From e92180a1d8c964d386fc5ffb80bfb05abdb6c153 Mon Sep 17 00:00:00 2001
From: Lukas Wirth <lukastw97@gmail.com>
Date: Tue, 9 Feb 2021 19:47:21 +0100
Subject: [PATCH] Show Self pattern completions for Adts if inside impls

---
 crates/completion/src/completions/pattern.rs  | 28 +++++++++++++++++++
 .../src/completions/unqualified_path.rs       |  2 +-
 crates/completion/src/context.rs              | 16 +++++++----
 3 files changed, 40 insertions(+), 6 deletions(-)

diff --git a/crates/completion/src/completions/pattern.rs b/crates/completion/src/completions/pattern.rs
index 595160ff57a..43a5160cba3 100644
--- a/crates/completion/src/completions/pattern.rs
+++ b/crates/completion/src/completions/pattern.rs
@@ -31,6 +31,14 @@ pub(crate) fn complete_pattern(acc: &mut Completions, ctx: &CompletionContext) {
                 _ => false,
             },
             hir::ScopeDef::MacroDef(_) => true,
+            hir::ScopeDef::ImplSelfType(impl_) => match impl_.target_ty(ctx.db).as_adt() {
+                Some(hir::Adt::Struct(strukt)) => {
+                    acc.add_struct_pat(ctx, strukt, Some(name.clone()));
+                    true
+                }
+                Some(hir::Adt::Enum(_)) => !ctx.is_irrefutable_pat_binding,
+                _ => true,
+            },
             _ => false,
         };
         if add_resolution {
@@ -258,4 +266,24 @@ fn main() {
 "#,
         );
     }
+
+    #[test]
+    fn completes_self_pats() {
+        check_snippet(
+            r#"
+struct Foo(i32);
+impl Foo {
+    fn foo() {
+        match () {
+            $0
+        }
+    }
+}
+    "#,
+            expect![[r#"
+                bn Self Self($1)$0
+                bn Foo  Foo($1)$0
+            "#]],
+        )
+    }
 }
diff --git a/crates/completion/src/completions/unqualified_path.rs b/crates/completion/src/completions/unqualified_path.rs
index fb67756bbfc..5112ecc2d9c 100644
--- a/crates/completion/src/completions/unqualified_path.rs
+++ b/crates/completion/src/completions/unqualified_path.rs
@@ -746,7 +746,7 @@ fn completes_enum_variant_impl() {
             r#"
 enum Foo { Bar, Baz, Quux }
 impl Foo {
-    fn foo() { let foo: Foo = Q$0 }
+    fn foo() { match Foo::Bar { Q$0 } }
 }
 "#,
             expect![[r#"
diff --git a/crates/completion/src/context.rs b/crates/completion/src/context.rs
index b1e8eba8564..3db3578555f 100644
--- a/crates/completion/src/context.rs
+++ b/crates/completion/src/context.rs
@@ -276,6 +276,14 @@ fn fill_keyword_patterns(&mut self, file_with_fake_ident: &SyntaxNode, offset: T
             });
     }
 
+    fn fill_impl_def(&mut self) {
+        self.impl_def = self
+            .sema
+            .ancestors_with_macros(self.token.parent())
+            .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
+            .find_map(ast::Impl::cast);
+    }
+
     fn fill(
         &mut self,
         original_file: &SyntaxNode,
@@ -345,6 +353,8 @@ fn fill(
                         self.is_irrefutable_pat_binding = true;
                     }
                 }
+
+                self.fill_impl_def();
             }
             if is_node::<ast::Param>(name.syntax()) {
                 self.is_param = true;
@@ -372,11 +382,7 @@ fn classify_name_ref(
                 self.sema.find_node_at_offset_with_macros(&original_file, offset);
         }
 
-        self.impl_def = self
-            .sema
-            .ancestors_with_macros(self.token.parent())
-            .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
-            .find_map(ast::Impl::cast);
+        self.fill_impl_def();
 
         let top_node = name_ref
             .syntax()