gc: keep pointer to original node in constant rewrites.
This allows printing meaningful expressions in error messages
instead of evaluated constants.
Fixes #2276.
R=golang-dev, rsc
CC=golang-dev, remy
https://golang.org/cl/5432082
diff --git a/test/fixedbugs/bug381.go b/test/fixedbugs/bug381.go
new file mode 100644
index 0000000..3f3232b
--- /dev/null
+++ b/test/fixedbugs/bug381.go
@@ -0,0 +1,20 @@
+// errchk $G $D/$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.
+
+// Issue 2276.
+
+// Check that the error messages says
+// bug378.go:19: unsafe.Alignof(0) not used
+// and not
+// bug378.go:19: 4 not used
+
+package main
+
+import "unsafe"
+
+func main() {
+ unsafe.Alignof(0) // ERROR "unsafe\.Alignof|value computed is not used"
+}
