cmd/ld: handle duplicate static symbols in COFF and Mach-O files.

Fixes issue 5740.

R=iant, rsc, luisbebop
CC=gobot, golang-dev
https://codereview.appspot.com/10345046

3 files changed, 33 insertions, 0 deletions

diff --git a/misc/cgo/test/issue5740.go b/misc/cgo/test/issue5740.go
new file mode 100644
index 000000000..25c86153f
--- /dev/null
+++ b/misc/cgo/test/issue5740.go
@@ -0,0 +1,15 @@
+// Copyright 2013 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 cgotest
+
+// int test5740a(void), test5740b(void);
+import "C"
+import "testing"
+
+func test5740(t *testing.T) {
+	if v := C.test5740a() + C.test5740b(); v != 5 {
+		t.Errorf("expected 5, got %v", v)
+	}
+}
diff --git a/misc/cgo/test/issue5740a.c b/misc/cgo/test/issue5740a.c
new file mode 100644
index 000000000..25f18e2a4
--- /dev/null
+++ b/misc/cgo/test/issue5740a.c
@@ -0,0 +1,9 @@
+// Copyright 2013 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.
+
+static int volatile val = 2;
+
+int test5740a() {
+	return val;
+}
diff --git a/misc/cgo/test/issue5740b.c b/misc/cgo/test/issue5740b.c
new file mode 100644
index 000000000..22893f35b
--- /dev/null
+++ b/misc/cgo/test/issue5740b.c
@@ -0,0 +1,9 @@
+// Copyright 2013 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.
+
+static int volatile val = 3;
+
+int test5740b() {
+	return val;
+}