78 files changed, 1606 insertions, 730 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 051d9e734..d8838cf2b 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -253,7 +253,6 @@ dependencies = [
 name = "completion"
 version = "0.0.0"
 dependencies = [
- "assists",
  "base_db",
  "either",
  "expect-test",
@@ -301,7 +300,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "dca26ee1f8d361640700bde38b2c37d8c22b3ce2d360e1fc1c74ea4b0aa7d775"
 dependencies = [
  "cfg-if 1.0.0",
- "crossbeam-utils 0.8.0",
+ "crossbeam-utils 0.8.1",
 ]
 
 [[package]]
@@ -312,18 +311,18 @@ checksum = "94af6efb46fef72616855b036a624cf27ba656ffc9be1b9a3c931cfc7749a9a9"
 dependencies = [
  "cfg-if 1.0.0",
  "crossbeam-epoch",
- "crossbeam-utils 0.8.0",
+ "crossbeam-utils 0.8.1",
 ]
 
 [[package]]
 name = "crossbeam-epoch"
-version = "0.9.0"
+version = "0.9.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ec0f606a85340376eef0d6d8fec399e6d4a544d648386c6645eb6d0653b27d9f"
+checksum = "a1aaa739f95311c2c7887a76863f500026092fb1dce0161dab577e559ef3569d"
 dependencies = [
  "cfg-if 1.0.0",
  "const_fn",
- "crossbeam-utils 0.8.0",
+ "crossbeam-utils 0.8.1",
  "lazy_static",
  "memoffset",
  "scopeguard",
@@ -342,13 +341,12 @@ dependencies = [
 
 [[package]]
 name = "crossbeam-utils"
-version = "0.8.0"
+version = "0.8.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ec91540d98355f690a86367e566ecad2e9e579f230230eb7c21398372be73ea5"
+checksum = "02d96d1e189ef58269ebe5b97953da3274d83a93af647c2ddd6f9dab28cedb8d"
 dependencies = [
  "autocfg",
  "cfg-if 1.0.0",
- "const_fn",
  "lazy_static",
 ]
 
@@ -682,6 +680,7 @@ dependencies = [
  "expect-test",
  "fst",
  "hir",
+ "itertools",
  "log",
  "once_cell",
  "profile",
@@ -865,9 +864,9 @@ dependencies = [
 
 [[package]]
 name = "lsp-types"
-version = "0.84.0"
+version = "0.85.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3b95be71fe205e44de754185bcf86447b65813ce1ceb298f8d3793ade5fff08d"
+checksum = "857650f3e83fb62f89d15410414e0ed7d0735445020da398d37f65d20a5423b9"
 dependencies = [
  "base64",
  "bitflags",
@@ -929,9 +928,9 @@ dependencies = [
 
 [[package]]
 name = "memoffset"
-version = "0.5.6"
+version = "0.6.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "043175f069eda7b85febe4a74abbaeff828d9f8b448515d3151a14a3542811aa"
+checksum = "157b4208e3059a8f9e78d559edc658e13df41410cb3ae03979c83130067fdd87"
 dependencies = [
  "autocfg",
 ]
@@ -988,9 +987,9 @@ dependencies = [
 
 [[package]]
 name = "miow"
-version = "0.2.1"
+version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8c1f2f3b1cf331de6896aabf6e9d55dca90356cc9960cca7eaaf408a355ae919"
+checksum = "ebd808424166322d4a38da87083bfddd3ac4c131334ed55856112eb06d46944d"
 dependencies = [
  "kernel32-sys",
  "net2",
@@ -1000,9 +999,9 @@ dependencies = [
 
 [[package]]
 name = "net2"
-version = "0.2.35"
+version = "0.2.36"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3ebc3ec692ed7c9a255596c67808dee269f64655d8baf7b4f0638e51ba1d6853"
+checksum = "d7cf75f38f16cb05ea017784dc6dbfd354f76c223dba37701734c4f5a9337d02"
 dependencies = [
  "cfg-if 0.1.10",
  "libc",
@@ -1298,7 +1297,7 @@ checksum = "9ab346ac5921dc62ffa9f89b7a773907511cdfa5490c572ae9be1be33e8afa4a"
 dependencies = [
  "crossbeam-channel 0.5.0",
  "crossbeam-deque",
- "crossbeam-utils 0.8.0",
+ "crossbeam-utils 0.8.1",
  "lazy_static",
  "num_cpus",
 ]
@@ -1396,9 +1395,9 @@ dependencies = [
 
 [[package]]
 name = "rustc-ap-rustc_lexer"
-version = "688.0.0"
+version = "691.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ebbdcc99bd015349093fcbae4780fda21416fec5d8843acfb3d1733e130cd4db"
+checksum = "44bc89d9ca7a78fb82e103b389362c55f03800745f8ba14e068b805cfaf783ec"
 dependencies = [
  "unicode-xid",
 ]
@@ -1436,7 +1435,7 @@ version = "0.16.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d8fadca2ab5de17acf66d744f4888049ca8f1bb9b8a1ab8afd9d032cc959c5dc"
 dependencies = [
- "crossbeam-utils 0.8.0",
+ "crossbeam-utils 0.8.1",
  "indexmap",
  "lock_api",
  "log",
@@ -1627,9 +1626,9 @@ version = "0.0.0"
 
 [[package]]
 name = "syn"
-version = "1.0.51"
+version = "1.0.53"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3b4f34193997d92804d359ed09953e25d5138df6bcc055a71bf68ee89fdf9223"
+checksum = "8833e20724c24de12bbaba5ad230ea61c3eafb05b881c7c9d3cfe8638b187e68"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -1658,6 +1657,7 @@ dependencies = [
  "itertools",
  "once_cell",
  "parser",
+ "profile",
  "rayon",
  "rowan",
  "rustc-ap-rustc_lexer",
@@ -1898,9 +1898,9 @@ dependencies = [
 
 [[package]]
 name = "unicode-segmentation"
-version = "1.7.0"
+version = "1.7.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "db8716a166f290ff49dabc18b44aa407cb7c6dbe1aa0971b44b8a24b0ca35aae"
+checksum = "bb0d2e7be6ae3a5fa87eed5fb451aff96f2573d2694942e40543ae0bbe19c796"
 
 [[package]]
 name = "unicode-xid"
diff --git a/crates/assists/Cargo.toml b/crates/assists/Cargo.toml
index 108f656e9..3fd8327d6 100644
--- a/crates/assists/Cargo.toml
+++ b/crates/assists/Cargo.toml
@@ -12,7 +12,7 @@ doctest = false
 [dependencies]
 rustc-hash = "1.1.0"
 itertools = "0.9.0"
-either = "1.5.3"
+either = "1.6.1"
 
 stdx = { path = "../stdx", version = "0.0.0" }
 syntax = { path = "../syntax", version = "0.0.0" }
diff --git a/crates/assists/src/assist_config.rs b/crates/assists/src/assist_config.rs
index b24527ec4..786224cfa 100644
--- a/crates/assists/src/assist_config.rs
+++ b/crates/assists/src/assist_config.rs
@@ -5,8 +5,9 @@
 //! assists if we are allowed to.
 
 use hir::PrefixKind;
+use ide_db::helpers::insert_use::MergeBehaviour;
 
-use crate::{utils::MergeBehaviour, AssistKind};
+use crate::AssistKind;
 
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub struct AssistConfig {
diff --git a/crates/assists/src/ast_transform.rs b/crates/assists/src/ast_transform.rs
index ac72f3f02..66e4634b1 100644
--- a/crates/assists/src/ast_transform.rs
+++ b/crates/assists/src/ast_transform.rs
@@ -1,5 +1,6 @@
 //! `AstTransformer`s are functions that replace nodes in an AST and can be easily combined.
 use hir::{HirDisplay, PathResolution, SemanticsScope};
+use ide_db::helpers::mod_path_to_ast;
 use rustc_hash::FxHashMap;
 use syntax::{
     algo::SyntaxRewriter,
@@ -7,8 +8,6 @@ use syntax::{
     SyntaxNode,
 };
 
-use crate::utils::mod_path_to_ast;
-
 pub fn apply<'a, N: AstNode>(transformer: &dyn AstTransform<'a>, node: N) -> N {
     SyntaxRewriter::from_fn(|element| match element {
         syntax::SyntaxElement::Node(n) => {
diff --git a/crates/assists/src/handlers/auto_import.rs b/crates/assists/src/handlers/auto_import.rs
index d665837a2..bd5bba646 100644
--- a/crates/assists/src/handlers/auto_import.rs
+++ b/crates/assists/src/handlers/auto_import.rs
@@ -1,8 +1,11 @@
+use ide_db::helpers::{
+    insert_use::{insert_use, ImportScope},
+    mod_path_to_ast,
+};
 use syntax::ast;
 
 use crate::{
     utils::import_assets::{ImportAssets, ImportCandidate},
-    utils::{insert_use, mod_path_to_ast, ImportScope},
     AssistContext, AssistId, AssistKind, Assists, GroupLabel,
 };
 
diff --git a/crates/assists/src/handlers/extract_struct_from_enum_variant.rs b/crates/assists/src/handlers/extract_struct_from_enum_variant.rs
index cac77c49b..d85767b4e 100644
--- a/crates/assists/src/handlers/extract_struct_from_enum_variant.rs
+++ b/crates/assists/src/handlers/extract_struct_from_enum_variant.rs
@@ -2,6 +2,10 @@ use std::iter;
 
 use either::Either;
 use hir::{AsName, EnumVariant, Module, ModuleDef, Name};
+use ide_db::helpers::{
+    insert_use::{insert_use, ImportScope},
+    mod_path_to_ast,
+};
 use ide_db::{defs::Definition, search::Reference, RootDatabase};
 use rustc_hash::{FxHashMap, FxHashSet};
 use syntax::{
@@ -10,10 +14,7 @@ use syntax::{
     SourceFile, SyntaxElement, SyntaxNode, T,
 };
 
-use crate::{
-    utils::{insert_use, mod_path_to_ast, ImportScope},
-    AssistContext, AssistId, AssistKind, Assists,
-};
+use crate::{AssistContext, AssistId, AssistKind, Assists};
 
 // Assist: extract_struct_from_enum_variant
 //
@@ -236,10 +237,9 @@ fn update_reference(
 
 #[cfg(test)]
 mod tests {
-    use crate::{
-        tests::{check_assist, check_assist_not_applicable},
-        utils::FamousDefs,
-    };
+    use ide_db::helpers::FamousDefs;
+
+    use crate::tests::{check_assist, check_assist_not_applicable};
 
     use super::*;
 
diff --git a/crates/assists/src/handlers/fill_match_arms.rs b/crates/assists/src/handlers/fill_match_arms.rs
index eda45f5b3..ef12ef0cf 100644
--- a/crates/assists/src/handlers/fill_match_arms.rs
+++ b/crates/assists/src/handlers/fill_match_arms.rs
@@ -1,13 +1,14 @@
 use std::iter;
 
 use hir::{Adt, HasSource, ModuleDef, Semantics};
+use ide_db::helpers::{mod_path_to_ast, FamousDefs};
 use ide_db::RootDatabase;
 use itertools::Itertools;
 use syntax::ast::{self, make, AstNode, MatchArm, NameOwner, Pat};
 use test_utils::mark;
 
 use crate::{
-    utils::{mod_path_to_ast, render_snippet, Cursor, FamousDefs},
+    utils::{render_snippet, Cursor},
     AssistContext, AssistId, AssistKind, Assists,
 };
 
@@ -212,12 +213,10 @@ fn build_pat(db: &RootDatabase, module: hir::Module, var: hir::EnumVariant) -> O
 
 #[cfg(test)]
 mod tests {
+    use ide_db::helpers::FamousDefs;
     use test_utils::mark;
 
-    use crate::{
-        tests::{check_assist, check_assist_not_applicable, check_assist_target},
-        utils::FamousDefs,
-    };
+    use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};
 
     use super::fill_match_arms;
 
diff --git a/crates/assists/src/handlers/generate_from_impl_for_enum.rs b/crates/assists/src/handlers/generate_from_impl_for_enum.rs
index 674e5a175..3c374e5d9 100644
--- a/crates/assists/src/handlers/generate_from_impl_for_enum.rs
+++ b/crates/assists/src/handlers/generate_from_impl_for_enum.rs
@@ -1,8 +1,9 @@
+use ide_db::helpers::FamousDefs;
 use ide_db::RootDatabase;
 use syntax::ast::{self, AstNode, NameOwner};
 use test_utils::mark;
 
-use crate::{utils::FamousDefs, AssistContext, AssistId, AssistKind, Assists};
+use crate::{AssistContext, AssistId, AssistKind, Assists};
 
 // Assist: generate_from_impl_for_enum
 //
diff --git a/crates/assists/src/handlers/infer_function_return_type.rs b/crates/assists/src/handlers/infer_function_return_type.rs
index 520d07ae0..aa584eb03 100644
--- a/crates/assists/src/handlers/infer_function_return_type.rs
+++ b/crates/assists/src/handlers/infer_function_return_type.rs
@@ -17,7 +17,7 @@ use crate::{AssistContext, AssistId, AssistKind, Assists};
 // fn foo() -> i32 { 42i32 }
 // ```
 pub(crate) fn infer_function_return_type(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
-    let (tail_expr, builder_edit_pos, wrap_expr) = extract_tail(ctx)?;
+    let (fn_type, tail_expr, builder_edit_pos) = extract_tail(ctx)?;
     let module = ctx.sema.scope(tail_expr.syntax()).module()?;
     let ty = ctx.sema.type_of_expr(&tail_expr)?;
     if ty.is_unit() {
@@ -27,7 +27,10 @@ pub(crate) fn infer_function_return_type(acc: &mut Assists, ctx: &AssistContext)
 
     acc.add(
         AssistId("infer_function_return_type", AssistKind::RefactorRewrite),
-        "Add this function's return type",
+        match fn_type {
+            FnType::Function => "Add this function's return type",
+            FnType::Closure { .. } => "Add this closure's return type",
+        },
         tail_expr.syntax().text_range(),
         |builder| {
             match builder_edit_pos {
@@ -38,7 +41,7 @@ pub(crate) fn infer_function_return_type(acc: &mut Assists, ctx: &AssistContext)
                     builder.replace(text_range, &format!("-> {}", ty))
                 }
             }
-            if wrap_expr {
+            if let FnType::Closure { wrap_expr: true } = fn_type {
                 mark::hit!(wrap_closure_non_block_expr);
                 // `|x| x` becomes `|x| -> T x` which is invalid, so wrap it in a block
                 builder.replace(tail_expr.syntax().text_range(), &format!("{{{}}}", tail_expr));
@@ -72,8 +75,13 @@ fn ret_ty_to_action(ret_ty: Option<ast::RetType>, insert_pos: TextSize) -> Optio
     }
 }
 
-fn extract_tail(ctx: &AssistContext) -> Option<(ast::Expr, InsertOrReplace, bool)> {
-    let (tail_expr, return_type_range, action, wrap_expr) =
+enum FnType {
+    Function,
+    Closure { wrap_expr: bool },
+}
+
+fn extract_tail(ctx: &AssistContext) -> Option<(FnType, ast::Expr, InsertOrReplace)> {
+    let (fn_type, tail_expr, return_type_range, action) =
         if let Some(closure) = ctx.find_node_at_offset::<ast::ClosureExpr>() {
             let rpipe_pos = closure.param_list()?.syntax().last_token()?.text_range().end();
             let action = ret_ty_to_action(closure.ret_type(), rpipe_pos)?;
@@ -86,7 +94,7 @@ fn extract_tail(ctx: &AssistContext) -> Option<(ast::Expr, InsertOrReplace, bool
             };
 
             let ret_range = TextRange::new(rpipe_pos, body_start);
-            (tail_expr, ret_range, action, wrap_expr)
+            (FnType::Closure { wrap_expr }, tail_expr, ret_range, action)
         } else {
             let func = ctx.find_node_at_offset::<ast::Fn>()?;
             let rparen_pos = func.param_list()?.r_paren_token()?.text_range().end();
@@ -97,7 +105,7 @@ fn extract_tail(ctx: &AssistContext) -> Option<(ast::Expr, InsertOrReplace, bool
 
             let ret_range_end = body.l_curly_token()?.text_range().start();
             let ret_range = TextRange::new(rparen_pos, ret_range_end);
-            (tail_expr, ret_range, action, false)
+            (FnType::Function, tail_expr, ret_range, action)
         };
     let frange = ctx.frange.range;
     if return_type_range.contains_range(frange) {
@@ -109,7 +117,7 @@ fn extract_tail(ctx: &AssistContext) -> Option<(ast::Expr, InsertOrReplace, bool
     } else {
         return None;
     }
-    Some((tail_expr, action, wrap_expr))
+    Some((fn_type, tail_expr, action))
 }
 
 #[cfg(test)]
diff --git a/crates/assists/src/handlers/merge_imports.rs b/crates/assists/src/handlers/merge_imports.rs
index fd9c9e03c..b7e853994 100644
--- a/crates/assists/src/handlers/merge_imports.rs
+++ b/crates/assists/src/handlers/merge_imports.rs
@@ -1,3 +1,4 @@
+use ide_db::helpers::insert_use::{try_merge_imports, try_merge_trees, MergeBehaviour};
 use syntax::{
     algo::{neighbor, SyntaxRewriter},
     ast, AstNode,
@@ -5,10 +6,7 @@ use syntax::{
 
 use crate::{
     assist_context::{AssistContext, Assists},
-    utils::{
-        insert_use::{try_merge_imports, try_merge_trees},
-        next_prev, MergeBehaviour,
-    },
+    utils::next_prev,
     AssistId, AssistKind,
 };
 
diff --git a/crates/assists/src/handlers/qualify_path.rs b/crates/assists/src/handlers/qualify_path.rs
index d5bc4e574..6f9810fe8 100644
--- a/crates/assists/src/handlers/qualify_path.rs
+++ b/crates/assists/src/handlers/qualify_path.rs
@@ -1,6 +1,7 @@
 use std::iter;
 
 use hir::AsName;
+use ide_db::helpers::mod_path_to_ast;
 use ide_db::RootDatabase;
 use syntax::{
     ast,
@@ -12,7 +13,6 @@ use test_utils::mark;
 use crate::{
     assist_context::{AssistContext, Assists},
     utils::import_assets::{ImportAssets, ImportCandidate},
-    utils::mod_path_to_ast,
     AssistId, AssistKind, GroupLabel,
 };
 
diff --git a/crates/assists/src/handlers/replace_derive_with_manual_impl.rs b/crates/assists/src/handlers/replace_derive_with_manual_impl.rs
index 453a6cebf..4d6a1956b 100644
--- a/crates/assists/src/handlers/replace_derive_with_manual_impl.rs
+++ b/crates/assists/src/handlers/replace_derive_with_manual_impl.rs
@@ -1,3 +1,4 @@
+use ide_db::helpers::mod_path_to_ast;
 use ide_db::imports_locator;
 use itertools::Itertools;
 use syntax::{
@@ -10,8 +11,7 @@ use syntax::{
 use crate::{
     assist_context::{AssistBuilder, AssistContext, Assists},
     utils::{
-        add_trait_assoc_items_to_impl, filter_assoc_items, mod_path_to_ast, render_snippet, Cursor,
-        DefaultMethods,
+        add_trait_assoc_items_to_impl, filter_assoc_items, render_snippet, Cursor, DefaultMethods,
     },
     AssistId, AssistKind,
 };
diff --git a/crates/assists/src/handlers/replace_qualified_name_with_use.rs b/crates/assists/src/handlers/replace_qualified_name_with_use.rs
index a66db9ae3..8193e45a8 100644
--- a/crates/assists/src/handlers/replace_qualified_name_with_use.rs
+++ b/crates/assists/src/handlers/replace_qualified_name_with_use.rs
@@ -1,10 +1,8 @@
+use ide_db::helpers::insert_use::{insert_use, ImportScope};
 use syntax::{algo::SyntaxRewriter, ast, match_ast, AstNode, SyntaxNode};
 use test_utils::mark;
 
-use crate::{
-    utils::{insert_use, ImportScope},
-    AssistContext, AssistId, AssistKind, Assists,
-};
+use crate::{AssistContext, AssistId, AssistKind, Assists};
 
 // Assist: replace_qualified_name_with_use
 //
@@ -409,7 +407,7 @@ impl std::fmt::Display<|> for Foo {
 }
 ",
             r"
-use std::fmt::{nested::Debug, Display};
+use std::fmt::{Display, nested::Debug};
 
 impl Display for Foo {
 }
diff --git a/crates/assists/src/handlers/ignore_test.rs b/crates/assists/src/handlers/toggle_ignore.rs
index 5096a0005..14b420421 100644
--- a/crates/assists/src/handlers/ignore_test.rs
+++ b/crates/assists/src/handlers/toggle_ignore.rs
@@ -5,7 +5,7 @@ use syntax::{
 
 use crate::{utils::test_related_attribute, AssistContext, AssistId, AssistKind, Assists};
 
-// Assist: ignore_test
+// Assist: toggle_ignore
 //
 // Adds `#[ignore]` attribute to the test.
 //
@@ -23,20 +23,20 @@ use crate::{utils::test_related_attribute, AssistContext, AssistId, AssistKind,
 //     assert_eq!(2 + 2, 5);
 // }
 // ```
-pub(crate) fn ignore_test(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+pub(crate) fn toggle_ignore(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let attr: ast::Attr = ctx.find_node_at_offset()?;
     let func = attr.syntax().parent().and_then(ast::Fn::cast)?;
     let attr = test_related_attribute(&func)?;
 
     match has_ignore_attribute(&func) {
         None => acc.add(
-            AssistId("ignore_test", AssistKind::None),
+            AssistId("toggle_ignore", AssistKind::None),
             "Ignore this test",
             attr.syntax().text_range(),
             |builder| builder.insert(attr.syntax().text_range().end(), &format!("\n#[ignore]")),
         ),
         Some(ignore_attr) => acc.add(
-            AssistId("unignore_test", AssistKind::None),
+            AssistId("toggle_ignore", AssistKind::None),
             "Re-enable this test",
             ignore_attr.syntax().text_range(),
             |builder| {
@@ -55,24 +55,19 @@ pub(crate) fn ignore_test(acc: &mut Assists, ctx: &AssistContext) -> Option<()>
 }
 
 fn has_ignore_attribute(fn_def: &ast::Fn) -> Option<ast::Attr> {
-    fn_def.attrs().find_map(|attr| {
-        if attr.path()?.syntax().text() == "ignore" {
-            Some(attr)
-        } else {
-            None
-        }
-    })
+    fn_def.attrs().find(|attr| attr.path().map(|it| it.syntax().text() == "ignore") == Some(true))
 }
 
 #[cfg(test)]
 mod tests {
-    use super::ignore_test;
     use crate::tests::check_assist;
 
+    use super::*;
+
     #[test]
     fn test_base_case() {
         check_assist(
-            ignore_test,
+            toggle_ignore,
             r#"
             #[test<|>]
             fn test() {}
@@ -88,7 +83,7 @@ mod tests {
     #[test]
     fn test_unignore() {
         check_assist(
-            ignore_test,
+            toggle_ignore,
             r#"
             #[test<|>]
             #[ignore]
diff --git a/crates/assists/src/lib.rs b/crates/assists/src/lib.rs
index 17e9312db..dfe6c2729 100644
--- a/crates/assists/src/lib.rs
+++ b/crates/assists/src/lib.rs
@@ -141,7 +141,6 @@ mod handlers {
     mod generate_function;
     mod generate_impl;
     mod generate_new;
-    mod ignore_test;
     mod infer_function_return_type;
     mod inline_local_variable;
     mod introduce_named_lifetime;
@@ -164,6 +163,7 @@ mod handlers {
     mod replace_string_with_char;
     mod replace_unwrap_with_match;
     mod split_import;
+    mod toggle_ignore;
     mod unwrap_block;
     mod wrap_return_type_in_result;
 
@@ -190,7 +190,6 @@ mod handlers {
             generate_function::generate_function,
             generate_impl::generate_impl,
             generate_new::generate_new,
-            ignore_test::ignore_test,
             infer_function_return_type::infer_function_return_type,
             inline_local_variable::inline_local_variable,
             introduce_named_lifetime::introduce_named_lifetime,
@@ -215,6 +214,7 @@ mod handlers {
             replace_qualified_name_with_use::replace_qualified_name_with_use,
             replace_unwrap_with_match::replace_unwrap_with_match,
             split_import::split_import,
+            toggle_ignore::toggle_ignore,
             unwrap_block::unwrap_block,
             wrap_return_type_in_result::wrap_return_type_in_result,
             // These are manually sorted for better priorities
diff --git a/crates/assists/src/tests/generated.rs b/crates/assists/src/tests/generated.rs
index 5a9d1a01b..8d50c8791 100644
--- a/crates/assists/src/tests/generated.rs
+++ b/crates/assists/src/tests/generated.rs
@@ -474,26 +474,6 @@ impl<T: Clone> Ctx<T> {
 }
 
 #[test]
-fn doctest_ignore_test() {
-    check_doc_test(
-        "ignore_test",
-        r#####"
-<|>#[test]
-fn arithmetics {
-    assert_eq!(2 + 2, 5);
-}
-"#####,
-        r#####"
-#[test]
-#[ignore]
-fn arithmetics {
-    assert_eq!(2 + 2, 5);
-}
-"#####,
-    )
-}
-
-#[test]
 fn doctest_infer_function_return_type() {
     check_doc_test(
         "infer_function_return_type",
@@ -979,6 +959,26 @@ use std::{collections::HashMap};
 }
 
 #[test]
+fn doctest_toggle_ignore() {
+    check_doc_test(
+        "toggle_ignore",
+        r#####"
+<|>#[test]
+fn arithmetics {
+    assert_eq!(2 + 2, 5);
+}
+"#####,
+        r#####"
+#[test]
+#[ignore]
+fn arithmetics {
+    assert_eq!(2 + 2, 5);
+}
+"#####,
+    )
+}
+
+#[test]
 fn doctest_unwrap_block() {
     check_doc_test(
         "unwrap_block",
diff --git a/crates/assists/src/utils.rs b/crates/assists/src/utils.rs
index 66c0cdd5f..01f5c291f 100644
--- a/crates/assists/src/utils.rs
+++ b/crates/assists/src/utils.rs
@@ -1,10 +1,9 @@
 //! Assorted functions shared by several assists.
-pub(crate) mod insert_use;
 pub(crate) mod import_assets;
 
 use std::ops;
 
-use hir::{Crate, Enum, HasSource, Module, ScopeDef, Semantics, Trait};
+use hir::HasSource;
 use ide_db::RootDatabase;
 use itertools::Itertools;
 use syntax::{
@@ -22,29 +21,6 @@ use crate::{
     ast_transform::{self, AstTransform, QualifyPaths, SubstituteTypeParams},
 };
 
-pub use insert_use::{insert_use, ImportScope, MergeBehaviour};
-
-pub fn mod_path_to_ast(path: &hir::ModPath) -> ast::Path {
-    let mut segments = Vec::new();
-    let mut is_abs = false;
-    match path.kind {
-        hir::PathKind::Plain => {}
-        hir::PathKind::Super(0) => segments.push(make::path_segment_self()),
-        hir::PathKind::Super(n) => segments.extend((0..n).map(|_| make::path_segment_super())),
-        hir::PathKind::DollarCrate(_) | hir::PathKind::Crate => {
-            segments.push(make::path_segment_crate())
-        }
-        hir::PathKind::Abs => is_abs = true,
-    }
-
-    segments.extend(
-        path.segments
-            .iter()
-            .map(|segment| make::path_segment(make::name_ref(&segment.to_string()))),
-    );
-    make::path_from_segments(segments, is_abs)
-}
-
 pub(crate) fn unwrap_trivial_block(block: ast::BlockExpr) -> ast::Expr {
     extract_trivial_expression(&block)
         .filter(|expr| !expr.syntax().text().contains_char('\n'))
@@ -259,179 +235,6 @@ fn invert_special_case(expr: &ast::Expr) -> Option<ast::Expr> {
     }
 }
 
-/// Helps with finding well-know things inside the standard library. This is
-/// somewhat similar to the known paths infra inside hir, but it different; We
-/// want to make sure that IDE specific paths don't become interesting inside
-/// the compiler itself as well.
-pub struct FamousDefs<'a, 'b>(pub &'a Semantics<'b, RootDatabase>, pub Option<Crate>);
-
-#[allow(non_snake_case)]
-impl FamousDefs<'_, '_> {
-    pub const FIXTURE: &'static str = r#"//- /libcore.rs crate:core
-pub mod convert {
-    pub trait From<T> {
-        fn from(t: T) -> Self;
-    }
-}
-
-pub mod default {
-    pub trait Default {
-       fn default() -> Self;
-    }
-}
-
-pub mod iter {
-    pub use self::traits::{collect::IntoIterator, iterator::Iterator};
-    mod traits {
-        pub(crate) mod iterator {
-            use crate::option::Option;
-            pub trait Iterator {
-                type Item;
-                fn next(&mut self) -> Option<Self::Item>;
-                fn by_ref(&mut self) -> &mut Self {
-                    self
-                }
-                fn take(self, n: usize) -> crate::iter::Take<Self> {
-                    crate::iter::Take { inner: self }
-                }
-            }
-
-            impl<I: Iterator> Iterator for &mut I {
-                type Item = I::Item;
-                fn next(&mut self) -> Option<I::Item> {
-                    (**self).next()
-                }
-            }
-        }
-        pub(crate) mod collect {
-            pub trait IntoIterator {
-                type Item;
-            }
-        }
-    }
-
-    pub use self::sources::*;
-    pub(crate) mod sources {
-        use super::Iterator;
-        use crate::option::Option::{self, *};
-        pub struct Repeat<A> {
-            element: A,
-        }
-
-        pub fn repeat<T>(elt: T) -> Repeat<T> {
-            Repeat { element: elt }
-        }
-
-        impl<A> Iterator for Repeat<A> {
-            type Item = A;
-
-            fn next(&mut self) -> Option<A> {
-                None
-            }
-        }
-    }
-
-    pub use self::adapters::*;
-    pub(crate) mod adapters {
-        use super::Iterator;
-        use crate::option::Option::{self, *};
-        pub struct Take<I> { pub(crate) inner: I }
-        impl<I> Iterator for Take<I> where I: Iterator {
-            type Item = <I as Iterator>::Item;
-            fn next(&mut self) -> Option<<I as Iterator>::Item> {
-                None
-            }
-        }
-    }
-}
-
-pub mod option {
-    pub enum Option<T> { None, Some(T)}
-}
-
-pub mod prelude {
-    pub use crate::{convert::From, iter::{IntoIterator, Iterator}, option::Option::{self, *}, default::Default};
-}
-#[prelude_import]
-pub use prelude::*;
-"#;
-
-    pub fn core(&self) -> Option<Crate> {
-        self.find_crate("core")
-    }
-
-    pub(crate) fn core_convert_From(&self) -> Option<Trait> {
-        self.find_trait("core:convert:From")
-    }
-
-    pub(crate) fn core_option_Option(&self) -> Option<Enum> {
-        self.find_enum("core:option:Option")
-    }
-
-    pub fn core_default_Default(&self) -> Option<Trait> {
-        self.find_trait("core:default:Default")
-    }
-
-    pub fn core_iter_Iterator(&self) -> Option<Trait> {
-        self.find_trait("core:iter:traits:iterator:Iterator")
-    }
-
-    pub fn core_iter(&self) -> Option<Module> {
-        self.find_module("core:iter")
-    }
-
-    fn find_trait(&self, path: &str) -> Option<Trait> {
-        match self.find_def(path)? {
-            hir::ScopeDef::ModuleDef(hir::ModuleDef::Trait(it)) => Some(it),
-            _ => None,
-        }
-    }
-
-    fn find_enum(&self, path: &str) -> Option<Enum> {
-        match self.find_def(path)? {
-            hir::ScopeDef::ModuleDef(hir::ModuleDef::Adt(hir::Adt::Enum(it))) => Some(it),
-            _ => None,
-        }
-    }
-
-    fn find_module(&self, path: &str) -> Option<Module> {
-        match self.find_def(path)? {
-            hir::ScopeDef::ModuleDef(hir::ModuleDef::Module(it)) => Some(it),
-            _ => None,
-        }
-    }
-
-    fn find_crate(&self, name: &str) -> Option<Crate> {
-        let krate = self.1?;
-        let db = self.0.db;
-        let res =
-            krate.dependencies(db).into_iter().find(|dep| dep.name.to_string() == name)?.krate;
-        Some(res)
-    }
-
-    fn find_def(&self, path: &str) -> Option<ScopeDef> {
-        let db = self.0.db;
-        let mut path = path.split(':');
-        let trait_ = path.next_back()?;
-        let std_crate = path.next()?;
-        let std_crate = self.find_crate(std_crate)?;
-        let mut module = std_crate.root_module(db);
-        for segment in path {
-            module = module.children(db).find_map(|child| {
-                let name = child.name(db)?;
-                if name.to_string() == segment {
-                    Some(child)
-                } else {
-                    None
-                }
-            })?;
-        }
-        let def =
-            module.scope(db, None).into_iter().find(|(name, _def)| name.to_string() == trait_)?.1;
-        Some(def)
-    }
-}
-
 pub(crate) fn next_prev() -> impl Iterator<Item = Direction> {
     [Direction::Next, Direction::Prev].iter().copied()
 }
diff --git a/crates/completion/Cargo.toml b/crates/completion/Cargo.toml
index e7df9d955..35e169a28 100644
--- a/crates/completion/Cargo.toml
+++ b/crates/completion/Cargo.toml
@@ -15,7 +15,6 @@ log = "0.4.8"
 rustc-hash = "1.1.0"
 either = "1.6.1"
 
-assists = { path = "../assists", version = "0.0.0" }
 stdx = { path = "../stdx", version = "0.0.0" }
 syntax = { path = "../syntax", version = "0.0.0" }
 text_edit = { path = "../text_edit", version = "0.0.0" }
diff --git a/crates/completion/src/completions/postfix.rs b/crates/completion/src/completions/postfix.rs
index 7fbda7a6b..c8ba63cd3 100644
--- a/crates/completion/src/completions/postfix.rs
+++ b/crates/completion/src/completions/postfix.rs
@@ -5,6 +5,7 @@ mod format_like;
 use ide_db::ty_filter::TryEnum;
 use syntax::{
     ast::{self, AstNode, AstToken},
+    SyntaxKind::{BLOCK_EXPR, EXPR_STMT},
     TextRange, TextSize,
 };
 use text_edit::TextEdit;
@@ -220,6 +221,29 @@ pub(crate) fn complete_postfix(acc: &mut Completions, ctx: &CompletionContext) {
     )
     .add_to(acc);
 
+    if let Some(parent) = dot_receiver.syntax().parent().and_then(|p| p.parent()) {
+        if matches!(parent.kind(), BLOCK_EXPR | EXPR_STMT) {
+            postfix_snippet(
+                ctx,
+                cap,
+                &dot_receiver,
+                "let",
+                "let",
+                &format!("let $0 = {};", receiver_text),
+            )
+            .add_to(acc);
+            postfix_snippet(
+                ctx,
+                cap,
+                &dot_receiver,
+                "letm",
+                "let mut",
+                &format!("let mut $0 = {};", receiver_text),
+            )
+            .add_to(acc);
+        }
+    }
+
     if let ast::Expr::Literal(literal) = dot_receiver.clone() {
         if let Some(literal_text) = ast::String::cast(literal.token()) {
             add_format_like_completions(acc, ctx, &dot_receiver, cap, &literal_text);
@@ -296,6 +320,38 @@ fn main() {
                 sn dbg   dbg!(expr)
                 sn dbgr  dbg!(&expr)
                 sn if    if expr {}
+                sn let   let
+                sn letm  let mut
+                sn match match expr {}
+                sn not   !expr
+                sn ok    Ok(expr)
+                sn ref   &expr
+                sn refm  &mut expr
+                sn some  Some(expr)
+                sn while while expr {}
+            "#]],
+        );
+    }
+
+    #[test]
+    fn postfix_completion_works_for_function_calln() {
+        check(
+            r#"
+fn foo(elt: bool) -> bool {
+    !elt
+}
+
+fn main() {
+    let bar = true;
+    foo(bar.<|>)
+}
+"#,
+            expect![[r#"
+                sn box   Box::new(expr)
+                sn call  function(expr)
+                sn dbg   dbg!(expr)
+                sn dbgr  dbg!(&expr)
+                sn if    if expr {}
                 sn match match expr {}
                 sn not   !expr
                 sn ok    Ok(expr)
@@ -321,6 +377,8 @@ fn main() {
                 sn call  function(expr)
                 sn dbg   dbg!(expr)
                 sn dbgr  dbg!(&expr)
+                sn let   let
+                sn letm  let mut
                 sn match match expr {}
                 sn ok    Ok(expr)
                 sn ref   &expr
@@ -331,6 +389,34 @@ fn main() {
     }
 
     #[test]
+    fn let_middle_block() {
+        check(
+            r#"
+fn main() {
+    baz.l<|>
+    res
+}
+"#,
+            expect![[r#"
+                sn box   Box::new(expr)
+                sn call  function(expr)
+                sn dbg   dbg!(expr)
+                sn dbgr  dbg!(&expr)
+                sn if    if expr {}
+                sn let   let
+                sn letm  let mut
+                sn match match expr {}
+                sn not   !expr
+                sn ok    Ok(expr)
+                sn ref   &expr
+                sn refm  &mut expr
+                sn some  Some(expr)
+                sn while while expr {}
+            "#]],
+        );
+    }
+
+    #[test]
     fn option_iflet() {
         check_edit(
             "ifl",
diff --git a/crates/completion/src/completions/qualified_path.rs b/crates/completion/src/completions/qualified_path.rs
index d9387054d..bc23bea3f 100644
--- a/crates/completion/src/completions/qualified_path.rs
+++ b/crates/completion/src/completions/qualified_path.rs
@@ -353,10 +353,10 @@ impl S {
 fn foo() { let _ = S::<|> }
 "#,
             expect![[r#"
-                ct C   const C: i32 = 42;
-                ta T   type T = i32;
-                fn a() fn a()
-                me b() fn b(&self)
+                ct C    const C: i32 = 42;
+                ta T    type T = i32;
+                fn a()  fn a()
+                me b(…) fn b(&self)
             "#]],
         );
     }
@@ -503,14 +503,14 @@ trait Sub: Super {
 fn foo<T: Sub>() { T::<|> }
 "#,
             expect![[r#"
-                ct C2          const C2: ();
-                ct CONST       const CONST: u8;
-                ta SubTy       type SubTy;
-                ta Ty          type Ty;
-                fn func()      fn func()
-                me method()    fn method(&self)
-                fn subfunc()   fn subfunc()
-                me submethod() fn submethod(&self)
+                ct C2           const C2: ();
+                ct CONST        const CONST: u8;
+                ta SubTy        type SubTy;
+                ta Ty           type Ty;
+                fn func()       fn func()
+                me method(…)    fn method(&self)
+                fn subfunc()    fn subfunc()
+                me submethod(…) fn submethod(&self)
             "#]],
         );
     }
@@ -543,14 +543,14 @@ impl<T> Sub for Wrap<T> {
 }
 "#,
             expect![[r#"
-                ct C2          const C2: () = ();
-                ct CONST       const CONST: u8 = 0;
-                ta SubTy       type SubTy;
-                ta Ty          type Ty;
-                fn func()      fn func()
-                me method()    fn method(&self)
-                fn subfunc()   fn subfunc()
-                me submethod() fn submethod(&self)
+                ct C2           const C2: () = ();
+                ct CONST        const CONST: u8 = 0;
+                ta SubTy        type SubTy;
+                ta Ty           type Ty;
+                fn func()       fn func()
+                me method(…)    fn method(&self)
+                fn subfunc()    fn subfunc()
+                me submethod(…) fn submethod(&self)
             "#]],
         );
     }
diff --git a/crates/completion/src/completions/record.rs b/crates/completion/src/completions/record.rs
index 2049b9d09..eaa44c97d 100644
--- a/crates/completion/src/completions/record.rs
+++ b/crates/completion/src/completions/record.rs
@@ -1,5 +1,5 @@
 //! Complete fields in record literals and patterns.
-use assists::utils::FamousDefs;
+use ide_db::helpers::FamousDefs;
 use syntax::ast::Expr;
 
 use crate::{
@@ -45,8 +45,8 @@ pub(crate) fn complete_record(acc: &mut Completions, ctx: &CompletionContext) ->
 
 #[cfg(test)]
 mod tests {
-    use assists::utils::FamousDefs;
     use expect_test::{expect, Expect};
+    use ide_db::helpers::FamousDefs;
 
     use crate::{test_utils::completion_list, CompletionKind};
 
diff --git a/crates/completion/src/completions/trait_impl.rs b/crates/completion/src/completions/trait_impl.rs
index a14be9c73..e2fe44aff 100644
--- a/crates/completion/src/completions/trait_impl.rs
+++ b/crates/completion/src/completions/trait_impl.rs
@@ -139,7 +139,7 @@ fn add_function_impl(
 ) {
     let fn_name = func.name(ctx.db).to_string();
 
-    let label = if func.params(ctx.db).is_empty() {
+    let label = if func.assoc_fn_params(ctx.db).is_empty() {
         format!("fn {}()", fn_name)
     } else {
         format!("fn {}(..)", fn_name)
diff --git a/crates/completion/src/completions/unqualified_path.rs b/crates/completion/src/completions/unqualified_path.rs
index 3bd776905..81691cd7f 100644
--- a/crates/completion/src/completions/unqualified_path.rs
+++ b/crates/completion/src/completions/unqualified_path.rs
@@ -1,8 +1,8 @@
 //! Completion of names from the current scope, e.g. locals and imported items.
 
-use assists::utils::ImportScope;
 use either::Either;
 use hir::{Adt, ModuleDef, ScopeDef, Type};
+use ide_db::helpers::insert_use::ImportScope;
 use ide_db::imports_locator;
 use syntax::AstNode;
 use test_utils::mark;
diff --git a/crates/completion/src/config.rs b/crates/completion/src/config.rs
index f50735372..654a76f7b 100644
--- a/crates/completion/src/config.rs
+++ b/crates/completion/src/config.rs
@@ -4,7 +4,7 @@
 //! module, and we use to statically check that we only produce snippet
 //! completions if we are allowed to.
 
-use assists::utils::MergeBehaviour;
+use ide_db::helpers::insert_use::MergeBehaviour;
 
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub struct CompletionConfig {
diff --git a/crates/completion/src/item.rs b/crates/completion/src/item.rs
index b13c3f376..e85549fef 100644
--- a/crates/completion/src/item.rs
+++ b/crates/completion/src/item.rs
@@ -2,8 +2,11 @@
 
 use std::fmt;
 
-use assists::utils::{insert_use, mod_path_to_ast, ImportScope, MergeBehaviour};
 use hir::{Documentation, ModPath, Mutability};
+use ide_db::helpers::{
+    insert_use::{self, ImportScope, MergeBehaviour},
+    mod_path_to_ast,
+};
 use syntax::{algo, TextRange};
 use text_edit::TextEdit;
 
@@ -201,7 +204,7 @@ impl CompletionItem {
             trigger_call_info: None,
             score: None,
             ref_match: None,
-            import_data: None,
+            import_to_add: None,
         }
     }
 
@@ -255,13 +258,21 @@ impl CompletionItem {
     }
 }
 
+/// An extra import to add after the completion is applied.
+#[derive(Clone)]
+pub(crate) struct ImportToAdd {
+    pub(crate) import_path: ModPath,
+    pub(crate) import_scope: ImportScope,
+    pub(crate) merge_behaviour: Option<MergeBehaviour>,
+}
+
 /// A helper to make `CompletionItem`s.
 #[must_use]
 #[derive(Clone)]
 pub(crate) struct Builder {
     source_range: TextRange,
     completion_kind: CompletionKind,
-    import_data: Option<(ModPath, ImportScope, Option<MergeBehaviour>)>,
+    import_to_add: Option<ImportToAdd>,
     label: String,
     insert_text: Option<String>,
     insert_text_format: InsertTextFormat,
@@ -278,14 +289,16 @@ pub(crate) struct Builder {
 
 impl Builder {
     pub(crate) fn build(self) -> CompletionItem {
+        let _p = profile::span("item::Builder::build");
+
         let mut label = self.label;
         let mut lookup = self.lookup;
         let mut insert_text = self.insert_text;
         let mut text_edits = TextEdit::builder();
 
-        if let Some((import_path, import_scope, merge_behaviour)) = self.import_data {
-            let import = mod_path_to_ast(&import_path);
-            let mut import_path_without_last_segment = import_path;
+        if let Some(import_data) = self.import_to_add {
+            let import = mod_path_to_ast(&import_data.import_path);
+            let mut import_path_without_last_segment = import_data.import_path;
             let _ = import_path_without_last_segment.segments.pop();
 
             if !import_path_without_last_segment.segments.is_empty() {
@@ -298,7 +311,11 @@ impl Builder {
                 label = format!("{}::{}", import_path_without_last_segment, label);
             }
 
-            let rewriter = insert_use(&import_scope, import, merge_behaviour);
+            let rewriter = insert_use::insert_use(
+                &import_data.import_scope,
+                import,
+                import_data.merge_behaviour,
+            );
             if let Some(old_ast) = rewriter.rewrite_root() {
                 algo::diff(&old_ast, &rewriter.rewrite(&old_ast)).into_text_edit(&mut text_edits);
             }
@@ -390,11 +407,8 @@ impl Builder {
         self.trigger_call_info = Some(true);
         self
     }
-    pub(crate) fn import_data(
-        mut self,
-        import_data: Option<(ModPath, ImportScope, Option<MergeBehaviour>)>,
-    ) -> Builder {
-        self.import_data = import_data;
+    pub(crate) fn add_import(mut self, import_to_add: Option<ImportToAdd>) -> Builder {
+        self.import_to_add = import_to_add;
         self
     }
     pub(crate) fn set_ref_match(
diff --git a/crates/completion/src/lib.rs b/crates/completion/src/lib.rs
index aecc1378b..1ec2e9be7 100644
--- a/crates/completion/src/lib.rs
+++ b/crates/completion/src/lib.rs
@@ -44,6 +44,8 @@ pub use crate::{
 // - `expr.while` -> `while expr {}` or `while let ... {}` for `Option` or `Result`
 // - `expr.ref` -> `&expr`
 // - `expr.refm` -> `&mut expr`
+// - `expr.let` -> `let <|> = expr;`
+// - `expr.letm` -> `let mut <|> = expr;`
 // - `expr.not` -> `!expr`
 // - `expr.dbg` -> `dbg!(expr)`
 // - `expr.dbgr` -> `dbg!(&expr)`
diff --git a/crates/completion/src/render.rs b/crates/completion/src/render.rs
index bce02f577..504757a6a 100644
--- a/crates/completion/src/render.rs
+++ b/crates/completion/src/render.rs
@@ -9,15 +9,15 @@ pub(crate) mod type_alias;
 
 mod builder_ext;
 
-use assists::utils::{ImportScope, MergeBehaviour};
 use hir::{Documentation, HasAttrs, HirDisplay, ModPath, Mutability, ScopeDef, Type};
+use ide_db::helpers::insert_use::{ImportScope, MergeBehaviour};
 use ide_db::RootDatabase;
 use syntax::TextRange;
 use test_utils::mark;
 
 use crate::{
-    config::SnippetCap, CompletionContext, CompletionItem, CompletionItemKind, CompletionKind,
-    CompletionScore,
+    config::SnippetCap, item::ImportToAdd, CompletionContext, CompletionItem, CompletionItemKind,
+    CompletionKind, CompletionScore,
 };
 
 use crate::render::{enum_variant::render_enum_variant, function::render_fn, macro_::render_macro};
@@ -48,15 +48,15 @@ pub(crate) fn render_resolution<'a>(
 
 pub(crate) fn render_resolution_with_import<'a>(
     ctx: RenderContext<'a>,
-    import: ModPath,
+    import_path: ModPath,
     import_scope: ImportScope,
     merge_behaviour: Option<MergeBehaviour>,
     resolution: &ScopeDef,
 ) -> Option<CompletionItem> {
-    let local_name = import.segments.last()?.to_string();
+    let local_name = import_path.segments.last()?.to_string();
     Render::new(ctx).render_resolution(
         local_name,
-        Some((import, import_scope, merge_behaviour)),
+        Some(ImportToAdd { import_path, import_scope, merge_behaviour }),
         resolution,
     )
 }
@@ -147,7 +147,7 @@ impl<'a> Render<'a> {
     fn render_resolution(
         self,
         local_name: String,
-        import_data: Option<(ModPath, ImportScope, Option<MergeBehaviour>)>,
+        import_to_add: Option<ImportToAdd>,
         resolution: &ScopeDef,
     ) -> Option<CompletionItem> {
         let _p = profile::span("render_resolution");
@@ -160,15 +160,16 @@ impl<'a> Render<'a> {
 
         let kind = match resolution {
             ScopeDef::ModuleDef(Function(func)) => {
-                let item = render_fn(self.ctx, import_data, Some(local_name), *func);
+                let item = render_fn(self.ctx, import_to_add, Some(local_name), *func);
                 return Some(item);
             }
             ScopeDef::ModuleDef(EnumVariant(var)) => {
-                let item = render_enum_variant(self.ctx, import_data, Some(local_name), *var, None);
+                let item =
+                    render_enum_variant(self.ctx, import_to_add, Some(local_name), *var, None);
                 return Some(item);
             }
             ScopeDef::MacroDef(mac) => {
-                let item = render_macro(self.ctx, import_data, local_name, *mac);
+                let item = render_macro(self.ctx, import_to_add, local_name, *mac);
                 return item;
             }
 
@@ -193,7 +194,7 @@ impl<'a> Render<'a> {
                     local_name,
                 )
                 .kind(CompletionItemKind::UnresolvedReference)
-                .import_data(import_data)
+                .add_import(import_to_add)
                 .build();
                 return Some(item);
             }
@@ -248,7 +249,7 @@ impl<'a> Render<'a> {
 
         let item = item
             .kind(kind)
-            .import_data(import_data)
+            .add_import(import_to_add)
             .set_documentation(docs)
             .set_ref_match(ref_match)
             .build();
diff --git a/crates/completion/src/render/builder_ext.rs b/crates/completion/src/render/builder_ext.rs
index 37b0d0459..ce8718bd5 100644
--- a/crates/completion/src/render/builder_ext.rs
+++ b/crates/completion/src/render/builder_ext.rs
@@ -5,6 +5,7 @@ use test_utils::mark;
 
 use crate::{item::Builder, CompletionContext};
 
+#[derive(Debug)]
 pub(super) enum Params {
     Named(Vec<String>),
     Anonymous(usize),
@@ -24,7 +25,7 @@ impl Params {
 }
 
 impl Builder {
-    pub(super) fn should_add_parems(&self, ctx: &CompletionContext) -> bool {
+    fn should_add_parens(&self, ctx: &CompletionContext) -> bool {
         if !ctx.config.add_call_parenthesis {
             return false;
         }
@@ -58,7 +59,7 @@ impl Builder {
         name: String,
         params: Params,
     ) -> Builder {
-        if !self.should_add_parems(ctx) {
+        if !self.should_add_parens(ctx) {
             return self;
         }
 
diff --git a/crates/completion/src/render/enum_variant.rs b/crates/completion/src/render/enum_variant.rs
index 6070e9b1d..f4bd02f25 100644
--- a/crates/completion/src/render/enum_variant.rs
+++ b/crates/completion/src/render/enum_variant.rs
@@ -1,23 +1,23 @@
 //! Renderer for `enum` variants.
 
-use assists::utils::{ImportScope, MergeBehaviour};
 use hir::{HasAttrs, HirDisplay, ModPath, StructKind};
 use itertools::Itertools;
 use test_utils::mark;
 
 use crate::{
-    item::{CompletionItem, CompletionItemKind, CompletionKind},
+    item::{CompletionItem, CompletionItemKind, CompletionKind, ImportToAdd},
     render::{builder_ext::Params, RenderContext},
 };
 
 pub(crate) fn render_enum_variant<'a>(
     ctx: RenderContext<'a>,
-    import_data: Option<(ModPath, ImportScope, Option<MergeBehaviour>)>,
+    import_to_add: Option<ImportToAdd>,
     local_name: Option<String>,
     variant: hir::EnumVariant,
     path: Option<ModPath>,
 ) -> CompletionItem {
-    EnumVariantRender::new(ctx, local_name, variant, path).render(import_data)
+    let _p = profile::span("render_enum_variant");
+    EnumVariantRender::new(ctx, local_name, variant, path).render(import_to_add)
 }
 
 #[derive(Debug)]
@@ -62,10 +62,7 @@ impl<'a> EnumVariantRender<'a> {
         }
     }
 
-    fn render(
-        self,
-        import_data: Option<(ModPath, ImportScope, Option<MergeBehaviour>)>,
-    ) -> CompletionItem {
+    fn render(self, import_to_add: Option<ImportToAdd>) -> CompletionItem {
         let mut builder = CompletionItem::new(
             CompletionKind::Reference,
             self.ctx.source_range(),
@@ -74,7 +71,7 @@ impl<'a> EnumVariantRender<'a> {
         .kind(CompletionItemKind::EnumVariant)
         .set_documentation(self.variant.docs(self.ctx.db()))
         .set_deprecated(self.ctx.is_deprecated(self.variant))
-        .import_data(import_data)
+        .add_import(import_to_add)
         .detail(self.detail());
 
         if self.variant_kind == StructKind::Tuple {
diff --git a/crates/completion/src/render/function.rs b/crates/completion/src/render/function.rs
index 9dd5cd18c..00e3eb203 100644
--- a/crates/completion/src/render/function.rs
+++ b/crates/completion/src/render/function.rs
@@ -1,28 +1,29 @@
 //! Renderer for function calls.
 
-use assists::utils::{ImportScope, MergeBehaviour};
-use hir::{HasSource, ModPath, Type};
+use hir::{HasSource, Type};
 use syntax::{ast::Fn, display::function_declaration};
+use test_utils::mark;
 
 use crate::{
-    item::{CompletionItem, CompletionItemKind, CompletionKind},
+    item::{CompletionItem, CompletionItemKind, CompletionKind, ImportToAdd},
     render::{builder_ext::Params, RenderContext},
 };
 
 pub(crate) fn render_fn<'a>(
     ctx: RenderContext<'a>,
-    import_data: Option<(ModPath, ImportScope, Option<MergeBehaviour>)>,
+    import_to_add: Option<ImportToAdd>,
     local_name: Option<String>,
     fn_: hir::Function,
 ) -> CompletionItem {
-    FunctionRender::new(ctx, local_name, fn_).render(import_data)
+    let _p = profile::span("render_fn");
+    FunctionRender::new(ctx, local_name, fn_).render(import_to_add)
 }
 
 #[derive(Debug)]
 struct FunctionRender<'a> {
     ctx: RenderContext<'a>,
     name: String,
-    fn_: hir::Function,
+    func: hir::Function,
     ast_node: Fn,
 }
 
@@ -35,21 +36,18 @@ impl<'a> FunctionRender<'a> {
         let name = local_name.unwrap_or_else(|| fn_.name(ctx.db()).to_string());
         let ast_node = fn_.source(ctx.db()).value;
 
-        FunctionRender { ctx, name, fn_, ast_node }
+        FunctionRender { ctx, name, func: fn_, ast_node }
     }
 
-    fn render(
-        self,
-        import_data: Option<(ModPath, ImportScope, Option<MergeBehaviour>)>,
-    ) -> CompletionItem {
+    fn render(self, import_to_add: Option<ImportToAdd>) -> CompletionItem {
         let params = self.params();
         CompletionItem::new(CompletionKind::Reference, self.ctx.source_range(), self.name.clone())
             .kind(self.kind())
-            .set_documentation(self.ctx.docs(self.fn_))
-            .set_deprecated(self.ctx.is_deprecated(self.fn_))
+            .set_documentation(self.ctx.docs(self.func))
+            .set_deprecated(self.ctx.is_deprecated(self.func))
             .detail(self.detail())
             .add_call_parens(self.ctx.completion, self.name, params)
-            .import_data(import_data)
+            .add_import(import_to_add)
             .build()
     }
 
@@ -70,27 +68,39 @@ impl<'a> FunctionRender<'a> {
     }
 
     fn params(&self) -> Params {
-        let params_ty = self.fn_.params(self.ctx.db());
-        let params = self
-            .ast_node
-            .param_list()
+        let ast_params = match self.ast_node.param_list() {
+            Some(it) => it,
+            None => return Params::Named(Vec::new()),
+        };
+
+        let mut params_pats = Vec::new();
+        let params_ty = if self.ctx.completion.dot_receiver.is_some() {
+            self.func.method_params(self.ctx.db()).unwrap_or_default()
+        } else {
+            if let Some(s) = ast_params.self_param() {
+                mark::hit!(parens_for_method_call_as_assoc_fn);
+                params_pats.push(Some(s.to_string()));
+            }
+            self.func.assoc_fn_params(self.ctx.db())
+        };
+        params_pats
+            .extend(ast_params.params().into_iter().map(|it| it.pat().map(|it| it.to_string())));
+
+        let params = params_pats
             .into_iter()
-            .flat_map(|it| it.params())
             .zip(params_ty)
-            .flat_map(|(it, param_ty)| {
-                if let Some(pat) = it.pat() {
-                    let name = pat.to_string();
-                    let arg = name.trim_start_matches("mut ").trim_start_matches('_');
-                    return Some(self.add_arg(arg, param_ty.ty()));
-                }
-                None
+            .flat_map(|(pat, param_ty)| {
+                let pat = pat?;
+                let name = pat.to_string();
+                let arg = name.trim_start_matches("mut ").trim_start_matches('_');
+                Some(self.add_arg(arg, param_ty.ty()))
             })
             .collect();
         Params::Named(params)
     }
 
     fn kind(&self) -> CompletionItemKind {
-        if self.fn_.self_param(self.ctx.db()).is_some() {
+        if self.func.self_param(self.ctx.db()).is_some() {
             CompletionItemKind::Method
         } else {
             CompletionItemKind::Function
@@ -176,6 +186,28 @@ fn bar(s: &S) {
     }
 
     #[test]
+    fn parens_for_method_call_as_assoc_fn() {
+        mark::check!(parens_for_method_call_as_assoc_fn);
+        check_edit(
+            "foo",
+            r#"
+struct S;
+impl S {
+    fn foo(&self) {}
+}
+fn main() { S::f<|> }
+"#,
+            r#"
+struct S;
+impl S {
+    fn foo(&self) {}
+}
+fn main() { S::foo(${1:&self})$0 }
+"#,
+        );
+    }
+
+    #[test]
     fn suppress_arg_snippets() {
         mark::check!(suppress_arg_snippets);
         check_edit_with_config(
diff --git a/crates/completion/src/render/macro_.rs b/crates/completion/src/render/macro_.rs
index fead59e41..b4ab32c6e 100644
--- a/crates/completion/src/render/macro_.rs
+++ b/crates/completion/src/render/macro_.rs
@@ -1,22 +1,22 @@
 //! Renderer for macro invocations.
 
-use assists::utils::{ImportScope, MergeBehaviour};
-use hir::{Documentation, HasSource, ModPath};
+use hir::{Documentation, HasSource};
 use syntax::display::macro_label;
 use test_utils::mark;
 
 use crate::{
-    item::{CompletionItem, CompletionItemKind, CompletionKind},
+    item::{CompletionItem, CompletionItemKind, CompletionKind, ImportToAdd},
     render::RenderContext,
 };
 
 pub(crate) fn render_macro<'a>(
     ctx: RenderContext<'a>,
-    import_data: Option<(ModPath, ImportScope, Option<MergeBehaviour>)>,
+    import_to_add: Option<ImportToAdd>,
     name: String,
     macro_: hir::MacroDef,
 ) -> Option<CompletionItem> {
-    MacroRender::new(ctx, name, macro_).render(import_data)
+    let _p = profile::span("render_macro");
+    MacroRender::new(ctx, name, macro_).render(import_to_add)
 }
 
 #[derive(Debug)]
@@ -38,10 +38,7 @@ impl<'a> MacroRender<'a> {
         MacroRender { ctx, name, macro_, docs, bra, ket }
     }
 
-    fn render(
-        &self,
-        import_data: Option<(ModPath, ImportScope, Option<MergeBehaviour>)>,
-    ) -> Option<CompletionItem> {
+    fn render(&self, import_to_add: Option<ImportToAdd>) -> Option<CompletionItem> {
         // FIXME: Currently proc-macro do not have ast-node,
         // such that it does not have source
         if self.macro_.is_proc_macro() {
@@ -53,7 +50,7 @@ impl<'a> MacroRender<'a> {
                 .kind(CompletionItemKind::Macro)
                 .set_documentation(self.docs.clone())
                 .set_deprecated(self.ctx.is_deprecated(self.macro_))
-                .import_data(import_data)
+                .add_import(import_to_add)
                 .detail(self.detail());
 
         let needs_bang = self.needs_bang();
diff --git a/crates/hir/src/code_model.rs b/crates/hir/src/code_model.rs
index 37ed092ad..4500050f1 100644
--- a/crates/hir/src/code_model.rs
+++ b/crates/hir/src/code_model.rs
@@ -744,14 +744,13 @@ impl Function {
         Some(SelfParam { func: self.id })
     }
 
-    pub fn params(self, db: &dyn HirDatabase) -> Vec<Param> {
+    pub fn assoc_fn_params(self, db: &dyn HirDatabase) -> Vec<Param> {
         let resolver = self.id.resolver(db.upcast());
         let ctx = hir_ty::TyLoweringContext::new(db, &resolver);
         let environment = TraitEnvironment::lower(db, &resolver);
         db.function_data(self.id)
             .params
             .iter()
-            .skip(if self.self_param(db).is_some() { 1 } else { 0 })
             .map(|type_ref| {
                 let ty = Type {
                     krate: self.id.lookup(db.upcast()).container.module(db.upcast()).krate,
@@ -764,6 +763,14 @@ impl Function {
             })
             .collect()
     }
+    pub fn method_params(self, db: &dyn HirDatabase) -> Option<Vec<Param>> {
+        if self.self_param(db).is_none() {
+            return None;
+        }
+        let mut res = self.assoc_fn_params(db);
+        res.remove(0);
+        Some(res)
+    }
 
     pub fn is_unsafe(self, db: &dyn HirDatabase) -> bool {
         db.function_data(self.id).is_unsafe
@@ -799,6 +806,7 @@ impl From<Mutability> for Access {
     }
 }
 
+#[derive(Debug)]
 pub struct Param {
     ty: Type,
 }
@@ -1420,11 +1428,11 @@ impl Type {
     pub fn normalize_trait_assoc_type(
         &self,
         db: &dyn HirDatabase,
-        r#trait: Trait,
+        trait_: Trait,
         args: &[Type],
         alias: TypeAlias,
     ) -> Option<Type> {
-        let subst = Substs::build_for_def(db, r#trait.id)
+        let subst = Substs::build_for_def(db, trait_.id)
             .push(self.ty.value.clone())
             .fill(args.iter().map(|t| t.ty.value.clone()))
             .build();
diff --git a/crates/hir/src/diagnostics.rs b/crates/hir/src/diagnostics.rs
index d9ad8db6f..eaf1a14ec 100644
--- a/crates/hir/src/diagnostics.rs
+++ b/crates/hir/src/diagnostics.rs
@@ -1,5 +1,5 @@
 //! FIXME: write short doc here
-pub use hir_def::diagnostics::{InactiveCode, UnresolvedModule};
+pub use hir_def::diagnostics::{InactiveCode, UnresolvedModule, UnresolvedProcMacro};
 pub use hir_expand::diagnostics::{
     Diagnostic, DiagnosticCode, DiagnosticSink, DiagnosticSinkBuilder,
 };
diff --git a/crates/hir_def/src/body.rs b/crates/hir_def/src/body.rs
index d10b1af01..33eb5e78c 100644
--- a/crates/hir_def/src/body.rs
+++ b/crates/hir_def/src/body.rs
@@ -14,8 +14,8 @@ use cfg::CfgOptions;
 use drop_bomb::DropBomb;
 use either::Either;
 use hir_expand::{
-    ast_id_map::AstIdMap, diagnostics::DiagnosticSink, hygiene::Hygiene, AstId, HirFileId, InFile,
-    MacroDefId,
+    ast_id_map::AstIdMap, diagnostics::DiagnosticSink, hygiene::Hygiene, AstId, ExpandResult,
+    HirFileId, InFile, MacroDefId,
 };
 use rustc_hash::FxHashMap;
 use syntax::{ast, AstNode, AstPtr};
@@ -102,11 +102,11 @@ impl Expander {
         db: &dyn DefDatabase,
         local_scope: Option<&ItemScope>,
         macro_call: ast::MacroCall,
-    ) -> Option<(Mark, T)> {
+    ) -> ExpandResult<Option<(Mark, T)>> {
         self.recursion_limit += 1;
         if self.recursion_limit > EXPANSION_RECURSION_LIMIT {
             mark::hit!(your_stack_belongs_to_me);
-            return None;
+            return ExpandResult::str_err("reached recursion limit during macro expansion".into());
         }
 
         let macro_call = InFile::new(self.current_file_id, &macro_call);
@@ -120,28 +120,55 @@ impl Expander {
             self.resolve_path_as_macro(db, &path)
         };
 
-        if let Some(call_id) = macro_call.as_call_id(db, self.crate_def_map.krate, resolver) {
-            let file_id = call_id.as_file();
-            if let Some(node) = db.parse_or_expand(file_id) {
-                if let Some(expr) = T::cast(node) {
-                    log::debug!("macro expansion {:#?}", expr.syntax());
-
-                    let mark = Mark {
-                        file_id: self.current_file_id,
-                        ast_id_map: mem::take(&mut self.ast_id_map),
-                        bomb: DropBomb::new("expansion mark dropped"),
-                    };
-                    self.cfg_expander.hygiene = Hygiene::new(db.upcast(), file_id);
-                    self.current_file_id = file_id;
-                    self.ast_id_map = db.ast_id_map(file_id);
-                    return Some((mark, expr));
+        let call_id = match macro_call.as_call_id(db, self.crate_def_map.krate, resolver) {
+            Some(it) => it,
+            None => {
+                // FIXME: this can mean other things too, but `as_call_id` doesn't provide enough
+                // info.
+                return ExpandResult::only_err(mbe::ExpandError::Other(
+                    "failed to parse or resolve macro invocation".into(),
+                ));
+            }
+        };
+
+        let err = db.macro_expand_error(call_id);
+
+        let file_id = call_id.as_file();
+
+        let raw_node = match db.parse_or_expand(file_id) {
+            Some(it) => it,
+            None => {
+                // Only `None` if the macro expansion produced no usable AST.
+                if err.is_none() {
+                    log::warn!("no error despite `parse_or_expand` failing");
                 }
+
+                return ExpandResult::only_err(err.unwrap_or_else(|| {
+                    mbe::ExpandError::Other("failed to parse macro invocation".into())
+                }));
             }
-        }
+        };
+
+        let node = match T::cast(raw_node) {
+            Some(it) => it,
+            None => {
+                // This can happen without being an error, so only forward previous errors.
+                return ExpandResult { value: None, err };
+            }
+        };
+
+        log::debug!("macro expansion {:#?}", node.syntax());
+
+        let mark = Mark {
+            file_id: self.current_file_id,
+            ast_id_map: mem::take(&mut self.ast_id_map),
+            bomb: DropBomb::new("expansion mark dropped"),
+        };
+        self.cfg_expander.hygiene = Hygiene::new(db.upcast(), file_id);
+        self.current_file_id = file_id;
+        self.ast_id_map = db.ast_id_map(file_id);
 
-        // FIXME: Instead of just dropping the error from expansion
-        // report it
-        None
+        ExpandResult { value: Some((mark, node)), err }
     }
 
     pub(crate) fn exit(&mut self, db: &dyn DefDatabase, mut mark: Mark) {
diff --git a/crates/hir_def/src/body/diagnostics.rs b/crates/hir_def/src/body/diagnostics.rs
index e57bdc133..1de7d30e2 100644
--- a/crates/hir_def/src/body/diagnostics.rs
+++ b/crates/hir_def/src/body/diagnostics.rs
@@ -2,11 +2,13 @@
 
 use hir_expand::diagnostics::DiagnosticSink;
 
-use crate::diagnostics::InactiveCode;
+use crate::diagnostics::{InactiveCode, MacroError, UnresolvedProcMacro};
 
 #[derive(Debug, Eq, PartialEq)]
 pub(crate) enum BodyDiagnostic {
     InactiveCode(InactiveCode),
+    MacroError(MacroError),
+    UnresolvedProcMacro(UnresolvedProcMacro),
 }
 
 impl BodyDiagnostic {
@@ -15,6 +17,12 @@ impl BodyDiagnostic {
             BodyDiagnostic::InactiveCode(diag) => {
                 sink.push(diag.clone());
             }
+            BodyDiagnostic::MacroError(diag) => {
+                sink.push(diag.clone());
+            }
+            BodyDiagnostic::UnresolvedProcMacro(diag) => {
+                sink.push(diag.clone());
+            }
         }
     }
 }
diff --git a/crates/hir_def/src/body/lower.rs b/crates/hir_def/src/body/lower.rs
index cd7958746..2c41c0005 100644
--- a/crates/hir_def/src/body/lower.rs
+++ b/crates/hir_def/src/body/lower.rs
@@ -8,7 +8,7 @@ use either::Either;
 use hir_expand::{
     hygiene::Hygiene,
     name::{name, AsName, Name},
-    HirFileId, MacroDefId, MacroDefKind,
+    ExpandError, HirFileId, MacroDefId, MacroDefKind,
 };
 use rustc_hash::FxHashMap;
 use syntax::{
@@ -25,7 +25,7 @@ use crate::{
     body::{Body, BodySourceMap, Expander, PatPtr, SyntheticSyntax},
     builtin_type::{BuiltinFloat, BuiltinInt},
     db::DefDatabase,
-    diagnostics::InactiveCode,
+    diagnostics::{InactiveCode, MacroError, UnresolvedProcMacro},
     expr::{
         dummy_expr_id, ArithOp, Array, BinaryOp, BindingAnnotation, CmpOp, Expr, ExprId, Literal,
         LogicOp, MatchArm, Ordering, Pat, PatId, RecordFieldPat, RecordLitField, Statement,
@@ -561,7 +561,32 @@ impl ExprCollector<'_> {
                     self.alloc_expr(Expr::Missing, syntax_ptr)
                 } else {
                     let macro_call = self.expander.to_source(AstPtr::new(&e));
-                    match self.expander.enter_expand(self.db, Some(&self.body.item_scope), e) {
+                    let res = self.expander.enter_expand(self.db, Some(&self.body.item_scope), e);
+
+                    match res.err {
+                        Some(ExpandError::UnresolvedProcMacro) => {
+                            self.source_map.diagnostics.push(BodyDiagnostic::UnresolvedProcMacro(
+                                UnresolvedProcMacro {
+                                    file: self.expander.current_file_id,
+                                    node: syntax_ptr.clone().into(),
+                                    precise_location: None,
+                                    macro_name: None,
+                                },
+                            ));
+                        }
+                        Some(err) => {
+                            self.source_map.diagnostics.push(BodyDiagnostic::MacroError(
+                                MacroError {
+                                    file: self.expander.current_file_id,
+                                    node: syntax_ptr.clone().into(),
+                                    message: err.to_string(),
+                                },
+                            ));
+                        }
+                        None => {}
+                    }
+
+                    match res.value {
                         Some((mark, expansion)) => {
                             self.source_map
                                 .expansions
diff --git a/crates/hir_def/src/data.rs b/crates/hir_def/src/data.rs
index ff1ef0df6..146045938 100644
--- a/crates/hir_def/src/data.rs
+++ b/crates/hir_def/src/data.rs
@@ -257,7 +257,7 @@ fn collect_items(
                 let root = db.parse_or_expand(file_id).unwrap();
                 let call = ast_id_map.get(call.ast_id).to_node(&root);
 
-                if let Some((mark, mac)) = expander.enter_expand(db, None, call) {
+                if let Some((mark, mac)) = expander.enter_expand(db, None, call).value {
                     let src: InFile<ast::MacroItems> = expander.to_source(mac);
                     let item_tree = db.item_tree(src.file_id);
                     let iter =
diff --git a/crates/hir_def/src/diagnostics.rs b/crates/hir_def/src/diagnostics.rs
index b221b290c..c71266dc0 100644
--- a/crates/hir_def/src/diagnostics.rs
+++ b/crates/hir_def/src/diagnostics.rs
@@ -6,7 +6,7 @@ use stdx::format_to;
 use cfg::{CfgExpr, CfgOptions, DnfExpr};
 use hir_expand::diagnostics::{Diagnostic, DiagnosticCode, DiagnosticSink};
 use hir_expand::{HirFileId, InFile};
-use syntax::{ast, AstPtr, SyntaxNodePtr};
+use syntax::{ast, AstPtr, SyntaxNodePtr, TextRange};
 
 use crate::{db::DefDatabase, DefWithBodyId};
 
@@ -127,3 +127,68 @@ impl Diagnostic for InactiveCode {
         self
     }
 }
+
+// Diagnostic: unresolved-proc-macro
+//
+// This diagnostic is shown when a procedural macro can not be found. This usually means that
+// procedural macro support is simply disabled (and hence is only a weak hint instead of an error),
+// but can also indicate project setup problems.
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct UnresolvedProcMacro {
+    pub file: HirFileId,
+    pub node: SyntaxNodePtr,
+    /// If the diagnostic can be pinpointed more accurately than via `node`, this is the `TextRange`
+    /// to use instead.
+    pub precise_location: Option<TextRange>,
+    pub macro_name: Option<String>,
+}
+
+impl Diagnostic for UnresolvedProcMacro {
+    fn code(&self) -> DiagnosticCode {
+        DiagnosticCode("unresolved-proc-macro")
+    }
+
+    fn message(&self) -> String {
+        match &self.macro_name {
+            Some(name) => format!("proc macro `{}` not expanded", name),
+            None => "proc macro not expanded".to_string(),
+        }
+    }
+
+    fn display_source(&self) -> InFile<SyntaxNodePtr> {
+        InFile::new(self.file, self.node.clone())
+    }
+
+    fn as_any(&self) -> &(dyn Any + Send + 'static) {
+        self
+    }
+}
+
+// Diagnostic: macro-error
+//
+// This diagnostic is shown for macro expansion errors.
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct MacroError {
+    pub file: HirFileId,
+    pub node: SyntaxNodePtr,
+    pub message: String,
+}
+
+impl Diagnostic for MacroError {
+    fn code(&self) -> DiagnosticCode {
+        DiagnosticCode("macro-error")
+    }
+    fn message(&self) -> String {
+        self.message.clone()
+    }
+    fn display_source(&self) -> InFile<SyntaxNodePtr> {
+        InFile::new(self.file, self.node.clone())
+    }
+    fn as_any(&self) -> &(dyn Any + Send + 'static) {
+        self
+    }
+    fn is_experimental(&self) -> bool {
+        // Newly added and not very well-tested, might contain false positives.
+        true
+    }
+}
diff --git a/crates/hir_def/src/nameres.rs b/crates/hir_def/src/nameres.rs
index 202a7dcb6..ffd0381d4 100644
--- a/crates/hir_def/src/nameres.rs
+++ b/crates/hir_def/src/nameres.rs
@@ -286,8 +286,9 @@ mod diagnostics {
     use cfg::{CfgExpr, CfgOptions};
     use hir_expand::diagnostics::DiagnosticSink;
     use hir_expand::hygiene::Hygiene;
-    use hir_expand::InFile;
-    use syntax::{ast, AstPtr};
+    use hir_expand::{InFile, MacroCallKind};
+    use syntax::ast::AttrsOwner;
+    use syntax::{ast, AstNode, AstPtr, SyntaxKind, SyntaxNodePtr};
 
     use crate::path::ModPath;
     use crate::{db::DefDatabase, diagnostics::*, nameres::LocalModuleId, AstId};
@@ -301,6 +302,10 @@ mod diagnostics {
         UnresolvedImport { ast: AstId<ast::Use>, index: usize },
 
         UnconfiguredCode { ast: AstId<ast::Item>, cfg: CfgExpr, opts: CfgOptions },
+
+        UnresolvedProcMacro { ast: MacroCallKind },
+
+        MacroError { ast: MacroCallKind, message: String },
     }
 
     #[derive(Debug, PartialEq, Eq)]
@@ -348,6 +353,18 @@ mod diagnostics {
             Self { in_module: container, kind: DiagnosticKind::UnconfiguredCode { ast, cfg, opts } }
         }
 
+        pub(super) fn unresolved_proc_macro(container: LocalModuleId, ast: MacroCallKind) -> Self {
+            Self { in_module: container, kind: DiagnosticKind::UnresolvedProcMacro { ast } }
+        }
+
+        pub(super) fn macro_error(
+            container: LocalModuleId,
+            ast: MacroCallKind,
+            message: String,
+        ) -> Self {
+            Self { in_module: container, kind: DiagnosticKind::MacroError { ast, message } }
+        }
+
         pub(super) fn add_to(
             &self,
             db: &dyn DefDatabase,
@@ -407,6 +424,72 @@ mod diagnostics {
                         opts: opts.clone(),
                     });
                 }
+
+                DiagnosticKind::UnresolvedProcMacro { ast } => {
+                    let mut precise_location = None;
+                    let (file, ast, name) = match ast {
+                        MacroCallKind::FnLike(ast) => {
+                            let node = ast.to_node(db.upcast());
+                            (ast.file_id, SyntaxNodePtr::from(AstPtr::new(&node)), None)
+                        }
+                        MacroCallKind::Attr(ast, name) => {
+                            let node = ast.to_node(db.upcast());
+
+                            // Compute the precise location of the macro name's token in the derive
+                            // list.
+                            // FIXME: This does not handle paths to the macro, but neither does the
+                            // rest of r-a.
+                            let derive_attrs =
+                                node.attrs().filter_map(|attr| match attr.as_simple_call() {
+                                    Some((name, args)) if name == "derive" => Some(args),
+                                    _ => None,
+                                });
+                            'outer: for attr in derive_attrs {
+                                let tokens =
+                                    attr.syntax().children_with_tokens().filter_map(|elem| {
+                                        match elem {
+                                            syntax::NodeOrToken::Node(_) => None,
+                                            syntax::NodeOrToken::Token(tok) => Some(tok),
+                                        }
+                                    });
+                                for token in tokens {
+                                    if token.kind() == SyntaxKind::IDENT
+                                        && token.to_string() == *name
+                                    {
+                                        precise_location = Some(token.text_range());
+                                        break 'outer;
+                                    }
+                                }
+                            }
+
+                            (
+                                ast.file_id,
+                                SyntaxNodePtr::from(AstPtr::new(&node)),
+                                Some(name.clone()),
+                            )
+                        }
+                    };
+                    sink.push(UnresolvedProcMacro {
+                        file,
+                        node: ast,
+                        precise_location,
+                        macro_name: name,
+                    });
+                }
+
+                DiagnosticKind::MacroError { ast, message } => {
+                    let (file, ast) = match ast {
+                        MacroCallKind::FnLike(ast) => {
+                            let node = ast.to_node(db.upcast());
+                            (ast.file_id, SyntaxNodePtr::from(AstPtr::new(&node)))
+                        }
+                        MacroCallKind::Attr(ast, _) => {
+                            let node = ast.to_node(db.upcast());
+                            (ast.file_id, SyntaxNodePtr::from(AstPtr::new(&node)))
+                        }
+                    };
+                    sink.push(MacroError { file, node: ast, message: message.clone() });
+                }
             }
         }
     }
diff --git a/crates/hir_def/src/nameres/collector.rs b/crates/hir_def/src/nameres/collector.rs
index 5ed9073e0..19cd713ba 100644
--- a/crates/hir_def/src/nameres/collector.rs
+++ b/crates/hir_def/src/nameres/collector.rs
@@ -7,7 +7,6 @@ use std::iter;
 
 use base_db::{CrateId, FileId, ProcMacroId};
 use cfg::{CfgExpr, CfgOptions};
-use hir_expand::InFile;
 use hir_expand::{
     ast_id_map::FileAstId,
     builtin_derive::find_builtin_derive,
@@ -16,6 +15,7 @@ use hir_expand::{
     proc_macro::ProcMacroExpander,
     HirFileId, MacroCallId, MacroDefId, MacroDefKind,
 };
+use hir_expand::{InFile, MacroCallLoc};
 use rustc_hash::{FxHashMap, FxHashSet};
 use syntax::ast;
 use test_utils::mark;
@@ -812,7 +812,30 @@ impl DefCollector<'_> {
             log::warn!("macro expansion is too deep");
             return;
         }
-        let file_id: HirFileId = macro_call_id.as_file();
+        let file_id = macro_call_id.as_file();
+
+        // First, fetch the raw expansion result for purposes of error reporting. This goes through
+        // `macro_expand_error` to avoid depending on the full expansion result (to improve
+        // incrementality).
+        let err = self.db.macro_expand_error(macro_call_id);
+        if let Some(err) = err {
+            if let MacroCallId::LazyMacro(id) = macro_call_id {
+                let loc: MacroCallLoc = self.db.lookup_intern_macro(id);
+
+                let diag = match err {
+                    hir_expand::ExpandError::UnresolvedProcMacro => {
+                        // Missing proc macros are non-fatal, so they are handled specially.
+                        DefDiagnostic::unresolved_proc_macro(module_id, loc.kind)
+                    }
+                    _ => DefDiagnostic::macro_error(module_id, loc.kind, err.to_string()),
+                };
+
+                self.def_map.diagnostics.push(diag);
+            }
+            // FIXME: Handle eager macros.
+        }
+
+        // Then, fetch and process the item tree. This will reuse the expansion result from above.
         let item_tree = self.db.item_tree(file_id);
         let mod_dir = self.mod_dirs[&module_id].clone();
         ModCollector {
diff --git a/crates/hir_def/src/nameres/tests/mod_resolution.rs b/crates/hir_def/src/nameres/tests/mod_resolution.rs
index ba295fd9e..ef6f85e15 100644
--- a/crates/hir_def/src/nameres/tests/mod_resolution.rs
+++ b/crates/hir_def/src/nameres/tests/mod_resolution.rs
@@ -798,3 +798,24 @@ mod foo;
 "#,
     );
 }
+
+#[test]
+fn abs_path_ignores_local() {
+    check(
+        r#"
+//- /main.rs crate:main deps:core
+pub use ::core::hash::Hash;
+pub mod core {}
+
+//- /lib.rs crate:core
+pub mod hash { pub trait Hash {} }
+"#,
+        expect![[r#"
+            crate
+            Hash: t
+            core: t
+
+            crate::core
+        "#]],
+    );
+}
diff --git a/crates/hir_def/src/path/lower/lower_use.rs b/crates/hir_def/src/path/lower/lower_use.rs
index 53cecb05f..ba0d1f0e7 100644
--- a/crates/hir_def/src/path/lower/lower_use.rs
+++ b/crates/hir_def/src/path/lower/lower_use.rs
@@ -76,7 +76,7 @@ fn convert_path(prefix: Option<ModPath>, path: ast::Path, hygiene: &Hygiene) ->
                 Either::Left(name) => {
                     // no type args in use
                     let mut res = prefix.unwrap_or_else(|| ModPath {
-                        kind: PathKind::Plain,
+                        kind: segment.coloncolon_token().map_or(PathKind::Plain, |_| PathKind::Abs),
                         segments: Vec::with_capacity(1),
                     });
                     res.segments.push(name);
diff --git a/crates/hir_expand/src/builtin_macro.rs b/crates/hir_expand/src/builtin_macro.rs
index aebbfc4df..7f4db106d 100644
--- a/crates/hir_expand/src/builtin_macro.rs
+++ b/crates/hir_expand/src/builtin_macro.rs
@@ -6,7 +6,7 @@ use crate::{
 
 use base_db::FileId;
 use either::Either;
-use mbe::parse_to_token_tree;
+use mbe::{parse_to_token_tree, ExpandResult};
 use parser::FragmentKind;
 use syntax::ast::{self, AstToken};
 
@@ -28,7 +28,7 @@ macro_rules! register_builtin {
                 db: &dyn AstDatabase,
                 id: LazyMacroId,
                 tt: &tt::Subtree,
-            ) -> Result<tt::Subtree, mbe::ExpandError> {
+            ) -> ExpandResult<tt::Subtree> {
                 let expander = match *self {
                     $( BuiltinFnLikeExpander::$kind => $expand, )*
                 };
@@ -42,7 +42,7 @@ macro_rules! register_builtin {
                 db: &dyn AstDatabase,
                 arg_id: EagerMacroId,
                 tt: &tt::Subtree,
-            ) -> Result<(tt::Subtree, FragmentKind), mbe::ExpandError> {
+            ) -> ExpandResult<Option<(tt::Subtree, FragmentKind)>> {
                 let expander = match *self {
                     $( EagerExpander::$e_kind => $e_expand, )*
                 };
@@ -109,25 +109,28 @@ fn line_expand(
     _db: &dyn AstDatabase,
     _id: LazyMacroId,
     _tt: &tt::Subtree,
-) -> Result<tt::Subtree, mbe::ExpandError> {
+) -> ExpandResult<tt::Subtree> {
     // dummy implementation for type-checking purposes
     let line_num = 0;
     let expanded = quote! {
         #line_num
     };
 
-    Ok(expanded)
+    ExpandResult::ok(expanded)
 }
 
 fn stringify_expand(
     db: &dyn AstDatabase,
     id: LazyMacroId,
     _tt: &tt::Subtree,
-) -> Result<tt::Subtree, mbe::ExpandError> {
+) -> ExpandResult<tt::Subtree> {
     let loc = db.lookup_intern_macro(id);
 
     let macro_content = {
-        let arg = loc.kind.arg(db).ok_or_else(|| mbe::ExpandError::UnexpectedToken)?;
+        let arg = match loc.kind.arg(db) {
+            Some(arg) => arg,
+            None => return ExpandResult::only_err(mbe::ExpandError::UnexpectedToken),
+        };
         let macro_args = arg;
         let text = macro_args.text();
         let without_parens = TextSize::of('(')..text.len() - TextSize::of(')');
@@ -138,28 +141,28 @@ fn stringify_expand(
         #macro_content
     };
 
-    Ok(expanded)
+    ExpandResult::ok(expanded)
 }
 
 fn column_expand(
     _db: &dyn AstDatabase,
     _id: LazyMacroId,
     _tt: &tt::Subtree,
-) -> Result<tt::Subtree, mbe::ExpandError> {
+) -> ExpandResult<tt::Subtree> {
     // dummy implementation for type-checking purposes
     let col_num = 0;
     let expanded = quote! {
         #col_num
     };
 
-    Ok(expanded)
+    ExpandResult::ok(expanded)
 }
 
 fn assert_expand(
     _db: &dyn AstDatabase,
     _id: LazyMacroId,
     tt: &tt::Subtree,
-) -> Result<tt::Subtree, mbe::ExpandError> {
+) -> ExpandResult<tt::Subtree> {
     // A hacky implementation for goto def and hover
     // We expand `assert!(cond, arg1, arg2)` to
     // ```
@@ -191,14 +194,14 @@ fn assert_expand(
     let expanded = quote! {
         { { (##arg_tts); } }
     };
-    Ok(expanded)
+    ExpandResult::ok(expanded)
 }
 
 fn file_expand(
     _db: &dyn AstDatabase,
     _id: LazyMacroId,
     _tt: &tt::Subtree,
-) -> Result<tt::Subtree, mbe::ExpandError> {
+) -> ExpandResult<tt::Subtree> {
     // FIXME: RA purposefully lacks knowledge of absolute file names
     // so just return "".
     let file_name = "";
@@ -207,31 +210,33 @@ fn file_expand(
         #file_name
     };
 
-    Ok(expanded)
+    ExpandResult::ok(expanded)
 }
 
 fn compile_error_expand(
     _db: &dyn AstDatabase,
     _id: LazyMacroId,
     tt: &tt::Subtree,
-) -> Result<tt::Subtree, mbe::ExpandError> {
+) -> ExpandResult<tt::Subtree> {
     if tt.count() == 1 {
         if let tt::TokenTree::Leaf(tt::Leaf::Literal(it)) = &tt.token_trees[0] {
             let s = it.text.as_str();
             if s.contains('"') {
-                return Ok(quote! { loop { #it }});
+                return ExpandResult::ok(quote! { loop { #it }});
             }
         };
     }
 
-    Err(mbe::ExpandError::BindingError("Must be a string".into()))
+    ExpandResult::only_err(mbe::ExpandError::BindingError(
+        "`compile_error!` argument be a string".into(),
+    ))
 }
 
 fn format_args_expand(
     _db: &dyn AstDatabase,
     _id: LazyMacroId,
     tt: &tt::Subtree,
-) -> Result<tt::Subtree, mbe::ExpandError> {
+) -> ExpandResult<tt::Subtree> {
     // We expand `format_args!("", a1, a2)` to
     // ```
     // std::fmt::Arguments::new_v1(&[], &[
@@ -257,7 +262,7 @@ fn format_args_expand(
         args.push(current);
     }
     if args.is_empty() {
-        return Err(mbe::ExpandError::NoMatchingRule);
+        return ExpandResult::only_err(mbe::ExpandError::NoMatchingRule);
     }
     let _format_string = args.remove(0);
     let arg_tts = args.into_iter().flat_map(|arg| {
@@ -266,7 +271,7 @@ fn format_args_expand(
     let expanded = quote! {
         std::fmt::Arguments::new_v1(&[], &[##arg_tts])
     };
-    Ok(expanded)
+    ExpandResult::ok(expanded)
 }
 
 fn unquote_str(lit: &tt::Literal) -> Option<String> {
@@ -279,19 +284,24 @@ fn concat_expand(
     _db: &dyn AstDatabase,
     _arg_id: EagerMacroId,
     tt: &tt::Subtree,
-) -> Result<(tt::Subtree, FragmentKind), mbe::ExpandError> {
+) -> ExpandResult<Option<(tt::Subtree, FragmentKind)>> {
     let mut text = String::new();
     for (i, t) in tt.token_trees.iter().enumerate() {
         match t {
             tt::TokenTree::Leaf(tt::Leaf::Literal(it)) if i % 2 == 0 => {
-                text += &unquote_str(&it).ok_or_else(|| mbe::ExpandError::ConversionError)?;
+                text += &match unquote_str(&it) {
+                    Some(s) => s,
+                    None => {
+                        return ExpandResult::only_err(mbe::ExpandError::ConversionError);
+                    }
+                };
             }
             tt::TokenTree::Leaf(tt::Leaf::Punct(punct)) if i % 2 == 1 && punct.char == ',' => (),
-            _ => return Err(mbe::ExpandError::UnexpectedToken),
+            _ => return ExpandResult::only_err(mbe::ExpandError::UnexpectedToken),
         }
     }
 
-    Ok((quote!(#text), FragmentKind::Expr))
+    ExpandResult::ok(Some((quote!(#text), FragmentKind::Expr)))
 }
 
 fn relative_file(
@@ -324,26 +334,35 @@ fn include_expand(
     db: &dyn AstDatabase,
     arg_id: EagerMacroId,
     tt: &tt::Subtree,
-) -> Result<(tt::Subtree, FragmentKind), mbe::ExpandError> {
-    let path = parse_string(tt)?;
-    let file_id = relative_file(db, arg_id.into(), &path, false)
-        .ok_or_else(|| mbe::ExpandError::ConversionError)?;
-
-    // FIXME:
-    // Handle include as expression
-    let res = parse_to_token_tree(&db.file_text(file_id))
-        .ok_or_else(|| mbe::ExpandError::ConversionError)?
-        .0;
-
-    Ok((res, FragmentKind::Items))
+) -> ExpandResult<Option<(tt::Subtree, FragmentKind)>> {
+    let res = (|| {
+        let path = parse_string(tt)?;
+        let file_id = relative_file(db, arg_id.into(), &path, false)
+            .ok_or_else(|| mbe::ExpandError::ConversionError)?;
+
+        Ok(parse_to_token_tree(&db.file_text(file_id))
+            .ok_or_else(|| mbe::ExpandError::ConversionError)?
+            .0)
+    })();
+
+    match res {
+        Ok(res) => {
+            // FIXME:
+            // Handle include as expression
+            ExpandResult::ok(Some((res, FragmentKind::Items)))
+        }
+        Err(e) => ExpandResult::only_err(e),
+    }
 }
 
 fn include_bytes_expand(
     _db: &dyn AstDatabase,
     _arg_id: EagerMacroId,
     tt: &tt::Subtree,
-) -> Result<(tt::Subtree, FragmentKind), mbe::ExpandError> {
-    let _path = parse_string(tt)?;
+) -> ExpandResult<Option<(tt::Subtree, FragmentKind)>> {
+    if let Err(e) = parse_string(tt) {
+        return ExpandResult::only_err(e);
+    }
 
     // FIXME: actually read the file here if the user asked for macro expansion
     let res = tt::Subtree {
@@ -353,15 +372,18 @@ fn include_bytes_expand(
             id: tt::TokenId::unspecified(),
         }))],
     };
-    Ok((res, FragmentKind::Expr))
+    ExpandResult::ok(Some((res, FragmentKind::Expr)))
 }
 
 fn include_str_expand(
     db: &dyn AstDatabase,
     arg_id: EagerMacroId,
     tt: &tt::Subtree,
-) -> Result<(tt::Subtree, FragmentKind), mbe::ExpandError> {
-    let path = parse_string(tt)?;
+) -> ExpandResult<Option<(tt::Subtree, FragmentKind)>> {
+    let path = match parse_string(tt) {
+        Ok(it) => it,
+        Err(e) => return ExpandResult::only_err(e),
+    };
 
     // FIXME: we're not able to read excluded files (which is most of them because
     // it's unusual to `include_str!` a Rust file), but we can return an empty string.
@@ -370,14 +392,14 @@ fn include_str_expand(
     let file_id = match relative_file(db, arg_id.into(), &path, true) {
         Some(file_id) => file_id,
         None => {
-            return Ok((quote!(""), FragmentKind::Expr));
+            return ExpandResult::ok(Some((quote!(""), FragmentKind::Expr)));
         }
     };
 
     let text = db.file_text(file_id);
     let text = &*text;
 
-    Ok((quote!(#text), FragmentKind::Expr))
+    ExpandResult::ok(Some((quote!(#text), FragmentKind::Expr)))
 }
 
 fn get_env_inner(db: &dyn AstDatabase, arg_id: EagerMacroId, key: &str) -> Option<String> {
@@ -389,8 +411,11 @@ fn env_expand(
     db: &dyn AstDatabase,
     arg_id: EagerMacroId,
     tt: &tt::Subtree,
-) -> Result<(tt::Subtree, FragmentKind), mbe::ExpandError> {
-    let key = parse_string(tt)?;
+) -> ExpandResult<Option<(tt::Subtree, FragmentKind)>> {
+    let key = match parse_string(tt) {
+        Ok(it) => it,
+        Err(e) => return ExpandResult::only_err(e),
+    };
 
     // FIXME:
     // If the environment variable is not defined int rustc, then a compilation error will be emitted.
@@ -402,21 +427,25 @@ fn env_expand(
     let s = get_env_inner(db, arg_id, &key).unwrap_or_else(|| "__RA_UNIMPLEMENTED__".to_string());
     let expanded = quote! { #s };
 
-    Ok((expanded, FragmentKind::Expr))
+    ExpandResult::ok(Some((expanded, FragmentKind::Expr)))
 }
 
 fn option_env_expand(
     db: &dyn AstDatabase,
     arg_id: EagerMacroId,
     tt: &tt::Subtree,
-) -> Result<(tt::Subtree, FragmentKind), mbe::ExpandError> {
-    let key = parse_string(tt)?;
+) -> ExpandResult<Option<(tt::Subtree, FragmentKind)>> {
+    let key = match parse_string(tt) {
+        Ok(it) => it,
+        Err(e) => return ExpandResult::only_err(e),
+    };
+
     let expanded = match get_env_inner(db, arg_id, &key) {
         None => quote! { std::option::Option::None::<&str> },
         Some(s) => quote! { std::option::Some(#s) },
     };
 
-    Ok((expanded, FragmentKind::Expr))
+    ExpandResult::ok(Some((expanded, FragmentKind::Expr)))
 }
 
 #[cfg(test)]
@@ -485,7 +514,7 @@ mod tests {
                     }
                 });
 
-                let (subtree, fragment) = expander.expand(&db, arg_id, &parsed_args).unwrap();
+                let (subtree, fragment) = expander.expand(&db, arg_id, &parsed_args).value.unwrap();
                 let eager = EagerCallLoc {
                     def,
                     fragment,
diff --git a/crates/hir_expand/src/db.rs b/crates/hir_expand/src/db.rs
index 46ebdbc74..4fd0ba290 100644
--- a/crates/hir_expand/src/db.rs
+++ b/crates/hir_expand/src/db.rs
@@ -3,7 +3,7 @@
 use std::sync::Arc;
 
 use base_db::{salsa, SourceDatabase};
-use mbe::{ExpandResult, MacroRules};
+use mbe::{ExpandError, ExpandResult, MacroRules};
 use parser::FragmentKind;
 use syntax::{algo::diff, AstNode, GreenNode, Parse, SyntaxKind::*, SyntaxNode};
 
@@ -30,8 +30,8 @@ impl TokenExpander {
     ) -> mbe::ExpandResult<tt::Subtree> {
         match self {
             TokenExpander::MacroRules(it) => it.expand(tt),
+            TokenExpander::Builtin(it) => it.expand(db, id, tt),
             // FIXME switch these to ExpandResult as well
-            TokenExpander::Builtin(it) => it.expand(db, id, tt).into(),
             TokenExpander::BuiltinDerive(it) => it.expand(db, id, tt).into(),
             TokenExpander::ProcMacro(_) => {
                 // We store the result in salsa db to prevent non-determinisc behavior in
@@ -81,6 +81,9 @@ pub trait AstDatabase: SourceDatabase {
     ) -> ExpandResult<Option<(Parse<SyntaxNode>, Arc<mbe::TokenMap>)>>;
     fn macro_expand(&self, macro_call: MacroCallId) -> ExpandResult<Option<Arc<tt::Subtree>>>;
 
+    /// Firewall query that returns the error from the `macro_expand` query.
+    fn macro_expand_error(&self, macro_call: MacroCallId) -> Option<ExpandError>;
+
     #[salsa::interned]
     fn intern_eager_expansion(&self, eager: EagerCallLoc) -> EagerMacroId;
 
@@ -171,6 +174,10 @@ fn macro_expand(db: &dyn AstDatabase, id: MacroCallId) -> ExpandResult<Option<Ar
     macro_expand_with_arg(db, id, None)
 }
 
+fn macro_expand_error(db: &dyn AstDatabase, macro_call: MacroCallId) -> Option<ExpandError> {
+    db.macro_expand(macro_call).err
+}
+
 fn expander(db: &dyn AstDatabase, id: MacroCallId) -> Option<Arc<(TokenExpander, mbe::TokenMap)>> {
     let lazy_id = match id {
         MacroCallId::LazyMacro(id) => id,
@@ -189,6 +196,7 @@ fn macro_expand_with_arg(
     id: MacroCallId,
     arg: Option<Arc<(tt::Subtree, mbe::TokenMap)>>,
 ) -> ExpandResult<Option<Arc<tt::Subtree>>> {
+    let _p = profile::span("macro_expand");
     let lazy_id = match id {
         MacroCallId::LazyMacro(id) => id,
         MacroCallId::EagerMacro(id) => {
@@ -276,14 +284,15 @@ fn parse_macro_with_arg(
     macro_file: MacroFile,
     arg: Option<Arc<(tt::Subtree, mbe::TokenMap)>>,
 ) -> ExpandResult<Option<(Parse<SyntaxNode>, Arc<mbe::TokenMap>)>> {
-    let _p = profile::span("parse_macro_query");
-
     let macro_call_id = macro_file.macro_call_id;
     let result = if let Some(arg) = arg {
         macro_expand_with_arg(db, macro_call_id, Some(arg))
     } else {
         db.macro_expand(macro_call_id)
     };
+
+    let _p = profile::span("parse_macro_expansion");
+
     if let Some(err) = &result.err {
         // Note:
         // The final goal we would like to make all parse_macro success,
diff --git a/crates/hir_expand/src/diagnostics.rs b/crates/hir_expand/src/diagnostics.rs
index 1043c6aeb..bf0b85ce9 100644
--- a/crates/hir_expand/src/diagnostics.rs
+++ b/crates/hir_expand/src/diagnostics.rs
@@ -5,7 +5,7 @@
 //!
 //! `DiagnosticSink` struct is used as an emitter for diagnostic. When creating
 //! a `DiagnosticSink`, you supply a callback which can react to a `dyn
-//! Diagnostic` or to any concrete diagnostic (downcasting is sued internally).
+//! Diagnostic` or to any concrete diagnostic (downcasting is used internally).
 //!
 //! Because diagnostics store file offsets, it's a bad idea to store them
 //! directly in salsa. For this reason, every hir subsytem defines it's own
@@ -32,7 +32,12 @@ impl DiagnosticCode {
 pub trait Diagnostic: Any + Send + Sync + fmt::Debug + 'static {
     fn code(&self) -> DiagnosticCode;
     fn message(&self) -> String;
-    /// Used in highlighting and related purposes
+    /// Source element that triggered the diagnostics.
+    ///
+    /// Note that this should reflect "semantics", rather than specific span we
+    /// want to highlight. When rendering the diagnostics into an error message,
+    /// the IDE will fetch the `SyntaxNode` and will narrow the span
+    /// appropriately.
     fn display_source(&self) -> InFile<SyntaxNodePtr>;
     fn as_any(&self) -> &(dyn Any + Send + 'static);
     fn is_experimental(&self) -> bool {
diff --git a/crates/hir_expand/src/eager.rs b/crates/hir_expand/src/eager.rs
index 2f37d7189..ab6b4477c 100644
--- a/crates/hir_expand/src/eager.rs
+++ b/crates/hir_expand/src/eager.rs
@@ -65,7 +65,7 @@ pub fn expand_eager_macro(
     let subtree = to_subtree(&result)?;
 
     if let MacroDefKind::BuiltInEager(eager) = def.kind {
-        let (subtree, fragment) = eager.expand(db, arg_id, &subtree).ok()?;
+        let (subtree, fragment) = eager.expand(db, arg_id, &subtree).value?;
         let eager = EagerCallLoc {
             def,
             fragment,
diff --git a/crates/hir_expand/src/lib.rs b/crates/hir_expand/src/lib.rs
index d5ba691b7..6dad2507b 100644
--- a/crates/hir_expand/src/lib.rs
+++ b/crates/hir_expand/src/lib.rs
@@ -255,7 +255,7 @@ pub enum MacroDefKind {
 pub struct MacroCallLoc {
     pub(crate) def: MacroDefId,
     pub(crate) krate: CrateId,
-    pub(crate) kind: MacroCallKind,
+    pub kind: MacroCallKind,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
diff --git a/crates/hir_expand/src/proc_macro.rs b/crates/hir_expand/src/proc_macro.rs
index 7505cb061..97edf0fb6 100644
--- a/crates/hir_expand/src/proc_macro.rs
+++ b/crates/hir_expand/src/proc_macro.rs
@@ -50,7 +50,7 @@ impl ProcMacroExpander {
 
                 proc_macro.expander.expand(&tt, None).map_err(mbe::ExpandError::from)
             }
-            None => Err(err!("Unresolved proc macro")),
+            None => Err(mbe::ExpandError::UnresolvedProcMacro),
         }
     }
 }
diff --git a/crates/ide/src/diagnostics.rs b/crates/ide/src/diagnostics.rs
index 3df73ed4f..9d3d88289 100644
--- a/crates/ide/src/diagnostics.rs
+++ b/crates/ide/src/diagnostics.rs
@@ -142,6 +142,15 @@ pub(crate) fn diagnostics(
                     .with_code(Some(d.code())),
             );
         })
+        .on::<hir::diagnostics::UnresolvedProcMacro, _>(|d| {
+            // Use more accurate position if available.
+            let display_range =
+                d.precise_location.unwrap_or_else(|| sema.diagnostics_display_range(d).range);
+
+            // FIXME: it would be nice to tell the user whether proc macros are currently disabled
+            res.borrow_mut()
+                .push(Diagnostic::hint(display_range, d.message()).with_code(Some(d.code())));
+        })
         // Only collect experimental diagnostics when they're enabled.
         .filter(|diag| !(diag.is_experimental() && config.disable_experimental))
         .filter(|diag| !config.disabled.contains(diag.code().as_str()));
diff --git a/crates/ide/src/goto_definition.rs b/crates/ide/src/goto_definition.rs
index 15792f947..b9810457f 100644
--- a/crates/ide/src/goto_definition.rs
+++ b/crates/ide/src/goto_definition.rs
@@ -1,14 +1,10 @@
 use hir::Semantics;
 use ide_db::{
+    base_db::FileId,
     defs::{NameClass, NameRefClass},
     symbol_index, RootDatabase,
 };
-use syntax::{
-    ast::{self},
-    match_ast, AstNode,
-    SyntaxKind::*,
-    SyntaxToken, TokenAtOffset, T,
-};
+use syntax::{ast, match_ast, AstNode, SyntaxKind::*, SyntaxToken, TokenAtOffset, T};
 
 use crate::{
     display::{ToNav, TryToNav},
@@ -44,6 +40,19 @@ pub(crate) fn goto_definition(
                 let nav = def.try_to_nav(sema.db)?;
                 vec![nav]
             },
+            ast::SelfParam(self_param) => {
+                vec![self_to_nav_target(self_param, position.file_id)?]
+            },
+            ast::PathSegment(segment) => {
+                segment.self_token()?;
+                let path = segment.parent_path();
+                if path.qualifier().is_some() && !ast::PathExpr::can_cast(path.syntax().parent()?.kind()) {
+                    return None;
+                }
+                let func = segment.syntax().ancestors().find_map(ast::Fn::cast)?;
+                let self_param = func.param_list()?.self_param()?;
+                vec![self_to_nav_target(self_param, position.file_id)?]
+            },
             _ => return None,
         }
     };
@@ -62,6 +71,20 @@ fn pick_best(tokens: TokenAtOffset<SyntaxToken>) -> Option<SyntaxToken> {
     }
 }
 
+fn self_to_nav_target(self_param: ast::SelfParam, file_id: FileId) -> Option<NavigationTarget> {
+    let self_token = self_param.self_token()?;
+    Some(NavigationTarget {
+        file_id,
+        full_range: self_param.syntax().text_range(),
+        focus_range: Some(self_token.text_range()),
+        name: self_token.text().clone(),
+        kind: self_token.kind(),
+        container_name: None,
+        description: None,
+        docs: None,
+    })
+}
+
 #[derive(Debug)]
 pub(crate) enum ReferenceResult {
     Exact(NavigationTarget),
@@ -984,4 +1007,33 @@ fn g() -> <() as Iterator<A = (), B<|> = u8>>::A {}
 "#,
         );
     }
+
+    #[test]
+    fn goto_self_param_ty_specified() {
+        check(
+            r#"
+struct Foo {}
+
+impl Foo {
+    fn bar(self: &Foo) {
+         //^^^^
+        let foo = sel<|>f;
+    }
+}"#,
+        )
+    }
+
+    #[test]
+    fn goto_self_param_on_decl() {
+        check(
+            r#"
+struct Foo {}
+
+impl Foo {
+    fn bar(&self<|>) {
+          //^^^^
+    }
+}"#,
+        )
+    }
 }
diff --git a/crates/ide/src/hover.rs b/crates/ide/src/hover.rs
index 832192881..462f5c2b8 100644
--- a/crates/ide/src/hover.rs
+++ b/crates/ide/src/hover.rs
@@ -139,14 +139,17 @@ pub(crate) fn hover(
         }
     }
 
-    let node = token
-        .ancestors()
-        .find(|n| ast::Expr::cast(n.clone()).is_some() || ast::Pat::cast(n.clone()).is_some())?;
+    let node = token.ancestors().find(|n| {
+        ast::Expr::can_cast(n.kind())
+            || ast::Pat::can_cast(n.kind())
+            || ast::SelfParam::can_cast(n.kind())
+    })?;