Support accepting __gnu__ as a scoped attribute namespace that aliases to gnu.

This is useful in libstdc++ to avoid clashes with identifiers in the user's namespace.

llvm-svn: 345132

1 files changed, 19 insertions, 7 deletions

diff --git a/clang/lib/Sema/ParsedAttr.cpp b/clang/lib/Sema/ParsedAttr.cpp
index 3dff0ad63e2..ccfbe66db97 100644
--- a/clang/lib/Sema/ParsedAttr.cpp
+++ b/clang/lib/Sema/ParsedAttr.cpp
@@ -103,14 +103,25 @@ void AttributePool::takePool(AttributePool &pool) {
 
 #include "clang/Sema/AttrParsedAttrKinds.inc"
 
-static StringRef normalizeAttrName(StringRef AttrName, StringRef ScopeName,
+static StringRef normalizeAttrScopeName(StringRef ScopeName,
+                                        ParsedAttr::Syntax SyntaxUsed) {
+  // We currently only normalize the "__gnu__" scope name to be "gnu".
+  if ((SyntaxUsed == ParsedAttr::AS_CXX11 ||
+       SyntaxUsed == ParsedAttr::AS_C2x) &&
+      ScopeName == "__gnu__")
+    ScopeName = ScopeName.slice(2, ScopeName.size() - 2);
+  return ScopeName;
+}
+
+static StringRef normalizeAttrName(StringRef AttrName,
+                                   StringRef NormalizedScopeName,
                                    ParsedAttr::Syntax SyntaxUsed) {
   // Normalize the attribute name, __foo__ becomes foo. This is only allowable
-  // for GNU attributes.
+  // for GNU attributes, and attributes using the double square bracket syntax.
   bool IsGNU = SyntaxUsed == ParsedAttr::AS_GNU ||
                ((SyntaxUsed == ParsedAttr::AS_CXX11 ||
                  SyntaxUsed == ParsedAttr::AS_C2x) &&
-                ScopeName == "gnu");
+                NormalizedScopeName == "gnu");
   if (IsGNU && AttrName.size() >= 4 && AttrName.startswith("__") &&
       AttrName.endswith("__"))
     AttrName = AttrName.slice(2, AttrName.size() - 2);
@@ -125,7 +136,7 @@ ParsedAttr::Kind ParsedAttr::getKind(const IdentifierInfo *Name,
 
   SmallString<64> FullName;
   if (ScopeName)
-    FullName += ScopeName->getName();
+    FullName += normalizeAttrScopeName(ScopeName->getName(), SyntaxUsed);
 
   AttrName = normalizeAttrName(AttrName, FullName, SyntaxUsed);
 
@@ -141,9 +152,10 @@ ParsedAttr::Kind ParsedAttr::getKind(const IdentifierInfo *Name,
 unsigned ParsedAttr::getAttributeSpellingListIndex() const {
   // Both variables will be used in tablegen generated
   // attribute spell list index matching code.
-  StringRef Scope = ScopeName ? ScopeName->getName() : "";
-  StringRef Name = normalizeAttrName(AttrName->getName(), Scope,
-                                     (ParsedAttr::Syntax)SyntaxUsed);
+  auto Syntax = static_cast<ParsedAttr::Syntax>(SyntaxUsed);
+  StringRef Scope =
+      ScopeName ? normalizeAttrScopeName(ScopeName->getName(), Syntax) : "";
+  StringRef Name = normalizeAttrName(AttrName->getName(), Scope, Syntax);
 
 #include "clang/Sema/AttrSpellingListIndex.inc"