gc: diagnose unused labels

R=ken2
CC=golang-dev
https://golang.org/cl/4287047

1 files changed, 60 insertions, 0 deletions

diff --git a/test/label.go b/test/label.go
new file mode 100644
index 0000000000..ab231232a8
--- /dev/null
+++ b/test/label.go
@@ -0,0 +1,60 @@
+// errchk $G -e $D/$F.go
+
+// Copyright 2011 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.
+
+// Pass 1 label errors.
+
+package main
+
+var x int
+
+func f() {
+L1: // ERROR "label L1 defined and not used"
+	for {
+	}
+L2: // ERROR "label L2 defined and not used"
+	select {
+	}
+L3: // ERROR "label L3 defined and not used"
+	switch {
+	}
+L4: // ERROR "label L4 defined and not used"
+	if true {
+	}
+L5: // ERROR "label L5 defined and not used"
+	f()
+L6:
+	f()
+L6: // ERROR "label L6 already defined at"
+	f()
+	if x == 20 {
+		goto L6
+	}
+
+L7:
+	for {
+		break L7
+	}
+
+L8:
+	for {
+		if x == 21 {
+			continue L8
+		}
+	}
+
+L9:
+	switch {
+	case true:
+		break L9
+	defalt: // ERROR "label defalt defined and not used"
+	}
+
+L10:
+	select {
+	default:
+		break L10
+	}
+}