Daniel convinced me that accepting "const va_list" arguments to va_arg is

a really really bad idea.  Now that we emit an error about the unpromoted
type, users should be able to understand what is going on.

llvm-svn: 68447

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -1464,8 +1464,6 @@ def err_va_start_used_in_non_variadic_function : Error<
   "'va_start' used in function with fixed args">;
 def warn_second_parameter_of_va_start_not_last_named_argument : Warning<
   "second parameter of 'va_start' not last named argument">;
-def warn_va_arg_with_qualified_va_list : Warning<
-  "va_arg applied to va_list type %0 with unexpected qualifiers">;
 def err_first_argument_to_va_arg_not_of_type_va_list : Error<
   "first argument to 'va_arg' is of type %0 and not 'va_list'">;
 

clang/lib/Sema/SemaExpr.cpp

@@ -4725,16 +4725,7 @@ Sema::OwningExprResult Sema::ActOnVAArg(SourceLocation BuiltinLoc,
   // Make sure the input expression also decays appropriately.
   UsualUnaryConversions(E);
 
-  AssignConvertType ConvResult = 
-    CheckAssignmentConstraints(VaListType, E->getType());
-  switch (ConvResult) {
-  case Compatible: break;  // Everything good.
-  case CompatiblePointerDiscardsQualifiers:
-    Diag(E->getLocStart(), diag::warn_va_arg_with_qualified_va_list)
-      << OrigExpr->getType() << E->getSourceRange();
-    break;
-
-  default:
+  if (CheckAssignmentConstraints(VaListType, E->getType()) != Compatible) {
     return ExprError(Diag(E->getLocStart(),
                          diag::err_first_argument_to_va_arg_not_of_type_va_list)
       << OrigExpr->getType() << E->getSourceRange());

clang/test/Sema/varargs-x86-64.c

@@ -3,6 +3,6 @@
 // rdar://6726818
 void f1() {
   const __builtin_va_list args2;
-  (void)__builtin_va_arg(args2, int); // expected-warning {{va_arg applied to va_list type '__builtin_va_list const' with unexpected qualifiers}}
+  (void)__builtin_va_arg(args2, int); // expected-error {{first argument to 'va_arg' is of type '__builtin_va_list const' and not 'va_list'}}
 }