Auto merge of #12580 - Veykril:completion, r=Veykril

internal: Move more things out of `CompletionContext::function_def` into more specific parts

9 files changed, 226 insertions, 112 deletions

diff --git a/crates/ide-completion/src/completions.rs b/crates/ide-completion/src/completions.rs
index b0763584432..284372f7fc5 100644
--- a/crates/ide-completion/src/completions.rs
+++ b/crates/ide-completion/src/completions.rs
@@ -24,6 +24,7 @@ use std::iter;
 
 use hir::{db::HirDatabase, known, ScopeDef};
 use ide_db::SymbolKind;
+use syntax::ast;
 
 use crate::{
     context::Visible,
@@ -110,12 +111,18 @@ impl Completions {
         ["self", "super", "crate"].into_iter().for_each(|kw| self.add_keyword(ctx, kw));
     }
 
-    pub(crate) fn add_keyword_snippet(&mut self, ctx: &CompletionContext, kw: &str, snippet: &str) {
+    pub(crate) fn add_keyword_snippet_expr(
+        &mut self,
+        ctx: &CompletionContext,
+        kw: &str,
+        snippet: &str,
+        incomplete_let: bool,
+    ) {
         let mut item = CompletionItem::new(CompletionItemKind::Keyword, ctx.source_range(), kw);
 
         match ctx.config.snippet_cap {
             Some(cap) => {
-                if snippet.ends_with('}') && ctx.incomplete_let {
+                if snippet.ends_with('}') && incomplete_let {
                     // complete block expression snippets with a trailing semicolon, if inside an incomplete let
                     cov_mark::hit!(let_semi);
                     item.insert_snippet(cap, format!("{};", snippet));
@@ -130,6 +137,16 @@ impl Completions {
         item.add_to(self);
     }
 
+    pub(crate) fn add_keyword_snippet(&mut self, ctx: &CompletionContext, kw: &str, snippet: &str) {
+        let mut item = CompletionItem::new(CompletionItemKind::Keyword, ctx.source_range(), kw);
+
+        match ctx.config.snippet_cap {
+            Some(cap) => item.insert_snippet(cap, snippet),
+            None => item.insert_text(if snippet.contains('$') { kw } else { snippet }),
+        };
+        item.add_to(self);
+    }
+
     pub(crate) fn add_crate_roots(&mut self, ctx: &CompletionContext) {
         ctx.process_all_names(&mut |name, res| match res {
             ScopeDef::ModuleDef(hir::ModuleDef::Module(m)) if m.is_crate_root(ctx.db) => {
@@ -393,11 +410,12 @@ fn enum_variants_with_paths(
     acc: &mut Completions,
     ctx: &CompletionContext,
     enum_: hir::Enum,
+    impl_: &Option<ast::Impl>,
     cb: impl Fn(&mut Completions, &CompletionContext, hir::Variant, hir::ModPath),
 ) {
     let variants = enum_.variants(ctx.db);
 
-    if let Some(impl_) = ctx.impl_def.as_ref().and_then(|impl_| ctx.sema.to_def(impl_)) {
+    if let Some(impl_) = impl_.as_ref().and_then(|impl_| ctx.sema.to_def(impl_)) {
         if impl_.self_ty(ctx.db).as_adt() == Some(hir::Adt::Enum(enum_)) {
             for &variant in &variants {
                 let self_path = hir::ModPath::from_segments(
diff --git a/crates/ide-completion/src/completions/dot.rs b/crates/ide-completion/src/completions/dot.rs
index a315d616d55..da26c2ad682 100644
--- a/crates/ide-completion/src/completions/dot.rs
+++ b/crates/ide-completion/src/completions/dot.rs
@@ -46,27 +46,26 @@ pub(crate) fn complete_undotted_self(
     if !ctx.config.enable_self_on_the_fly {
         return;
     }
-    match path_ctx {
-        PathCompletionCtx { qualified: Qualified::No, kind: PathKind::Expr { .. }, .. }
-            if path_ctx.is_trivial_path() && ctx.qualifier_ctx.none() => {}
+    let self_param = match path_ctx {
+        PathCompletionCtx {
+            qualified: Qualified::No,
+            kind: PathKind::Expr { self_param: Some(self_param), .. },
+            ..
+        } if path_ctx.is_trivial_path() && ctx.qualifier_ctx.none() => self_param,
         _ => return,
-    }
+    };
 
-    if let Some(func) = ctx.function_def.as_ref().and_then(|fn_| ctx.sema.to_def(fn_)) {
-        if let Some(self_) = func.self_param(ctx.db) {
-            let ty = self_.ty(ctx.db);
-            complete_fields(
-                acc,
-                ctx,
-                &ty,
-                |acc, field, ty| acc.add_field(ctx, Some(hir::known::SELF_PARAM), field, &ty),
-                |acc, field, ty| acc.add_tuple_field(ctx, Some(hir::known::SELF_PARAM), field, &ty),
-            );
-            complete_methods(ctx, &ty, |func| {
-                acc.add_method(ctx, func, Some(hir::known::SELF_PARAM), None)
-            });
-        }
-    }
+    let ty = self_param.ty(ctx.db);
+    complete_fields(
+        acc,
+        ctx,
+        &ty,
+        |acc, field, ty| acc.add_field(ctx, Some(hir::known::SELF_PARAM), field, &ty),
+        |acc, field, ty| acc.add_tuple_field(ctx, Some(hir::known::SELF_PARAM), field, &ty),
+    );
+    complete_methods(ctx, &ty, |func| {
+        acc.add_method(ctx, func, Some(hir::known::SELF_PARAM), None)
+    });
 }
 
 fn complete_fields(
diff --git a/crates/ide-completion/src/completions/expr.rs b/crates/ide-completion/src/completions/expr.rs
index 6152ccb711f..83ecb51aaab 100644
--- a/crates/ide-completion/src/completions/expr.rs
+++ b/crates/ide-completion/src/completions/expr.rs
@@ -14,7 +14,9 @@ pub(crate) fn complete_expr_path(
     path_ctx: &PathCompletionCtx,
 ) {
     let _p = profile::span("complete_expr_path");
-
+    if !ctx.qualifier_ctx.none() {
+        return;
+    }
     let (
         qualified,
         in_block_expr,
@@ -23,6 +25,9 @@ pub(crate) fn complete_expr_path(
         after_if_expr,
         wants_mut_token,
         in_condition,
+        ty,
+        incomplete_let,
+        impl_,
     ) = match path_ctx {
         &PathCompletionCtx {
             kind:
@@ -31,12 +36,16 @@ pub(crate) fn complete_expr_path(
                     in_loop_body,
                     after_if_expr,
                     in_condition,
+                    incomplete_let,
                     ref ref_expr_parent,
                     ref is_func_update,
+                    ref innermost_ret_ty,
+                    ref impl_,
+                    ..
                 },
             ref qualified,
             ..
-        } if ctx.qualifier_ctx.none() => (
+        } => (
             qualified,
             in_block_expr,
             in_loop_body,
@@ -44,6 +53,9 @@ pub(crate) fn complete_expr_path(
             after_if_expr,
             ref_expr_parent.as_ref().map(|it| it.mut_token().is_none()).unwrap_or(false),
             in_condition,
+            innermost_ret_ty,
+            incomplete_let,
+            impl_,
         ),
         _ => return,
     };
@@ -172,8 +184,7 @@ pub(crate) fn complete_expr_path(
             if let Some(adt) =
                 ctx.expected_type.as_ref().and_then(|ty| ty.strip_references().as_adt())
             {
-                let self_ty =
-                    (|| ctx.sema.to_def(ctx.impl_def.as_ref()?)?.self_ty(ctx.db).as_adt())();
+                let self_ty = (|| ctx.sema.to_def(impl_.as_ref()?)?.self_ty(ctx.db).as_adt())();
                 let complete_self = self_ty == Some(adt);
 
                 match adt {
@@ -201,9 +212,15 @@ pub(crate) fn complete_expr_path(
                         }
                     }
                     hir::Adt::Enum(e) => {
-                        super::enum_variants_with_paths(acc, ctx, e, |acc, ctx, variant, path| {
-                            acc.add_qualified_enum_variant(ctx, variant, path)
-                        });
+                        super::enum_variants_with_paths(
+                            acc,
+                            ctx,
+                            e,
+                            impl_,
+                            |acc, ctx, variant, path| {
+                                acc.add_qualified_enum_variant(ctx, variant, path)
+                            },
+                        );
                     }
                 }
             }
@@ -214,7 +231,8 @@ pub(crate) fn complete_expr_path(
             });
 
             if !is_func_update {
-                let mut add_keyword = |kw, snippet| acc.add_keyword_snippet(ctx, kw, snippet);
+                let mut add_keyword =
+                    |kw, snippet| acc.add_keyword_snippet_expr(ctx, kw, snippet, incomplete_let);
 
                 if !in_block_expr {
                     add_keyword("unsafe", "unsafe {\n    $0\n}");
@@ -252,10 +270,10 @@ pub(crate) fn complete_expr_path(
                     }
                 }
 
-                if let Some(fn_def) = &ctx.function_def {
+                if let Some(ty) = ty {
                     add_keyword(
                         "return",
-                        match (in_block_expr, fn_def.ret_type().is_some()) {
+                        match (in_block_expr, ty.is_unit()) {
                             (true, true) => "return ;",
                             (true, false) => "return;",
                             (false, true) => "return $0",
diff --git a/crates/ide-completion/src/completions/fn_param.rs b/crates/ide-completion/src/completions/fn_param.rs
index a62b966e019..94e2f489f57 100644
--- a/crates/ide-completion/src/completions/fn_param.rs
+++ b/crates/ide-completion/src/completions/fn_param.rs
@@ -24,8 +24,8 @@ pub(crate) fn complete_fn_param(
     ctx: &CompletionContext,
     pattern_ctx: &PatternContext,
 ) -> Option<()> {
-    let (param_list, _, param_kind) = match pattern_ctx {
-        PatternContext { param_ctx: Some(kind), .. } => kind,
+    let ((param_list, _, param_kind), impl_) = match pattern_ctx {
+        PatternContext { param_ctx: Some(kind), impl_, .. } => (kind, impl_),
         _ => return None,
     };
 
@@ -45,7 +45,7 @@ pub(crate) fn complete_fn_param(
 
     match param_kind {
         ParamKind::Function(function) => {
-            fill_fn_params(ctx, function, param_list, add_new_item_to_acc);
+            fill_fn_params(ctx, function, param_list, impl_, add_new_item_to_acc);
         }
         ParamKind::Closure(closure) => {
             let stmt_list = closure.syntax().ancestors().find_map(ast::StmtList::cast)?;
@@ -62,6 +62,7 @@ fn fill_fn_params(
     ctx: &CompletionContext,
     function: &ast::Fn,
     param_list: &ast::ParamList,
+    impl_: &Option<ast::Impl>,
     mut add_new_item_to_acc: impl FnMut(&str),
 ) {
     let mut file_params = FxHashMap::default();
@@ -104,7 +105,7 @@ fn fill_fn_params(
     }
     remove_duplicated(&mut file_params, param_list.params());
     let self_completion_items = ["self", "&self", "mut self", "&mut self"];
-    if should_add_self_completions(ctx, param_list) {
+    if should_add_self_completions(param_list, impl_) {
         self_completion_items.into_iter().for_each(|self_item| add_new_item_to_acc(self_item));
     }
 
@@ -155,11 +156,10 @@ fn remove_duplicated(
     })
 }
 
-fn should_add_self_completions(ctx: &CompletionContext, param_list: &ast::ParamList) -> bool {
-    let inside_impl = ctx.impl_def.is_some();
+fn should_add_self_completions(param_list: &ast::ParamList, impl_: &Option<ast::Impl>) -> bool {
     let no_params = param_list.params().next().is_none() && param_list.self_param().is_none();
 
-    inside_impl && no_params
+    impl_.is_some() && no_params
 }
 
 fn comma_wrapper(ctx: &CompletionContext) -> Option<(impl Fn(&str) -> String, TextRange)> {
diff --git a/crates/ide-completion/src/completions/item_list.rs b/crates/ide-completion/src/completions/item_list.rs
index f4402a3f87a..941273fa971 100644
--- a/crates/ide-completion/src/completions/item_list.rs
+++ b/crates/ide-completion/src/completions/item_list.rs
@@ -66,7 +66,7 @@ fn add_keywords(acc: &mut Completions, ctx: &CompletionContext, kind: Option<&It
     let in_assoc_non_trait_impl = matches!(kind, Some(ItemListKind::Impl | ItemListKind::Trait));
     let in_extern_block = matches!(kind, Some(ItemListKind::ExternBlock));
     let in_trait = matches!(kind, Some(ItemListKind::Trait));
-    let in_trait_impl = matches!(kind, Some(ItemListKind::TraitImpl));
+    let in_trait_impl = matches!(kind, Some(ItemListKind::TraitImpl(_)));
     let in_inherent_impl = matches!(kind, Some(ItemListKind::Impl));
     let no_qualifiers = ctx.qualifier_ctx.vis_node.is_none();
     let in_block = matches!(kind, None);
diff --git a/crates/ide-completion/src/completions/item_list/trait_impl.rs b/crates/ide-completion/src/completions/item_list/trait_impl.rs
index c0c29d4cd22..58b894bdd43 100644
--- a/crates/ide-completion/src/completions/item_list/trait_impl.rs
+++ b/crates/ide-completion/src/completions/item_list/trait_impl.rs
@@ -81,7 +81,7 @@ pub(crate) fn complete_trait_impl_name(
         kind,
         replacement_range(ctx, &item),
         // item -> ASSOC_ITEM_LIST -> IMPL
-        ast::Impl::cast(item.parent()?.parent()?)?,
+        &ast::Impl::cast(item.parent()?.parent()?)?,
     );
     Some(())
 }
@@ -97,7 +97,7 @@ pub(crate) fn complete_trait_impl_name_ref(
             kind:
                 NameRefKind::Path(
                     path_ctx @ PathCompletionCtx {
-                        kind: PathKind::Item { kind: ItemListKind::TraitImpl },
+                        kind: PathKind::Item { kind: ItemListKind::TraitImpl(Some(impl_)) },
                         ..
                     },
                 ),
@@ -109,7 +109,7 @@ pub(crate) fn complete_trait_impl_name_ref(
                 Some(name) => name.syntax().text_range(),
                 None => ctx.source_range(),
             },
-            ctx.impl_def.clone()?,
+            impl_,
         ),
         _ => (),
     }
@@ -121,10 +121,10 @@ fn complete_trait_impl(
     ctx: &CompletionContext,
     kind: ImplCompletionKind,
     replacement_range: TextRange,
-    impl_def: ast::Impl,
+    impl_def: &ast::Impl,
 ) {
-    if let Some(hir_impl) = ctx.sema.to_def(&impl_def) {
-        get_missing_assoc_items(&ctx.sema, &impl_def).into_iter().for_each(|item| {
+    if let Some(hir_impl) = ctx.sema.to_def(impl_def) {
+        get_missing_assoc_items(&ctx.sema, impl_def).into_iter().for_each(|item| {
             use self::ImplCompletionKind::*;
             match (item, kind) {
                 (hir::AssocItem::Function(func), All | Fn) => {
diff --git a/crates/ide-completion/src/completions/pattern.rs b/crates/ide-completion/src/completions/pattern.rs
index dd08ef703e4..149acb3c1be 100644
--- a/crates/ide-completion/src/completions/pattern.rs
+++ b/crates/ide-completion/src/completions/pattern.rs
@@ -51,9 +51,15 @@ pub(crate) fn complete_pattern(
         ctx.expected_type.as_ref().and_then(|ty| ty.strip_references().as_adt())
     {
         if refutable || single_variant_enum(e) {
-            super::enum_variants_with_paths(acc, ctx, e, |acc, ctx, variant, path| {
-                acc.add_qualified_variant_pat(ctx, variant, path);
-            });
+            super::enum_variants_with_paths(
+                acc,
+                ctx,
+                e,
+                &patctx.impl_,
+                |acc, ctx, variant, path| {
+                    acc.add_qualified_variant_pat(ctx, variant, path);
+                },
+            );
         }
     }
 
diff --git a/crates/ide-completion/src/context.rs b/crates/ide-completion/src/context.rs
index d73cb6034d2..0c7c6ab5af6 100644
--- a/crates/ide-completion/src/context.rs
+++ b/crates/ide-completion/src/context.rs
@@ -93,8 +93,12 @@ pub(super) enum PathKind {
         after_if_expr: bool,
         /// Whether this expression is the direct condition of an if or while expression
         in_condition: bool,
+        incomplete_let: bool,
         ref_expr_parent: Option<ast::RefExpr>,
         is_func_update: Option<ast::RecordExpr>,
+        self_param: Option<hir::SelfParam>,
+        innermost_ret_ty: Option<hir::Type>,
+        impl_: Option<ast::Impl>,
     },
     Type {
         location: TypeLocation,
@@ -140,12 +144,12 @@ pub(crate) enum TypeAscriptionTarget {
 }
 
 /// The kind of item list a [`PathKind::Item`] belongs to.
-#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+#[derive(Debug, PartialEq, Eq)]
 pub(super) enum ItemListKind {
     SourceFile,
     Module,
     Impl,
-    TraitImpl,
+    TraitImpl(Option<ast::Impl>),
     Trait,
     ExternBlock,
 }
@@ -176,6 +180,7 @@ pub(super) struct PatternContext {
     pub(super) mut_token: Option<SyntaxToken>,
     /// The record pattern this name or ref is a field of
     pub(super) record_pat: Option<ast::RecordPat>,
+    pub(super) impl_: Option<ast::Impl>,
 }
 
 /// The state of the lifetime we are completing.
@@ -317,16 +322,6 @@ pub(crate) struct CompletionContext<'a> {
     /// The expected type of what we are completing.
     pub(super) expected_type: Option<Type>,
 
-    /// The parent function of the cursor position if it exists.
-    // FIXME: This probably doesn't belong here
-    pub(super) function_def: Option<ast::Fn>,
-    /// The parent impl of the cursor position if it exists.
-    // FIXME: This probably doesn't belong here
-    pub(super) impl_def: Option<ast::Impl>,
-    /// Are we completing inside a let statement with a missing semicolon?
-    // FIXME: This should be part of PathKind::Expr
-    pub(super) incomplete_let: bool,
-
     // FIXME: This shouldn't exist
     pub(super) previous_token: Option<SyntaxToken>,
 
@@ -500,9 +495,6 @@ impl<'a> CompletionContext<'a> {
             module,
             expected_name: None,
             expected_type: None,
-            function_def: None,
-            impl_def: None,
-            incomplete_let: false,
             previous_token: None,
             // dummy value, will be overwritten
             ident_ctx: IdentContext::UnexpandedAttrTT { fake_attribute_under_caret: None },
diff --git a/crates/ide-completion/src/context/analysis.rs b/crates/ide-completion/src/context/analysis.rs
index fc6ee70a0bc..9ceb60f90f1 100644
--- a/crates/ide-completion/src/context/analysis.rs
+++ b/crates/ide-completion/src/context/analysis.rs
@@ -330,11 +330,6 @@ impl<'a> CompletionContext<'a> {
         self.previous_token =
             syntax_element.clone().into_token().and_then(previous_non_trivia_token);
 
-        self.incomplete_let =
-            syntax_element.ancestors().take(6).find_map(ast::LetStmt::cast).map_or(false, |it| {
-                it.syntax().text_range().end() == syntax_element.text_range().end()
-            });
-
         (self.expected_type, self.expected_name) = self.expected_type_and_name();
 
         // Overwrite the path kind for derives
@@ -394,28 +389,6 @@ impl<'a> CompletionContext<'a> {
                 return Some(());
             }
         };
-        self.impl_def = self
-            .sema
-            .token_ancestors_with_macros(self.token.clone())
-            .take_while(|it| it.kind() != SyntaxKind::SOURCE_FILE)
-            .filter_map(ast::Item::cast)
-            .take(2)
-            .find_map(|it| match it {
-                ast::Item::Impl(impl_) => Some(impl_),
-                _ => None,
-            });
-        self.function_def = self
-            .sema
-            .token_ancestors_with_macros(self.token.clone())
-            .take_while(|it| {
-                it.kind() != SyntaxKind::SOURCE_FILE && it.kind() != SyntaxKind::MODULE
-            })
-            .filter_map(ast::Item::cast)
-            .take(2)
-            .find_map(|it| match it {
-                ast::Item::Fn(fn_) => Some(fn_),
-                _ => None,
-            });
 
         match name_like {
             ast::NameLike::Lifetime(lifetime) => {
@@ -469,7 +442,7 @@ impl<'a> CompletionContext<'a> {
     }
 
     fn classify_name(
-        _sema: &Semantics<RootDatabase>,
+        sema: &Semantics<RootDatabase>,
         original_file: &SyntaxNode,
         name: ast::Name,
     ) -> Option<NameContext> {
@@ -481,9 +454,9 @@ impl<'a> CompletionContext<'a> {
                 ast::Enum(_) => NameKind::Enum,
                 ast::Fn(_) => NameKind::Function,
                 ast::IdentPat(bind_pat) => {
-                    let mut pat_ctx = pattern_context_for(original_file, bind_pat.into());
+                    let mut pat_ctx = pattern_context_for(sema, original_file, bind_pat.into());
                     if let Some(record_field) = ast::RecordPatField::for_field_name(&name) {
-                        pat_ctx.record_pat = find_node_in_file_compensated(original_file, &record_field.parent_record_pat());
+                        pat_ctx.record_pat = find_node_in_file_compensated(sema, original_file, &record_field.parent_record_pat());
                     }
 
                     NameKind::IdentPat(pat_ctx)
@@ -520,9 +493,13 @@ impl<'a> CompletionContext<'a> {
             |kind| (NameRefContext { nameref: nameref.clone(), kind }, Default::default());
 
         if let Some(record_field) = ast::RecordExprField::for_field_name(&name_ref) {
-            return find_node_in_file_compensated(original_file, &record_field.parent_record_lit())
-                .map(NameRefKind::RecordExpr)
-                .map(make_res);
+            return find_node_in_file_compensated(
+                sema,
+                original_file,
+                &record_field.parent_record_lit(),
+            )
+            .map(NameRefKind::RecordExpr)
+            .map(make_res);
         }
         if let Some(record_field) = ast::RecordPatField::for_field_name_ref(&name_ref) {
             let kind = NameRefKind::Pattern(PatternContext {
@@ -531,10 +508,12 @@ impl<'a> CompletionContext<'a> {
                 ref_token: None,
                 mut_token: None,
                 record_pat: find_node_in_file_compensated(
+                    sema,
                     original_file,
                     &record_field.parent_record_pat(),
                 ),
                 ..pattern_context_for(
+                    sema,
                     original_file,
                     record_field.parent_record_pat().clone().into(),
                 )
@@ -594,7 +573,7 @@ impl<'a> CompletionContext<'a> {
         };
         let func_update_record = |syn: &SyntaxNode| {
             if let Some(record_expr) = syn.ancestors().nth(2).and_then(ast::RecordExpr::cast) {
-                find_node_in_file_compensated(original_file, &record_expr)
+                find_node_in_file_compensated(sema, original_file, &record_expr)
             } else {
                 None
             }
@@ -696,9 +675,9 @@ impl<'a> CompletionContext<'a> {
                     ast::TypeBound(_) => TypeLocation::TypeBound,
                     // is this case needed?
                     ast::TypeBoundList(_) => TypeLocation::TypeBound,
-                    ast::GenericArg(it) => TypeLocation::GenericArgList(find_opt_node_in_file_compensated(original_file, it.syntax().parent().and_then(ast::GenericArgList::cast))),
+                    ast::GenericArg(it) => TypeLocation::GenericArgList(find_opt_node_in_file_compensated(sema, original_file, it.syntax().parent().and_then(ast::GenericArgList::cast))),
                     // is this case needed?
-                    ast::GenericArgList(it) => TypeLocation::GenericArgList(find_opt_node_in_file_compensated(original_file, Some(it))),
+                    ast::GenericArgList(it) => TypeLocation::GenericArgList(find_opt_node_in_file_compensated(sema, original_file, Some(it))),
                     ast::TupleField(_) => TypeLocation::TupleField,
                     _ => return None,
                 }
@@ -727,8 +706,63 @@ impl<'a> CompletionContext<'a> {
             let after_if_expr = after_if_expr(it.clone());
             let ref_expr_parent =
                 path.as_single_name_ref().and_then(|_| it.parent()).and_then(ast::RefExpr::cast);
+            let (innermost_ret_ty, self_param) = {
+                let find_ret_ty = |it: SyntaxNode| {
+                    if let Some(item) = ast::Item::cast(it.clone()) {
+                        match item {
+                            ast::Item::Fn(f) => {
+                                Some(sema.to_def(&f).map(|it| it.ret_type(sema.db)))
+                            }
+                            ast::Item::MacroCall(_) => None,
+                            _ => Some(None),
+                        }
+                    } else {
+                        let expr = ast::Expr::cast(it)?;
+                        let callable = match expr {
+                            // FIXME
+                            // ast::Expr::BlockExpr(b) if b.async_token().is_some() || b.try_token().is_some() => sema.type_of_expr(b),
+                            ast::Expr::ClosureExpr(_) => sema.type_of_expr(&expr),
+                            _ => return None,
+                        };
+                        Some(
+                            callable
+                                .and_then(|c| c.adjusted().as_callable(sema.db))
+                                .map(|it| it.return_type()),
+                        )
+                    }
+                };
+                let find_fn_self_param = |it| match it {
+                    ast::Item::Fn(fn_) => {
+                        Some(sema.to_def(&fn_).and_then(|it| it.self_param(sema.db)))
+                    }
+                    ast::Item::MacroCall(_) => None,
+                    _ => Some(None),
+                };
+
+                match find_node_in_file_compensated(sema, original_file, &expr) {
+                    Some(it) => {
+                        let innermost_ret_ty = sema
+                            .ancestors_with_macros(it.syntax().clone())
+                            .find_map(find_ret_ty)
+                            .flatten();
+
+                        let self_param = sema
+                            .ancestors_with_macros(it.syntax().clone())
+                            .filter_map(ast::Item::cast)
+                            .find_map(find_fn_self_param)
+                            .flatten();
+                        (innermost_ret_ty, self_param)
+                    }
+                    None => (None, None),
+                }
+            };
             let is_func_update = func_update_record(it);
             let in_condition = is_in_condition(&expr);
+            let incomplete_let = it
+                .parent()
+                .and_then(ast::LetStmt::cast)
+                .map_or(false, |it| it.semicolon_token().is_none());
+            let impl_ = fetch_immediate_impl(sema, original_file, expr.syntax());
 
             PathKind::Expr {
                 in_block_expr,
@@ -737,6 +771,10 @@ impl<'a> CompletionContext<'a> {
                 in_condition,
                 ref_expr_parent,
                 is_func_update,
+                innermost_ret_ty,
+                self_param,
+                incomplete_let,
+                impl_,
             }
         };
         let make_path_kind_type = |ty: ast::Type| {
@@ -764,14 +802,14 @@ impl<'a> CompletionContext<'a> {
                     },
                     ast::TupleStructPat(it) => {
                         path_ctx.has_call_parens = true;
-                        PathKind::Pat { pat_ctx: pattern_context_for(original_file, it.into())}
+                        PathKind::Pat { pat_ctx: pattern_context_for(sema, original_file, it.into())}
                     },
                     ast::RecordPat(it) => {
                         path_ctx.has_call_parens = true;
-                        PathKind::Pat { pat_ctx: pattern_context_for(original_file, it.into())}
+                        PathKind::Pat { pat_ctx: pattern_context_for(sema, original_file, it.into())}
                     },
                     ast::PathPat(it) => {
-                        PathKind::Pat { pat_ctx: pattern_context_for(original_file, it.into())}
+                        PathKind::Pat { pat_ctx: pattern_context_for(sema, original_file, it.into())}
                     },
                     ast::MacroCall(it) => {
                         // A macro call in this position is usually a result of parsing recovery, so check that
@@ -785,7 +823,7 @@ impl<'a> CompletionContext<'a> {
                         match_ast! {
                             match parent {
                                 ast::MacroExpr(expr) => make_path_kind_expr(expr.into()),
-                                ast::MacroPat(it) => PathKind::Pat { pat_ctx: pattern_context_for(original_file, it.into())},
+                                ast::MacroPat(it) => PathKind::Pat { pat_ctx: pattern_context_for(sema, original_file, it.into())},
                                 ast::MacroType(ty) => make_path_kind_type(ty.into()),
                                 ast::ItemList(_) => PathKind::Item { kind: ItemListKind::Module },
                                 ast::AssocItemList(_) => PathKind::Item { kind: match parent.parent() {
@@ -793,7 +831,7 @@ impl<'a> CompletionContext<'a> {
                                         match it {
                                             ast::Trait(_) => ItemListKind::Trait,
                                             ast::Impl(it) => if it.trait_().is_some() {
-                                                ItemListKind::TraitImpl
+                                                ItemListKind::TraitImpl(find_node_in_file_compensated(sema, original_file, &it))
                                             } else {
                                                 ItemListKind::Impl
                                             },
@@ -930,7 +968,11 @@ impl<'a> CompletionContext<'a> {
     }
 }
 
-fn pattern_context_for(original_file: &SyntaxNode, pat: ast::Pat) -> PatternContext {
+fn pattern_context_for(
+    sema: &Semantics<RootDatabase>,
+    original_file: &SyntaxNode,
+    pat: ast::Pat,
+) -> PatternContext {
     let mut is_param = None;
     let (refutability, has_type_ascription) =
     pat
@@ -946,7 +988,7 @@ fn pattern_context_for(original_file: &SyntaxNode, pat: ast::Pat) -> PatternCont
                         let has_type_ascription = param.ty().is_some();
                         is_param = (|| {
                             let fake_param_list = param.syntax().parent().and_then(ast::ParamList::cast)?;
-                            let param_list = find_node_in_file_compensated(original_file, &fake_param_list)?;
+                            let param_list = find_node_in_file_compensated(sema, original_file, &fake_param_list)?;
                             let param_list_owner = param_list.syntax().parent()?;
                             let kind = match_ast! {
                                 match param_list_owner {
@@ -971,6 +1013,7 @@ fn pattern_context_for(original_file: &SyntaxNode, pat: ast::Pat) -> PatternCont
         ast::Pat::IdentPat(it) => (it.ref_token(), it.mut_token()),
         _ => (None, None),
     };
+
     PatternContext {
         refutability,
         param_ctx: is_param,
@@ -979,6 +1022,27 @@ fn pattern_context_for(original_file: &SyntaxNode, pat: ast::Pat) -> PatternCont
         mut_token,
         ref_token,
         record_pat: None,
+        impl_: fetch_immediate_impl(sema, original_file, pat.syntax()),
+    }
+}
+
+fn fetch_immediate_impl(
+    sema: &Semantics<RootDatabase>,
+    original_file: &SyntaxNode,
+    node: &SyntaxNode,
+) -> Option<ast::Impl> {
+    let mut ancestors = ancestors_in_file_compensated(sema, original_file, node)?
+        .filter_map(ast::Item::cast)
+        .filter(|it| !matches!(it, ast::Item::MacroCall(_)));
+
+    match ancestors.next()? {
+        ast::Item::Const(_) | ast::Item::Fn(_) | ast::Item::TypeAlias(_) => (),
+        ast::Item::Impl(it) => return Some(it),
+        _ => return None,
+    }
+    match ancestors.next()? {
+        ast::Item::Impl(it) => Some(it),
+        _ => None,
     }
 }
 
@@ -1000,9 +1064,21 @@ fn find_node_in_file<N: AstNode>(syntax: &SyntaxNode, node: &N) -> Option<N> {
 /// Attempts to find `node` inside `syntax` via `node`'s text range while compensating
 /// for the offset introduced by the fake ident.
 /// This is wrong if `node` comes before the insertion point! Use `find_node_in_file` instead.
-fn find_node_in_file_compensated<N: AstNode>(syntax: &SyntaxNode, node: &N) -> Option<N> {
-    let syntax_range = syntax.text_range();
-    let range = node.syntax().text_range();
+fn find_node_in_file_compensated<N: AstNode>(
+    sema: &Semantics<RootDatabase>,
+    in_file: &SyntaxNode,
+    node: &N,
+) -> Option<N> {
+    ancestors_in_file_compensated(sema, in_file, node.syntax())?.find_map(N::cast)
+}
+
+fn ancestors_in_file_compensated<'sema>(
+    sema: &'sema Semantics<RootDatabase>,
+    in_file: &SyntaxNode,
+    node: &SyntaxNode,
+) -> Option<impl Iterator<Item = SyntaxNode> + 'sema> {
+    let syntax_range = in_file.text_range();
+    let range = node.text_range();
     let end = range.end().checked_sub(TextSize::try_from(COMPLETION_MARKER.len()).ok()?)?;
     if end < range.start() {
         return None;
@@ -1010,17 +1086,22 @@ fn find_node_in_file_compensated<N: AstNode>(syntax: &SyntaxNode, node: &N) -> O
     let range = TextRange::new(range.start(), end);
     // our inserted ident could cause `range` to go outside of the original syntax, so cap it
     let intersection = range.intersect(syntax_range)?;
-    syntax.covering_element(intersection).ancestors().find_map(N::cast)
+    let node = match in_file.covering_element(intersection) {
+        NodeOrToken::Node(node) => node,
+        NodeOrToken::Token(tok) => tok.parent()?,
+    };
+    Some(sema.ancestors_with_macros(node))
 }
 
 /// Attempts to find `node` inside `syntax` via `node`'s text range while compensating
 /// for the offset introduced by the fake ident..
 /// This is wrong if `node` comes before the insertion point! Use `find_node_in_file` instead.
 fn find_opt_node_in_file_compensated<N: AstNode>(
+    sema: &Semantics<RootDatabase>,
     syntax: &SyntaxNode,
     node: Option<N>,
 ) -> Option<N> {
-    find_node_in_file_compensated(syntax, &node?)
+    find_node_in_file_compensated(sema, syntax, &node?)
 }
 
 fn path_or_use_tree_qualifier(path: &ast::Path) -> Option<(ast::Path, bool)> {