Go patch committed: Accept general expression in case x := <-c

[Ian Lance Taylor]

The Go language specification permits a general expression in
        select {
        case x := <-c:
        }
which basically means that it can look like
        case x := (<-c):
The gccgo parser was failing to handle that case.  This patch fixes it.
Bootstrapped and ran Go testsuite on x86_64-unknown-linux-gnu.
Committed to mainline.

Ian


diff -r 36a50b3d3a7d go/parse.cc
--- a/go/parse.cc	Tue Jan 31 16:00:53 2012 -0800
+++ b/go/parse.cc	Wed Feb 01 06:26:31 2012 -0800
@@ -4640,9 +4640,14 @@
       if (token->is_op(OPERATOR_COLONEQ))
 	{
 	  // case rv := <-c:
-	  if (!this->advance_token()->is_op(OPERATOR_CHANOP))
+	  this->advance_token();
+	  Expression* e = this->expression(PRECEDENCE_NORMAL, false, false,
+					   NULL);
+	  Receive_expression* re = e->receive_expression();
+	  if (re == NULL)
 	    {
-	      error_at(this->location(), "expected %<<-%>");
+	      if (!e->is_error_expression())
+		error_at(this->location(), "expected receive expression");
 	      return false;
 	    }
 	  if (recv_var == "_")
@@ -4653,8 +4658,7 @@
 	    }
 	  *is_send = false;
 	  *varname = gogo->pack_hidden_name(recv_var, is_rv_exported);
-	  this->advance_token();
-	  *channel = this->expression(PRECEDENCE_NORMAL, false, true, NULL);
+	  *channel = re->channel();
 	  return true;
 	}
       else if (token->is_op(OPERATOR_COMMA))
@@ -4671,9 +4675,15 @@
 	      if (token->is_op(OPERATOR_COLONEQ))
 		{
 		  // case rv, rc := <-c:
-		  if (!this->advance_token()->is_op(OPERATOR_CHANOP))
+		  this->advance_token();
+		  Expression* e = this->expression(PRECEDENCE_NORMAL, false,
+						   false, NULL);
+		  Receive_expression* re = e->receive_expression();
+		  if (re == NULL)
 		    {
-		      error_at(this->location(), "expected %<<-%>");
+		      if (!e->is_error_expression())
+			error_at(this->location(),
+				 "expected receive expression");
 		      return false;
 		    }
 		  if (recv_var == "_" && recv_closed == "_")
@@ -4689,9 +4699,7 @@
 		  if (recv_closed != "_")
 		    *closedname = gogo->pack_hidden_name(recv_closed,
 							 is_rc_exported);
-		  this->advance_token();
-		  *channel = this->expression(PRECEDENCE_NORMAL, false, true,
-					      NULL);
+		  *channel = re->channel();
 		  return true;
 		}