Don't trap when passing non-POD arguments to variadic functions in MS-compatibility mode

Clang warns (treated as error by default, but still ignored in system headers)
when passing non-POD arguments to variadic functions, and generates a trap
instruction to crash the program if that code is ever run.

Unfortunately, MSVC happily generates code for such calls without a warning,
and there is code in system headers that use it.

This makes Clang not insert the trap instruction when in -fms-compatibility
mode, while still generating the warning/error message.

Differential Revision: http://reviews.llvm.org/D5492

llvm-svn: 218640

1 files changed, 4 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 5edabc03b69..0c7cb2e6df1 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -800,6 +800,9 @@ Sema::VarArgKind Sema::isValidVarArgType(const QualType &Ty) {
   if (Ty->isObjCObjectType())
     return VAK_Invalid;
 
+  if (getLangOpts().MSVCCompat)
+    return VAK_MSVCUndefined;
+
   // FIXME: In C++11, these cases are conditionally-supported, meaning we're
   // permitted to reject them. We should consider doing so.
   return VAK_Undefined;
@@ -829,6 +832,7 @@ void Sema::checkVariadicArgument(const Expr *E, VariadicCallType CT) {
     break;
 
   case VAK_Undefined:
+  case VAK_MSVCUndefined:
     DiagRuntimeBehavior(
         E->getLocStart(), nullptr,
         PDiag(diag::warn_cannot_pass_non_pod_arg_to_vararg)