Modify __has_attribute so that it only looks for GNU-style attributes. Removes the ability to look for generic attributes and keywords via this macro, which has the potential to be a breaking change. However, since there is __has_cpp_attribute and __has_declspec_attribute, and given the limited usefulness of querying a generic attribute name regardless of syntax, this seems like the correct path forward.

llvm-svn: 223468

clang/docs/ReleaseNotes.rst

@@ -47,7 +47,11 @@ sections with improvements to Clang's support for those languages.
 Major New Features
 ------------------
 
-- A big one.
+- The __has_attribute built-in macro no longer queries for attributes across
+  multiple attribute syntaxes (GNU, C++11, __declspec, etc). Instead, it only
+  queries GNU-style attributes. With the addition of __has_cpp_attribute and
+  __has_declspec_attribute, this allows for more precise coverage of attribute
+  syntax querying.
 
 
 Improvements to Clang's diagnostics

clang/include/clang/Basic/Attributes.h

@@ -18,8 +18,6 @@ namespace clang {
 class IdentifierInfo;
 
 enum class AttrSyntax {
-  /// Is the attribute identifier generally known for any syntax?
-  Generic,
   /// Is the identifier known as a GNU-style attribute?
   GNU,
   /// Is the identifier known as a __declspec-style attribute?

clang/lib/Lex/PPMacroExpansion.cpp

@@ -1425,7 +1425,7 @@ void Preprocessor::ExpandBuiltinMacro(Token &Tok) {
       // Check for a builtin is trivial.
       Value = FeatureII->getBuiltinID() != 0;
     } else if (II == Ident__has_attribute)
-      Value = hasAttribute(AttrSyntax::Generic, nullptr, FeatureII,
+      Value = hasAttribute(AttrSyntax::GNU, nullptr, FeatureII,
                            getTargetInfo().getTriple(), getLangOpts());
     else if (II == Ident__has_cpp_attribute)
       Value = hasAttribute(AttrSyntax::CXX, ScopeII, FeatureII,

clang/test/Preprocessor/has_attribute.c

@@ -48,3 +48,8 @@ int has_no_volatile_attribute();
 #if !__has_attribute(dllexport)
   int does_not_have_dllexport();
 #endif
+
+// CHECK: does_not_have_uuid
+#if !__has_attribute(uuid)
+  int does_not_have_uuid
+#endif

clang/utils/TableGen/ClangAttrEmitter.cpp

@@ -1920,9 +1920,6 @@ void EmitClangAttrHasAttrImpl(RecordKeeper &Records, raw_ostream &OS) {
   }
 
   OS << "switch (Syntax) {\n";
-  OS << "case AttrSyntax::Generic:\n";
-  OS << "  return llvm::StringSwitch<int>(Name)\n";
-  GenerateHasAttrSpellingStringSwitch(Attrs, OS);
   OS << "case AttrSyntax::GNU:\n";
   OS << "  return llvm::StringSwitch<int>(Name)\n";
   GenerateHasAttrSpellingStringSwitch(GNU, OS, "GNU");