[clang] [llvm] [Clang] restrict use of attribute names reserved by the C++ standard (PR #106036)

[Erich Keane via cfe-commits]

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@@ -177,6 +180,20 @@ static bool isLanguageDefinedBuiltin(const SourceManager &SourceMgr,
   return false;
 }
 
+static bool isReservedCXXAttributeName(Preprocessor &PP, IdentifierInfo *II) {
+  const LangOptions &Lang = PP.getLangOpts();
+  if (Lang.CPlusPlus &&
+      hasAttribute(AttributeCommonInfo::Syntax::AS_CXX11, /*Scope*/ nullptr, II,
+                   PP.getTargetInfo(), Lang) > 0) {
+    AttributeCommonInfo::Kind AttrKind = AttributeCommonInfo::getParsedKind(
+        II, /*Scope*/ nullptr, AttributeCommonInfo::Syntax::AS_CXX11);
+    return !((AttrKind == AttributeCommonInfo::Kind::AT_Likely ||
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erichkeane wrote:

I'm kinda confused how this works, can you explain it here?  Why the likely/unlikely exception here?

https://github.com/llvm/llvm-project/pull/106036