(re)implement PR6542, accepting and discarding the __gcc_tdiag__

format attribute specifier.

llvm-svn: 99213

clang/lib/Sema/SemaDeclAttr.cpp

@@ -1115,6 +1115,7 @@ enum FormatAttrKind {
   NSStringFormat,
   StrftimeFormat,
   SupportedFormat,
+  IgnoredFormat,
   InvalidFormat
 };
 
@@ -1136,6 +1137,9 @@ static FormatAttrKind getFormatAttrKind(llvm::StringRef Format) {
       Format == "zcmn_err")
     return SupportedFormat;
 
+  if (Format == "gcc_tdiag")
+    return IgnoredFormat;
+  
   return InvalidFormat;
 }
 
@@ -1171,6 +1175,10 @@ static void HandleFormatAttr(Decl *d, const AttributeList &Attr, Sema &S) {
 
   // Check for supported formats.
   FormatAttrKind Kind = getFormatAttrKind(Format);
+  
+  if (Kind == IgnoredFormat)
+    return;
+  
   if (Kind == InvalidFormat) {
     S.Diag(Attr.getLoc(), diag::warn_attribute_type_not_supported)
       << "format" << Attr.getParameterName()->getName();

clang/test/Sema/attr-format.c

@@ -68,3 +68,7 @@ void __attribute__((format(printf, 1, 0)))
 foo2(const char *fmt, va_list va) {
   xx_vprintf(foo(fmt), va);
 }
+
+// PR6542
+extern void gcc_format (const char *, ...)
+  __attribute__ ((__format__(__gcc_tdiag__, 1, 2)));