1 files changed, 45 insertions, 0 deletions
diff --git a/libgo/misc/cgo/test/issue21809.go b/libgo/misc/cgo/test/issue21809.go
new file mode 100644
index 00000000000..a3a6b88897e
--- /dev/null
+++ b/libgo/misc/cgo/test/issue21809.go
@@ -0,0 +1,45 @@
+// Copyright 2017 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
+
+// Issue 21809.  Compile C `typedef` to go type aliases.
+
+// typedef long MySigned_t;
+// /* tests alias-to-alias */
+// typedef MySigned_t MySigned2_t;
+//
+// long takes_long(long x) { return x * x; }
+// MySigned_t takes_typedef(MySigned_t x) { return x * x; }
+import "C"
+
+import "testing"
+
+func test21809(t *testing.T) {
+	longVar := C.long(3)
+	typedefVar := C.MySigned_t(4)
+	typedefTypedefVar := C.MySigned2_t(5)
+
+	// all three should be considered identical to `long`
+	if ret := C.takes_long(longVar); ret != 9 {
+		t.Errorf("got %v but expected %v", ret, 9)
+	}
+	if ret := C.takes_long(typedefVar); ret != 16 {
+		t.Errorf("got %v but expected %v", ret, 16)
+	}
+	if ret := C.takes_long(typedefTypedefVar); ret != 25 {
+		t.Errorf("got %v but expected %v", ret, 25)
+	}
+
+	// They should also be identical to the typedef'd type
+	if ret := C.takes_typedef(longVar); ret != 9 {
+		t.Errorf("got %v but expected %v", ret, 9)
+	}
+	if ret := C.takes_typedef(typedefVar); ret != 16 {
+		t.Errorf("got %v but expected %v", ret, 16)
+	}
+	if ret := C.takes_typedef(typedefTypedefVar); ret != 25 {
+		t.Errorf("got %v but expected %v", ret, 25)
+	}
+}