@ struct Test<K, T = u8> {
 }
 
 fn main() {
-    let test<|>: Test<i32> = Test { t: 23, k: 33 };
+    let test<|>: Test<i32, u8> = Test { t: 23, k: 33 };
 }"#,
         );
     }
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 81deb3dfa..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
@@ -1,13 +1,10 @@
 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 crate::{utils::FamousDefs, Assist, AssistCtx, AssistId};
 use test_utils::tested_by;
 
+use crate::{utils::FamousDefs, AssistContext, AssistId, Assists};
+
 // Assist add_from_impl_for_enum
 //
 // Adds a From impl for an enum variant with one tuple field
@@ -25,7 +22,7 @@ use test_utils::tested_by;
 //     }
 // }
 // ```
-pub(crate) fn add_from_impl_for_enum(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn add_from_impl_for_enum(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let variant = ctx.find_node_at_offset::<ast::EnumVariant>()?;
     let variant_name = variant.name()?;
     let enum_name = variant.parent_enum().name()?;
@@ -42,13 +39,13 @@ pub(crate) fn add_from_impl_for_enum(ctx: AssistCtx) -> Option<Assist> {
         _ => return None,
     };
 
-    if existing_from_impl(ctx.sema, &variant).is_some() {
+    if existing_from_impl(&ctx.sema, &variant).is_some() {
         tested_by!(test_add_from_impl_already_exists);
         return None;
     }
 
     let target = variant.syntax().text_range();
-    ctx.add_assist(
+    acc.add(
         AssistId("add_from_impl_for_enum"),
         "Add From impl for this enum variant",
         target,
@@ -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 278079665..de016ae4e 100644
--- a/crates/ra_assists/src/handlers/add_function.rs
+++ b/crates/ra_assists/src/handlers/add_function.rs
@@ -1,14 +1,17 @@
+use hir::HirDisplay;
+use ra_db::FileId;
 use ra_syntax::{
-    ast::{self, AstNode},
+    ast::{
+        self,
+        edit::{AstNodeEdit, IndentLevel},
+        ArgListOwner, AstNode, ModuleItemOwner,
+    },
     SyntaxKind, SyntaxNode, TextSize,
 };
-
-use crate::{Assist, AssistCtx, AssistId};
-use ast::{edit::IndentLevel, ArgListOwner, ModuleItemOwner};
-use hir::HirDisplay;
-use ra_db::FileId;
 use rustc_hash::{FxHashMap, FxHashSet};
 
+use crate::{AssistContext, AssistId, Assists};
+
 // Assist: add_function
 //
 // Adds a stub function with a signature matching the function under the cursor.
@@ -34,7 +37,7 @@ use rustc_hash::{FxHashMap, FxHashSet};
 // }
 //
 // ```
-pub(crate) fn add_function(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn add_function(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let path_expr: ast::PathExpr = ctx.find_node_at_offset()?;
     let call = path_expr.syntax().parent().and_then(ast::CallExpr::cast)?;
     let path = path_expr.path()?;
@@ -44,22 +47,18 @@ pub(crate) fn add_function(ctx: AssistCtx) -> Option<Assist> {
         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)?;
 
     let target = call.syntax().text_range();
-    ctx.add_assist(AssistId("add_function"), "Add function", target, |edit| {
+    acc.add(AssistId("add_function"), "Add function", target, |edit| {
         let function_template = function_builder.render();
         edit.set_file(function_template.file);
         edit.set_cursor(function_template.cursor_offset);
@@ -84,25 +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: &AssistCtx,
+        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 })
     }
 
@@ -117,17 +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('{'))
             }
         };
@@ -145,6 +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))
@@ -152,18 +163,18 @@ fn fn_name(call: &ast::Path) -> Option<ast::Name> {
 
 /// Computes the type variables and arguments required for the generated function
 fn fn_args(
-    ctx: &AssistCtx,
+    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("()"),
         });
@@ -219,12 +230,21 @@ fn fn_arg_name(fn_arg: &ast::Expr) -> Option<String> {
     }
 }
 
-fn fn_arg_type(ctx: &AssistCtx, 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
@@ -253,10 +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())
@@ -600,8 +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,
@@ -610,10 +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"
@@ -621,14 +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!()
 }
 ",
         )
@@ -810,6 +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,
@@ -921,21 +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_impl.rs b/crates/ra_assists/src/handlers/add_impl.rs
index 557344ebb..df114a0d8 100644
--- a/crates/ra_assists/src/handlers/add_impl.rs
+++ b/crates/ra_assists/src/handlers/add_impl.rs
@@ -4,7 +4,7 @@ use ra_syntax::{
 };
 use stdx::{format_to, SepBy};
 
-use crate::{Assist, AssistCtx, AssistId};
+use crate::{AssistContext, AssistId, Assists};
 
 // Assist: add_impl
 //
@@ -25,43 +25,36 @@ use crate::{Assist, AssistCtx, AssistId};
 //
 // }
 // ```
-pub(crate) fn add_impl(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn add_impl(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let nominal = ctx.find_node_at_offset::<ast::NominalDef>()?;
     let name = nominal.name()?;
     let target = nominal.syntax().text_range();
-    ctx.add_assist(
-        AssistId("add_impl"),
-        format!("Implement {}", name.text().as_str()),
-        target,
-        |edit| {
-            let type_params = nominal.type_param_list();
-            let start_offset = nominal.syntax().text_range().end();
-            let mut buf = String::new();
-            buf.push_str("\n\nimpl");
-            if let Some(type_params) = &type_params {
-                format_to!(buf, "{}", type_params.syntax());
-            }
-            buf.push_str(" ");
-            buf.push_str(name.text().as_str());
-            if let Some(type_params) = type_params {
-                let lifetime_params = type_params
-                    .lifetime_params()
-                    .filter_map(|it| it.lifetime_token())
-                    .map(|it| it.text().clone());
-                let type_params = type_params
-                    .type_params()
-                    .filter_map(|it| it.name())
-                    .map(|it| it.text().clone());
+    acc.add(AssistId("add_impl"), format!("Implement {}", name.text().as_str()), target, |edit| {
+        let type_params = nominal.type_param_list();
+        let start_offset = nominal.syntax().text_range().end();
+        let mut buf = String::new();
+        buf.push_str("\n\nimpl");
+        if let Some(type_params) = &type_params {
+            format_to!(buf, "{}", type_params.syntax());
+        }
+        buf.push_str(" ");
+        buf.push_str(name.text().as_str());
+        if let Some(type_params) = type_params {
+            let lifetime_params = type_params
+                .lifetime_params()
+                .filter_map(|it| it.lifetime_token())
+                .map(|it| it.text().clone());
+            let type_params =
+                type_params.type_params().filter_map(|it| it.name()).map(|it| it.text().clone());
 
-                let generic_params = lifetime_params.chain(type_params).sep_by(", ");
-                format_to!(buf, "<{}>", generic_params)
-            }
-            buf.push_str(" {\n");
-            edit.set_cursor(start_offset + TextSize::of(&buf));
-            buf.push_str("\n}");
-            edit.insert(start_offset, buf);
-        },
-    )
+            let generic_params = lifetime_params.chain(type_params).sep_by(", ");
+            format_to!(buf, "<{}>", generic_params)
+        }
+        buf.push_str(" {\n");
+        edit.set_cursor(start_offset + TextSize::of(&buf));
+        buf.push_str("\n}");
+        edit.insert(start_offset, buf);
+    })
 }
 
 #[cfg(test)]
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 7df786590..c1ce87914 100644
--- a/crates/ra_assists/src/handlers/add_missing_impl_members.rs
+++ b/crates/ra_assists/src/handlers/add_missing_impl_members.rs
@@ -2,16 +2,17 @@ use hir::HasSource;
 use ra_syntax::{
     ast::{
         self,
-        edit::{self, IndentLevel},
+        edit::{self, AstNodeEdit, IndentLevel},
         make, AstNode, NameOwner,
     },
     SmolStr,
 };
 
 use crate::{
+    assist_context::{AssistContext, Assists},
     ast_transform::{self, AstTransform, QualifyPaths, SubstituteTypeParams},
     utils::{get_missing_assoc_items, resolve_target_trait},
-    Assist, AssistCtx, AssistId,
+    AssistId,
 };
 
 #[derive(PartialEq)]
@@ -50,8 +51,9 @@ enum AddMissingImplMembersMode {
 //
 // }
 // ```
-pub(crate) fn add_missing_impl_members(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn add_missing_impl_members(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     add_missing_impl_members_inner(
+        acc,
         ctx,
         AddMissingImplMembersMode::NoDefaultMethods,
         "add_impl_missing_members",
@@ -91,8 +93,9 @@ pub(crate) fn add_missing_impl_members(ctx: AssistCtx) -> Option<Assist> {
 //
 // }
 // ```
-pub(crate) fn add_missing_default_members(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn add_missing_default_members(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     add_missing_impl_members_inner(
+        acc,
         ctx,
         AddMissingImplMembersMode::DefaultMethodsOnly,
         "add_impl_default_members",
@@ -101,11 +104,12 @@ pub(crate) fn add_missing_default_members(ctx: AssistCtx) -> Option<Assist> {
 }
 
 fn add_missing_impl_members_inner(
-    ctx: AssistCtx,
+    acc: &mut Assists,
+    ctx: &AssistContext,
     mode: AddMissingImplMembersMode,
     assist_id: &'static str,
     label: &'static str,
-) -> Option<Assist> {
+) -> Option<()> {
     let _p = ra_prof::profile("add_missing_impl_members_inner");
     let impl_def = ctx.find_node_at_offset::<ast::ImplDef>()?;
     let impl_item_list = impl_def.item_list()?;
@@ -142,12 +146,11 @@ fn add_missing_impl_members_inner(
         return None;
     }
 
-    let sema = ctx.sema;
     let target = impl_def.syntax().text_range();
-    ctx.add_assist(AssistId(assist_id), label, target, |edit| {
+    acc.add(AssistId(assist_id), label, target, |edit| {
         let n_existing_items = impl_item_list.assoc_items().count();
-        let source_scope = sema.scope_for_def(trait_);
-        let target_scope = sema.scope(impl_item_list.syntax());
+        let source_scope = ctx.sema.scope_for_def(trait_);
+        let target_scope = ctx.sema.scope(impl_item_list.syntax());
         let ast_transform = QualifyPaths::new(&target_scope, &source_scope)
             .or(SubstituteTypeParams::for_trait_impl(&source_scope, trait_, impl_def));
         let items = missing_items
@@ -170,13 +173,11 @@ fn add_missing_impl_members_inner(
 }
 
 fn add_body(fn_def: ast::FnDef) -> ast::FnDef {
-    if fn_def.body().is_none() {
-        let body = make::block_expr(None, Some(make::expr_todo()));
-        let body = IndentLevel(1).increase_indent(body);
-        fn_def.with_body(body)
-    } else {
-        fn_def
+    if fn_def.body().is_some() {
+        return fn_def;
     }
+    let body = make::block_expr(None, Some(make::expr_todo())).indent(IndentLevel(1));
+    fn_def.with_body(body)
 }
 
 #[cfg(test)]
diff --git a/crates/ra_assists/src/handlers/add_new.rs b/crates/ra_assists/src/handlers/add_new.rs
index 1c3f8435a..fe7451dcf 100644
--- a/crates/ra_assists/src/handlers/add_new.rs
+++ b/crates/ra_assists/src/handlers/add_new.rs
@@ -7,7 +7,7 @@ use ra_syntax::{
 };
 use stdx::{format_to, SepBy};
 
-use crate::{Assist, AssistCtx, AssistId};
+use crate::{AssistContext, AssistId, Assists};
 
 // Assist: add_new
 //
@@ -29,7 +29,7 @@ use crate::{Assist, AssistCtx, AssistId};
 // }
 //
 // ```
-pub(crate) fn add_new(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn add_new(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let strukt = ctx.find_node_at_offset::<ast::StructDef>()?;
 
     // We want to only apply this to non-union structs with named fields
@@ -42,7 +42,7 @@ pub(crate) fn add_new(ctx: AssistCtx) -> Option<Assist> {
     let impl_def = find_struct_impl(&ctx, &strukt)?;
 
     let target = strukt.syntax().text_range();
-    ctx.add_assist(AssistId("add_new"), "Add default constructor", target, |edit| {
+    acc.add(AssistId("add_new"), "Add default constructor", target, |edit| {
         let mut buf = String::with_capacity(512);
 
         if impl_def.is_some() {
@@ -123,7 +123,7 @@ fn generate_impl_text(strukt: &ast::StructDef, code: &str) -> String {
 //
 // FIXME: change the new fn checking to a more semantic approach when that's more
 // viable (e.g. we process proc macros, etc)
-fn find_struct_impl(ctx: &AssistCtx, strukt: &ast::StructDef) -> Option<Option<ast::ImplDef>> {
+fn find_struct_impl(ctx: &AssistContext, strukt: &ast::StructDef) -> Option<Option<ast::ImplDef>> {
     let db = ctx.db;
     let module = strukt.syntax().ancestors().find(|node| {
         ast::Module::can_cast(node.kind()) || ast::SourceFile::can_cast(node.kind())
diff --git a/crates/ra_assists/src/handlers/apply_demorgan.rs b/crates/ra_assists/src/handlers/apply_demorgan.rs
index a5b26e5b9..0feba5e11 100644
--- a/crates/ra_assists/src/handlers/apply_demorgan.rs
+++ b/crates/ra_assists/src/handlers/apply_demorgan.rs
@@ -1,6 +1,6 @@
 use ra_syntax::ast::{self, AstNode};
 
-use crate::{utils::invert_boolean_expression, Assist, AssistCtx, AssistId};
+use crate::{utils::invert_boolean_expression, AssistContext, AssistId, Assists};
 
 // Assist: apply_demorgan
 //
@@ -21,7 +21,7 @@ use crate::{utils::invert_boolean_expression, Assist, AssistCtx, AssistId};
 //     if !(x == 4 && y) {}
 // }
 // ```
-pub(crate) fn apply_demorgan(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn apply_demorgan(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let expr = ctx.find_node_at_offset::<ast::BinExpr>()?;
     let op = expr.op_kind()?;
     let op_range = expr.op_token()?.text_range();
@@ -39,7 +39,7 @@ pub(crate) fn apply_demorgan(ctx: AssistCtx) -> Option<Assist> {
     let rhs_range = rhs.syntax().text_range();
     let not_rhs = invert_boolean_expression(rhs);
 
-    ctx.add_assist(AssistId("apply_demorgan"), "Apply De Morgan's law", op_range, |edit| {
+    acc.add(AssistId("apply_demorgan"), "Apply De Morgan's law", op_range, |edit| {
         edit.replace(op_range, opposite_op);
         edit.replace(lhs_range, format!("!({}", not_lhs.syntax().text()));
         edit.replace(rhs_range, format!("{})", not_rhs.syntax().text()));
diff --git a/crates/ra_assists/src/handlers/auto_import.rs b/crates/ra_assists/src/handlers/auto_import.rs
index 2224b9714..78d23150d 100644
--- a/crates/ra_assists/src/handlers/auto_import.rs
+++ b/crates/ra_assists/src/handlers/auto_import.rs
@@ -1,5 +1,6 @@
 use std::collections::BTreeSet;
 
+use either::Either;
 use hir::{
     AsAssocItem, AssocItemContainer, ModPath, Module, ModuleDef, PathResolution, Semantics, Trait,
     Type,
@@ -12,12 +13,7 @@ use ra_syntax::{
 };
 use rustc_hash::FxHashSet;
 
-use crate::{
-    assist_ctx::{Assist, AssistCtx},
-    utils::insert_use_statement,
-    AssistId,
-};
-use either::Either;
+use crate::{utils::insert_use_statement, AssistContext, AssistId, Assists, GroupLabel};
 
 // Assist: auto_import
 //
@@ -38,7 +34,7 @@ use either::Either;
 // }
 // # pub mod std { pub mod collections { pub struct HashMap { } } }
 // ```
-pub(crate) fn auto_import(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn auto_import(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let auto_import_assets = AutoImportAssets::new(&ctx)?;
     let proposed_imports = auto_import_assets.search_for_imports(ctx.db);
     if proposed_imports.is_empty() {
@@ -46,13 +42,19 @@ pub(crate) fn auto_import(ctx: AssistCtx) -> Option<Assist> {
     }
 
     let range = ctx.sema.original_range(&auto_import_assets.syntax_under_caret).range;
-    let mut group = ctx.add_assist_group(auto_import_assets.get_import_group_message());
+    let group = auto_import_assets.get_import_group_message();
     for import in proposed_imports {
-        group.add_assist(AssistId("auto_import"), format!("Import `{}`", &import), range, |edit| {
-            insert_use_statement(&auto_import_assets.syntax_under_caret, &import, edit);
-        });
+        acc.add_group(
+            &group,
+            AssistId("auto_import"),
+            format!("Import `{}`", &import),
+            range,
+            |builder| {
+                insert_use_statement(&auto_import_assets.syntax_under_caret, &import, ctx, builder);
+            },
+        );
     }
-    group.finish()
+    Some(())
 }
 
 #[derive(Debug)]
@@ -63,7 +65,7 @@ struct AutoImportAssets {
 }
 
 impl AutoImportAssets {
-    fn new(ctx: &AssistCtx) -> Option<Self> {
+    fn new(ctx: &AssistContext) -> Option<Self> {
         if let Some(path_under_caret) = ctx.find_node_at_offset_with_descend::<ast::Path>() {
             Self::for_regular_path(path_under_caret, &ctx)
         } else {
@@ -71,7 +73,7 @@ impl AutoImportAssets {
         }
     }
 
-    fn for_method_call(method_call: ast::MethodCallExpr, ctx: &AssistCtx) -> Option<Self> {
+    fn for_method_call(method_call: ast::MethodCallExpr, ctx: &AssistContext) -> Option<Self> {
         let syntax_under_caret = method_call.syntax().to_owned();
         let module_with_name_to_import = ctx.sema.scope(&syntax_under_caret).module()?;
         Some(Self {
@@ -81,7 +83,7 @@ impl AutoImportAssets {
         })
     }
 
-    fn for_regular_path(path_under_caret: ast::Path, ctx: &AssistCtx) -> Option<Self> {
+    fn for_regular_path(path_under_caret: ast::Path, ctx: &AssistContext) -> Option<Self> {
         let syntax_under_caret = path_under_caret.syntax().to_owned();
         if syntax_under_caret.ancestors().find_map(ast::UseItem::cast).is_some() {
             return None;
@@ -104,8 +106,8 @@ impl AutoImportAssets {
         }
     }
 
-    fn get_import_group_message(&self) -> String {
-        match &self.import_candidate {
+    fn get_import_group_message(&self) -> GroupLabel {
+        let name = match &self.import_candidate {
             ImportCandidate::UnqualifiedName(name) => format!("Import {}", name),
             ImportCandidate::QualifierStart(qualifier_start) => {
                 format!("Import {}", qualifier_start)
@@ -116,7 +118,8 @@ impl AutoImportAssets {
             ImportCandidate::TraitMethod(_, trait_method_name) => {
                 format!("Import a trait for method {}", trait_method_name)
             }
-        }
+        };
+        GroupLabel(name)
     }
 
     fn search_for_imports(&self, db: &RootDatabase) -> BTreeSet<ModPath> {
@@ -383,7 +386,7 @@ mod tests {
             }
             ",
             r"
-            use PubMod1::PubStruct;
+            use PubMod3::PubStruct;
 
             PubSt<|>ruct
 
diff --git a/crates/ra_assists/src/handlers/change_return_type_to_result.rs b/crates/ra_assists/src/handlers/change_return_type_to_result.rs
index 1e8d986cd..5c907097e 100644
--- a/crates/ra_assists/src/handlers/change_return_type_to_result.rs
+++ b/crates/ra_assists/src/handlers/change_return_type_to_result.rs
@@ -1,11 +1,11 @@
 use ra_syntax::{
-    ast, AstNode,
+    ast::{self, BlockExpr, Expr, LoopBodyOwner},
+    AstNode,
     SyntaxKind::{COMMENT, WHITESPACE},
     SyntaxNode, TextSize,
 };
 
-use crate::{Assist, AssistCtx, AssistId};
-use ast::{BlockExpr, Expr, LoopBodyOwner};
+use crate::{AssistContext, AssistId, Assists};
 
 // Assist: change_return_type_to_result
 //
@@ -18,7 +18,7 @@ use ast::{BlockExpr, Expr, LoopBodyOwner};
 // ```
 // fn foo() -> Result<i32, > { Ok(42i32) }
 // ```
-pub(crate) fn change_return_type_to_result(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn change_return_type_to_result(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let fn_def = ctx.find_node_at_offset::<ast::FnDef>();
     let fn_def = &mut fn_def?;
     let ret_type = &fn_def.ret_type()?.type_ref()?;
@@ -33,7 +33,7 @@ pub(crate) fn change_return_type_to_result(ctx: AssistCtx) -> Option<Assist> {
         return None;
     }
 
-    ctx.add_assist(
+    acc.add(
         AssistId("change_return_type_to_result"),
         "Change return type to Result",
         ret_type.syntax().text_range(),
diff --git a/crates/ra_assists/src/handlers/change_visibility.rs b/crates/ra_assists/src/handlers/change_visibility.rs
index 489db83e6..e631766ef 100644
--- a/crates/ra_assists/src/handlers/change_visibility.rs
+++ b/crates/ra_assists/src/handlers/change_visibility.rs
@@ -7,10 +7,10 @@ use ra_syntax::{
     },
     SyntaxNode, TextSize, T,
 };
-
-use crate::{Assist, AssistCtx, AssistId};
 use test_utils::tested_by;
 
+use crate::{AssistContext, AssistId, Assists};
+
 // Assist: change_visibility
 //
 // Adds or changes existing visibility specifier.
@@ -22,14 +22,14 @@ use test_utils::tested_by;
 // ```
 // pub(crate) fn frobnicate() {}
 // ```
-pub(crate) fn change_visibility(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn change_visibility(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     if let Some(vis) = ctx.find_node_at_offset::<ast::Visibility>() {
-        return change_vis(ctx, vis);
+        return change_vis(acc, vis);
     }
-    add_vis(ctx)
+    add_vis(acc, ctx)
 }
 
-fn add_vis(ctx: AssistCtx) -> Option<Assist> {
+fn add_vis(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let item_keyword = ctx.token_at_offset().find(|leaf| match leaf.kind() {
         T![const] | T![fn] | T![mod] | T![struct] | T![enum] | T![trait] => true,
         _ => false,
@@ -66,15 +66,10 @@ fn add_vis(ctx: AssistCtx) -> Option<Assist> {
         return None;
     };
 
-    ctx.add_assist(
-        AssistId("change_visibility"),
-        "Change visibility to pub(crate)",
-        target,
-        |edit| {
-            edit.insert(offset, "pub(crate) ");
-            edit.set_cursor(offset);
-        },
-    )
+    acc.add(AssistId("change_visibility"), "Change visibility to pub(crate)", target, |edit| {
+        edit.insert(offset, "pub(crate) ");
+        edit.set_cursor(offset);
+    })
 }
 
 fn vis_offset(node: &SyntaxNode) -> TextSize {
@@ -88,10 +83,10 @@ fn vis_offset(node: &SyntaxNode) -> TextSize {
         .unwrap_or_else(|| node.text_range().start())
 }
 
-fn change_vis(ctx: AssistCtx, vis: ast::Visibility) -> Option<Assist> {
+fn change_vis(acc: &mut Assists, vis: ast::Visibility) -> Option<()> {
     if vis.syntax().text() == "pub" {
         let target = vis.syntax().text_range();
-        return ctx.add_assist(
+        return acc.add(
             AssistId("change_visibility"),
             "Change Visibility to pub(crate)",
             target,
@@ -103,7 +98,7 @@ fn change_vis(ctx: AssistCtx, vis: ast::Visibility) -> Option<Assist> {
     }
     if vis.syntax().text() == "pub(crate)" {
         let target = vis.syntax().text_range();
-        return ctx.add_assist(
+        return acc.add(
             AssistId("change_visibility"),
             "Change visibility to pub",
             target,
diff --git a/crates/ra_assists/src/handlers/early_return.rs b/crates/ra_assists/src/handlers/early_return.rs
index 4bd6040b2..66b296081 100644
--- a/crates/ra_assists/src/handlers/early_return.rs
+++ b/crates/ra_assists/src/handlers/early_return.rs
@@ -2,14 +2,18 @@ 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,
 };
 
 use crate::{
-    assist_ctx::{Assist, AssistCtx},
+    assist_context::{AssistContext, Assists},
     utils::invert_boolean_expression,
     AssistId,
 };
@@ -36,7 +40,7 @@ use crate::{
 //     bar();
 // }
 // ```
-pub(crate) fn convert_to_guarded_return(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn convert_to_guarded_return(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let if_expr: ast::IfExpr = ctx.find_node_at_offset()?;
     if if_expr.else_branch().is_some() {
         return None;
@@ -93,96 +97,90 @@ pub(crate) fn convert_to_guarded_return(ctx: AssistCtx) -> Option<Assist> {
     }
 
     then_block.syntax().last_child_or_token().filter(|t| t.kind() == R_CURLY)?;
-    let cursor_position = ctx.frange.range.start();
+    let cursor_position = ctx.offset();
 
     let target = if_expr.syntax().text_range();
-    ctx.add_assist(
-        AssistId("convert_to_guarded_return"),
-        "Convert to guarded return",
-        target,
-        |edit| {
-            let if_indent_level = IndentLevel::from_node(&if_expr.syntax());
-            let new_block = match if_let_pat {
-                None => {
-                    // If.
-                    let new_expr = {
-                        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)
-                    };
-                    replace(new_expr.syntax(), &then_block, &parent_block, &if_expr)
-                }
-                Some((path, bound_ident)) => {
-                    // If-let.
-                    let match_expr = {
-                        let happy_arm = {
-                            let pat = make::tuple_struct_pat(
-                                path,
-                                once(make::bind_pat(make::name("it")).into()),
-                            );
-                            let expr = {
-                                let name_ref = make::name_ref("it");
-                                let segment = make::path_segment(name_ref);
-                                let path = make::path_unqualified(segment);
-                                make::expr_path(path)
-                            };
-                            make::match_arm(once(pat.into()), expr)
-                        };
-
-                        let sad_arm = make::match_arm(
-                            // FIXME: would be cool to use `None` or `Err(_)` if appropriate
-                            once(make::placeholder_pat().into()),
-                            early_expression,
+    acc.add(AssistId("convert_to_guarded_return"), "Convert to guarded return", target, |edit| {
+        let if_indent_level = IndentLevel::from_node(&if_expr.syntax());
+        let new_block = match if_let_pat {
+            None => {
+                // If.
+                let new_expr = {
+                    let then_branch =
+                        make::block_expr(once(make::expr_stmt(early_expression).into()), None);
+                    let cond = invert_boolean_expression(cond_expr);
+                    make::expr_if(make::condition(cond, None), then_branch).indent(if_indent_level)
+                };
+                replace(new_expr.syntax(), &then_block, &parent_block, &if_expr)
+            }
+            Some((path, bound_ident)) => {
+                // If-let.
+                let match_expr = {
+                    let happy_arm = {
+                        let pat = make::tuple_struct_pat(
+                            path,
+                            once(make::bind_pat(make::name("it")).into()),
                         );
-
-                        make::expr_match(cond_expr, make::match_arm_list(vec![happy_arm, sad_arm]))
+                        let expr = {
+                            let name_ref = make::name_ref("it");
+                            let segment = make::path_segment(name_ref);
+                            let path = make::path_unqualified(segment);
+                            make::expr_path(path)
+                        };
+                        make::match_arm(once(pat.into()), expr)
                     };
 
-                    let let_stmt = make::let_stmt(
-                        make::bind_pat(make::name(&bound_ident.syntax().to_string())).into(),
-                        Some(match_expr),
+                    let sad_arm = make::match_arm(
+                        // FIXME: would be cool to use `None` or `Err(_)` if appropriate
+                        once(make::placeholder_pat().into()),
+                        early_expression,
                     );
-                    let let_stmt = if_indent_level.increase_indent(let_stmt);
-                    replace(let_stmt.syntax(), &then_block, &parent_block, &if_expr)
-                }
-            };
-            edit.replace_ast(parent_block, ast::BlockExpr::cast(new_block).unwrap());
-            edit.set_cursor(cursor_position);
-
-            fn replace(
-                new_expr: &SyntaxNode,
-                then_block: &ast::BlockExpr,
-                parent_block: &ast::BlockExpr,
-                if_expr: &ast::IfExpr,
-            ) -> SyntaxNode {
-                let then_block_items = IndentLevel::from(1).decrease_indent(then_block.clone());
-                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) {
-                        end_of_then.prev_sibling_or_token().unwrap()
-                    } else {
-                        end_of_then
-                    };
-                let mut then_statements = new_expr.children_with_tokens().chain(
-                    then_block_items
-                        .syntax()
-                        .children_with_tokens()
-                        .skip(1)
-                        .take_while(|i| *i != end_of_then),
+
+                    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),
                 );
-                replace_children(
-                    &parent_block.syntax(),
-                    RangeInclusive::new(
-                        if_expr.clone().syntax().clone().into(),
-                        if_expr.syntax().clone().into(),
-                    ),
-                    &mut then_statements,
-                )
+                let let_stmt = let_stmt.indent(if_indent_level);
+                replace(let_stmt.syntax(), &then_block, &parent_block, &if_expr)
             }
-        },
-    )
+        };
+        edit.replace_ast(parent_block, ast::BlockExpr::cast(new_block).unwrap());
+        edit.set_cursor(cursor_position);
+
+        fn replace(
+            new_expr: &SyntaxNode,
+            then_block: &ast::BlockExpr,
+            parent_block: &ast::BlockExpr,
+            if_expr: &ast::IfExpr,
+        ) -> SyntaxNode {
+            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) {
+                    end_of_then.prev_sibling_or_token().unwrap()
+                } else {
+                    end_of_then
+                };
+            let mut then_statements = new_expr.children_with_tokens().chain(
+                then_block_items
+                    .syntax()
+                    .children_with_tokens()
+                    .skip(1)
+                    .take_while(|i| *i != end_of_then),
+            );
+            replace_children(
+                &parent_block.syntax(),
+                RangeInclusive::new(
+                    if_expr.clone().syntax().clone().into(),
+                    if_expr.syntax().clone().into(),
+                ),
+                &mut then_statements,
+            )
+        }
+    })
 }
 
 #[cfg(test)]
diff --git a/crates/ra_assists/src/handlers/fill_match_arms.rs b/crates/ra_assists/src/handlers/fill_match_arms.rs
index 7c8f8bdf2..13c1e7e80 100644
--- a/crates/ra_assists/src/handlers/fill_match_arms.rs
+++ b/crates/ra_assists/src/handlers/fill_match_arms.rs
@@ -5,7 +5,7 @@ use itertools::Itertools;
 use ra_ide_db::RootDatabase;
 use ra_syntax::ast::{self, make, AstNode, MatchArm, NameOwner, Pat};
 
-use crate::{Assist, AssistCtx, AssistId};
+use crate::{AssistContext, AssistId, Assists};
 
 // Assist: fill_match_arms
 //
@@ -31,7 +31,7 @@ use crate::{Assist, AssistCtx, AssistId};
 //     }
 // }
 // ```
-pub(crate) fn fill_match_arms(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn fill_match_arms(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let match_expr = ctx.find_node_at_offset::<ast::MatchExpr>()?;
     let match_arm_list = match_expr.match_arm_list()?;
 
@@ -93,7 +93,7 @@ pub(crate) fn fill_match_arms(ctx: AssistCtx) -> Option<Assist> {
     }
 
     let target = match_expr.syntax().text_range();
-    ctx.add_assist(AssistId("fill_match_arms"), "Fill match arms", target, |edit| {
+    acc.add(AssistId("fill_match_arms"), "Fill match arms", target, |edit| {
         let new_arm_list = match_arm_list.remove_placeholder().append_arms(missing_arms);
         edit.set_cursor(expr.syntax().text_range().start());
         edit.replace_ast(match_arm_list, new_arm_list);
diff --git a/crates/ra_assists/src/handlers/flip_binexpr.rs b/crates/ra_assists/src/handlers/flip_binexpr.rs
index cb7264d7b..692ba4895 100644
--- a/crates/ra_assists/src/handlers/flip_binexpr.rs
+++ b/crates/ra_assists/src/handlers/flip_binexpr.rs
@@ -1,6 +1,6 @@
 use ra_syntax::ast::{AstNode, BinExpr, BinOp};
 
-use crate::{Assist, AssistCtx, AssistId};
+use crate::{AssistContext, AssistId, Assists};
 
 // Assist: flip_binexpr
 //
@@ -17,7 +17,7 @@ use crate::{Assist, AssistCtx, AssistId};
 //     let _ = 2 + 90;
 // }
 // ```
-pub(crate) fn flip_binexpr(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn flip_binexpr(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let expr = ctx.find_node_at_offset::<BinExpr>()?;
     let lhs = expr.lhs()?.syntax().clone();
     let rhs = expr.rhs()?.syntax().clone();
@@ -33,7 +33,7 @@ pub(crate) fn flip_binexpr(ctx: AssistCtx) -> Option<Assist> {
         return None;
     }
 
-    ctx.add_assist(AssistId("flip_binexpr"), "Flip binary expression", op_range, |edit| {
+    acc.add(AssistId("flip_binexpr"), "Flip binary expression", op_range, |edit| {
         if let FlipAction::FlipAndReplaceOp(new_op) = action {
             edit.replace(op_range, new_op);
         }
diff --git a/crates/ra_assists/src/handlers/flip_comma.rs b/crates/ra_assists/src/handlers/flip_comma.rs
index 24982ae22..dfe2a7fed 100644
--- a/crates/ra_assists/src/handlers/flip_comma.rs
+++ b/crates/ra_assists/src/handlers/flip_comma.rs
@@ -1,6 +1,6 @@
 use ra_syntax::{algo::non_trivia_sibling, Direction, T};
 
-use crate::{Assist, AssistCtx, AssistId};
+use crate::{AssistContext, AssistId, Assists};
 
 // Assist: flip_comma
 //
@@ -17,7 +17,7 @@ use crate::{Assist, AssistCtx, AssistId};
 //     ((3, 4), (1, 2));
 // }
 // ```
-pub(crate) fn flip_comma(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn flip_comma(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let comma = ctx.find_token_at_offset(T![,])?;
     let prev = non_trivia_sibling(comma.clone().into(), Direction::Prev)?;
     let next = non_trivia_sibling(comma.clone().into(), Direction::Next)?;
@@ -28,7 +28,7 @@ pub(crate) fn flip_comma(ctx: AssistCtx) -> Option<Assist> {
         return None;
     }
 
-    ctx.add_assist(AssistId("flip_comma"), "Flip comma", comma.text_range(), |edit| {
+    acc.add(AssistId("flip_comma"), "Flip comma", comma.text_range(), |edit| {
         edit.replace(prev.text_range(), next.to_string());
         edit.replace(next.text_range(), prev.to_string());
     })
diff --git a/crates/ra_assists/src/handlers/flip_trait_bound.rs b/crates/ra_assists/src/handlers/flip_trait_bound.rs
index 6a3b2df67..8a08702ab 100644
--- a/crates/ra_assists/src/handlers/flip_trait_bound.rs
+++ b/crates/ra_assists/src/handlers/flip_trait_bound.rs
@@ -4,7 +4,7 @@ use ra_syntax::{
     Direction, T,
 };
 
-use crate::{Assist, AssistCtx, AssistId};
+use crate::{AssistContext, AssistId, Assists};
 
 // Assist: flip_trait_bound
 //
@@ -17,7 +17,7 @@ use crate::{Assist, AssistCtx, AssistId};
 // ```
 // fn foo<T: Copy + Clone>() { }
 // ```
-pub(crate) fn flip_trait_bound(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn flip_trait_bound(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     // We want to replicate the behavior of `flip_binexpr` by only suggesting
     // the assist when the cursor is on a `+`
     let plus = ctx.find_token_at_offset(T![+])?;
@@ -33,7 +33,7 @@ pub(crate) fn flip_trait_bound(ctx: AssistCtx) -> Option<Assist> {
     );
 
     let target = plus.text_range();
-    ctx.add_assist(AssistId("flip_trait_bound"), "Flip trait bounds", target, |edit| {
+    acc.add(AssistId("flip_trait_bound"), "Flip trait bounds", target, |edit| {
         edit.replace(before.text_range(), after.to_string());
         edit.replace(after.text_range(), before.to_string());
     })
diff --git a/crates/ra_assists/src/handlers/inline_local_variable.rs b/crates/ra_assists/src/handlers/inline_local_variable.rs
index e5765c845..5b26814d3 100644
--- a/crates/ra_assists/src/handlers/inline_local_variable.rs
+++ b/crates/ra_assists/src/handlers/inline_local_variable.rs
@@ -5,7 +5,10 @@ use ra_syntax::{
 };
 use test_utils::tested_by;
 
-use crate::{assist_ctx::ActionBuilder, Assist, AssistCtx, AssistId};
+use crate::{
+    assist_context::{AssistContext, Assists},
+    AssistId,
+};
 
 // Assist: inline_local_variable
 //
@@ -23,7 +26,7 @@ use crate::{assist_ctx::ActionBuilder, Assist, AssistCtx, AssistId};
 //     (1 + 2) * 4;
 // }
 // ```
-pub(crate) fn inline_local_variable(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn inline_local_variable(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let let_stmt = ctx.find_node_at_offset::<ast::LetStmt>()?;
     let bind_pat = match let_stmt.pat()? {
         ast::Pat::BindPat(pat) => pat,
@@ -33,7 +36,7 @@ pub(crate) fn inline_local_variable(ctx: AssistCtx) -> Option<Assist> {
         tested_by!(test_not_inline_mut_variable);
         return None;
     }
-    if !bind_pat.syntax().text_range().contains_inclusive(ctx.frange.range.start()) {
+    if !bind_pat.syntax().text_range().contains_inclusive(ctx.offset()) {
         tested_by!(not_applicable_outside_of_bind_pat);
         return None;
     }
@@ -107,20 +110,14 @@ pub(crate) fn inline_local_variable(ctx: AssistCtx) -> Option<Assist> {
     let init_in_paren = format!("({})", &init_str);
 
     let target = bind_pat.syntax().text_range();
-    ctx.add_assist(
-        AssistId("inline_local_variable"),
-        "Inline variable",
-        target,
-        move |edit: &mut ActionBuilder| {
-            edit.delete(delete_range);
-            for (desc, should_wrap) in refs.iter().zip(wrap_in_parens) {
-                let replacement =
-                    if should_wrap { init_in_paren.clone() } else { init_str.clone() };
-                edit.replace(desc.file_range.range, replacement)
-            }
-            edit.set_cursor(delete_range.start())
-        },
-    )
+    acc.add(AssistId("inline_local_variable"), "Inline variable", target, move |builder| {
+        builder.delete(delete_range);
+        for (desc, should_wrap) in refs.iter().zip(wrap_in_parens) {
+            let replacement = if should_wrap { init_in_paren.clone() } else { init_str.clone() };
+            builder.replace(desc.file_range.range, replacement)
+        }
+        builder.set_cursor(delete_range.start())
+    })
 }
 
 #[cfg(test)]
diff --git a/crates/ra_assists/src/handlers/introduce_variable.rs b/crates/ra_assists/src/handlers/introduce_variable.rs
index 3c340ff3b..fdf3ada0d 100644
--- a/crates/ra_assists/src/handlers/introduce_variable.rs
+++ b/crates/ra_assists/src/handlers/introduce_variable.rs
@@ -9,7 +9,7 @@ use ra_syntax::{
 use stdx::format_to;
 use test_utils::tested_by;
 
-use crate::{Assist, AssistCtx, AssistId};
+use crate::{AssistContext, AssistId, Assists};
 
 // Assist: introduce_variable
 //
@@ -27,7 +27,7 @@ use crate::{Assist, AssistCtx, AssistId};
 //     var_name * 4;
 // }
 // ```
-pub(crate) fn introduce_variable(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn introduce_variable(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     if ctx.frange.range.is_empty() {
         return None;
     }
@@ -43,7 +43,7 @@ pub(crate) fn introduce_variable(ctx: AssistCtx) -> Option<Assist> {
         return None;
     }
     let target = expr.syntax().text_range();
-    ctx.add_assist(AssistId("introduce_variable"), "Extract into variable", target, move |edit| {
+    acc.add(AssistId("introduce_variable"), "Extract into variable", target, move |edit| {
         let mut buf = String::new();
 
         let cursor_offset = if wrap_in_block {
diff --git a/crates/ra_assists/src/handlers/invert_if.rs b/crates/ra_assists/src/handlers/invert_if.rs
index b16271443..527c7caef 100644
--- a/crates/ra_assists/src/handlers/invert_if.rs
+++ b/crates/ra_assists/src/handlers/invert_if.rs
@@ -3,7 +3,11 @@ use ra_syntax::{
     T,
 };
 
-use crate::{utils::invert_boolean_expression, Assist, AssistCtx, AssistId};
+use crate::{
+    assist_context::{AssistContext, Assists},
+    utils::invert_boolean_expression,
+    AssistId,
+};
 
 // Assist: invert_if
 //
@@ -24,7 +28,7 @@ use crate::{utils::invert_boolean_expression, Assist, AssistCtx, AssistId};
 // }
 // ```
 
-pub(crate) fn invert_if(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn invert_if(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let if_keyword = ctx.find_token_at_offset(T![if])?;
     let expr = ast::IfExpr::cast(if_keyword.parent())?;
     let if_range = if_keyword.text_range();
@@ -40,21 +44,21 @@ pub(crate) fn invert_if(ctx: AssistCtx) -> Option<Assist> {
 
     let cond = expr.condition()?.expr()?;
     let then_node = expr.then_branch()?.syntax().clone();
+    let else_block = match expr.else_branch()? {
+        ast::ElseBranch::Block(it) => it,
+        ast::ElseBranch::IfExpr(_) => return None,
+    };
 
-    if let ast::ElseBranch::Block(else_block) = expr.else_branch()? {
-        let cond_range = cond.syntax().text_range();
-        let flip_cond = invert_boolean_expression(cond);
-        let else_node = else_block.syntax();
-        let else_range = else_node.text_range();
-        let then_range = then_node.text_range();
-        return ctx.add_assist(AssistId("invert_if"), "Invert if", if_range, |edit| {
-            edit.replace(cond_range, flip_cond.syntax().text());
-            edit.replace(else_range, then_node.text());
-            edit.replace(then_range, else_node.text());
-        });
-    }
-
-    None
+    let cond_range = cond.syntax().text_range();
+    let flip_cond = invert_boolean_expression(cond);
+    let else_node = else_block.syntax();
+    let else_range = else_node.text_range();
+    let then_range = then_node.text_range();
+    acc.add(AssistId("invert_if"), "Invert if", if_range, |edit| {
+        edit.replace(cond_range, flip_cond.syntax().text());
+        edit.replace(else_range, then_node.text());
+        edit.replace(then_range, else_node.text());
+    })
 }
 
 #[cfg(test)]
diff --git a/crates/ra_assists/src/handlers/merge_imports.rs b/crates/ra_assists/src/handlers/merge_imports.rs
index de74d83d8..ac3e53c27 100644
--- a/crates/ra_assists/src/handlers/merge_imports.rs
+++ b/crates/ra_assists/src/handlers/merge_imports.rs
@@ -6,7 +6,10 @@ use ra_syntax::{
     AstNode, Direction, InsertPosition, SyntaxElement, T,
 };
 
-use crate::{Assist, AssistCtx, AssistId};
+use crate::{
+    assist_context::{AssistContext, Assists},
+    AssistId,
+};
 
 // Assist: merge_imports
 //
@@ -20,10 +23,10 @@ use crate::{Assist, AssistCtx, AssistId};
 // ```
 // use std::{fmt::Formatter, io};
 // ```
-pub(crate) fn merge_imports(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn merge_imports(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let tree: ast::UseTree = ctx.find_node_at_offset()?;
     let mut rewriter = SyntaxRewriter::default();
-    let mut offset = ctx.frange.range.start();
+    let mut offset = ctx.offset();
 
     if let Some(use_item) = tree.syntax().parent().and_then(ast::UseItem::cast) {
         let (merged, to_delete) = next_prev()
@@ -53,10 +56,10 @@ pub(crate) fn merge_imports(ctx: AssistCtx) -> Option<Assist> {
     };
 
     let target = tree.syntax().text_range();
-    ctx.add_assist(AssistId("merge_imports"), "Merge imports", target, |edit| {
-        edit.rewrite(rewriter);
+    acc.add(AssistId("merge_imports"), "Merge imports", target, |builder| {
+        builder.rewrite(rewriter);
         // FIXME: we only need because our diff is imprecise
-        edit.set_cursor(offset);
+        builder.set_cursor(offset);
     })
 }
 
diff --git a/crates/ra_assists/src/handlers/merge_match_arms.rs b/crates/ra_assists/src/handlers/merge_match_arms.rs
index 7c4d9d55d..d4e38aa6a 100644
--- a/crates/ra_assists/src/handlers/merge_match_arms.rs
+++ b/crates/ra_assists/src/handlers/merge_match_arms.rs
@@ -6,7 +6,7 @@ use ra_syntax::{
     Direction, TextSize,
 };
 
-use crate::{Assist, AssistCtx, AssistId, TextRange};
+use crate::{AssistContext, AssistId, Assists, TextRange};
 
 // Assist: merge_match_arms
 //
@@ -32,7 +32,7 @@ use crate::{Assist, AssistCtx, AssistId, TextRange};
 //     }
 // }
 // ```
-pub(crate) fn merge_match_arms(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn merge_match_arms(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let current_arm = ctx.find_node_at_offset::<ast::MatchArm>()?;
     // Don't try to handle arms with guards for now - can add support for this later
     if current_arm.guard().is_some() {
@@ -45,7 +45,7 @@ pub(crate) fn merge_match_arms(ctx: AssistCtx) -> Option<Assist> {
         InExpr(TextSize),
         InPat(TextSize),
     }
-    let cursor_pos = ctx.frange.range.start();
+    let cursor_pos = ctx.offset();
     let cursor_pos = if current_expr.syntax().text_range().contains(cursor_pos) {
         CursorPos::InExpr(current_text_range.end() - cursor_pos)
     } else {
@@ -70,7 +70,7 @@ pub(crate) fn merge_match_arms(ctx: AssistCtx) -> Option<Assist> {
         return None;
     }
 
-    ctx.add_assist(AssistId("merge_match_arms"), "Merge match arms", current_text_range, |edit| {
+    acc.add(AssistId("merge_match_arms"), "Merge match arms", current_text_range, |edit| {
         let pats = if arms_to_merge.iter().any(contains_placeholder) {
             "_".into()
         } else {
diff --git a/crates/ra_assists/src/handlers/move_bounds.rs b/crates/ra_assists/src/handlers/move_bounds.rs
index 44e50cb6e..a41aacfc3 100644
--- a/crates/ra_assists/src/handlers/move_bounds.rs
+++ b/crates/ra_assists/src/handlers/move_bounds.rs
@@ -5,7 +5,7 @@ use ra_syntax::{
     T,
 };
 
-use crate::{Assist, AssistCtx, AssistId};
+use crate::{AssistContext, AssistId, Assists};
 
 // Assist: move_bounds_to_where_clause
 //
@@ -22,7 +22,7 @@ use crate::{Assist, AssistCtx, AssistId};
 //     f(x)
 // }
 // ```
-pub(crate) fn move_bounds_to_where_clause(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn move_bounds_to_where_clause(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let type_param_list = ctx.find_node_at_offset::<ast::TypeParamList>()?;
 
     let mut type_params = type_param_list.type_params();
@@ -50,36 +50,29 @@ pub(crate) fn move_bounds_to_where_clause(ctx: AssistCtx) -> Option<Assist> {
     };
 
     let target = type_param_list.syntax().text_range();
-    ctx.add_assist(
-        AssistId("move_bounds_to_where_clause"),
-        "Move to where clause",
-        target,
-        |edit| {
-            let new_params = type_param_list
-                .type_params()
-                .filter(|it| it.type_bound_list().is_some())
-                .map(|type_param| {
-                    let without_bounds = type_param.remove_bounds();
-                    (type_param, without_bounds)
-                });
-
-            let new_type_param_list = type_param_list.replace_descendants(new_params);
-            edit.replace_ast(type_param_list.clone(), new_type_param_list);
-
-            let where_clause = {
-                let predicates = type_param_list.type_params().filter_map(build_predicate);
-                make::where_clause(predicates)
-            };
-
-            let to_insert = match anchor.prev_sibling_or_token() {
-                Some(ref elem) if elem.kind() == WHITESPACE => {
-                    format!("{} ", where_clause.syntax())
-                }
-                _ => format!(" {}", where_clause.syntax()),
-            };
-            edit.insert(anchor.text_range().start(), to_insert);
-        },
-    )
+    acc.add(AssistId("move_bounds_to_where_clause"), "Move to where clause", target, |edit| {
+        let new_params = type_param_list
+            .type_params()
+            .filter(|it| it.type_bound_list().is_some())
+            .map(|type_param| {
+                let without_bounds = type_param.remove_bounds();
+                (type_param, without_bounds)
+            });
+
+        let new_type_param_list = type_param_list.replace_descendants(new_params);
+        edit.replace_ast(type_param_list.clone(), new_type_param_list);
+
+        let where_clause = {
+            let predicates = type_param_list.type_params().filter_map(build_predicate);
+            make::where_clause(predicates)
+        };
+
+        let to_insert = match anchor.prev_sibling_or_token() {
+            Some(ref elem) if elem.kind() == WHITESPACE => format!("{} ", where_clause.syntax()),
+            _ => format!(" {}", where_clause.syntax()),
+        };
+        edit.insert(anchor.text_range().start(), to_insert);
+    })
 }
 
 fn build_predicate(param: ast::TypeParam) -> Option<ast::WherePred> {
diff --git a/crates/ra_assists/src/handlers/move_guard.rs b/crates/ra_assists/src/handlers/move_guard.rs
index 29bc9a9ff..fc0335b57 100644
--- a/crates/ra_assists/src/handlers/move_guard.rs
+++ b/crates/ra_assists/src/handlers/move_guard.rs
@@ -4,7 +4,7 @@ use ra_syntax::{
     TextSize,
 };
 
-use crate::{Assist, AssistCtx, AssistId};
+use crate::{AssistContext, AssistId, Assists};
 
 // Assist: move_guard_to_arm_body
 //
@@ -31,7 +31,7 @@ use crate::{Assist, AssistCtx, AssistId};
 //     }
 // }
 // ```
-pub(crate) fn move_guard_to_arm_body(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn move_guard_to_arm_body(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let match_arm = ctx.find_node_at_offset::<MatchArm>()?;
     let guard = match_arm.guard()?;
     let space_before_guard = guard.syntax().prev_sibling_or_token();
@@ -41,7 +41,7 @@ pub(crate) fn move_guard_to_arm_body(ctx: AssistCtx) -> Option<Assist> {
     let buf = format!("if {} {{ {} }}", guard_conditions.syntax().text(), arm_expr.syntax().text());
 
     let target = guard.syntax().text_range();
-    ctx.add_assist(AssistId("move_guard_to_arm_body"), "Move guard to arm body", target, |edit| {
+    acc.add(AssistId("move_guard_to_arm_body"), "Move guard to arm body", target, |edit| {
         let offseting_amount = match space_before_guard.and_then(|it| it.into_token()) {
             Some(tok) => {
                 if ast::Whitespace::cast(tok.clone()).is_some() {
@@ -88,7 +88,7 @@ pub(crate) fn move_guard_to_arm_body(ctx: AssistCtx) -> Option<Assist> {
 //     }
 // }
 // ```
-pub(crate) fn move_arm_cond_to_match_guard(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn move_arm_cond_to_match_guard(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let match_arm: MatchArm = ctx.find_node_at_offset::<MatchArm>()?;
     let match_pat = match_arm.pat()?;
 
@@ -109,7 +109,7 @@ pub(crate) fn move_arm_cond_to_match_guard(ctx: AssistCtx) -> Option<Assist> {
     let buf = format!(" if {}", cond.syntax().text());
 
     let target = if_expr.syntax().text_range();
-    ctx.add_assist(
+    acc.add(
         AssistId("move_arm_cond_to_match_guard"),
         "Move condition to match guard",
         target,
diff --git a/crates/ra_assists/src/handlers/raw_string.rs b/crates/ra_assists/src/handlers/raw_string.rs
index 155c679b4..c20ffe0b3 100644
--- a/crates/ra_assists/src/handlers/raw_string.rs
+++ b/crates/ra_assists/src/handlers/raw_string.rs
@@ -5,7 +5,7 @@ use ra_syntax::{
     TextSize,
 };
 
-use crate::{Assist, AssistCtx, AssistId};
+use crate::{AssistContext, AssistId, Assists};
 
 // Assist: make_raw_string
 //
@@ -22,11 +22,11 @@ use crate::{Assist, AssistCtx, AssistId};
 //     r#"Hello, World!"#;
 // }
 // ```
-pub(crate) fn make_raw_string(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn make_raw_string(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let token = ctx.find_token_at_offset(STRING).and_then(ast::String::cast)?;
     let value = token.value()?;
     let target = token.syntax().text_range();
-    ctx.add_assist(AssistId("make_raw_string"), "Rewrite as raw string", target, |edit| {
+    acc.add(AssistId("make_raw_string"), "Rewrite as raw string", target, |edit| {
         let max_hash_streak = count_hashes(&value);
         let mut hashes = String::with_capacity(max_hash_streak + 1);
         for _ in 0..hashes.capacity() {
@@ -51,11 +51,11 @@ pub(crate) fn make_raw_string(ctx: AssistCtx) -> Option<Assist> {
 //     "Hello, \"World!\"";
 // }
 // ```
-pub(crate) fn make_usual_string(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn make_usual_string(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let token = ctx.find_token_at_offset(RAW_STRING).and_then(ast::RawString::cast)?;
     let value = token.value()?;
     let target = token.syntax().text_range();
-    ctx.add_assist(AssistId("make_usual_string"), "Rewrite as regular string", target, |edit| {
+    acc.add(AssistId("make_usual_string"), "Rewrite as regular string", target, |edit| {
         // parse inside string to escape `"`
         let escaped = value.escape_default().to_string();
         edit.replace(token.syntax().text_range(), format!("\"{}\"", escaped));
@@ -77,10 +77,10 @@ pub(crate) fn make_usual_string(ctx: AssistCtx) -> Option<Assist> {
 //     r##"Hello, World!"##;
 // }
 // ```
-pub(crate) fn add_hash(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn add_hash(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let token = ctx.find_token_at_offset(RAW_STRING)?;
     let target = token.text_range();
-    ctx.add_assist(AssistId("add_hash"), "Add # to raw string", target, |edit| {
+    acc.add(AssistId("add_hash"), "Add # to raw string", target, |edit| {
         edit.insert(token.text_range().start() + TextSize::of('r'), "#");
         edit.insert(token.text_range().end(), "#");
     })
@@ -101,7 +101,7 @@ pub(crate) fn add_hash(ctx: AssistCtx) -> Option<Assist> {
 //     r"Hello, World!";
 // }
 // ```
-pub(crate) fn remove_hash(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn remove_hash(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let token = ctx.find_token_at_offset(RAW_STRING)?;
     let text = token.text().as_str();
     if text.starts_with("r\"") {
@@ -109,7 +109,7 @@ pub(crate) fn remove_hash(ctx: AssistCtx) -> Option<Assist> {
         return None;
     }
     let target = token.text_range();
-    ctx.add_assist(AssistId("remove_hash"), "Remove hash from raw string", target, |edit| {
+    acc.add(AssistId("remove_hash"), "Remove hash from raw string", target, |edit| {
         let result = &text[2..text.len() - 1];
         let result = if result.starts_with('\"') {
             // FIXME: this logic is wrong, not only the last has has to handled specially
diff --git a/crates/ra_assists/src/handlers/remove_dbg.rs b/crates/ra_assists/src/handlers/remove_dbg.rs
index e6e02f2ae..8eef578cf 100644
--- a/crates/ra_assists/src/handlers/remove_dbg.rs
+++ b/crates/ra_assists/src/handlers/remove_dbg.rs
@@ -3,7 +3,7 @@ use ra_syntax::{
     TextSize, T,
 };
 
-use crate::{Assist, AssistCtx, AssistId};
+use crate::{AssistContext, AssistId, Assists};
 
 // Assist: remove_dbg
 //
@@ -20,7 +20,7 @@ use crate::{Assist, AssistCtx, AssistId};
 //     92;
 // }
 // ```
-pub(crate) fn remove_dbg(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn remove_dbg(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let macro_call = ctx.find_node_at_offset::<ast::MacroCall>()?;
 
     if !is_valid_macrocall(&macro_call, "dbg")? {
@@ -58,7 +58,7 @@ pub(crate) fn remove_dbg(ctx: AssistCtx) -> Option<Assist> {
     };
 
     let target = macro_call.syntax().text_range();
-    ctx.add_assist(AssistId("remove_dbg"), "Remove dbg!()", target, |edit| {
+    acc.add(AssistId("remove_dbg"), "Remove dbg!()", target, |edit| {
         edit.replace(macro_range, macro_content);
         edit.set_cursor(cursor_pos);
     })
diff --git a/crates/ra_assists/src/handlers/remove_mut.rs b/crates/ra_assists/src/handlers/remove_mut.rs
index 9f72f879d..dce546db7 100644
--- a/crates/ra_assists/src/handlers/remove_mut.rs
+++ b/crates/ra_assists/src/handlers/remove_mut.rs
@@ -1,6 +1,6 @@
 use ra_syntax::{SyntaxKind, TextRange, T};
 
-use crate::{Assist, AssistCtx, AssistId};
+use crate::{AssistContext, AssistId, Assists};
 
 // Assist: remove_mut
 //
@@ -17,7 +17,7 @@ use crate::{Assist, AssistCtx, AssistId};
 //     fn feed(&self, amount: u32) {}
 // }
 // ```
-pub(crate) fn remove_mut(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn remove_mut(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let mut_token = ctx.find_token_at_offset(T![mut])?;
     let delete_from = mut_token.text_range().start();
     let delete_to = match mut_token.next_token() {
@@ -26,7 +26,7 @@ pub(crate) fn remove_mut(ctx: AssistCtx) -> Option<Assist> {
     };
 
     let target = mut_token.text_range();
-    ctx.add_assist(AssistId("remove_mut"), "Remove `mut` keyword", target, |edit| {
+    acc.add(AssistId("remove_mut"), "Remove `mut` keyword", target, |edit| {
         edit.set_cursor(delete_from);
         edit.delete(TextRange::new(delete_from, delete_to));
     })
diff --git a/crates/ra_assists/src/handlers/reorder_fields.rs b/crates/ra_assists/src/handlers/reorder_fields.rs
index 0b930dea2..757f6406e 100644
--- a/crates/ra_assists/src/handlers/reorder_fields.rs
+++ b/crates/ra_assists/src/handlers/reorder_fields.rs
@@ -3,18 +3,9 @@ use std::collections::HashMap;
 use hir::{Adt, ModuleDef, PathResolution, Semantics, Struct};
 use itertools::Itertools;
 use ra_ide_db::RootDatabase;
-use ra_syntax::{
-    algo,
-    ast::{self, Path, RecordLit, RecordPat},
-    match_ast, AstNode, SyntaxKind,
-    SyntaxKind::*,
-    SyntaxNode,
-};
-
-use crate::{
-    assist_ctx::{Assist, AssistCtx},
-    AssistId,
-};
+use ra_syntax::{algo, ast, match_ast, AstNode, SyntaxKind, SyntaxKind::*, SyntaxNode};
+
+use crate::{AssistContext, AssistId, Assists};
 
 // Assist: reorder_fields
 //
@@ -31,13 +22,13 @@ use crate::{
 // const test: Foo = Foo {foo: 1, bar: 0}
 // ```
 //
-pub(crate) fn reorder_fields(ctx: AssistCtx) -> Option<Assist> {
-    reorder::<RecordLit>(ctx.clone()).or_else(|| reorder::<RecordPat>(ctx))
+pub(crate) fn reorder_fields(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    reorder::<ast::RecordLit>(acc, ctx.clone()).or_else(|| reorder::<ast::RecordPat>(acc, ctx))
 }
 
-fn reorder<R: AstNode>(ctx: AssistCtx) -> Option<Assist> {
+fn reorder<R: AstNode>(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let record = ctx.find_node_at_offset::<R>()?;
-    let path = record.syntax().children().find_map(Path::cast)?;
+    let path = record.syntax().children().find_map(ast::Path::cast)?;
 
     let ranks = compute_fields_ranks(&path, &ctx)?;
 
@@ -51,7 +42,7 @@ fn reorder<R: AstNode>(ctx: AssistCtx) -> Option<Assist> {
     }
 
     let target = record.syntax().text_range();
-    ctx.add_assist(AssistId("reorder_fields"), "Reorder record fields", target, |edit| {
+    acc.add(AssistId("reorder_fields"), "Reorder record fields", target, |edit| {
         for (old, new) in fields.iter().zip(&sorted_fields) {
             algo::diff(old, new).into_text_edit(edit.text_edit_builder());
         }
@@ -96,9 +87,9 @@ fn struct_definition(path: &ast::Path, sema: &Semantics<RootDatabase>) -> Option
     }
 }
 
-fn compute_fields_ranks(path: &Path, ctx: &AssistCtx) -> Option<HashMap<String, usize>> {
+fn compute_fields_ranks(path: &ast::Path, ctx: &AssistContext) -> Option<HashMap<String, usize>> {
     Some(
-        struct_definition(path, ctx.sema)?
+        struct_definition(path, &ctx.sema)?
             .fields(ctx.db)
             .iter()
             .enumerate()
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 2eb8348f8..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
@@ -1,10 +1,14 @@
 use ra_fmt::unwrap_trivial_block;
 use ra_syntax::{
-    ast::{self, edit::IndentLevel, make},
+    ast::{
+        self,
+        edit::{AstNodeEdit, IndentLevel},
+        make,
+    },
     AstNode,
 };
 
-use crate::{utils::TryEnum, Assist, AssistCtx, AssistId};
+use crate::{utils::TryEnum, AssistContext, AssistId, Assists};
 
 // Assist: replace_if_let_with_match
 //
@@ -32,7 +36,7 @@ use crate::{utils::TryEnum, Assist, AssistCtx, AssistId};
 //     }
 // }
 // ```
-pub(crate) fn replace_if_let_with_match(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn replace_if_let_with_match(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let if_expr: ast::IfExpr = ctx.find_node_at_offset()?;
     let cond = if_expr.condition()?;
     let pat = cond.pat()?;
@@ -43,36 +47,30 @@ pub(crate) fn replace_if_let_with_match(ctx: AssistCtx) -> Option<Assist> {
         ast::ElseBranch::IfExpr(_) => return None,
     };
 
-    let sema = ctx.sema;
     let target = if_expr.syntax().text_range();
-    ctx.add_assist(
-        AssistId("replace_if_let_with_match"),
-        "Replace with match",
-        target,
-        move |edit| {
-            let match_expr = {
-                let then_arm = {
-                    let then_expr = unwrap_trivial_block(then_block);
-                    make::match_arm(vec![pat.clone()], then_expr)
-                };
-                let else_arm = {
-                    let pattern = sema
-                        .type_of_pat(&pat)
-                        .and_then(|ty| TryEnum::from_ty(sema, &ty))
-                        .map(|it| it.sad_pattern())
-                        .unwrap_or_else(|| make::placeholder_pat().into());
-                    let else_expr = unwrap_trivial_block(else_block);
-                    make::match_arm(vec![pattern], else_expr)
-                };
-                make::expr_match(expr, make::match_arm_list(vec![then_arm, else_arm]))
+    acc.add(AssistId("replace_if_let_with_match"), "Replace with match", target, move |edit| {
+        let match_expr = {
+            let then_arm = {
+                let then_expr = unwrap_trivial_block(then_block);
+                make::match_arm(vec![pat.clone()], then_expr)
             };
+            let else_arm = {
+                let pattern = ctx
+                    .sema
+                    .type_of_pat(&pat)
+                    .and_then(|ty| TryEnum::from_ty(&ctx.sema, &ty))
+                    .map(|it| it.sad_pattern())
+                    .unwrap_or_else(|| make::placeholder_pat().into());
+                let else_expr = unwrap_trivial_block(else_block);
+                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);
-        },
-    )
+        edit.set_cursor(if_expr.syntax().text_range().start());
+        edit.replace_ast::<ast::Expr>(if_expr.into(), match_expr);
+    })
 }
 
 #[cfg(test)]
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 a5509a567..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
@@ -9,11 +9,7 @@ use ra_syntax::{
     AstNode, T,
 };
 
-use crate::{
-    assist_ctx::{Assist, AssistCtx},
-    utils::TryEnum,
-    AssistId,
-};
+use crate::{utils::TryEnum, AssistContext, AssistId, Assists};
 
 // Assist: replace_let_with_if_let
 //
@@ -39,16 +35,16 @@ use crate::{
 //
 // fn compute() -> Option<i32> { None }
 // ```
-pub(crate) fn replace_let_with_if_let(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn replace_let_with_if_let(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let let_kw = ctx.find_token_at_offset(T![let])?;
     let let_stmt = let_kw.ancestors().find_map(ast::LetStmt::cast)?;
     let init = let_stmt.initializer()?;
     let original_pat = let_stmt.pat()?;
     let ty = ctx.sema.type_of_expr(&init)?;
-    let happy_variant = TryEnum::from_ty(ctx.sema, &ty).map(|it| it.happy_case());
+    let happy_variant = TryEnum::from_ty(&ctx.sema, &ty).map(|it| it.happy_case());
 
     let target = let_kw.text_range();
-    ctx.add_assist(AssistId("replace_let_with_if_let"), "Replace with if-let", target, |edit| {
+    acc.add(AssistId("replace_let_with_if_let"), "Replace with if-let", target, |edit| {
         let with_placeholder: ast::Pat = match happy_variant {
             None => make::placeholder_pat().into(),
             Some(var_name) => make::tuple_struct_pat(
@@ -57,8 +53,7 @@ pub(crate) fn replace_let_with_if_let(ctx: AssistCtx) -> Option<Assist> {
             )
             .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_qualified_name_with_use.rs b/crates/ra_assists/src/handlers/replace_qualified_name_with_use.rs
index fd41da64b..1a81d8a0e 100644
--- a/crates/ra_assists/src/handlers/replace_qualified_name_with_use.rs
+++ b/crates/ra_assists/src/handlers/replace_qualified_name_with_use.rs
@@ -1,11 +1,7 @@
 use hir;
 use ra_syntax::{ast, AstNode, SmolStr, TextRange};
 
-use crate::{
-    assist_ctx::{Assist, AssistCtx},
-    utils::insert_use_statement,
-    AssistId,
-};
+use crate::{utils::insert_use_statement, AssistContext, AssistId, Assists};
 
 // Assist: replace_qualified_name_with_use
 //
@@ -20,7 +16,10 @@ use crate::{
 //
 // fn process(map: HashMap<String, String>) {}
 // ```
-pub(crate) fn replace_qualified_name_with_use(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn replace_qualified_name_with_use(
+    acc: &mut Assists,
+    ctx: &AssistContext,
+) -> Option<()> {
     let path: ast::Path = ctx.find_node_at_offset()?;
     // We don't want to mess with use statements
     if path.syntax().ancestors().find_map(ast::UseItem::cast).is_some() {
@@ -34,18 +33,18 @@ pub(crate) fn replace_qualified_name_with_use(ctx: AssistCtx) -> Option<Assist>
     }
 
     let target = path.syntax().text_range();
-    ctx.add_assist(
+    acc.add(
         AssistId("replace_qualified_name_with_use"),
         "Replace qualified path with use",
         target,
-        |edit| {
+        |builder| {
             let path_to_import = hir_path.mod_path().clone();
-            insert_use_statement(path.syntax(), &path_to_import, edit);
+            insert_use_statement(path.syntax(), &path_to_import, ctx, builder);
 
             if let Some(last) = path.segment() {
                 // Here we are assuming the assist will provide a correct use statement
                 // so we can delete the path qualifier
-                edit.delete(TextRange::new(
+                builder.delete(TextRange::new(
                     path.syntax().text_range().start(),
                     last.syntax().text_range().start(),
                 ));
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 c6b73da67..c4b56f6e9 100644
--- a/crates/ra_assists/src/handlers/replace_unwrap_with_match.rs
+++ b/crates/ra_assists/src/handlers/replace_unwrap_with_match.rs
@@ -1,11 +1,15 @@
 use std::iter;
 
 use ra_syntax::{
-    ast::{self, edit::IndentLevel, make},
+    ast::{
+        self,
+        edit::{AstNodeEdit, IndentLevel},
+        make,
+    },
     AstNode,
 };
 
-use crate::{utils::TryEnum, Assist, AssistCtx, AssistId};
+use crate::{utils::TryEnum, AssistContext, AssistId, Assists};
 
 // Assist: replace_unwrap_with_match
 //
@@ -29,7 +33,7 @@ use crate::{utils::TryEnum, Assist, AssistCtx, AssistId};
 //     };
 // }
 // ```
-pub(crate) fn replace_unwrap_with_match(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn replace_unwrap_with_match(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let method_call: ast::MethodCallExpr = ctx.find_node_at_offset()?;
     let name = method_call.name_ref()?;
     if name.text() != "unwrap" {
@@ -37,33 +41,26 @@ pub(crate) fn replace_unwrap_with_match(ctx: AssistCtx) -> Option<Assist> {
     }
     let caller = method_call.expr()?;
     let ty = ctx.sema.type_of_expr(&caller)?;
-    let happy_variant = TryEnum::from_ty(ctx.sema, &ty)?.happy_case();
+    let happy_variant = TryEnum::from_ty(&ctx.sema, &ty)?.happy_case();
     let target = method_call.syntax().text_range();
-    ctx.add_assist(
-        AssistId("replace_unwrap_with_match"),
-        "Replace unwrap with match",
-        target,
-        |edit| {
-            let ok_path = make::path_unqualified(make::path_segment(make::name_ref(happy_variant)));
-            let it = make::bind_pat(make::name("a")).into();
-            let ok_tuple = make::tuple_struct_pat(ok_path, iter::once(it)).into();
+    acc.add(AssistId("replace_unwrap_with_match"), "Replace unwrap with match", target, |edit| {
+        let ok_path = make::path_unqualified(make::path_segment(make::name_ref(happy_variant)));
+        let it = make::bind_pat(make::name("a")).into();
+        let ok_tuple = make::tuple_struct_pat(ok_path, iter::once(it)).into();
 
-            let bind_path = make::path_unqualified(make::path_segment(make::name_ref("a")));
-            let ok_arm = make::match_arm(iter::once(ok_tuple), make::expr_path(bind_path));
+        let bind_path = make::path_unqualified(make::path_segment(make::name_ref("a")));
+        let ok_arm = make::match_arm(iter::once(ok_tuple), make::expr_path(bind_path));
 
-            let unreachable_call = make::unreachable_macro_call().into();
-            let err_arm =
-                make::match_arm(iter::once(make::placeholder_pat().into()), unreachable_call);
+        let unreachable_call = make::unreachable_macro_call().into();
+        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_arm_list = make::match_arm_list(vec![ok_arm, err_arm]);
+        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);
-        },
-    )
+        edit.set_cursor(caller.syntax().text_range().start());
+        edit.replace_ast::<ast::Expr>(method_call.into(), match_expr);
+    })
 }
 
 #[cfg(test)]
diff --git a/crates/ra_assists/src/handlers/split_import.rs b/crates/ra_assists/src/handlers/split_import.rs
index d49563974..b2757e50c 100644
--- a/crates/ra_assists/src/handlers/split_import.rs
+++ b/crates/ra_assists/src/handlers/split_import.rs
@@ -2,7 +2,7 @@ use std::iter::successors;
 
 use ra_syntax::{ast, AstNode, T};
 
-use crate::{Assist, AssistCtx, AssistId};
+use crate::{AssistContext, AssistId, Assists};
 
 // Assist: split_import
 //
@@ -15,7 +15,7 @@ use crate::{Assist, AssistCtx, AssistId};
 // ```
 // use std::{collections::HashMap};
 // ```
-pub(crate) fn split_import(ctx: AssistCtx) -> Option<Assist> {
+pub(crate) fn split_import(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let colon_colon = ctx.find_token_at_offset(T![::])?;
     let path = ast::Path::cast(colon_colon.parent())?.qualifier()?;
     let top_path = successors(Some(path.clone()), |it| it.parent_path()).last()?;
@@ -26,10 +26,10 @@ pub(crate) fn split_import(ctx: AssistCtx) -> Option<Assist> {
     if new_tree == use_tree {
         return None;
     }
-    let cursor = ctx.frange.range.start();
+    let cursor = ctx.offset();
 
     let target = colon_colon.text_range();
-    ctx.add_assist(AssistId("split_import"), "Split import", target, |edit| {
+    acc.add(AssistId("split_import"), "Split import", target, |edit| {
         edit.replace_ast(use_tree, new_tree);
         edit.set_cursor(cursor);
     })
diff --git a/crates/ra_assists/src/handlers/unwrap_block.rs b/crates/ra_assists/src/handlers/unwrap_block.rs
index 6df927abb..eba0631a4 100644
--- a/crates/ra_assists/src/handlers/unwrap_block.rs
+++ b/crates/ra_assists/src/handlers/unwrap_block.rs
@@ -1,4 +1,4 @@
-use crate::{Assist, AssistCtx, AssistId};
+use crate::{AssistContext, AssistId, Assists};
 
 use ast::LoopBodyOwner;
 use ra_fmt::unwrap_trivial_block;
@@ -21,7 +21,7 @@ use ra_syntax::{ast, match_ast, AstNode, TextRange, T};
 //     println!("foo");
 // }
 // ```
-pub(crate) fn unwrap_block(ctx: AssistCtx) -> Option<Assist> {
+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()?;
@@ -58,7 +58,7 @@ pub(crate) fn unwrap_block(ctx: AssistCtx) -> Option<Assist> {
     };
 
     let target = expr_to_unwrap.syntax().text_range();
-    ctx.add_assist(AssistId("unwrap_block"), "Unwrap block", target, |edit| {
+    acc.add(AssistId("unwrap_block"), "Unwrap block", target, |edit| {
         edit.set_cursor(expr.syntax().text_range().start());
 
         let pat_start: &[_] = &[' ', '{', '\n'];
diff --git a/crates/ra_assists/src/lib.rs b/crates/ra_assists/src/lib.rs
index 0473fd8c2..b6dc7cb1b 100644
--- a/crates/ra_assists/src/lib.rs
+++ b/crates/ra_assists/src/lib.rs
@@ -10,7 +10,7 @@ macro_rules! eprintln {
     ($($tt:tt)*) => { stdx::eprintln!($($tt)*) };
 }
 
-mod assist_ctx;
+mod assist_context;
 mod marks;
 #[cfg(test)]
 mod tests;
@@ -22,15 +22,18 @@ use ra_db::FileRange;
 use ra_ide_db::{source_change::SourceChange, RootDatabase};
 use ra_syntax::TextRange;
 
-pub(crate) use crate::assist_ctx::{Assist, AssistCtx};
+pub(crate) use crate::assist_context::{AssistContext, Assists};
 
 /// Unique identifier of the assist, should not be shown to the user
 /// directly.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub struct AssistId(pub &'static str);
 
+#[derive(Clone, Debug)]
+pub struct GroupLabel(pub String);
+
 #[derive(Debug, Clone)]
-pub struct AssistLabel {
+pub struct Assist {
     pub id: AssistId,
     /// Short description of the assist, as shown in the UI.
     pub label: String,
@@ -40,74 +43,69 @@ pub struct AssistLabel {
     pub target: TextRange,
 }
 
-#[derive(Clone, Debug)]
-pub struct GroupLabel(pub String);
+#[derive(Debug, Clone)]
+pub struct ResolvedAssist {
+    pub assist: Assist,
+    pub source_change: SourceChange,
+}
+
+impl Assist {
+    /// Return all the assists applicable at the given position.
+    ///
+    /// Assists are returned in the "unresolved" state, that is only labels are
+    /// returned, without actual edits.
+    pub fn unresolved(db: &RootDatabase, range: FileRange) -> Vec<Assist> {
+        let sema = Semantics::new(db);
+        let ctx = AssistContext::new(sema, range);
+        let mut acc = Assists::new_unresolved(&ctx);
+        handlers::all().iter().for_each(|handler| {
+            handler(&mut acc, &ctx);
+        });
+        acc.finish_unresolved()
+    }
+
+    /// Return all the assists applicable at the given position.
+    ///
+    /// Assists are returned in the "resolved" state, that is with edit fully
+    /// computed.
+    pub fn resolved(db: &RootDatabase, range: FileRange) -> Vec<ResolvedAssist> {
+        let sema = Semantics::new(db);
+        let ctx = AssistContext::new(sema, range);
+        let mut acc = Assists::new_resolved(&ctx);
+        handlers::all().iter().for_each(|handler| {
+            handler(&mut acc, &ctx);
+        });
+        acc.finish_resolved()
+    }
 
-impl AssistLabel {
     pub(crate) fn new(
         id: AssistId,
         label: String,
         group: Option<GroupLabel>,
         target: TextRange,
-    ) -> AssistLabel {
+    ) -> Assist {
         // FIXME: make fields private, so that this invariant can't be broken
         assert!(label.starts_with(|c: char| c.is_uppercase()));
-        AssistLabel { id, label, group, target }
+        Assist { id, label, group, target }
     }
 }
 
-#[derive(Debug, Clone)]
-pub struct ResolvedAssist {
-    pub label: AssistLabel,
-    pub source_change: SourceChange,
-}
-
-/// Return all the assists applicable at the given position.
-///
-/// Assists are returned in the "unresolved" state, that is only labels are
-/// returned, without actual edits.
-pub fn unresolved_assists(db: &RootDatabase, range: FileRange) -> Vec<AssistLabel> {
-    let sema = Semantics::new(db);
-    let ctx = AssistCtx::new(&sema, range, false);
-    handlers::all()
-        .iter()
-        .filter_map(|f| f(ctx.clone()))
-        .flat_map(|it| it.0)
-        .map(|a| a.label)
-        .collect()
-}
-
-/// Return all the assists applicable at the given position.
-///
-/// Assists are returned in the "resolved" state, that is with edit fully
-/// computed.
-pub fn resolved_assists(db: &RootDatabase, range: FileRange) -> Vec<ResolvedAssist> {
-    let sema = Semantics::new(db);
-    let ctx = AssistCtx::new(&sema, range, true);
-    let mut a = handlers::all()
-        .iter()
-        .filter_map(|f| f(ctx.clone()))
-        .flat_map(|it| it.0)
-        .map(|it| it.into_resolved().unwrap())
-        .collect::<Vec<_>>();
-    a.sort_by_key(|it| it.label.target.len());
-    a
-}
-
 mod handlers {
-    use crate::{Assist, AssistCtx};
+    use crate::{AssistContext, Assists};
 
-    pub(crate) type Handler = fn(AssistCtx) -> Option<Assist>;
+    pub(crate) type Handler = fn(&mut Assists, &AssistContext) -> Option<()>;
 
     mod add_custom_impl;
     mod add_derive;
     mod add_explicit_type;
+    mod add_from_impl_for_enum;
     mod add_function;
     mod add_impl;
     mod add_missing_impl_members;
     mod add_new;
     mod apply_demorgan;
     mod auto_import;
+    mod change_return_type_to_result;
     mod change_visibility;
     mod early_return;
     mod fill_match_arms;
@@ -124,14 +122,12 @@ mod handlers {
     mod raw_string;
     mod remove_dbg;
     mod remove_mut;
+    mod reorder_fields;
     mod replace_if_let_with_match;
     mod replace_let_with_if_let;
     mod replace_qualified_name_with_use;
     mod replace_unwrap_with_match;
     mod split_import;
-    mod change_return_type_to_result;
-    mod add_from_impl_for_enum;
-    mod reorder_fields;
     mod unwrap_block;
 
     pub(crate) fn all() -> &'static [Handler] {
diff --git a/crates/ra_assists/src/tests.rs b/crates/ra_assists/src/tests.rs
index 17e3ece9f..a3eacb8f1 100644
--- a/crates/ra_assists/src/tests.rs
+++ b/crates/ra_assists/src/tests.rs
@@ -11,7 +11,7 @@ use test_utils::{
     RangeOrOffset,
 };
 
-use crate::{handlers::Handler, resolved_assists, AssistCtx};
+use crate::{handlers::Handler, Assist, AssistContext, Assists};
 
 pub(crate) fn with_single_file(text: &str) -> (RootDatabase, FileId) {
     let (mut db, file_id) = RootDatabase::with_single_file(text);
@@ -41,16 +41,16 @@ fn check_doc_test(assist_id: &str, before: &str, after: &str) {
     let (db, file_id) = crate::tests::with_single_file(&before);
     let frange = FileRange { file_id, range: selection.into() };
 
-    let mut assist = resolved_assists(&db, frange)
+    let mut assist = Assist::resolved(&db, frange)
         .into_iter()
-        .find(|assist| assist.label.id.0 == assist_id)
+        .find(|assist| assist.assist.id.0 == assist_id)
         .unwrap_or_else(|| {
             panic!(
                 "\n\nAssist is not applicable: {}\nAvailable assists: {}",
                 assist_id,
-                resolved_assists(&db, frange)
+                Assist::resolved(&db, frange)
                     .into_iter()
-                    .map(|assist| assist.label.id.0)
+                    .map(|assist| assist.assist.id.0)
                     .collect::<Vec<_>>()
                     .join(", ")
             )
@@ -71,7 +71,7 @@ enum ExpectedResult<'a> {
     Target(&'a str),
 }
 
-fn check(assist: Handler, before: &str, expected: ExpectedResult) {
+fn check(handler: Handler, before: &str, expected: ExpectedResult) {
     let (text_without_caret, file_with_caret_id, range_or_offset, db) = if before.contains("//-") {
         let (mut db, position) = RootDatabase::with_position(before);
         db.set_local_roots(Arc::new(vec![db.file_source_root(position.file_id)]));
@@ -90,17 +90,20 @@ fn check(assist: Handler, before: &str, expected: ExpectedResult) {
     let frange = FileRange { file_id: file_with_caret_id, range: range_or_offset.into() };
 
     let sema = Semantics::new(&db);
-    let assist_ctx = AssistCtx::new(&sema, frange, true);
-
-    match (assist(assist_ctx), expected) {
+    let ctx = AssistContext::new(sema, frange);
+    let mut acc = Assists::new_resolved(&ctx);
+    handler(&mut acc, &ctx);
+    let mut res = acc.finish_resolved();
+    let assist = res.pop();
+    match (assist, expected) {
         (Some(assist), ExpectedResult::After(after)) => {
-            let mut action = assist.0[0].source_change.clone().unwrap();
-            let change = action.source_file_edits.pop().unwrap();
+            let mut source_change = assist.source_change;
+            let change = source_change.source_file_edits.pop().unwrap();
 
             let mut actual = db.file_text(change.file_id).as_ref().to_owned();
             change.edit.apply(&mut actual);
 
-            match action.cursor_position {
+            match source_change.cursor_position {
                 None => {
                     if let RangeOrOffset::Offset(before_cursor_pos) = range_or_offset {
                         let off = change
@@ -116,7 +119,7 @@ fn check(assist: Handler, before: &str, expected: ExpectedResult) {
             assert_eq_text!(after, &actual);
         }
         (Some(assist), ExpectedResult::Target(target)) => {
-            let range = assist.0[0].label.target;
+            let range = assist.assist.target;
             assert_eq_text!(&text_without_caret[range], target);
         }
         (Some(_), ExpectedResult::NotApplicable) => panic!("assist should not be applicable!"),
@@ -133,14 +136,14 @@ fn assist_order_field_struct() {
     let (before_cursor_pos, before) = extract_offset(before);
     let (db, file_id) = with_single_file(&before);
     let frange = FileRange { file_id, range: TextRange::empty(before_cursor_pos) };
-    let assists = resolved_assists(&db, frange);
+    let assists = Assist::resolved(&db, frange);
     let mut assists = assists.iter();
 
     assert_eq!(
-        assists.next().expect("expected assist").label.label,
+        assists.next().expect("expected assist").assist.label,
         "Change visibility to pub(crate)"
     );
-    assert_eq!(assists.next().expect("expected assist").label.label, "Add `#[derive]`");
+    assert_eq!(assists.next().expect("expected assist").assist.label, "Add `#[derive]`");
 }
 
 #[test]
@@ -156,9 +159,9 @@ fn assist_order_if_expr() {
     let (range, before) = extract_range(before);
     let (db, file_id) = with_single_file(&before);
     let frange = FileRange { file_id, range };
-    let assists = resolved_assists(&db, frange);
+    let assists = Assist::resolved(&db, frange);
     let mut assists = assists.iter();
 
-    assert_eq!(assists.next().expect("expected assist").label.label, "Extract into variable");
-    assert_eq!(assists.next().expect("expected assist").label.label, "Replace with match");
+    assert_eq!(assists.next().expect("expected assist").assist.label, "Extract into variable");
+    assert_eq!(assists.next().expect("expected assist").assist.label, "Replace with match");
 }
diff --git a/crates/ra_assists/src/utils/insert_use.rs b/crates/ra_assists/src/utils/insert_use.rs
index c1f447efe..1214e3cd4 100644
--- a/crates/ra_assists/src/utils/insert_use.rs
+++ b/crates/ra_assists/src/utils/insert_use.rs
@@ -2,7 +2,6 @@
 // FIXME: rewrite according to the plan, outlined in
 // https://github.com/rust-analyzer/rust-analyzer/issues/3301#issuecomment-592931553
 
-use crate::assist_ctx::ActionBuilder;
 use hir::{self, ModPath};
 use ra_syntax::{
     ast::{self, NameOwner},
@@ -12,6 +11,8 @@ use ra_syntax::{
 };
 use ra_text_edit::TextEditBuilder;
 
+use crate::assist_context::{AssistBuilder, AssistContext};
+
 /// Creates and inserts a use statement for the given path to import.
 /// The use statement is inserted in the scope most appropriate to the
 /// the cursor position given, additionally merged with the existing use imports.
@@ -19,10 +20,11 @@ pub(crate) fn insert_use_statement(
     // Ideally the position of the cursor, used to
     position: &SyntaxNode,
     path_to_import: &ModPath,
-    edit: &mut ActionBuilder,
+    ctx: &AssistContext,
+    builder: &mut AssistBuilder,
 ) {
     let target = path_to_import.to_string().split("::").map(SmolStr::new).collect::<Vec<_>>();
-    let container = edit.ctx().sema.ancestors_with_macros(position.clone()).find_map(|n| {
+    let container = ctx.sema.ancestors_with_macros(position.clone()).find_map(|n| {
         if let Some(module) = ast::Module::cast(n.clone()) {
             return module.item_list().map(|it| it.syntax().clone());
         }
@@ -31,7 +33,7 @@ pub(crate) fn insert_use_statement(
 
     if let Some(container) = container {
         let action = best_action_for_target(container, position.clone(), &target);
-        make_assist(&action, &target, edit.text_edit_builder());
+        make_assist(&action, &target, builder.text_edit_builder());
     }
 }
 
diff --git a/crates/ra_cfg/src/lib.rs b/crates/ra_cfg/src/lib.rs
index 51d953f6e..57feabcb2 100644
--- a/crates/ra_cfg/src/lib.rs
+++ b/crates/ra_cfg/src/lib.rs
@@ -2,8 +2,6 @@
 
 mod cfg_expr;
 
-use std::iter::IntoIterator;
-
 use ra_syntax::SmolStr;
 use rustc_hash::FxHashSet;
 
@@ -48,9 +46,4 @@ impl CfgOptions {
     pub fn insert_key_value(&mut self, key: SmolStr, value: SmolStr) {
         self.key_values.insert((key, value));
     }
-
-    /// Shortcut to set features
-    pub fn insert_features(&mut self, iter: impl IntoIterator<Item = SmolStr>) {
-        iter.into_iter().for_each(|feat| self.insert_key_value("feature".into(), feat));
-    }
 }
diff --git a/crates/ra_flycheck/Cargo.toml b/crates/ra_flycheck/Cargo.toml
index 3d5093264..03e557148 100644
--- a/crates/ra_flycheck/Cargo.toml
+++ b/crates/ra_flycheck/Cargo.toml
@@ -14,6 +14,7 @@ log = "0.4.8"
 cargo_metadata = "0.9.1"
 serde_json = "1.0.48"
 jod-thread = "0.1.1"
+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 f27252949..68dcee285 100644
--- a/crates/ra_flycheck/src/lib.rs
+++ b/crates/ra_flycheck/src/lib.rs
@@ -4,7 +4,6 @@
 mod conv;
 
 use std::{
-    env,
     io::{self, BufRead, BufReader},
     path::PathBuf,
     process::{Command, Stdio},
@@ -216,10 +215,10 @@ impl FlycheckThread {
 
         let mut cmd = match &self.config {
             FlycheckConfig::CargoCommand { command, all_targets, all_features, extra_args } => {
-                let mut cmd = Command::new(cargo_binary());
+                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");
                 }
@@ -337,7 +336,3 @@ fn run_cargo(
 
     Ok(())
 }
-
-fn cargo_binary() -> String {
-    env::var("CARGO").unwrap_or_else(|_| "cargo".to_string())
-}
diff --git a/crates/ra_hir/src/code_model.rs b/crates/ra_hir/src/code_model.rs
index 7e840add5..6d8444462 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;
@@ -1341,7 +1344,7 @@ 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_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..f5edaea8c 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 +125,76 @@ 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 },
+}
+
+#[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);
         }
@@ -191,12 +277,30 @@ 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() {
@@ -269,7 +373,7 @@ 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 +391,7 @@ 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 +436,7 @@ 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 +498,7 @@ 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 +520,19 @@ 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 +556,15 @@ 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..a21ad8d86 100644
--- a/crates/ra_hir_ty/src/infer.rs
+++ b/crates/ra_hir_ty/src/infer.rs
@@ -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(),
         }
     }
 
@@ -666,15 +675,57 @@ 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 +741,13 @@ 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/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..ca1748615
--- /dev/null
+++ b/crates/ra_hir_ty/src/tests/display_source_code.rs
@@ -0,0 +1,23 @@
+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));
+}
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..3820175f6 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': !
     "###
     );
diff --git a/crates/ra_ide/src/display/function_signature.rs b/crates/ra_ide/src/display/function_signature.rs
index db3907fe6..9572debd8 100644
--- a/crates/ra_ide/src/display/function_signature.rs
+++ b/crates/ra_ide/src/display/function_signature.rs
@@ -1,5 +1,7 @@
 //! FIXME: write short doc here
 
+// FIXME: this modules relies on strings and AST way too much, and it should be
+// rewritten (matklad 2020-05-07)
 use std::{
     convert::From,
     fmt::{self, Display},
@@ -82,8 +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());
@@ -127,8 +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);
@@ -195,14 +197,23 @@ 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);
                 }
 
                 res.extend(param_list.params().map(|param| param.syntax().text().to_string()));
                 res_types.extend(param_list.params().map(|param| {
-                    param.syntax().text().to_string().split(':').nth(1).unwrap()[1..].to_string()
+                    let param_text = param.syntax().text().to_string();
+                    match param_text.split(':').nth(1).and_then(|it| it.get(1..)) {
+                        Some(it) => it.to_string(),
+                        None => param_text,
+                    }
                 }));
             }
             (has_self_param, res, res_types)
diff --git a/crates/ra_ide/src/lib.rs b/crates/ra_ide/src/lib.rs
index 737f87109..915199bd8 100644
--- a/crates/ra_ide/src/lib.rs
+++ b/crates/ra_ide/src/lib.rs
@@ -472,12 +472,12 @@ impl Analysis {
     /// position.
     pub fn assists(&self, frange: FileRange) -> Cancelable<Vec<Assist>> {
         self.with_db(|db| {
-            ra_assists::resolved_assists(db, frange)
+            ra_assists::Assist::resolved(db, frange)
                 .into_iter()
                 .map(|assist| Assist {
-                    id: assist.label.id,
-                    label: assist.label.label,
-                    group_label: assist.label.group.map(|it| it.0),
+                    id: assist.assist.id,
+                    label: assist.assist.label,
+                    group_label: assist.assist.group.map(|it| it.0),
                     source_change: assist.source_change,
                 })
                 .collect()
diff --git a/crates/ra_ide/src/references/rename.rs b/crates/ra_ide/src/references/rename.rs
index 0398d53bc..2cbb82c1a 100644
--- a/crates/ra_ide/src/references/rename.rs
+++ b/crates/ra_ide/src/references/rename.rs
@@ -712,6 +712,68 @@ mod tests {
         "###);
     }
 
+    #[test]
+    fn test_enum_variant_from_module_1() {
+        test_rename(
+            r#"
+    mod foo {
+        pub enum Foo {
+            Bar<|>,
+        }
+    }
+
+    fn func(f: foo::Foo) {
+        match f {
+            foo::Foo::Bar => {}
+        }
+    }
+    "#,
+            "Baz",
+            r#"
+    mod foo {
+        pub enum Foo {
+            Baz,
+        }
+    }
+
+    fn func(f: foo::Foo) {
+        match f {
+            foo::Foo::Baz => {}
+        }
+    }
+    "#,
+        );
+    }
+
+    #[test]
+    fn test_enum_variant_from_module_2() {
+        test_rename(
+            r#"
+    mod foo {
+        pub struct Foo {
+            pub bar<|>: uint,
+        }
+    }
+
+    fn foo(f: foo::Foo) {
+        let _ = f.bar;
+    }
+    "#,
+            "baz",
+            r#"
+    mod foo {
+        pub struct Foo {
+            pub baz: uint,
+        }
+    }
+
+    fn foo(f: foo::Foo) {
+        let _ = f.baz;
+    }
+    "#,
+        );
+    }
+
     fn test_rename(text: &str, new_name: &str, expected: &str) {
         let (analysis, position) = single_file_with_position(text);
         let source_change = analysis.rename(position, new_name).unwrap();
diff --git a/crates/ra_ide_db/src/defs.rs b/crates/ra_ide_db/src/defs.rs
index 40d0e77b5..f990e3bb9 100644
--- a/crates/ra_ide_db/src/defs.rs
+++ b/crates/ra_ide_db/src/defs.rs
@@ -6,7 +6,7 @@
 // FIXME: this badly needs rename/rewrite (matklad, 2020-02-06).
 
 use hir::{
-    Field, HasVisibility, ImplDef, Local, MacroDef, Module, ModuleDef, Name, PathResolution,
+    Adt, Field, HasVisibility, ImplDef, Local, MacroDef, Module, ModuleDef, Name, PathResolution,
     Semantics, TypeParam, Visibility,
 };
 use ra_prof::profile;
@@ -47,7 +47,13 @@ impl Definition {
         match self {
             Definition::Macro(_) => None,
             Definition::Field(sf) => Some(sf.visibility(db)),
-            Definition::ModuleDef(def) => module?.visibility_of(db, def),
+            Definition::ModuleDef(def) => match def {
+                ModuleDef::EnumVariant(id) => {
+                    let parent = id.parent_enum(db);
+                    module?.visibility_of(db, &ModuleDef::Adt(Adt::Enum(parent)))
+                }
+                _ => module?.visibility_of(db, def),
+            },
             Definition::SelfType(_) => None,
             Definition::Local(_) => None,
             Definition::TypeParam(_) => None,
diff --git a/crates/ra_project_model/Cargo.toml b/crates/ra_project_model/Cargo.toml
index 5e651fe70..a32a5daab 100644
--- a/crates/ra_project_model/Cargo.toml
+++ b/crates/ra_project_model/Cargo.toml
@@ -14,8 +14,9 @@ rustc-hash = "1.1.0"
 cargo_metadata = "0.9.1"
 
 ra_arena = { path = "../ra_arena" }
-ra_db = { path = "../ra_db" }
 ra_cfg = { path = "../ra_cfg" }
+ra_db = { path = "../ra_db" }
+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 59f46a2a0..082af4f96 100644
--- a/crates/ra_project_model/src/cargo_workspace.rs
+++ b/crates/ra_project_model/src/cargo_workspace.rs
@@ -1,7 +1,6 @@
 //! FIXME: write short doc here
 
 use std::{
-    env,
     ffi::OsStr,
     ops,
     path::{Path, PathBuf},
@@ -87,6 +86,7 @@ pub struct PackageData {
     pub dependencies: Vec<PackageDependency>,
     pub edition: Edition,
     pub features: Vec<String>,
+    pub cfgs: Vec<String>,
     pub out_dir: Option<PathBuf>,
     pub proc_macro_dylib_path: Option<PathBuf>,
 }
@@ -145,12 +145,8 @@ impl CargoWorkspace {
         cargo_toml: &Path,
         cargo_features: &CargoConfig,
     ) -> Result<CargoWorkspace> {
-        let _ = Command::new(cargo_binary())
-            .arg("--version")
-            .output()
-            .context("failed to run `cargo --version`, is `cargo` in PATH?")?;
-
         let mut meta = MetadataCommand::new();
+        meta.cargo_path(ra_toolchain::cargo());
         meta.manifest_path(cargo_toml);
         if cargo_features.all_features {
             meta.features(CargoOpt::AllFeatures);
@@ -172,10 +168,12 @@ impl CargoWorkspace {
         })?;
 
         let mut out_dir_by_id = FxHashMap::default();
+        let mut cfgs = FxHashMap::default();
         let mut proc_macro_dylib_paths = FxHashMap::default();
         if cargo_features.load_out_dirs_from_check {
             let resources = load_extern_resources(cargo_toml, cargo_features)?;
             out_dir_by_id = resources.out_dirs;
+            cfgs = resources.cfgs;
             proc_macro_dylib_paths = resources.proc_dylib_paths;
         }
 
@@ -201,6 +199,7 @@ impl CargoWorkspace {
                 edition,
                 dependencies: Vec::new(),
                 features: Vec::new(),
+                cfgs: cfgs.get(&id).cloned().unwrap_or_default(),
                 out_dir: out_dir_by_id.get(&id).cloned(),
                 proc_macro_dylib_path: proc_macro_dylib_paths.get(&id).cloned(),
             });
@@ -282,13 +281,14 @@ impl CargoWorkspace {
 pub struct ExternResources {
     out_dirs: FxHashMap<PackageId, PathBuf>,
     proc_dylib_paths: FxHashMap<PackageId, PathBuf>,
+    cfgs: FxHashMap<PackageId, Vec<String>>,
 }
 
 pub fn load_extern_resources(
     cargo_toml: &Path,
     cargo_features: &CargoConfig,
 ) -> Result<ExternResources> {
-    let mut cmd = Command::new(cargo_binary());
+    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");
@@ -307,8 +307,14 @@ pub fn load_extern_resources(
     for message in cargo_metadata::parse_messages(output.stdout.as_slice()) {
         if let Ok(message) = message {
             match message {
-                Message::BuildScriptExecuted(BuildScript { package_id, out_dir, .. }) => {
-                    res.out_dirs.insert(package_id, out_dir);
+                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(),
+                    );
                 }
 
                 Message::CompilerArtifact(message) => {
@@ -336,7 +342,3 @@ fn is_dylib(path: &Path) -> bool {
         Some(ext) => matches!(ext.as_str(), "dll" | "dylib" | "so"),
     }
 }
-
-fn cargo_binary() -> String {
-    env::var("CARGO").unwrap_or_else(|_| "cargo".to_string())
-}
diff --git a/crates/ra_project_model/src/lib.rs b/crates/ra_project_model/src/lib.rs
index c2b33c1dc..4f098b706 100644
--- a/crates/ra_project_model/src/lib.rs
+++ b/crates/ra_project_model/src/lib.rs
@@ -8,7 +8,7 @@ use std::{
     fs::{read_dir, File, ReadDir},
     io::{self, BufReader},
     path::{Path, PathBuf},
-    process::Command,
+    process::{Command, Output},
 };
 
 use anyhow::{bail, Context, Result};
@@ -88,46 +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);
                 }
@@ -139,14 +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()
         }
     }
 }
@@ -398,7 +377,18 @@ impl ProjectWorkspace {
                             let edition = cargo[pkg].edition;
                             let cfg_options = {
                                 let mut opts = default_cfg_options.clone();
-                                opts.insert_features(cargo[pkg].features.iter().map(Into::into));
+                                for feature in cargo[pkg].features.iter() {
+                                    opts.insert_key_value("feature".into(), feature.into());
+                                }
+                                for cfg in cargo[pkg].cfgs.iter() {
+                                    match cfg.find('=') {
+                                        Some(split) => opts.insert_key_value(
+                                            cfg[..split].into(),
+                                            cfg[split + 1..].trim_matches('"').into(),
+                                        ),
+                                        None => opts.insert_atom(cfg.into()),
+                                    };
+                                }
                                 opts
                             };
                             let mut env = Env::default();
@@ -556,25 +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("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('=') {
@@ -587,8 +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 55ff5ad80..a8a196e64 100644
--- a/crates/ra_project_model/src/sysroot.rs
+++ b/crates/ra_project_model/src/sysroot.rs
@@ -1,14 +1,16 @@
 //! 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 crate::output;
+
 #[derive(Default, Debug, Clone)]
 pub struct Sysroot {
     crates: Arena<SysrootCrateData>,
@@ -84,43 +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: &Path, program: &str, args: &[&str]) -> Result<Output> {
-    let output = Command::new(program)
-        .current_dir(cargo_toml.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_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() {
-        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_toolchain/Cargo.toml b/crates/ra_toolchain/Cargo.toml
new file mode 100644
index 000000000..1873fbe16
--- /dev/null
+++ b/crates/ra_toolchain/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+edition = "2018"
+name = "ra_toolchain"
+version = "0.1.0"
+authors = ["rust-analyzer developers"]
+
+[dependencies]
+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..3c307a0ea
--- /dev/null
+++ b/crates/ra_toolchain/src/lib.rs
@@ -0,0 +1,64 @@
+//! 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 = if env::consts::EXE_EXTENSION == "" {
+            None
+        } else {
+            Some(candidate.with_extension(env::consts::EXE_EXTENSION))
+        };
+        iter::once(candidate).chain(with_exe)
+    });
+    candidates.any(|it| it.is_file())
+}
diff --git a/crates/rust-analyzer/src/main_loop.rs b/crates/rust-analyzer/src/main_loop.rs
index b77f0c5a9..17b0b95b9 100644
--- a/crates/rust-analyzer/src/main_loop.rs
+++ b/crates/rust-analyzer/src/main_loop.rs
@@ -96,23 +96,21 @@ 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,
-                    );
+                    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,
+                );
             };
 
             project_roots
diff --git a/crates/rust-analyzer/src/main_loop/handlers.rs b/crates/rust-analyzer/src/main_loop/handlers.rs
index 15e8305f8..f4353af64 100644
--- a/crates/rust-analyzer/src/main_loop/handlers.rs
+++ b/crates/rust-analyzer/src/main_loop/handlers.rs
@@ -42,6 +42,7 @@ use crate::{
     world::WorldSnapshot,
     LspError, Result,
 };
+use ra_project_model::TargetKind;
 
 pub fn handle_analyzer_status(world: WorldSnapshot, _: ()) -> Result<String> {
     let _p = profile("handle_analyzer_status");
@@ -384,16 +385,27 @@ pub fn handle_runnables(
     let offset = params.position.map(|it| it.conv_with(&line_index));
     let mut res = Vec::new();
     let workspace_root = world.workspace_root_for(file_id);
+    let cargo_spec = CargoTargetSpec::for_file(&world, file_id)?;
     for runnable in world.analysis().runnables(file_id)? {
         if let Some(offset) = offset {
             if !runnable.range.contains_inclusive(offset) {
                 continue;
             }
         }
+        // Do not suggest binary run on other target than binary
+        if let RunnableKind::Bin = runnable.kind {
+            if let Some(spec) = &cargo_spec {
+                match spec.target_kind {
+                    TargetKind::Bin => {}
+                    _ => continue,
+                }
+            }
+        }
         res.push(to_lsp_runnable(&world, file_id, runnable)?);
     }
+
     // Add `cargo check` and `cargo test` for the whole package
-    match CargoTargetSpec::for_file(&world, file_id)? {
+    match cargo_spec {
         Some(spec) => {
             for &cmd in ["check", "test"].iter() {
                 res.push(req::Runnable {
@@ -831,13 +843,23 @@ pub fn handle_code_lens(
 
     let mut lenses: Vec<CodeLens> = Default::default();
 
+    let cargo_spec = CargoTargetSpec::for_file(&world, file_id)?;
     // Gather runnables
     for runnable in world.analysis().runnables(file_id)? {
         let title = match &runnable.kind {
             RunnableKind::Test { .. } | RunnableKind::TestMod { .. } => "▶️\u{fe0e}Run Test",
             RunnableKind::DocTest { .. } => "▶️\u{fe0e}Run Doctest",
             RunnableKind::Bench { .. } => "Run Bench",
-            RunnableKind::Bin => "Run",
+            RunnableKind::Bin => {
+                // Do not suggest binary run on other target than binary
+                match &cargo_spec {
+                    Some(spec) => match spec.target_kind {
+                        TargetKind::Bin => "Run",
+                        _ => continue,
+                    },
+                    None => continue,
+                }
+            }
         }
         .to_string();
         let mut r = to_lsp_runnable(&world, file_id, runnable)?;
diff --git a/crates/rust-analyzer/tests/heavy_tests/main.rs b/crates/rust-analyzer/tests/heavy_tests/main.rs
index 1efa5dd63..e459e3a3c 100644
--- a/crates/rust-analyzer/tests/heavy_tests/main.rs
+++ b/crates/rust-analyzer/tests/heavy_tests/main.rs
@@ -9,7 +9,8 @@ use lsp_types::{
 };
 use rust_analyzer::req::{
     CodeActionParams, CodeActionRequest, Completion, CompletionParams, DidOpenTextDocument,
-    Formatting, GotoDefinition, HoverRequest, OnEnter, Runnables, RunnablesParams,
+    Formatting, GotoDefinition, GotoTypeDefinition, HoverRequest, OnEnter, Runnables,
+    RunnablesParams,
 };
 use serde_json::json;
 use tempfile::TempDir;
@@ -574,7 +575,7 @@ version = \"0.0.0\"
 }
 
 #[test]
-fn resolve_include_concat_env() {
+fn out_dirs_check() {
     if skip_slow_tests() {
         return;
     }
@@ -597,11 +598,28 @@ fn main() {
         r#"pub fn message() -> &'static str { "Hello, World!" }"#,
     )
     .unwrap();
+    println!("cargo:rustc-cfg=atom_cfg");
+    println!("cargo:rustc-cfg=featlike=\"set\"");
     println!("cargo:rerun-if-changed=build.rs");
 }
 //- src/main.rs
 include!(concat!(env!("OUT_DIR"), "/hello.rs"));
 
+#[cfg(atom_cfg)]
+struct A;
+#[cfg(bad_atom_cfg)]
+struct A;
+#[cfg(featlike = "set")]
+struct B;
+#[cfg(featlike = "not_set")]
+struct B;
+
+fn main() {
+    let va = A;
+    let vb = B;
+    message();
+}
+
 fn main() { message(); }
 "###,
     )
@@ -613,12 +631,98 @@ fn main() { message(); }
     let res = server.send_request::<GotoDefinition>(GotoDefinitionParams {
         text_document_position_params: TextDocumentPositionParams::new(
             server.doc_id("src/main.rs"),
-            Position::new(2, 15),
+            Position::new(14, 8),
         ),
         work_done_progress_params: Default::default(),
         partial_result_params: Default::default(),
     });
     assert!(format!("{}", res).contains("hello.rs"));
+    server.request::<GotoTypeDefinition>(
+        GotoDefinitionParams {
+            text_document_position_params: TextDocumentPositionParams::new(
+                server.doc_id("src/main.rs"),
+                Position::new(12, 9),
+            ),
+            work_done_progress_params: Default::default(),
+            partial_result_params: Default::default(),
+        },
+        json!([{
+            "originSelectionRange": {
+                "end": {
+                    "character": 10,
+                    "line": 12
+                },
+                "start": {
+                    "character": 8,
+                    "line": 12
+                }
+            },
+            "targetRange": {
+                "end": {
+                    "character": 9,
+                    "line": 3
+                },
+                "start": {
+                    "character": 0,
+                    "line": 2
+                }
+            },
+            "targetSelectionRange": {
+                "end": {
+                    "character": 8,
+                    "line": 3
+                },
+                "start": {
+                    "character": 7,
+                    "line": 3
+                }
+            },
+            "targetUri": "file:///[..]src/main.rs"
+        }]),
+    );
+    server.request::<GotoTypeDefinition>(
+        GotoDefinitionParams {
+            text_document_position_params: TextDocumentPositionParams::new(
+                server.doc_id("src/main.rs"),
+                Position::new(13, 9),
+            ),
+            work_done_progress_params: Default::default(),
+            partial_result_params: Default::default(),
+        },
+        json!([{
+            "originSelectionRange": {
+                "end": {
+                    "character": 10,
+                    "line": 13
+                },
+                "start": {
+                    "character": 8,
+                    "line":13
+                }
+            },
+            "targetRange": {
+                "end": {
+                    "character": 9,
+                    "line": 7
+                },
+                "start": {
+                    "character": 0,
+                    "line":6
+                }
+            },
+            "targetSelectionRange": {
+                "end": {
+                    "character": 8,
+                    "line": 7
+                },
+                "start": {
+                    "character": 7,
+                    "line": 7
+                }
+            },
+            "targetUri": "file:///[..]src/main.rs"
+        }]),
+    );
 }
 
 #[test]
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 12a08ba40..c6fc13519 100644
--- a/editors/code/package.json
+++ b/editors/code/package.json
@@ -300,6 +300,11 @@
                     "default": true,
                     "markdownDescription": "Check with all features (will be passed as `--all-features`)"
                 },
+                "rust-analyzer.inlayHints.enable": {
+                    "type": "boolean",
+                    "default": true,
+                    "description": "Disable all inlay hints"
+                },
                 "rust-analyzer.inlayHints.typeHints": {
                     "type": "boolean",
                     "default": true,
@@ -418,6 +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\"} }"
                 }
             }
         },
@@ -589,6 +604,9 @@
                     "union": [
                         "entity.name.union"
                     ],
+                    "struct": [
+                        "entity.name.type.struct"
+                    ],
                     "keyword.unsafe": [
                         "keyword.other.unsafe"
                     ],
diff --git a/editors/code/src/cargo.ts b/editors/code/src/cargo.ts
index a328ba9bd..2a2c2e0e1 100644
--- a/editors/code/src/cargo.ts
+++ b/editors/code/src/cargo.ts
@@ -1,6 +1,9 @@
 import * as cp from 'child_process';
+import * as os from 'os';
+import * as path from 'path';
 import * as readline from 'readline';
 import { OutputChannel } from 'vscode';
+import { isValidExecutable } from './util';
 
 interface CompilationArtifact {
     fileName: string;
@@ -10,17 +13,9 @@ interface CompilationArtifact {
 }
 
 export class Cargo {
-    rootFolder: string;
-    env?: Record<string, string>;
-    output: OutputChannel;
-
-    public constructor(cargoTomlFolder: string, output: OutputChannel, env: Record<string, string> | undefined = undefined) {
-        this.rootFolder = cargoTomlFolder;
-        this.output = output;
-        this.env = env;
-    }
+    constructor(readonly rootFolder: string, readonly output: OutputChannel) { }
 
-    public async artifactsFromArgs(cargoArgs: string[]): Promise<CompilationArtifact[]> {
+    private async artifactsFromArgs(cargoArgs: string[]): Promise<CompilationArtifact[]> {
         const artifacts: CompilationArtifact[] = [];
 
         try {
@@ -37,17 +32,13 @@ export class Cargo {
                                 isTest: message.profile.test
                             });
                         }
-                    }
-                    else if (message.reason === 'compiler-message') {
+                    } else if (message.reason === 'compiler-message') {
                         this.output.append(message.message.rendered);
                     }
                 },
-                stderr => {
-                    this.output.append(stderr);
-                }
+                stderr => this.output.append(stderr),
             );
-        }
-        catch (err) {
+        } catch (err) {
             this.output.show(true);
             throw new Error(`Cargo invocation has failed: ${err}`);
         }
@@ -55,9 +46,8 @@ export class Cargo {
         return artifacts;
     }
 
-    public async executableFromArgs(args: string[]): Promise<string> {
-        const cargoArgs = [...args]; // to remain  args unchanged
-        cargoArgs.push("--message-format=json");
+    async executableFromArgs(args: readonly string[]): Promise<string> {
+        const cargoArgs = [...args, "--message-format=json"];
 
         const artifacts = await this.artifactsFromArgs(cargoArgs);
 
@@ -70,24 +60,27 @@ export class Cargo {
         return artifacts[0].fileName;
     }
 
-    runCargo(
+    private runCargo(
         cargoArgs: string[],
         onStdoutJson: (obj: any) => void,
         onStderrString: (data: string) => void
     ): Promise<number> {
-        return new Promise<number>((resolve, reject) => {
-            const cargo = cp.spawn('cargo', cargoArgs, {
+        return new Promise((resolve, reject) => {
+            let cargoPath;
+            try {
+                cargoPath = getCargoPathOrFail();
+            } catch (err) {
+                return reject(err);
+            }
+
+            const cargo = cp.spawn(cargoPath, cargoArgs, {
                 stdio: ['ignore', 'pipe', 'pipe'],
-                cwd: this.rootFolder,
-                env: this.env,
+                cwd: this.rootFolder
             });
 
-            cargo.on('error', err => {
-                reject(new Error(`could not launch cargo: ${err}`));
-            });
-            cargo.stderr.on('data', chunk => {
-                onStderrString(chunk.toString());
-            });
+            cargo.on('error', err => reject(new Error(`could not launch cargo: ${err}`)));
+
+            cargo.stderr.on('data', chunk => onStderrString(chunk.toString()));
 
             const rl = readline.createInterface({ input: cargo.stdout });
             rl.on('line', line => {
@@ -103,4 +96,28 @@ export class Cargo {
             });
         });
     }
-}
\ No newline at end of file
+}
+
+// Mirrors `ra_env::get_path_for_executable` implementation
+function getCargoPathOrFail(): string {
+    const envVar = process.env.CARGO;
+    const executableName = "cargo";
+
+    if (envVar) {
+        if (isValidExecutable(envVar)) return envVar;
+
+        throw new Error(`\`${envVar}\` environment variable points to something that's not a valid executable`);
+    }
+
+    if (isValidExecutable(executableName)) return executableName;
+
+    const standardLocation = path.join(os.homedir(), '.cargo', 'bin', executableName);
+
+    if (isValidExecutable(standardLocation)) return standardLocation;
+
+    throw new Error(
+        `Failed to find \`${executableName}\` executable. ` +
+        `Make sure \`${executableName}\` is in \`$PATH\`, ` +
+        `or set \`${envVar}\` to point to a valid executable.`
+    );
+}
diff --git a/editors/code/src/commands/runnables.ts b/editors/code/src/commands/runnables.ts
index d77e8188c..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",
@@ -98,36 +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/config.ts b/editors/code/src/config.ts
index 110e54180..be2e27aec 100644
--- a/editors/code/src/config.ts
+++ b/editors/code/src/config.ts
@@ -94,6 +94,7 @@ export class Config {
 
     get inlayHints() {
         return {
+            enable: this.get<boolean>("inlayHints.enable"),
             typeHints: this.get<boolean>("inlayHints.typeHints"),
             parameterHints: this.get<boolean>("inlayHints.parameterHints"),
             chainingHints: this.get<boolean>("inlayHints.chainingHints"),
@@ -108,10 +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,
         };
     }
-
 }
diff --git a/editors/code/src/inlay_hints.ts b/editors/code/src/inlay_hints.ts
index a09531797..a2b07d003 100644
--- a/editors/code/src/inlay_hints.ts
+++ b/editors/code/src/inlay_hints.ts
@@ -10,13 +10,13 @@ export function activateInlayHints(ctx: Ctx) {
     const maybeUpdater = {
         updater: null as null | HintsUpdater,
         async onConfigChange() {
-            if (
-                !ctx.config.inlayHints.typeHints &&
-                !ctx.config.inlayHints.parameterHints &&
-                !ctx.config.inlayHints.chainingHints
-            ) {
-                return this.dispose();
-            }
+            const anyEnabled = ctx.config.inlayHints.typeHints
+                || ctx.config.inlayHints.parameterHints
+                || ctx.config.inlayHints.chainingHints;
+            const enabled = ctx.config.inlayHints.enable && anyEnabled;
+
+            if (!enabled) return this.dispose();
+
             await sleep(100);
             if (this.updater) {
                 this.updater.syncCacheAndRenderHints();
diff --git a/editors/code/src/main.ts b/editors/code/src/main.ts
index efd56a84b..9b020d001 100644
--- a/editors/code/src/main.ts
+++ b/editors/code/src/main.ts
@@ -8,10 +8,9 @@ import { activateInlayHints } from './inlay_hints';
 import { activateStatusDisplay } from './status_display';
 import { Ctx } from './ctx';
 import { Config, NIGHTLY_TAG } from './config';
-import { log, assert } from './util';
+import { log, assert, isValidExecutable } from './util';
 import { PersistentState } from './persistent_state';
 import { fetchRelease, download } from './net';
-import { spawnSync } from 'child_process';
 import { activateTaskProvider } from './tasks';
 
 let ctx: Ctx | undefined;
@@ -179,10 +178,7 @@ async function bootstrapServer(config: Config, state: PersistentState): Promise<
 
     log.debug("Using server binary at", path);
 
-    const res = spawnSync(path, ["--version"], { encoding: 'utf8' });
-    log.debug("Checked binary availability via --version", res);
-    log.debug(res, "--version output:", res.output);
-    if (res.status !== 0) {
+    if (!isValidExecutable(path)) {
         throw new Error(`Failed to execute ${path} --version`);
     }
 
diff --git a/editors/code/src/util.ts b/editors/code/src/util.ts
index 6f91f81d6..127a9e911 100644
--- a/editors/code/src/util.ts
+++ b/editors/code/src/util.ts
@@ -1,6 +1,7 @@
 import * as lc from "vscode-languageclient";
 import * as vscode from "vscode";
 import { strict as nativeAssert } from "assert";
+import { spawnSync } from "child_process";
 
 export function assert(condition: boolean, explanation: string): asserts condition {
     try {
@@ -82,3 +83,13 @@ export function isRustDocument(document: vscode.TextDocument): document is RustD
 export function isRustEditor(editor: vscode.TextEditor): editor is RustEditor {
     return isRustDocument(editor.document);
 }
+
+export function isValidExecutable(path: string): boolean {
+    log.debug("Checking availability of a binary at", path);
+
+    const res = spawnSync(path, ["--version"], { encoding: 'utf8' });
+
+    log.debug(res, "--version output:", res.output);
+
+    return res.status === 0;
+}