Rollup merge of #67783 - LeSeulArtichaut:pattern-ref-warning, r=Centril

Warn for bindings named same as variants when matching against a borrow

Fixes #67776

Author: JohnTitor

src/librustc_mir/hair/pattern/check_match.rs

@@ -284,7 +284,7 @@ fn check_for_bindings_named_same_as_variants(cx: &MatchVisitor<'_, '_>, pat: &Pa
             if let Some(ty::BindByValue(hir::Mutability::Not)) =
                 cx.tables.extract_binding_mode(cx.tcx.sess, p.hir_id, p.span)
             {
-                let pat_ty = cx.tables.pat_ty(p);
+                let pat_ty = cx.tables.pat_ty(p).peel_refs();
                 if let ty::Adt(edef, _) = pat_ty.kind {
                     if edef.is_enum()
                         && edef.variants.iter().any(|variant| {

src/test/ui/pattern/issue-67776-match-same-name-enum-variant-refs.rs

@@ -0,0 +1,42 @@
+// Test for issue #67776: binding named the same as enum variant
+// should report a warning even when matching against a reference type
+
+// check-pass
+
+#![allow(unused_variables)]
+#![allow(non_snake_case)]
+
+enum Foo {
+    Bar,
+    Baz,
+}
+
+
+fn fn1(e: Foo) {
+    match e {
+        Bar => {},
+        //~^ WARNING named the same as one of the variants of the type `Foo`
+        Baz => {},
+        //~^ WARNING named the same as one of the variants of the type `Foo`
+    }
+}
+
+fn fn2(e: &Foo) {
+    match e {
+        Bar => {},
+        //~^ WARNING named the same as one of the variants of the type `Foo`
+        Baz => {},
+        //~^ WARNING named the same as one of the variants of the type `Foo`
+    }
+}
+
+fn fn3(e: &mut &&mut Foo) {
+    match e {
+        Bar => {},
+        //~^ WARNING named the same as one of the variants of the type `Foo`
+        Baz => {},
+        //~^ WARNING named the same as one of the variants of the type `Foo`
+    }
+}
+
+fn main() {}

src/test/ui/pattern/issue-67776-match-same-name-enum-variant-refs.stderr

@@ -0,0 +1,36 @@
+warning[E0170]: pattern binding `Bar` is named the same as one of the variants of the type `Foo`
+  --> $DIR/issue-67776-match-same-name-enum-variant-refs.rs:17:9
+   |
+LL |         Bar => {},
+   |         ^^^ help: to match on the variant, qualify the path: `Foo::Bar`
+
+warning[E0170]: pattern binding `Baz` is named the same as one of the variants of the type `Foo`
+  --> $DIR/issue-67776-match-same-name-enum-variant-refs.rs:19:9
+   |
+LL |         Baz => {},
+   |         ^^^ help: to match on the variant, qualify the path: `Foo::Baz`
+
+warning[E0170]: pattern binding `Bar` is named the same as one of the variants of the type `Foo`
+  --> $DIR/issue-67776-match-same-name-enum-variant-refs.rs:26:9
+   |
+LL |         Bar => {},
+   |         ^^^ help: to match on the variant, qualify the path: `Foo::Bar`
+
+warning[E0170]: pattern binding `Baz` is named the same as one of the variants of the type `Foo`
+  --> $DIR/issue-67776-match-same-name-enum-variant-refs.rs:28:9
+   |
+LL |         Baz => {},
+   |         ^^^ help: to match on the variant, qualify the path: `Foo::Baz`
+
+warning[E0170]: pattern binding `Bar` is named the same as one of the variants of the type `Foo`
+  --> $DIR/issue-67776-match-same-name-enum-variant-refs.rs:35:9
+   |
+LL |         Bar => {},
+   |         ^^^ help: to match on the variant, qualify the path: `Foo::Bar`
+
+warning[E0170]: pattern binding `Baz` is named the same as one of the variants of the type `Foo`
+  --> $DIR/issue-67776-match-same-name-enum-variant-refs.rs:37:9
+   |
+LL |         Baz => {},
+   |         ^^^ help: to match on the variant, qualify the path: `Foo::Baz`
+