test: add test that gofrontend gets wrong

For #52856

Change-Id: Iab3e8352f64d774058391f0422cd01c53c3e711d
Reviewed-on: https://go-review.googlesource.com/c/go/+/414235
Reviewed-by: Robert Griesemer <gri@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>

test/fixedbugs/issue52856.dir/a.go

@@ -0,0 +1,9 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+func F() any {
+	return struct{ int }{0}
+}

test/fixedbugs/issue52856.dir/main.go

@@ -0,0 +1,19 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import "./a"
+
+func F() any {
+	return struct{ int }{0}
+}
+
+func main() {
+	_, ok1 := F().(struct{ int })
+	_, ok2 := a.F().(struct{ int })
+	if !ok1 || ok2 {
+		panic(0)
+	}
+}

test/fixedbugs/issue52856.go

@@ -0,0 +1,10 @@
+// rundir
+
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Test that an embedded unexported type has a different name in
+// different packages.
+
+package ignored