From 7657ab90b46149b27703a397f3764ef9517eb988 Mon Sep 17 00:00:00 2001
From: Ian Lance Taylor <ian@gcc.gnu.org>
Date: Fri, 25 Mar 2011 19:23:10 +0000
Subject: [PATCH] Avoid overflow error after negative shift count error.

From-SVN: r171523
---
 gcc/go/gofrontend/expressions.cc | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/gcc/go/gofrontend/expressions.cc b/gcc/go/gofrontend/expressions.cc
index 861d5c0ca99..2ee4a696db9 100644
--- a/gcc/go/gofrontend/expressions.cc
+++ b/gcc/go/gofrontend/expressions.cc
@@ -5747,7 +5747,13 @@ Binary_expression::do_check_types(Gogo*)
 	  if (this->right_->integer_constant_value(true, val, &type))
 	    {
 	      if (mpz_sgn(val) < 0)
-		this->report_error(_("negative shift count"));
+		{
+		  this->report_error(_("negative shift count"));
+		  mpz_set_ui(val, 0);
+		  source_location rloc = this->right_->location();
+		  this->right_ = Expression::make_integer(&val, right_type,
+							  rloc);
+		}
 	    }
 	  mpz_clear(val);
 	}
-- 
2.30.2