test: add failing test case for inlined type switches

The unified frontend ICEs when inlining a function that contains a
function literal, which captures both a type switch case variable and
another variable.

Updates #54912.

Change-Id: I0e16d371ed5df48a70823beb0bf12110a5a17266
Reviewed-on: https://go-review.googlesource.com/c/go/+/428917
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

test/fixedbugs/issue54912.dir/a.go

@@ -0,0 +1,18 @@
+// 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 inlining a function literal that captures both a type
+// switch case variable and another local variable works correctly.
+
+package a
+
+func F(p *int, x any) func() {
+	switch x := x.(type) {
+	case int:
+		return func() {
+			*p += x
+		}
+	}
+	return nil
+}

test/fixedbugs/issue54912.dir/main.go

@@ -0,0 +1,11 @@
+// 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 "test/a"
+
+func main() {
+	a.F(new(int), 0)()
+}

test/fixedbugs/issue54912.go

@@ -0,0 +1,7 @@
+// 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.
+
+package ignored

test/run.go

@@ -2021,6 +2021,8 @@ var unifiedFailures = setOf(
 	"closure3.go", // unified IR numbers closures differently than -d=inlfuncswithclosures
 	"escape4.go",  // unified IR can inline f5 and f6; test doesn't expect this
 
+	"fixedbugs/issue54912.go", // ICE when inlined type switch case variable captured in function literal
+
 	"typeparam/issue47631.go", // unified IR can handle local type declarations
 )