1 files changed, 34 insertions, 0 deletions
diff --git a/test/typeparam/mdempsky/16.go b/test/typeparam/mdempsky/16.go
new file mode 100644
index 0000000..f4f79b9
--- /dev/null
+++ b/test/typeparam/mdempsky/16.go
@@ -0,0 +1,34 @@
+// run
+
+// 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 type assertion panics mention the real interface type,
+// not their shape type.
+
+package main
+
+import (
+	"fmt"
+	"runtime"
+	"strings"
+)
+
+func main() {
+	// The exact error message isn't important, but it should mention
+	// `main.T`, not `go.shape.int_0`.
+	if have := F[T](); !strings.Contains(have, "interface { T() main.T }") {
+		fmt.Printf("FAIL: unexpected panic message: %q\n", have)
+	}
+}
+
+type T int
+
+func F[T any]() (res string) {
+	defer func() {
+		res = recover().(runtime.Error).Error()
+	}()
+	_ = interface{ T() T }(nil).(T)
+	return
+}