[release-branch.go1] cmd/8g: fix miscompilation due to BADWIDTH.

««« backport f6a6fe780649
cmd/8g: fix miscompilation due to BADWIDTH.

Fixes #3899.

R=rsc
CC=golang-dev, remy
https://golang.org/cl/6453084

»»»

diff --git a/src/cmd/8g/gsubr.c b/src/cmd/8g/gsubr.c
index 5e89af04ab2b0365c928944ee362346cb7da93cc..6aa75bb75d6877fccd15e5d790d0f8dd67ce55ac 100644 (file)
--- a/src/cmd/8g/gsubr.c
+++ b/src/cmd/8g/gsubr.c
@@ -1847,6 +1847,7 @@ naddr(Node *n, Addr *a, int canemitcode)
                a->width = 0;
                if(n->type != T) {
                        a->etype = simtype[n->type->etype];
+                       dowidth(n->type);
                        a->width = n->type->width;
                        a->gotype = ngotype(n);
                }

diff --git a/test/fixedbugs/bug450.go b/test/fixedbugs/bug450.go
new file mode 100644 (file)
index 0000000..3f13de1
--- /dev/null
+++ b/test/fixedbugs/bug450.go
@@ -0,0 +1,28 @@
+// run
+
+// Copyright 2012 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 3899: 8g incorrectly thinks a variable is
+// "set but not used" and elides an assignment, causing
+// variables to end up with wrong data.
+//
+// The reason is a miscalculation of variable width.
+
+package main
+
+func bar(f func()) {
+       f()
+}
+
+func foo() {
+       f := func() {}
+       if f == nil {
+       }
+       bar(f)
+}
+
+func main() {
+       foo()
+}