[Clang] restrict use of attribute names reserved by the C++ standard

clang/include/clang/Basic/AttributeCommonInfo.h

@@ -68,6 +68,11 @@ class AttributeCommonInfo {
     UnknownAttribute,
   };
   enum class Scope { NONE, CLANG, GNU, MSVC, OMP, HLSL, GSL, RISCV };
+  enum class AttrArgsInfo {
+    None,
+    Optional,
+    Required,
+  };
 
 private:
   const IdentifierInfo *AttrName = nullptr;
@@ -241,6 +246,8 @@ class AttributeCommonInfo {
   static Kind getParsedKind(const IdentifierInfo *Name,
                             const IdentifierInfo *Scope, Syntax SyntaxUsed);
 
+  static AttrArgsInfo getCXX11AttrArgsInfo(const IdentifierInfo *Name);
+
 private:
   /// Get an index into the attribute spelling list
   /// defined in Attr.td. This index is used by an attribute

clang/include/clang/Basic/Attributes.h

@@ -23,6 +23,11 @@ int hasAttribute(AttributeCommonInfo::Syntax Syntax,
                  const IdentifierInfo *Scope, const IdentifierInfo *Attr,
                  const TargetInfo &Target, const LangOptions &LangOpts);
 
+int hasAttribute(AttributeCommonInfo::Syntax Syntax,
+                 const IdentifierInfo *Scope, const IdentifierInfo *Attr,
+                 const TargetInfo &Target, const LangOptions &LangOpts,
+                 bool CheckPlugins);
+
 } // end namespace clang
 
 #endif // LLVM_CLANG_BASIC_ATTRIBUTES_H

clang/include/clang/Basic/CMakeLists.txt

@@ -53,6 +53,12 @@ clang_tablegen(AttrHasAttributeImpl.inc -gen-clang-attr-has-attribute-impl
   TARGET ClangAttrHasAttributeImpl
   )
 
+clang_tablegen(CXX11AttributeInfo.inc -gen-cxx11-attribute-info
+  -I ${CMAKE_CURRENT_SOURCE_DIR}/../../
+  SOURCE Attr.td
+  TARGET CXX11AttributeInfo
+  )
+
 clang_tablegen(Builtins.inc -gen-clang-builtins
   SOURCE Builtins.td
   TARGET ClangBuiltins)

clang/include/clang/Basic/DiagnosticGroups.td

@@ -936,7 +936,8 @@ def SignedEnumBitfield : DiagGroup<"signed-enum-bitfield">;
 
 def ReservedModuleIdentifier : DiagGroup<"reserved-module-identifier">;
 def ReservedIdentifier : DiagGroup<"reserved-identifier",
-    [ReservedIdAsMacro, ReservedModuleIdentifier, UserDefinedLiterals]>;
+    [ReservedIdAsMacro, ReservedModuleIdentifier,
+     UserDefinedLiterals, ReservedAttributeIdentifier]>;
 
 // Unreachable code warning groups.
 //

clang/lib/Basic/Attributes.cpp

@@ -33,7 +33,8 @@ static int hasAttributeImpl(AttributeCommonInfo::Syntax Syntax, StringRef Name,
 
 int clang::hasAttribute(AttributeCommonInfo::Syntax Syntax,
                         const IdentifierInfo *Scope, const IdentifierInfo *Attr,
-                        const TargetInfo &Target, const LangOptions &LangOpts) {
+                        const TargetInfo &Target, const LangOptions &LangOpts,
+                        bool CheckPlugins) {
   StringRef Name = Attr->getName();
   // Normalize the attribute name, __foo__ becomes foo.
   if (Name.size() >= 4 && Name.starts_with("__") && Name.ends_with("__"))
@@ -61,14 +62,23 @@ int clang::hasAttribute(AttributeCommonInfo::Syntax Syntax,
   if (res)
     return res;
 
-  // Check if any plugin provides this attribute.
-  for (auto &Ptr : getAttributePluginInstances())
-    if (Ptr->hasSpelling(Syntax, Name))
-      return 1;
+  if (CheckPlugins) {
+    // Check if any plugin provides this attribute.
+    for (auto &Ptr : getAttributePluginInstances())
+      if (Ptr->hasSpelling(Syntax, Name))
+        return 1;
+  }
 
   return 0;
 }
 
+int clang::hasAttribute(AttributeCommonInfo::Syntax Syntax,
+                        const IdentifierInfo *Scope, const IdentifierInfo *Attr,
+                        const TargetInfo &Target, const LangOptions &LangOpts) {
+  return hasAttribute(Syntax, Scope, Attr, Target, LangOpts,
+                      /*CheckPlugins*/ true);
+}
+
 const char *attr::getSubjectMatchRuleSpelling(attr::SubjectMatchRule Rule) {
   switch (Rule) {
 #define ATTR_MATCH_RULE(NAME, SPELLING, IsAbstract)                            \
@@ -151,6 +161,17 @@ AttributeCommonInfo::getParsedKind(const IdentifierInfo *Name,
   return ::getAttrKind(normalizeName(Name, ScopeName, SyntaxUsed), SyntaxUsed);
 }
 
+AttributeCommonInfo::AttrArgsInfo
+AttributeCommonInfo::getCXX11AttrArgsInfo(const IdentifierInfo *Name) {
+  StringRef AttrName =
+      normalizeAttrName(Name, /*NormalizedScopeName*/ "", Syntax::AS_CXX11);
+#define CXX11_ATTR_ARGS_INFO
+  return llvm::StringSwitch<AttributeCommonInfo::AttrArgsInfo>(AttrName)
+#include "clang/Basic/CXX11AttributeInfo.inc"
+      .Default(AttributeCommonInfo::AttrArgsInfo::None);
+#undef CXX11_ATTR_ARGS_INFO
+}
+
 std::string AttributeCommonInfo::getNormalizedFullName() const {
   return static_cast<std::string>(
       normalizeName(getAttrName(), getScopeName(), getSyntax()));

clang/lib/Lex/PPDirectives.cpp

@@ -179,13 +179,15 @@ static bool isLanguageDefinedBuiltin(const SourceManager &SourceMgr,
 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 ||
-              AttrKind == AttributeCommonInfo::Kind::AT_Unlikely) &&
-             PP.isNextPPTokenLParen());
+      hasAttribute(AttributeCommonInfo::AS_CXX11, /* Scope*/ nullptr, II,
+                   PP.getTargetInfo(), Lang, /*CheckPlugins*/ false) > 0) {
+    AttributeCommonInfo::AttrArgsInfo AttrArgsInfo =
+        AttributeCommonInfo::getCXX11AttrArgsInfo(II);
+    if (AttrArgsInfo == AttributeCommonInfo::AttrArgsInfo::Required)
+      return PP.isNextPPTokenLParen();
+
+    return !PP.isNextPPTokenLParen() ||
+           AttrArgsInfo == AttributeCommonInfo::AttrArgsInfo::Optional;
   }
   return false;
 }

clang/test/Preprocessor/macro-reserved-attrs-cxx11.cpp

@@ -0,0 +1,100 @@
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -std=c++11 -fsyntax-only -verify -pedantic %s -DTEST1
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -std=c++11 -fsyntax-only -verify -pedantic %s -DTEST2
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -std=c++11 -fsyntax-only -verify -pedantic %s -DTEST3
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -std=c++11 -fsyntax-only -verify -pedantic %s -DTEST4
+
+#ifdef TEST1
+
+#define assume
+#undef assume
+
+#define noreturn // expected-warning {{noreturn is a reserved attribute identifier}}
+#undef noreturn  // expected-warning {{noreturn is a reserved attribute identifier}}
+
+#define carries_dependency // expected-warning {{carries_dependency is a reserved attribute identifier}}
+#undef carries_dependency  // expected-warning {{carries_dependency is a reserved attribute identifier}}
+
+#define deprecated // expected-warning {{deprecated is a reserved attribute identifier}}
+#undef deprecated  // expected-warning {{deprecated is a reserved attribute identifier}}
+
+#define fallthrough // expected-warning {{fallthrough is a reserved attribute identifier}}
+#undef fallthrough  // expected-warning {{fallthrough is a reserved attribute identifier}}
+
+#define likely // expected-warning {{likely is a reserved attribute identifier}}
+#undef likely  // expected-warning {{likely is a reserved attribute identifier}}
+
+#define no_unique_address // expected-warning {{no_unique_address is a reserved attribute identifier}}
+#undef no_unique_address  // expected-warning {{no_unique_address is a reserved attribute identifier}}
+
+#define unlikely // expected-warning {{unlikely is a reserved attribute identifier}}
+#undef unlikely  // expected-warning {{unlikely is a reserved attribute identifier}}
+
+#define maybe_unused // expected-warning {{maybe_unused is a reserved attribute identifier}}
+#undef maybe_unused  // expected-warning {{maybe_unused is a reserved attribute identifier}}
+
+#define nodiscard // expected-warning {{nodiscard is a reserved attribute identifier}}
+#undef nodiscard  // expected-warning {{nodiscard is a reserved attribute identifier}}
+
+#elif TEST2
+
+#define assume "test"
+#undef assume
+
+#define noreturn "test" // expected-warning {{noreturn is a reserved attribute identifier}}
+#undef noreturn         // expected-warning {{noreturn is a reserved attribute identifier}}
+
+#define carries_dependency "test" // expected-warning {{carries_dependency is a reserved attribute identifier}}
+#undef carries_dependency         // expected-warning {{carries_dependency is a reserved attribute identifier}}
+
+#define deprecated "test" // expected-warning {{deprecated is a reserved attribute identifier}}
+#undef deprecated         // expected-warning {{deprecated is a reserved attribute identifier}}
+
+#define fallthrough "test" // expected-warning {{fallthrough is a reserved attribute identifier}}
+#undef fallthrough         // expected-warning {{fallthrough is a reserved attribute identifier}}
+
+#define likely "test" // expected-warning {{likely is a reserved attribute identifier}}
+#undef likely         // expected-warning {{likely is a reserved attribute identifier}}
+
+#define no_unique_address "test" // expected-warning {{no_unique_address is a reserved attribute identifier}}
+#undef no_unique_address         // expected-warning {{no_unique_address is a reserved attribute identifier}}
+
+#define unlikely "test" // expected-warning {{unlikely is a reserved attribute identifier}}
+#undef unlikely         // expected-warning {{unlikely is a reserved attribute identifier}}
+
+#define maybe_unused "test" // expected-warning {{maybe_unused is a reserved attribute identifier}}
+#undef maybe_unused         // expected-warning {{maybe_unused is a reserved attribute identifier}}
+
+#define nodiscard "test" // expected-warning {{nodiscard is a reserved attribute identifier}}
+#undef nodiscard         // expected-warning {{nodiscard is a reserved attribute identifier}}
+
+#elif TEST3
+
+#define assume() "test"     // expected-warning {{assume is a reserved attribute identifier}}
+#define deprecated() "test" // expected-warning {{deprecated is a reserved attribute identifier}}
+#define nodiscard() "test"  // expected-warning {{nodiscard is a reserved attribute identifier}}
+#define noreturn() "test"
+#define carries_dependency() "test"
+#define fallthrough() "test"
+#define likely() "test"
+#define no_unique_address() "test"
+#define unlikely() "test"
+#define maybe_unused() "test"
+
+#elif TEST4
+
+#define assume()     // expected-warning {{assume is a reserved attribute identifier}}
+#define deprecated() // expected-warning {{deprecated is a reserved attribute identifier}}
+#define nodiscard()  // expected-warning {{nodiscard is a reserved attribute identifier}}
+#define noreturn()
+#define carries_dependency()
+#define fallthrough()
+#define likely()
+#define no_unique_address()
+#define unlikely()
+#define maybe_unused()
+
+#else
+
+#error Unknown test
+
+#endif

clang/utils/TableGen/ClangAttrEmitter.cpp

@@ -3743,6 +3743,36 @@ void EmitClangRegularKeywordAttributeInfo(const RecordKeeper &Records,
   OS << "#undef KEYWORD_ATTRIBUTE\n";
 }
 
+void EmitCXX11AttributeInfo(const RecordKeeper &Records, raw_ostream &OS) {
+  OS << "#if defined(CXX11_ATTR_ARGS_INFO)\n";
+  for (auto *R : Records.getAllDerivedDefinitions("Attr")) {
+    for (const FlattenedSpelling &SI : GetFlattenedSpellings(*R)) {
+      if (SI.variety() == "CXX11" && SI.nameSpace().empty()) {
+        unsigned RequiredArgs = 0;
+        unsigned OptionalArgs = 0;
+        for (const auto *Arg : R->getValueAsListOfDefs("Args")) {
+          if (Arg->getValueAsBit("Fake"))
+            continue;
+
+          if (Arg->getValueAsBit("Optional"))
+            OptionalArgs++;
+          else
+            RequiredArgs++;
+        }
+        OS << ".Case(\"" << SI.getSpellingRecord().getValueAsString("Name")
+           << "\","
+           << "AttributeCommonInfo::AttrArgsInfo::"
+           << (RequiredArgs   ? "Required"
+               : OptionalArgs ? "Optional"
+                              : "None")
+           << ")"
+           << "\n";
+      }
+    }
+  }
+  OS << "#endif // CXX11_ATTR_ARGS_INFO\n";
+}
+
 // Emits the list of spellings for attributes.
 void EmitClangAttrHasAttrImpl(const RecordKeeper &Records, raw_ostream &OS) {
   emitSourceFileHeader("Code to implement the __has_attribute logic", OS,

clang/utils/TableGen/TableGen.cpp

@@ -68,6 +68,7 @@ enum ActionType {
   GenClangOpenCLBuiltins,
   GenClangOpenCLBuiltinHeader,
   GenClangOpenCLBuiltinTests,
+  GenCXX11AttributeInfo,
   GenArmNeon,
   GenArmFP16,
   GenArmBF16,
@@ -225,6 +226,8 @@ cl::opt<ActionType> Action(
                    "Generate OpenCL builtin header"),
         clEnumValN(GenClangOpenCLBuiltinTests, "gen-clang-opencl-builtin-tests",
                    "Generate OpenCL builtin declaration tests"),
+        clEnumValN(GenCXX11AttributeInfo, "gen-cxx11-attribute-info",
+                   "Generate CXX11 attributes info"),
         clEnumValN(GenArmNeon, "gen-arm-neon", "Generate arm_neon.h for clang"),
         clEnumValN(GenArmFP16, "gen-arm-fp16", "Generate arm_fp16.h for clang"),
         clEnumValN(GenArmBF16, "gen-arm-bf16", "Generate arm_bf16.h for clang"),
@@ -333,6 +336,9 @@ bool ClangTableGenMain(raw_ostream &OS, const RecordKeeper &Records) {
   case GenClangAttrSubjectMatchRulesParserStringSwitches:
     EmitClangAttrSubjectMatchRulesParserStringSwitches(Records, OS);
     break;
+  case GenCXX11AttributeInfo:
+    EmitCXX11AttributeInfo(Records, OS);
+    break;
   case GenClangAttrImpl:
     EmitClangAttrImpl(Records, OS);
     break;

clang/utils/TableGen/TableGenBackends.h

@@ -49,6 +49,8 @@ void EmitClangAttrParserStringSwitches(const llvm::RecordKeeper &Records,
                                        llvm::raw_ostream &OS);
 void EmitClangAttrSubjectMatchRulesParserStringSwitches(
     const llvm::RecordKeeper &Records, llvm::raw_ostream &OS);
+void EmitCXX11AttributeInfo(const llvm::RecordKeeper &Records,
+                            llvm::raw_ostream &OS);
 void EmitClangAttrClass(const llvm::RecordKeeper &Records,
                         llvm::raw_ostream &OS);
 void EmitClangAttrImpl(const llvm::RecordKeeper &Records,