test: add a test for gccgo bug in handling break statement in a select

Gccgo CL 184998 added optimizations for one- and two-case select
statements. But it didn't handle break statement in the select
case correctly. The fix is CL 185519. This CL adds a test.

Change-Id: Ide1b199f106172b41dd77c1f6e0d662fccdd8cc5
Reviewed-on: https://go-review.googlesource.com/c/go/+/185520
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

diff --git a/test/chan/select8.go b/test/chan/select8.go
new file mode 100644 (file)
index 0000000..20bca3a
--- /dev/null
+++ b/test/chan/select8.go
@@ -0,0 +1,55 @@
+// run
+
+// Copyright 2019 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 break statements in a select.
+// Gccgo had a bug in handling this.
+// Test 1,2,3-case selects, so it covers both the general
+// code path and the specialized optimizations for one-
+// and two-case selects.
+
+package main
+
+var ch = make(chan int)
+
+func main() {
+       go func() {
+               for {
+                       ch <- 5
+               }
+       }()
+
+       select {
+       case <-ch:
+               break
+               panic("unreachable")
+       }
+
+       select {
+       default:
+               break
+               panic("unreachable")
+       }
+
+       select {
+       case <-ch:
+               break
+               panic("unreachable")
+       default:
+               break
+               panic("unreachable")
+       }
+
+       select {
+       case <-ch:
+               break
+               panic("unreachable")
+       case ch <- 10:
+               panic("unreachable")
+       default:
+               break
+               panic("unreachable")
+       }
+}