From patchwork Wed Jun 30 21:32:27 2010
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Subject: [gccgo] A type assertion with nil does not succeed
Date: Wed, 30 Jun 2010 11:32:27 -0000
From: Ian Taylor <iant@google.com>
X-Patchwork-Id: 57455
Message-Id: <mcrzkycyzo4.fsf@google.com>
To: gcc-patches@gcc.gnu.org, gofrontend-dev@googlegroups.com

When doing a type assertion such as
    if v, ok := x.(t); ok { }
where x is nil, the type assertion is not considered to succeed.  This
is true even though v := x.(t) does not cause a panic.  This patch
implements that for gccgo.  Committed to gccgo branch.

Ian


diff -r 509de793fde1 libgo/runtime/go-convert-interface.c
--- a/libgo/runtime/go-convert-interface.c	Wed Jun 30 14:07:44 2010 -0700
+++ b/libgo/runtime/go-convert-interface.c	Wed Jun 30 14:29:05 2010 -0700
@@ -35,7 +35,7 @@
   if (rhs == NULL)
     {
       if (success != NULL)
-	*success = 1;
+	*success = 0;
       return NULL;
     }