Permit comparing non-empty interfaces with empty interfaces.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@170385 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 32 insertions, 0 deletions

diff --git a/libgo/runtime/go-interface-eface-compare.c b/libgo/runtime/go-interface-eface-compare.c
new file mode 100644
index 00000000000..9de8424acc1
--- /dev/null
+++ b/libgo/runtime/go-interface-eface-compare.c
@@ -0,0 +1,32 @@
+/* go-interface-eface-compare.c -- compare non-empty and empty interface.
+
+   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.  */
+
+#include "interface.h"
+
+/* Compare a non-empty interface value with an empty interface value.
+   Return 0 for equal, not zero for not equal (return value is like
+   strcmp).  */
+
+int
+__go_interface_empty_compare (struct __go_interface left,
+			      struct __go_empty_interface right)
+{
+  const struct __go_type_descriptor *left_descriptor;
+
+  if (left.__methods == NULL && right.__type_descriptor == NULL)
+    return 0;
+  if (left.__methods == NULL || right.__type_descriptor == NULL)
+    return 1;
+  left_descriptor = left.__methods[0];
+  if (!__go_type_descriptors_equal (left_descriptor, right.__type_descriptor))
+    return 1;
+  if (__go_is_pointer_type (left_descriptor))
+    return left.__object == right.__object ? 0 : 1;
+  if (!left_descriptor->__equalfn (left.__object, right.__object,
+				   left_descriptor->__size))
+    return 1;
+  return 0;
+}