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

clang/docs/ReleaseNotes.rst

@@ -788,6 +788,8 @@ Improvements to Clang's diagnostics
       require(scope); // Warning!  Requires mu1.
     }
 
+- Clang now diagnoses the use of attribute names reserved by the C++ standard (#GH92196).
+
 Improvements to Clang's time-trace
 ----------------------------------
 

clang/include/clang/Basic/AttributeCommonInfo.h

@@ -61,13 +61,18 @@ class AttributeCommonInfo {
   };
   enum Kind {
 #define PARSED_ATTR(NAME) AT_##NAME,
-#include "clang/Sema/AttrParsedAttrList.inc"
+#include "clang/Basic/AttrParsedAttrList.inc"
 #undef PARSED_ATTR
     NoSemaHandlerAttribute,
     IgnoredAttribute,
     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/CMakeLists.txt

@@ -31,6 +31,11 @@ clang_tablegen(AttrList.inc -gen-clang-attr-list
   SOURCE Attr.td
   TARGET ClangAttrList)
 
+clang_tablegen(AttrParsedAttrList.inc -gen-clang-attr-parsed-attr-list
+  -I ${CMAKE_CURRENT_SOURCE_DIR}/../../
+  SOURCE Attr.td
+  TARGET ClangAttrParsedAttrList)
+
 clang_tablegen(AttrSubMatchRulesList.inc -gen-clang-attr-subject-match-rule-list
   -I ${CMAKE_CURRENT_SOURCE_DIR}/../../
   SOURCE Attr.td
@@ -48,6 +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

@@ -760,6 +760,7 @@ def AmbiguousMacro : DiagGroup<"ambiguous-macro">;
 def KeywordAsMacro : DiagGroup<"keyword-macro">;
 def ReservedIdAsMacro : DiagGroup<"reserved-macro-identifier">;
 def ReservedIdAsMacroAlias : DiagGroup<"reserved-id-macro", [ReservedIdAsMacro]>;
+def ReservedAttributeIdentifier : DiagGroup<"reserved-attribute-identifier">;
 def RestrictExpansionMacro : DiagGroup<"restrict-expansion">;
 def FinalMacro : DiagGroup<"final-macro">;
 

clang/include/clang/Basic/DiagnosticLexKinds.td

@@ -407,6 +407,8 @@ def warn_pp_macro_hides_keyword : Extension<
 def warn_pp_macro_is_reserved_id : Warning<
   "macro name is a reserved identifier">, DefaultIgnore,
   InGroup<ReservedIdAsMacro>;
+def warn_pp_macro_is_reserved_attribute_id : Warning<
+  "%0 is a reserved attribute identifier">, InGroup<ReservedAttributeIdentifier>;
 def warn_pp_objc_macro_redef_ignored : Warning<
   "ignoring redefinition of Objective-C qualifier macro">,
   InGroup<DiagGroup<"objc-macro-redefinition">>;

clang/include/clang/Lex/Preprocessor.h

@@ -2271,6 +2271,11 @@ class Preprocessor {
     }
   }
 
+  /// Determine whether the next preprocessor token to be
+  /// lexed is a '('.  If so, consume the token and return true, if not, this
+  /// method should have no observable side-effect on the lexed tokens.
+  bool isNextPPTokenLParen();
+
 private:
   /// Identifiers used for SEH handling in Borland. These are only
   /// allowed in particular circumstances
@@ -2648,11 +2653,6 @@ class Preprocessor {
 
   void removeCachedMacroExpandedTokensOfLastLexer();
 
-  /// Determine whether the next preprocessor token to be
-  /// lexed is a '('.  If so, consume the token and return true, if not, this
-  /// method should have no observable side-effect on the lexed tokens.
-  bool isNextPPTokenLParen();
-
   /// After reading "MACRO(", this method is invoked to read all of the formal
   /// arguments specified for the macro invocation.  Returns null on error.
   MacroArgs *ReadMacroCallArgumentList(Token &MacroName, MacroInfo *MI,

clang/include/clang/Sema/CMakeLists.txt

@@ -3,11 +3,6 @@ clang_tablegen(AttrTemplateInstantiate.inc -gen-clang-attr-template-instantiate
   SOURCE ../Basic/Attr.td
   TARGET ClangAttrTemplateInstantiate)
 
-clang_tablegen(AttrParsedAttrList.inc -gen-clang-attr-parsed-attr-list
-  -I ${CMAKE_CURRENT_SOURCE_DIR}/../../
-  SOURCE ../Basic/Attr.td
-  TARGET ClangAttrParsedAttrList)
-
 clang_tablegen(AttrParsedAttrKinds.inc -gen-clang-attr-parsed-attr-kinds
   -I ${CMAKE_CURRENT_SOURCE_DIR}/../../
   SOURCE ../Basic/Attr.td

clang/lib/Basic/Attributes.cpp

@@ -151,6 +151,16 @@ AttributeCommonInfo::getParsedKind(const IdentifierInfo *Name,
   return ::getAttrKind(normalizeName(Name, ScopeName, SyntaxUsed), SyntaxUsed);
 }
 
+AttributeCommonInfo::AttrArgsInfo
+AttributeCommonInfo::getCXX11AttrArgsInfo(const IdentifierInfo *Name) {
+#define CXX11_ATTR_ARGS_INFO
+  return llvm::StringSwitch<AttributeCommonInfo::AttrArgsInfo>(
+             normalizeName(Name, /*Scope*/ nullptr, Syntax::AS_CXX11))
+#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

@@ -11,6 +11,8 @@
 ///
 //===----------------------------------------------------------------------===//
 
+#include "clang/Basic/AttributeCommonInfo.h"
+#include "clang/Basic/Attributes.h"
 #include "clang/Basic/CharInfo.h"
 #include "clang/Basic/DirectoryEntry.h"
 #include "clang/Basic/FileManager.h"
@@ -97,7 +99,8 @@ SourceRange Preprocessor::DiscardUntilEndOfDirective(Token &Tmp) {
 enum MacroDiag {
   MD_NoWarn,        //> Not a reserved identifier
   MD_KeywordDef,    //> Macro hides keyword, enabled by default
-  MD_ReservedMacro  //> #define of #undef reserved id, disabled by default
+  MD_ReservedMacro, //> #define of #undef reserved id, disabled by default
+  MD_ReservedAttributeIdentifier
 };
 
 /// Enumerates possible %select values for the pp_err_elif_after_else and
@@ -173,6 +176,22 @@ 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::AttrArgsInfo AttrArgsInfo =
+        AttributeCommonInfo::getCXX11AttrArgsInfo(II);
+    if (AttrArgsInfo == AttributeCommonInfo::AttrArgsInfo::Required)
+      return PP.isNextPPTokenLParen();
+
+    return !PP.isNextPPTokenLParen() ||
+           AttrArgsInfo == AttributeCommonInfo::AttrArgsInfo::Optional;
+  }
+  return false;
+}
+
 static MacroDiag shouldWarnOnMacroDef(Preprocessor &PP, IdentifierInfo *II) {
   const LangOptions &Lang = PP.getLangOpts();
   StringRef Text = II->getName();
@@ -182,6 +201,8 @@ static MacroDiag shouldWarnOnMacroDef(Preprocessor &PP, IdentifierInfo *II) {
     return MD_KeywordDef;
   if (Lang.CPlusPlus11 && (Text == "override" || Text == "final"))
     return MD_KeywordDef;
+  if (isReservedCXXAttributeName(PP, II))
+    return MD_ReservedAttributeIdentifier;
   return MD_NoWarn;
 }
 
@@ -190,6 +211,8 @@ static MacroDiag shouldWarnOnMacroUndef(Preprocessor &PP, IdentifierInfo *II) {
   // Do not warn on keyword undef.  It is generally harmless and widely used.
   if (isReservedInAllContexts(II->isReserved(Lang)))
     return MD_ReservedMacro;
+  if (isReservedCXXAttributeName(PP, II))
+    return MD_ReservedAttributeIdentifier;
   return MD_NoWarn;
 }
 
@@ -365,6 +388,9 @@ bool Preprocessor::CheckMacroName(Token &MacroNameTok, MacroUse isDefineUndef,
     }
     if (D == MD_ReservedMacro)
       Diag(MacroNameTok, diag::warn_pp_macro_is_reserved_id);
+    if (D == MD_ReservedAttributeIdentifier)
+      Diag(MacroNameTok, diag::warn_pp_macro_is_reserved_attribute_id)
+          << II->getName();
   }
 
   // Okay, we got a good identifier.

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,

llvm/utils/gn/secondary/clang/lib/Basic/BUILD.gn

@@ -22,6 +22,7 @@ static_library("Basic") {
   public_deps = [
     # public_dep because public header Version.h includes generated Version.inc.
     "//clang/include/clang/Basic:AttrList",
+    "//clang/include/clang/Basic:AttrParsedAttrList",
     "//clang/include/clang/Basic:AttrSubMatchRulesList",
     "//clang/include/clang/Basic:Builtins",
     "//clang/include/clang/Basic:BuiltinsBPF",
@@ -42,10 +43,6 @@ static_library("Basic") {
     "//clang/include/clang/Basic:riscv_vector_builtins",
     "//clang/include/clang/Basic:version",
 
-    # public_dep because public header AttributeCommonInfo.h includes generated
-    # AttrParsedAttrList.inc.
-    "//clang/include/clang/Sema:AttrParsedAttrList",
-
     # public_dep because public header OpenMPKinds.h includes generated
     # OMP.h.inc.
     "//llvm/include/llvm/Frontend/OpenMP:public_tablegen",