Go patch committed: Avoid ICE on invalid len call

[Ian Lance Taylor]

This Go frontend patch from Rémy Oudompheng avoids an ICE on an invalid
call to the builtin len function.  Bootstrapped on
x86_64-unknown-linux-gnu.  Committed to mainline and 4.7 branch.

Ian


diff -r 5b52b07a8cf4 go/expressions.cc
--- a/go/expressions.cc	Wed Mar 28 15:24:30 2012 -0700
+++ b/go/expressions.cc	Wed Mar 28 15:29:03 2012 -0700
@@ -6609,7 +6609,7 @@
       if (this->code_ == BUILTIN_LEN || this->code_ == BUILTIN_CAP)
 	{
 	  Expression* arg = this->one_arg();
-	  if (!arg->is_constant())
+	  if (arg != NULL && !arg->is_constant())
 	    {
 	      Find_call_expression find_call;
 	      Expression::traverse(&arg, &find_call);
@@ -6929,7 +6929,7 @@
 Builtin_call_expression::one_arg() const
 {
   const Expression_list* args = this->args();
-  if (args->size() != 1)
+  if (args == NULL || args->size() != 1)
     return NULL;
   return args->front();
 }