Allow standards-based attributes to have leading and trailing underscores.

This gives library implementers a way to use standards-based attributes that do not conflict with user-defined macros of the same name. Attributes in C2x require this behavior normatively (C2x 6.7.11p4), but there's no reason to not have the same behavior in C++, especially given that such attributes may be used by a C library consumed by a C++ compilation.

llvm-svn: 369033

1 files changed, 2 insertions, 1 deletions

diff --git a/clang/lib/Sema/ParsedAttr.cpp b/clang/lib/Sema/ParsedAttr.cpp
index 5c04443460b..6c103081c60 100644
--- a/clang/lib/Sema/ParsedAttr.cpp
+++ b/clang/lib/Sema/ParsedAttr.cpp
@@ -125,7 +125,8 @@ static StringRef normalizeAttrName(StringRef AttrName,
       SyntaxUsed == ParsedAttr::AS_GNU ||
       ((SyntaxUsed == ParsedAttr::AS_CXX11 ||
         SyntaxUsed == ParsedAttr::AS_C2x) &&
-       (NormalizedScopeName == "gnu" || NormalizedScopeName == "clang"));
+       (NormalizedScopeName.empty() || NormalizedScopeName == "gnu" ||
+        NormalizedScopeName == "clang"));
   if (ShouldNormalize && AttrName.size() >= 4 && AttrName.startswith("__") &&
       AttrName.endswith("__"))
     AttrName = AttrName.slice(2, AttrName.size() - 2);