From patchwork Tue Dec  4 06:44:23 2012
Content-Type: text/plain; charset="utf-8"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Subject: Go patch committed: Reject nil == nil
Date: Mon, 03 Dec 2012 20:44:23 -0000
From: Ian Taylor <iant@google.com>
X-Patchwork-Id: 203570
Message-Id: <mcrlides4e0.fsf@google.com>
To: gcc-patches@gcc.gnu.org, gofrontend-dev@googlegroups.com

This patch to the Go frontend rejects invalid comparisons in Go of nil
with nil.  These comparisons have no type and no particular meaning, and
they are not permitted.  Bootstrapped and ran Go testsuite on
x86_64-unknown-linux-gnu.  Committed to mainline.

Ian


diff -r 4d8871577da5 go/expressions.cc
--- a/go/expressions.cc	Mon Dec 03 22:22:34 2012 -0800
+++ b/go/expressions.cc	Mon Dec 03 22:38:58 2012 -0800
@@ -5610,6 +5610,11 @@
       || this->op_ == OPERATOR_GT
       || this->op_ == OPERATOR_GE)
     {
+      if (left_type->is_nil_type() && right_type->is_nil_type())
+	{
+	  this->report_error(_("invalid comparison of nil with nil"));
+	  return;
+	}
       if (!Type::are_assignable(left_type, right_type, NULL)
 	  && !Type::are_assignable(right_type, left_type, NULL))
 	{