Add ParsedAttrInfo::handleDeclAttribute

This makes it possible for plugin attributes to actually do something, and also
removes a lot of boilerplate for simple attributes in SemaDeclAttr.cpp.

Differential Revision: https://reviews.llvm.org/D31342

clang/docs/ClangPlugins.rst

@@ -63,6 +63,53 @@ registering it using ``PragmaHandlerRegistry::Add<>``:
 
   static PragmaHandlerRegistry::Add<ExamplePragmaHandler> Y("example_pragma","example pragma description");
 
+Defining attributes
+===================
+
+Plugins can define attributes by declaring a ``ParsedAttrInfo`` and registering
+it using ``ParsedAttrInfoRegister::Add<>``:
+
+.. code-block:: c++
+
+  class ExampleAttrInfo : public ParsedAttrInfo {
+  public:
+    ExampleAttrInfo() {
+      Spellings.push_back({ParsedAttr::AS_GNU,"example"});
+    }
+    AttrHandling handleDeclAttribute(Sema &S, Decl *D,
+                                     const ParsedAttr &Attr) const override {
+      // Handle the attribute
+      return AttributeApplied;
+    }
+  };
+
+  static ParsedAttrInfoRegistry::Add<ExampleAttrInfo> Z("example_attr","example attribute description");
+
+The members of ``ParsedAttrInfo`` that a plugin attribute must define are:
+
+ * ``Spellings``, which must be populated with every `Spelling
+   </doxygen/structclang_1_1ParsedAttrInfo_1_1Spelling.html>`_ of the
+   attribute, each of which consists of an attribute syntax and how the
+   attribute name is spelled for that syntax. If the syntax allows a scope then
+   the spelling must be "scope::attr" if a scope is present or "::attr" if not.
+ * ``handleDeclAttribute``, which is the function that applies the attribute to
+   a declaration. It is responsible for checking that the attribute's arguments
+   are valid, and typically applies the attribute by adding an ``Attr`` to the
+   ``Decl``. It returns either ``AttributeApplied``, to indicate that the
+   attribute was successfully applied, or ``AttributeNotApplied`` if it wasn't.
+
+The members of ``ParsedAttrInfo`` that may need to be defined, depending on the
+attribute, are:
+
+ * ``NumArgs`` and ``OptArgs``, which set the number of required and optional
+   arguments to the attribute.
+ * ``diagAppertainsToDecl``, which checks if the attribute has been used on the
+   right kind of declaration and issues a diagnostic if not.
+ * ``diagLangOpts``, which checks if the attribute is permitted for the current
+   language mode and issues a diagnostic if not.
+ * ``existsInTarget``, which checks if the attribute is permitted for the given
+   target.
+
 Putting it all together
 =======================
 

clang/docs/InternalsManual.rst

@@ -2455,6 +2455,9 @@ Attributes that do not require custom semantic handling should set the
 attributes are assumed to use a semantic handler by default. Attributes
 without a semantic handler are not given a parsed attribute ``Kind`` enumerator.
 
+"Simple" attributes, that require no custom semantic processing aside from what
+is automatically provided, should set the ``SimpleHandler`` field to ``1``.
+
 Target-specific attributes may share a spelling with other attributes in
 different targets. For instance, the ARM and MSP430 targets both have an
 attribute spelled ``GNU<"interrupt">``, but with different parsing and semantic
@@ -2481,12 +2484,11 @@ Boilerplate
 All semantic processing of declaration attributes happens in `lib/Sema/SemaDeclAttr.cpp
 <https://github.com/llvm/llvm-project/blob/master/clang/lib/Sema/SemaDeclAttr.cpp>`_,
 and generally starts in the ``ProcessDeclAttribute()`` function. If the
-attribute is a "simple" attribute -- meaning that it requires no custom semantic
+attribute has the ``SimpleHandler`` field set to ``1`` then the function to
-processing aside from what is automatically  provided, add a call to
+process the attribute will be automatically generated, and nothing needs to be
-``handleSimpleAttribute<YourAttr>(S, D, Attr);`` to the switch statement.
+done here. Otherwise, write a new ``handleYourAttr()`` function, and add that to
-Otherwise, write a new ``handleYourAttr()`` function, and add that to the switch
+the switch statement. Please do not implement handling logic directly in the
-statement. Please do not implement handling logic directly in the ``case`` for
+``case`` for the attribute.
-the attribute.
 
 Unless otherwise specified by the attribute definition, common semantic checking
 of the parsed attribute is handled automatically. This includes diagnosing

clang/include/clang/Basic/Attr.td

@@ -513,6 +513,8 @@ class Attr {
   bit ASTNode = 1;
   // Set to true for attributes which have handler in Sema.
   bit SemaHandler = 1;
+  // Set to true if this attribute doesn't need custom handling in Sema.
+  bit SimpleHandler = 0;
   // Set to true for attributes that are completely ignored.
   bit Ignored = 0;
   // Set to true if the attribute's parsing does not match its semantic
@@ -681,6 +683,7 @@ def Artificial : InheritableAttr {
   let Spellings = [GCC<"artificial">];
   let Subjects = SubjectList<[InlineFunction]>;
   let Documentation = [ArtificialDocs];
+  let SimpleHandler = 1;
 }
 
 def XRayInstrument : InheritableAttr {
@@ -692,6 +695,7 @@ def XRayInstrument : InheritableAttr {
                    Accessor<"neverXRayInstrument",
                      [Clang<"xray_never_instrument">]>];
   let Documentation = [XRayDocs];
+  let SimpleHandler = 1;
 }
 
 def XRayLogArgs : InheritableAttr {
@@ -948,6 +952,7 @@ def OSConsumesThis : InheritableAttr {
   let Spellings = [Clang<"os_consumes_this">];
   let Subjects = SubjectList<[NonStaticCXXMethod]>;
   let Documentation = [RetainBehaviorDocs];
+  let SimpleHandler = 1;
 }
 
 def Cleanup : InheritableAttr {
@@ -972,6 +977,7 @@ def Common : InheritableAttr {
 def Const : InheritableAttr {
   let Spellings = [GCC<"const">, GCC<"__const">];
   let Documentation = [Undocumented];
+  let SimpleHandler = 1;
 }
 
 def ConstInit : InheritableAttr {
@@ -983,6 +989,7 @@ def ConstInit : InheritableAttr {
   let Accessors = [Accessor<"isConstinit", [Keyword<"constinit">]>];
   let Documentation = [ConstInitDocs];
   let LangOpts = [CPlusPlus];
+  let SimpleHandler = 1;
 }
 
 def Constructor : InheritableAttr {
@@ -1113,6 +1120,7 @@ def CXX11NoReturn : InheritableAttr {
   let Spellings = [CXX11<"", "noreturn", 200809>];
   let Subjects = SubjectList<[Function], ErrorDiag>;
   let Documentation = [CXX11NoReturnDocs];
+  let SimpleHandler = 1;
 }
 
 // Similar to CUDA, OpenCL attributes do not receive a [[]] spelling because
@@ -1121,6 +1129,7 @@ def OpenCLKernel : InheritableAttr {
   let Spellings = [Keyword<"__kernel">, Keyword<"kernel">];
   let Subjects = SubjectList<[Function], ErrorDiag>;
   let Documentation = [Undocumented];
+  let SimpleHandler = 1;
 }
 
 def OpenCLUnrollHint : InheritableAttr {
@@ -1190,6 +1199,7 @@ def RenderScriptKernel : Attr {
   let Subjects = SubjectList<[Function]>;
   let Documentation = [RenderScriptKernelAttributeDocs];
   let LangOpts = [RenderScript];
+  let SimpleHandler = 1;
 }
 
 def Deprecated : InheritableAttr {
@@ -1214,6 +1224,7 @@ def EmptyBases : InheritableAttr, TargetSpecificAttr<TargetMicrosoftCXXABI> {
   let Spellings = [Declspec<"empty_bases">];
   let Subjects = SubjectList<[CXXRecord]>;
   let Documentation = [EmptyBasesDocs];
+  let SimpleHandler = 1;
 }
 
 def AllocSize : InheritableAttr {
@@ -1285,6 +1296,7 @@ def FlagEnum : InheritableAttr {
   let Spellings = [Clang<"flag_enum">];
   let Subjects = SubjectList<[Enum]>;
   let Documentation = [FlagEnumDocs];
+  let SimpleHandler = 1;
 }
 
 def EnumExtensibility : InheritableAttr {
@@ -1299,6 +1311,7 @@ def Flatten : InheritableAttr {
   let Spellings = [GCC<"flatten">];
   let Subjects = SubjectList<[Function], ErrorDiag>;
   let Documentation = [FlattenDocs];
+  let SimpleHandler = 1;
 }
 
 def Format : InheritableAttr {
@@ -1344,6 +1357,7 @@ def IBAction : InheritableAttr {
   // of the compiler. However, this node needs to exist in the AST because
   // external tools rely on it.
   let Documentation = [Undocumented];
+  let SimpleHandler = 1;
 }
 
 def IBOutlet : InheritableAttr {
@@ -1384,6 +1398,7 @@ def LifetimeBound : DeclOrTypeAttr {
   let Subjects = SubjectList<[ParmVar, ImplicitObjectParameter], ErrorDiag>;
   let Documentation = [LifetimeBoundDocs];
   let LangOpts = [CPlusPlus];
+  let SimpleHandler = 1;
 }
 
 def TrivialABI : InheritableAttr {
@@ -1393,6 +1408,7 @@ def TrivialABI : InheritableAttr {
   let Subjects = SubjectList<[CXXRecord]>;
   let Documentation = [TrivialABIDocs];
   let LangOpts = [CPlusPlus];
+  let SimpleHandler = 1;
 }
 
 def MaxFieldAlignment : InheritableAttr {
@@ -1407,6 +1423,7 @@ def MayAlias : InheritableAttr {
   // FIXME: this is a type attribute in GCC, but a declaration attribute here.
   let Spellings = [GCC<"may_alias">];
   let Documentation = [Undocumented];
+  let SimpleHandler = 1;
 }
 
 def MIGServerRoutine : InheritableAttr {
@@ -1512,12 +1529,14 @@ def NoUniqueAddress : InheritableAttr, TargetSpecificAttr<TargetItaniumCXXABI> {
   let Spellings = [CXX11<"", "no_unique_address", 201803>];
   let Subjects = SubjectList<[NonBitField], ErrorDiag>;
   let Documentation = [NoUniqueAddressDocs];
+  let SimpleHandler = 1;
 }
 
 def ReturnsTwice : InheritableAttr {
   let Spellings = [GCC<"returns_twice">];
   let Subjects = SubjectList<[Function]>;
   let Documentation = [Undocumented];
+  let SimpleHandler = 1;
 }
 
 def DisableTailCalls : InheritableAttr {
@@ -1530,12 +1549,14 @@ def NoAlias : InheritableAttr {
   let Spellings = [Declspec<"noalias">];
   let Subjects = SubjectList<[Function]>;
   let Documentation = [NoAliasDocs];
+  let SimpleHandler = 1;
 }
 
 def NoCommon : InheritableAttr {
   let Spellings = [GCC<"nocommon">];
   let Subjects = SubjectList<[Var]>;
   let Documentation = [Undocumented];
+  let SimpleHandler = 1;
 }
 
 def NoDebug : InheritableAttr {
@@ -1548,30 +1569,35 @@ def NoDuplicate : InheritableAttr {
   let Spellings = [Clang<"noduplicate">];
   let Subjects = SubjectList<[Function]>;
   let Documentation = [NoDuplicateDocs];
+  let SimpleHandler = 1;
 }
 
 def Convergent : InheritableAttr {
   let Spellings = [Clang<"convergent">];
   let Subjects = SubjectList<[Function]>;
   let Documentation = [ConvergentDocs];
+  let SimpleHandler = 1;
 }
 
 def NoInline : InheritableAttr {
   let Spellings = [GCC<"noinline">, Declspec<"noinline">];
   let Subjects = SubjectList<[Function]>;
   let Documentation = [Undocumented];
+  let SimpleHandler = 1;
 }
 
 def NoMips16 : InheritableAttr, TargetSpecificAttr<TargetMips32> {
   let Spellings = [GCC<"nomips16">];
   let Subjects = SubjectList<[Function], ErrorDiag>;
   let Documentation = [Undocumented];
+  let SimpleHandler = 1;
 }
 
 def NoMicroMips : InheritableAttr, TargetSpecificAttr<TargetMips32> {
   let Spellings = [GCC<"nomicromips">];
   let Subjects = SubjectList<[Function], ErrorDiag>;
   let Documentation = [MicroMipsDocs];
+  let SimpleHandler = 1;
 }
 
 def RISCVInterrupt : InheritableAttr, TargetSpecificAttr<TargetRISCV> {
@@ -1666,6 +1692,7 @@ def NoSplitStack : InheritableAttr {
   let Spellings = [GCC<"no_split_stack">];
   let Subjects = SubjectList<[Function], ErrorDiag>;
   let Documentation = [NoSplitStackDocs];
+  let SimpleHandler = 1;
 }
 
 def NonNull : InheritableParamAttr {
@@ -1763,6 +1790,7 @@ def NoInstrumentFunction : InheritableAttr {
   let Spellings = [GCC<"no_instrument_function">];
   let Subjects = SubjectList<[Function]>;
   let Documentation = [Undocumented];
+  let SimpleHandler = 1;
 }
 
 def NotTailCalled : InheritableAttr {
@@ -1775,6 +1803,7 @@ def NoStackProtector : InheritableAttr {
   let Spellings = [Clang<"no_stack_protector">];
   let Subjects = SubjectList<[Function]>;
   let Documentation = [NoStackProtectorDocs];
+  let SimpleHandler = 1;
 }
 
 def NoThrow : InheritableAttr {
@@ -1837,6 +1866,7 @@ def NSConsumesSelf : InheritableAttr {
   let Spellings = [Clang<"ns_consumes_self">];
   let Subjects = SubjectList<[ObjCMethod]>;
   let Documentation = [RetainBehaviorDocs];
+  let SimpleHandler = 1;
 }
 
 def NSConsumed : InheritableParamAttr {
@@ -1849,6 +1879,7 @@ def ObjCException : InheritableAttr {
   let Spellings = [Clang<"objc_exception">];
   let Subjects = SubjectList<[ObjCInterface], ErrorDiag>;
   let Documentation = [Undocumented];
+  let SimpleHandler = 1;
 }
 
 def ObjCMethodFamily : InheritableAttr {
@@ -1893,6 +1924,7 @@ def ObjCRootClass : InheritableAttr {
   let Spellings = [Clang<"objc_root_class">];
   let Subjects = SubjectList<[ObjCInterface], ErrorDiag>;
   let Documentation = [Undocumented];
+  let SimpleHandler = 1;
 }
 
 def ObjCNonLazyClass : Attr {
@@ -1900,12 +1932,14 @@ def ObjCNonLazyClass : Attr {
   let Subjects = SubjectList<[ObjCInterface, ObjCImpl], ErrorDiag>;
   let LangOpts = [ObjC];
   let Documentation = [ObjCNonLazyClassDocs];
+  let SimpleHandler = 1;
 }
 
 def ObjCSubclassingRestricted : InheritableAttr {
   let Spellings = [Clang<"objc_subclassing_restricted">];
   let Subjects = SubjectList<[ObjCInterface], ErrorDiag>;
   let Documentation = [ObjCSubclassingRestrictedDocs];
+  let SimpleHandler = 1;
 }
 
 def ObjCExplicitProtocolImpl : InheritableAttr {
@@ -1945,6 +1979,7 @@ def ObjCRuntimeVisible : Attr {
   let Spellings = [Clang<"objc_runtime_visible">];
   let Subjects = SubjectList<[ObjCInterface], ErrorDiag>;
   let Documentation = [ObjCRuntimeVisibleDocs];
+  let SimpleHandler = 1;
 }
 
 def ObjCClassStub : Attr {
@@ -1952,6 +1987,7 @@ def ObjCClassStub : Attr {
   let Subjects = SubjectList<[ObjCInterface], ErrorDiag>;
   let Documentation = [ObjCClassStubDocs];
   let LangOpts = [ObjCNonFragileRuntime];
+  let SimpleHandler = 1;
 }
 
 def ObjCBoxable : Attr {
@@ -1970,6 +2006,7 @@ def Overloadable : Attr {
   let Spellings = [Clang<"overloadable">];
   let Subjects = SubjectList<[Function], ErrorDiag>;
   let Documentation = [OverloadableDocs];
+  let SimpleHandler = 1;
 }
 
 def Override : InheritableAttr {
@@ -2027,6 +2064,7 @@ def AArch64VectorPcs: DeclOrTypeAttr {
 def Pure : InheritableAttr {
   let Spellings = [GCC<"pure">];
   let Documentation = [Undocumented];
+  let SimpleHandler = 1;
 }
 
 def Regparm : TypeAttr {
@@ -2350,6 +2388,7 @@ def ArcWeakrefUnavailable : InheritableAttr {
   let Spellings = [Clang<"objc_arc_weak_reference_unavailable">];
   let Subjects = SubjectList<[ObjCInterface], ErrorDiag>;
   let Documentation = [Undocumented];
+  let SimpleHandler = 1;
 }
 
 def ObjCGC : TypeAttr {
@@ -2368,6 +2407,7 @@ def ObjCRequiresPropertyDefs : InheritableAttr {
   let Spellings = [Clang<"objc_requires_property_definitions">];
   let Subjects = SubjectList<[ObjCInterface], ErrorDiag>;
   let Documentation = [Undocumented];
+  let SimpleHandler = 1;
 }
 
 def Unused : InheritableAttr {
@@ -2382,6 +2422,7 @@ def Used : InheritableAttr {
   let Spellings = [GCC<"used">];
   let Subjects = SubjectList<[NonLocalVar, Function, ObjCMethod]>;
   let Documentation = [Undocumented];
+  let SimpleHandler = 1;
 }
 
 def Uuid : InheritableAttr {
@@ -2443,6 +2484,7 @@ def WarnUnused : InheritableAttr {
   let Spellings = [GCC<"warn_unused">];
   let Subjects = SubjectList<[Record]>;
   let Documentation = [Undocumented];
+  let SimpleHandler = 1;
 }
 
 def WarnUnusedResult : InheritableAttr {
@@ -2465,6 +2507,7 @@ def Weak : InheritableAttr {
   let Spellings = [GCC<"weak">];
   let Subjects = SubjectList<[Var, Function, CXXRecord]>;
   let Documentation = [Undocumented];
+  let SimpleHandler = 1;
 }
 
 def WeakImport : InheritableAttr {
@@ -2484,6 +2527,7 @@ def LTOVisibilityPublic : InheritableAttr {
   let Spellings = [Clang<"lto_visibility_public">];
   let Subjects = SubjectList<[Record]>;
   let Documentation = [LTOVisibilityDocs];
+  let SimpleHandler = 1;
 }
 
 def AnyX86Interrupt : InheritableAttr, TargetSpecificAttr<TargetAnyX86> {
@@ -2500,6 +2544,7 @@ def AnyX86NoCallerSavedRegisters : InheritableAttr,
                                    TargetSpecificAttr<TargetAnyX86> {
   let Spellings = [GCC<"no_caller_saved_registers">];
   let Documentation = [AnyX86NoCallerSavedRegistersDocs];
+  let SimpleHandler = 1;
 }
 
 def AnyX86NoCfCheck : DeclOrTypeAttr, TargetSpecificAttr<TargetAnyX86>{
@@ -2551,6 +2596,7 @@ def CFICanonicalJumpTable : InheritableAttr {
   let Spellings = [Clang<"cfi_canonical_jump_table">];
   let Subjects = SubjectList<[Function], ErrorDiag>;
   let Documentation = [CFICanonicalJumpTableDocs];
+  let SimpleHandler = 1;
 }
 
 // C/C++ Thread safety attributes (e.g. for deadlock, data race checking)
@@ -2563,6 +2609,7 @@ def GuardedVar : InheritableAttr {
   let Spellings = [Clang<"guarded_var", 0>];
   let Subjects = SubjectList<[Field, SharedVar]>;
   let Documentation = [Undocumented];
+  let SimpleHandler = 1;
 }
 
 def PtGuardedVar : InheritableAttr {
@@ -2582,6 +2629,7 @@ def ScopedLockable : InheritableAttr {
   let Spellings = [Clang<"scoped_lockable", 0>];
   let Subjects = SubjectList<[Record]>;
   let Documentation = [Undocumented];
+  let SimpleHandler = 1;
 }
 
 def Capability : InheritableAttr {
@@ -2678,6 +2726,7 @@ def NoThreadSafetyAnalysis : InheritableAttr {
   let Spellings = [Clang<"no_thread_safety_analysis">];
   let Subjects = SubjectList<[Function]>;
   let Documentation = [Undocumented];
+  let SimpleHandler = 1;
 }
 
 def GuardedBy : InheritableAttr {
@@ -2814,6 +2863,7 @@ def ConsumableAutoCast : InheritableAttr {
   let Spellings = [Clang<"consumable_auto_cast_state", 0>];
   let Subjects = SubjectList<[CXXRecord]>;
   let Documentation = [Undocumented];
+  let SimpleHandler = 1;
 }
 
 def ConsumableSetOnRead : InheritableAttr {
@@ -2823,6 +2873,7 @@ def ConsumableSetOnRead : InheritableAttr {
   let Spellings = [Clang<"consumable_set_state_on_read", 0>];
   let Subjects = SubjectList<[CXXRecord]>;
   let Documentation = [Undocumented];
+  let SimpleHandler = 1;
 }
 
 def CallableWhen : InheritableAttr {
@@ -2929,6 +2980,7 @@ def MSNoVTable : InheritableAttr, TargetSpecificAttr<TargetMicrosoftCXXABI> {
   let Spellings = [Declspec<"novtable">];
   let Subjects = SubjectList<[CXXRecord]>;
   let Documentation = [MSNoVTableDocs];
+  let SimpleHandler = 1;
 }
 
 def : IgnoredAttr {
@@ -2954,6 +3006,7 @@ def MSStruct : InheritableAttr {
   let Spellings = [GCC<"ms_struct">];
   let Subjects = SubjectList<[Record]>;
   let Documentation = [Undocumented];
+  let SimpleHandler = 1;
 }
 
 def DLLExport : InheritableAttr, TargetSpecificAttr<TargetWindows> {
@@ -3002,6 +3055,7 @@ def DLLImportStaticLocal : InheritableAttr, TargetSpecificAttr<TargetWindows> {
 def SelectAny : InheritableAttr {
   let Spellings = [Declspec<"selectany">, GCC<"selectany">];
   let Documentation = [SelectAnyDocs];
+  let SimpleHandler = 1;
 }
 
 def Thread : Attr {
@@ -3277,12 +3331,14 @@ def ExcludeFromExplicitInstantiation : InheritableAttr {
   let Subjects = SubjectList<[Var, Function, CXXRecord]>;
   let Documentation = [ExcludeFromExplicitInstantiationDocs];
   let MeaningfulToClassTemplateDefinition = 1;
+  let SimpleHandler = 1;
 }
 
 def Reinitializes : InheritableAttr {
   let Spellings = [Clang<"reinitializes", 0>];
   let Subjects = SubjectList<[NonStaticNonConstCXXMethod], ErrorDiag>;
   let Documentation = [ReinitializesDocs];
+  let SimpleHandler = 1;
 }
 
 def NoDestroy : InheritableAttr {

clang/include/clang/Sema/ParsedAttr.h

@@ -68,7 +68,7 @@ struct ParsedAttrInfo {
   std::vector<Spelling> Spellings;
 
   ParsedAttrInfo(AttributeCommonInfo::Kind AttrKind =
-                     AttributeCommonInfo::UnknownAttribute)
+                     AttributeCommonInfo::NoSemaHandlerAttribute)
       : AttrKind(AttrKind), NumArgs(0), OptArgs(0), HasCustomParsing(0),
         IsTargetSpecific(0), IsType(0), IsStmt(0), IsKnownToGCC(0),
         IsSupportedByPragmaAttribute(0) {}
@@ -99,6 +99,18 @@ struct ParsedAttrInfo {
       llvm::SmallVectorImpl<std::pair<attr::SubjectMatchRule, bool>> &Rules,
       const LangOptions &LangOpts) const {
   }
+  enum AttrHandling {
+    NotHandled,
+    AttributeApplied,
+    AttributeNotApplied
+  };
+  /// If this ParsedAttrInfo knows how to handle this ParsedAttr applied to this
+  /// Decl then do so and return either AttributeApplied if it was applied or
+  /// AttributeNotApplied if it wasn't. Otherwise return NotHandled.
+  virtual AttrHandling handleDeclAttribute(Sema &S, Decl *D,
+                                           const ParsedAttr &Attr) const {
+    return NotHandled;
+  }
 
   static const ParsedAttrInfo &get(const AttributeCommonInfo &A);
 };

clang/lib/Sema/ParsedAttr.cpp

@@ -140,7 +140,8 @@ const ParsedAttrInfo &ParsedAttrInfo::get(const AttributeCommonInfo &A) {
         return *Ptr;
 
   // If we failed to find a match then return a default ParsedAttrInfo.
-  static ParsedAttrInfo DefaultParsedAttrInfo;
+  static ParsedAttrInfo DefaultParsedAttrInfo(
+      AttributeCommonInfo::UnknownAttribute);
   return DefaultParsedAttrInfo;
 }
 

clang/lib/Sema/SemaDeclAttr.cpp

@@ -6747,6 +6747,8 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
 
   switch (AL.getKind()) {
   default:
+    if (AL.getInfo().handleDeclAttribute(S, D, AL) != ParsedAttrInfo::NotHandled)
+      break;
     if (!AL.isStmtAttr()) {
       // Type attributes are handled elsewhere; silently move on.
       assert(AL.isTypeAttr() && "Non-type attribute not handled");
@@ -6769,15 +6771,9 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
     handleSimpleAttributeWithExclusions<Mips16Attr, MicroMipsAttr,
                                         MipsInterruptAttr>(S, D, AL);
     break;
-  case ParsedAttr::AT_NoMips16:
-    handleSimpleAttribute<NoMips16Attr>(S, D, AL);
-    break;
   case ParsedAttr::AT_MicroMips:
     handleSimpleAttributeWithExclusions<MicroMipsAttr, Mips16Attr>(S, D, AL);
     break;
-  case ParsedAttr::AT_NoMicroMips:
-    handleSimpleAttribute<NoMicroMipsAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_MipsLongCall:
     handleSimpleAttributeWithExclusions<MipsLongCallAttr, MipsShortCallAttr>(
         S, D, AL);
@@ -6813,9 +6809,6 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case ParsedAttr::AT_WebAssemblyImportName:
     handleWebAssemblyImportNameAttr(S, D, AL);
     break;
-  case ParsedAttr::AT_IBAction:
-    handleSimpleAttribute<IBActionAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_IBOutlet:
     handleIBOutlet(S, D, AL);
     break;
@@ -6840,9 +6833,6 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case ParsedAttr::AT_AlwaysInline:
     handleAlwaysInlineAttr(S, D, AL);
     break;
-  case ParsedAttr::AT_Artificial:
-    handleSimpleAttribute<ArtificialAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_AnalyzerNoReturn:
     handleAnalyzerNoReturnAttr(S, D, AL);
     break;
@@ -6874,9 +6864,6 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case ParsedAttr::AT_Constructor:
     handleConstructorAttr(S, D, AL);
     break;
-  case ParsedAttr::AT_CXX11NoReturn:
-    handleSimpleAttribute<CXX11NoReturnAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_Deprecated:
     handleDeprecatedAttr(S, D, AL);
     break;
@@ -6904,15 +6891,9 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case ParsedAttr::AT_OptimizeNone:
     handleOptimizeNoneAttr(S, D, AL);
     break;
-  case ParsedAttr::AT_FlagEnum:
-    handleSimpleAttribute<FlagEnumAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_EnumExtensibility:
     handleEnumExtensibilityAttr(S, D, AL);
     break;
-  case ParsedAttr::AT_Flatten:
-    handleSimpleAttribute<FlattenAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_SYCLKernel:
     handleSYCLKernelAttr(S, D, AL);
     break;
@@ -6948,27 +6929,9 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case ParsedAttr::AT_Restrict:
     handleRestrictAttr(S, D, AL);
     break;
-  case ParsedAttr::AT_LifetimeBound:
-    handleSimpleAttribute<LifetimeBoundAttr>(S, D, AL);
-    break;
-  case ParsedAttr::AT_MayAlias:
-    handleSimpleAttribute<MayAliasAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_Mode:
     handleModeAttr(S, D, AL);
     break;
-  case ParsedAttr::AT_NoAlias:
-    handleSimpleAttribute<NoAliasAttr>(S, D, AL);
-    break;
-  case ParsedAttr::AT_NoCommon:
-    handleSimpleAttribute<NoCommonAttr>(S, D, AL);
-    break;
-  case ParsedAttr::AT_NoSplitStack:
-    handleSimpleAttribute<NoSplitStackAttr>(S, D, AL);
-    break;
-  case ParsedAttr::AT_NoUniqueAddress:
-    handleSimpleAttribute<NoUniqueAddressAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_NonNull:
     if (auto *PVD = dyn_cast<ParmVarDecl>(D))
       handleNonNullAttrParameter(S, PVD, AL);
@@ -6987,9 +6950,6 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case ParsedAttr::AT_AllocAlign:
     handleAllocAlignAttr(S, D, AL);
     break;
-  case ParsedAttr::AT_Overloadable:
-    handleSimpleAttribute<OverloadableAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_Ownership:
     handleOwnershipAttr(S, D, AL);
     break;
@@ -7045,9 +7005,6 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case ParsedAttr::AT_ObjCRuntimeName:
     handleObjCRuntimeName(S, D, AL);
     break;
-  case ParsedAttr::AT_ObjCRuntimeVisible:
-    handleSimpleAttribute<ObjCRuntimeVisibleAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_ObjCBoxable:
     handleObjCBoxable(S, D, AL);
     break;
@@ -7065,12 +7022,6 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
     S.AddXConsumedAttr(D, AL, parsedAttrToRetainOwnershipKind(AL),
                        /*IsTemplateInstantiation=*/false);
     break;
-  case ParsedAttr::AT_NSConsumesSelf:
-    handleSimpleAttribute<NSConsumesSelfAttr>(S, D, AL);
-    break;
-  case ParsedAttr::AT_OSConsumesThis:
-    handleSimpleAttribute<OSConsumesThisAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_OSReturnsRetainedOnZero:
     handleSimpleAttributeOrDiagnose<OSReturnsRetainedOnZeroAttr>(
         S, D, AL, isValidOSObjectOutParameter(D),
@@ -7104,9 +7055,6 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case ParsedAttr::AT_VecTypeHint:
     handleVecTypeHint(S, D, AL);
     break;
-  case ParsedAttr::AT_ConstInit:
-    handleSimpleAttribute<ConstInitAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_InitPriority:
     handleInitPriorityAttr(S, D, AL);
     break;
@@ -7137,12 +7085,6 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case ParsedAttr::AT_Unavailable:
     handleAttrWithMessage<UnavailableAttr>(S, D, AL);
     break;
-  case ParsedAttr::AT_ArcWeakrefUnavailable:
-    handleSimpleAttribute<ArcWeakrefUnavailableAttr>(S, D, AL);
-    break;
-  case ParsedAttr::AT_ObjCRootClass:
-    handleSimpleAttribute<ObjCRootClassAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_ObjCDirect:
     handleObjCDirectAttr(S, D, AL);
     break;
@@ -7150,27 +7092,12 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
     handleObjCDirectMembersAttr(S, D, AL);
     handleSimpleAttribute<ObjCDirectMembersAttr>(S, D, AL);
     break;
-  case ParsedAttr::AT_ObjCNonLazyClass:
-    handleSimpleAttribute<ObjCNonLazyClassAttr>(S, D, AL);
-    break;
-  case ParsedAttr::AT_ObjCSubclassingRestricted:
-    handleSimpleAttribute<ObjCSubclassingRestrictedAttr>(S, D, AL);
-    break;
-  case ParsedAttr::AT_ObjCClassStub:
-    handleSimpleAttribute<ObjCClassStubAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_ObjCExplicitProtocolImpl:
     handleObjCSuppresProtocolAttr(S, D, AL);
     break;
-  case ParsedAttr::AT_ObjCRequiresPropertyDefs:
-    handleSimpleAttribute<ObjCRequiresPropertyDefsAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_Unused:
     handleUnusedAttr(S, D, AL);
     break;
-  case ParsedAttr::AT_ReturnsTwice:
-    handleSimpleAttribute<ReturnsTwiceAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_NotTailCalled:
     handleSimpleAttributeWithExclusions<NotTailCalledAttr, AlwaysInlineAttr>(
         S, D, AL);
@@ -7179,24 +7106,15 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
     handleSimpleAttributeWithExclusions<DisableTailCallsAttr, NakedAttr>(S, D,
                                                                          AL);
     break;
-  case ParsedAttr::AT_Used:
-    handleSimpleAttribute<UsedAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_Visibility:
     handleVisibilityAttr(S, D, AL, false);
     break;
   case ParsedAttr::AT_TypeVisibility:
     handleVisibilityAttr(S, D, AL, true);
     break;
-  case ParsedAttr::AT_WarnUnused:
-    handleSimpleAttribute<WarnUnusedAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_WarnUnusedResult:
     handleWarnUnusedResult(S, D, AL);
     break;
-  case ParsedAttr::AT_Weak:
-    handleSimpleAttribute<WeakAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_WeakRef:
     handleWeakRefAttr(S, D, AL);
     break;
@@ -7206,9 +7124,6 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case ParsedAttr::AT_TransparentUnion:
     handleTransparentUnionAttr(S, D, AL);
     break;
-  case ParsedAttr::AT_ObjCException:
-    handleSimpleAttribute<ObjCExceptionAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_ObjCMethodFamily:
     handleObjCMethodFamilyAttr(S, D, AL);
     break;
@@ -7224,37 +7139,12 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case ParsedAttr::AT_Sentinel:
     handleSentinelAttr(S, D, AL);
     break;
-  case ParsedAttr::AT_Const:
-    handleSimpleAttribute<ConstAttr>(S, D, AL);
-    break;
-  case ParsedAttr::AT_Pure:
-    handleSimpleAttribute<PureAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_Cleanup:
     handleCleanupAttr(S, D, AL);
     break;
   case ParsedAttr::AT_NoDebug:
     handleNoDebugAttr(S, D, AL);
     break;
-  case ParsedAttr::AT_NoDuplicate:
-    handleSimpleAttribute<NoDuplicateAttr>(S, D, AL);
-    break;
-  case ParsedAttr::AT_Convergent:
-    handleSimpleAttribute<ConvergentAttr>(S, D, AL);
-    break;
-  case ParsedAttr::AT_NoInline:
-    handleSimpleAttribute<NoInlineAttr>(S, D, AL);
-    break;
-  case ParsedAttr::AT_NoInstrumentFunction: // Interacts with -pg.
-    handleSimpleAttribute<NoInstrumentFunctionAttr>(S, D, AL);
-    break;
-  case ParsedAttr::AT_NoStackProtector:
-    // Interacts with -fstack-protector options.
-    handleSimpleAttribute<NoStackProtectorAttr>(S, D, AL);
-    break;
-  case ParsedAttr::AT_CFICanonicalJumpTable:
-    handleSimpleAttribute<CFICanonicalJumpTableAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_StdCall:
   case ParsedAttr::AT_CDecl:
   case ParsedAttr::AT_FastCall:
@@ -7279,9 +7169,6 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case ParsedAttr::AT_Pointer:
     handleLifetimeCategoryAttr(S, D, AL);
     break;
-  case ParsedAttr::AT_OpenCLKernel:
-    handleSimpleAttribute<OpenCLKernelAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_OpenCLAccess:
     handleOpenCLAccessAttr(S, D, AL);
     break;
@@ -7300,38 +7187,17 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case ParsedAttr::AT_InternalLinkage:
     handleInternalLinkageAttr(S, D, AL);
     break;
-  case ParsedAttr::AT_ExcludeFromExplicitInstantiation:
-    handleSimpleAttribute<ExcludeFromExplicitInstantiationAttr>(S, D, AL);
-    break;
-  case ParsedAttr::AT_LTOVisibilityPublic:
-    handleSimpleAttribute<LTOVisibilityPublicAttr>(S, D, AL);
-    break;
 
   // Microsoft attributes:
-  case ParsedAttr::AT_EmptyBases:
-    handleSimpleAttribute<EmptyBasesAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_LayoutVersion:
     handleLayoutVersion(S, D, AL);
     break;
-  case ParsedAttr::AT_TrivialABI:
-    handleSimpleAttribute<TrivialABIAttr>(S, D, AL);
-    break;
-  case ParsedAttr::AT_MSNoVTable:
-    handleSimpleAttribute<MSNoVTableAttr>(S, D, AL);
-    break;
-  case ParsedAttr::AT_MSStruct:
-    handleSimpleAttribute<MSStructAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_Uuid:
     handleUuidAttr(S, D, AL);
     break;
   case ParsedAttr::AT_MSInheritance:
     handleMSInheritanceAttr(S, D, AL);
     break;
-  case ParsedAttr::AT_SelectAny:
-    handleSimpleAttribute<SelectAnyAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_Thread:
     handleDeclspecThreadAttr(S, D, AL);
     break;
@@ -7350,24 +7216,15 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case ParsedAttr::AT_AssertSharedLock:
     handleAssertSharedLockAttr(S, D, AL);
     break;
-  case ParsedAttr::AT_GuardedVar:
-    handleSimpleAttribute<GuardedVarAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_PtGuardedVar:
     handlePtGuardedVarAttr(S, D, AL);
     break;
-  case ParsedAttr::AT_ScopedLockable:
-    handleSimpleAttribute<ScopedLockableAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_NoSanitize:
     handleNoSanitizeAttr(S, D, AL);
     break;
   case ParsedAttr::AT_NoSanitizeSpecific:
     handleNoSanitizeSpecificAttr(S, D, AL);
     break;
-  case ParsedAttr::AT_NoThreadSafetyAnalysis:
-    handleSimpleAttribute<NoThreadSafetyAnalysisAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_GuardedBy:
     handleGuardedByAttr(S, D, AL);
     break;
@@ -7419,12 +7276,6 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case ParsedAttr::AT_Consumable:
     handleConsumableAttr(S, D, AL);
     break;
-  case ParsedAttr::AT_ConsumableAutoCast:
-    handleSimpleAttribute<ConsumableAutoCastAttr>(S, D, AL);
-    break;
-  case ParsedAttr::AT_ConsumableSetOnRead:
-    handleSimpleAttribute<ConsumableSetOnReadAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_CallableWhen:
     handleCallableWhenAttr(S, D, AL);
     break;
@@ -7448,16 +7299,8 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case ParsedAttr::AT_TypeTagForDatatype:
     handleTypeTagForDatatypeAttr(S, D, AL);
     break;
-  case ParsedAttr::AT_AnyX86NoCallerSavedRegisters:
+
-    handleSimpleAttribute<AnyX86NoCallerSavedRegistersAttr>(S, D, AL);
-    break;
-  case ParsedAttr::AT_RenderScriptKernel:
-    handleSimpleAttribute<RenderScriptKernelAttr>(S, D, AL);
-    break;
   // XRay attributes.
-  case ParsedAttr::AT_XRayInstrument:
-    handleSimpleAttribute<XRayInstrumentAttr>(S, D, AL);
-    break;
   case ParsedAttr::AT_XRayLogArgs:
     handleXRayLogArgsAttr(S, D, AL);
     break;
@@ -7466,11 +7309,6 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
     handlePatchableFunctionEntryAttr(S, D, AL);
     break;
 
-  // Move semantics attribute.
-  case ParsedAttr::AT_Reinitializes:
-    handleSimpleAttribute<ReinitializesAttr>(S, D, AL);
-    break;
-
   case ParsedAttr::AT_AlwaysDestroy:
   case ParsedAttr::AT_NoDestroy:
     handleDestroyAttr(S, D, AL);

clang/utils/TableGen/ClangAttrEmitter.cpp

@@ -3661,6 +3661,20 @@ static void GenerateSpellingIndexToSemanticSpelling(const Record &Attr,
   OS << "}\n\n";
 }
 
+static void GenerateHandleDeclAttribute(const Record &Attr, raw_ostream &OS) {
+  // Only generate if Attr can be handled simply.
+  if (!Attr.getValueAsBit("SimpleHandler"))
+    return;
+
+  // Generate a function which just converts from ParsedAttr to the Attr type.
+  OS << "virtual AttrHandling handleDeclAttribute(Sema &S, Decl *D,";
+  OS << "const ParsedAttr &Attr) const {\n";
+  OS << "  D->addAttr(::new (S.Context) " << Attr.getName();
+  OS << "Attr(S.Context, Attr));\n";
+  OS << "  return AttributeApplied;\n";
+  OS << "}\n\n";
+}
+
 static bool IsKnownToGCC(const Record &Attr) {
   // Look at the spellings for this subject; if there are any spellings which
   // claim to be known to GCC, the attribute is known to GCC.
@@ -3742,6 +3756,7 @@ void EmitClangAttrParsedAttrImpl(RecordKeeper &Records, raw_ostream &OS) {
     GenerateTargetRequirements(Attr, Dupes, OS);
     GenerateSpellingIndexToSemanticSpelling(Attr, OS);
     PragmaAttributeSupport.generateStrictConformsTo(*I->second, OS);
+    GenerateHandleDeclAttribute(Attr, OS);
     OS << "static const ParsedAttrInfo" << I->first << " Instance;\n";
     OS << "};\n";
     OS << "const ParsedAttrInfo" << I->first << " ParsedAttrInfo" << I->first