(expand_builtin, case BUILT_IN_NEXT_ARG): Test whether an argunment

has been passed to __builtin_next_arg; warn if not.

From-SVN: r6994

diff --git a/gcc/expr.c b/gcc/expr.c
index 6339b459941da6f53d627ccdddf4500da29db3d5..f8531ff8de04785a33336dfd8de3e9aaeb220710 100644 (file)
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -6961,8 +6961,6 @@ expand_builtin (exp, target, subtarget, mode, ignore)
     case BUILT_IN_NEXT_ARG:
       {
        tree fntype = TREE_TYPE (current_function_decl);
-       tree last_parm = tree_last (DECL_ARGUMENTS (current_function_decl));
-       tree arg;
 
        if (TYPE_ARG_TYPES (fntype) == 0
            || (TREE_VALUE (tree_last (TYPE_ARG_TYPES (fntype)))
@@ -6973,15 +6971,24 @@ expand_builtin (exp, target, subtarget, mode, ignore)
            return const0_rtx;
          }
 
-       arg = TREE_VALUE (arglist);
-       /* Strip off all nops for the sake of the comparison.  This is not
-          quite the same as STRIP_NOPS.  It does more.  */
-       while (TREE_CODE (arg) == NOP_EXPR
-              || TREE_CODE (arg) == CONVERT_EXPR
-              || TREE_CODE (arg) == NON_LVALUE_EXPR)
-         arg = TREE_OPERAND (arg, 0);
-       if (arg != last_parm)
-         warning ("second parameter of `va_start' not last named argument");
+       if (arglist)
+         {
+           tree last_parm = tree_last (DECL_ARGUMENTS (current_function_decl));
+           tree arg = TREE_VALUE (arglist);
+
+           /* Strip off all nops for the sake of the comparison.  This
+              is not quite the same as STRIP_NOPS.  It does more.  */
+           while (TREE_CODE (arg) == NOP_EXPR
+                  || TREE_CODE (arg) == CONVERT_EXPR
+                  || TREE_CODE (arg) == NON_LVALUE_EXPR)
+             arg = TREE_OPERAND (arg, 0);
+           if (arg != last_parm)
+             warning ("second parameter of `va_start' not last named argument");
+         }
+       else
+         /* Evidently an out of date version of <stdarg.h>; can't validate
+            va_start's second argument, but can still work as intended.  */
+         warning ("`__builtin_next_arg' called without an argument");
       }
 
       return expand_binop (Pmode, add_optab,