cmd/cgo: reject names that are likely to be mangled C name

Fixes #28721

Change-Id: I00356f3a9b0c2fb21dc9c2237dd5296fcb3b319b
Reviewed-on: https://go-review.googlesource.com/c/152657
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

2 files changed, 30 insertions, 0 deletions

diff --git a/misc/cgo/errors/errors_test.go b/misc/cgo/errors/errors_test.go
index 0d7ca4cf9d..d2a72a46f4 100644
--- a/misc/cgo/errors/errors_test.go
+++ b/misc/cgo/errors/errors_test.go
@@ -121,6 +121,7 @@ func TestReportsTypeErrors(t *testing.T) {
 		"issue16591.go",
 		"issue18452.go",
 		"issue18889.go",
+		"issue28721.go",
 	} {
 		check(t, file)
 	}
diff --git a/misc/cgo/errors/src/issue28721.go b/misc/cgo/errors/src/issue28721.go
new file mode 100644
index 0000000000..0eb2a9271c
--- /dev/null
+++ b/misc/cgo/errors/src/issue28721.go
@@ -0,0 +1,29 @@
+// Copyright 2018 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.
+
+// cgo should reject the use of mangled C names.
+
+package main
+
+/*
+typedef struct a {
+	int i;
+} a;
+void fn(void) {}
+*/
+import "C"
+
+type B _Ctype_struct_a // ERROR HERE
+
+var a _Ctype_struct_a // ERROR HERE
+
+type A struct {
+	a *_Ctype_struct_a // ERROR HERE
+}
+
+var notExist _Ctype_NotExist // ERROR HERE
+
+func main() {
+	_Cfunc_fn() // ERROR HERE
+}