From 8b94bf7b2dd4743ce87d12b9892405cab48ac6da Mon Sep 17 00:00:00 2001
From: Lukas Tobias Wirth <lukastw97@gmail.com>
Date: Tue, 4 May 2021 21:03:35 +0200
Subject: Complete enum variants through type aliases

---
 .../src/completions/qualified_path.rs              | 40 ++++++++++++++++++----
 1 file changed, 33 insertions(+), 7 deletions(-)

diff --git a/crates/ide_completion/src/completions/qualified_path.rs b/crates/ide_completion/src/completions/qualified_path.rs
index d8f23d1eb..d2ebba65f 100644
--- a/crates/ide_completion/src/completions/qualified_path.rs
+++ b/crates/ide_completion/src/completions/qualified_path.rs
@@ -52,13 +52,17 @@ pub(crate) fn complete_qualified_path(acc: &mut Completions, ctx: &CompletionCon
         | PathResolution::Def(def @ hir::ModuleDef::TypeAlias(_))
         | PathResolution::Def(def @ hir::ModuleDef::BuiltinType(_)) => {
             if let hir::ModuleDef::Adt(Adt::Enum(e)) = def {
-                for variant in e.variants(ctx.db) {
-                    acc.add_enum_variant(ctx, variant, None);
-                }
+                add_enum_variants(ctx, acc, e);
             }
             let ty = match def {
                 hir::ModuleDef::Adt(adt) => adt.ty(ctx.db),
-                hir::ModuleDef::TypeAlias(a) => a.ty(ctx.db),
+                hir::ModuleDef::TypeAlias(a) => {
+                    let ty = a.ty(ctx.db);
+                    if let Some(Adt::Enum(e)) = ty.as_adt() {
+                        add_enum_variants(ctx, acc, e);
+                    }
+                    ty
+                }
                 hir::ModuleDef::BuiltinType(builtin) => {
                     let module = match ctx.scope.module() {
                         Some(it) => it,
@@ -122,9 +126,7 @@ pub(crate) fn complete_qualified_path(acc: &mut Completions, ctx: &CompletionCon
                 };
 
                 if let Some(Adt::Enum(e)) = ty.as_adt() {
-                    for variant in e.variants(ctx.db) {
-                        acc.add_enum_variant(ctx, variant, None);
-                    }
+                    add_enum_variants(ctx, acc, e);
                 }
 
                 let traits_in_scope = ctx.scope.traits_in_scope();
@@ -151,6 +153,12 @@ pub(crate) fn complete_qualified_path(acc: &mut Completions, ctx: &CompletionCon
     }
 }
 
+fn add_enum_variants(ctx: &CompletionContext, acc: &mut Completions, e: hir::Enum) {
+    for variant in e.variants(ctx.db) {
+        acc.add_enum_variant(ctx, variant, None);
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use expect_test::{expect, Expect};
@@ -782,4 +790,22 @@ impl u8 {
             "#]],
         );
     }
+
+    #[test]
+    fn completes_through_alias() {
+        check(
+            r#"
+enum Foo {
+    Bar
+}
+type Foo2 = Foo;
+fn main() {
+    Foo2::$0
+}
+"#,
+            expect![[r#"
+                ev Bar ()
+            "#]],
+        );
+    }
 }
-- 
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