[Clang] Bugfixes and improved support for AttributedTypes in lambdas

clang/include/clang/AST/ASTContext.h

@@ -1295,6 +1295,11 @@ class ASTContext : public RefCountedBase<ASTContext> {
   const FunctionType *adjustFunctionType(const FunctionType *Fn,
                                          FunctionType::ExtInfo EInfo);
 
+  /// Change the result type of a function type, preserving sugar such as
+  /// attributed types.
+  QualType adjustFunctionResultType(QualType FunctionType,
+                                    QualType NewResultType);
+
   /// Adjust the given function result type.
   CanQualType getCanonicalFunctionResultType(QualType ResultType) const;
 

clang/include/clang/AST/Attr.h

@@ -112,6 +112,8 @@ class Attr : public AttributeCommonInfo {
   // Pretty print this attribute.
   void printPretty(raw_ostream &OS, const PrintingPolicy &Policy) const;
 
+  void dump() const;
+
   static StringRef getDocumentation(attr::Kind);
 };
 

clang/include/clang/Sema/Template.h

@@ -411,6 +411,11 @@ enum class TemplateSubstitutionKind : char {
     /// lookup will search our outer scope.
     bool CombineWithOuterScope;
 
+    /// Whether this scope is being used to instantiate a lambda expression,
+    /// in which case it should be reused for instantiating the lambda's
+    /// FunctionProtoType.
+    bool InstantiatingLambda = false;
+
     /// If non-NULL, the template parameter pack that has been
     /// partially substituted per C++0x [temp.arg.explicit]p9.
     NamedDecl *PartiallySubstitutedPack = nullptr;
@@ -425,9 +430,11 @@ enum class TemplateSubstitutionKind : char {
     unsigned NumArgsInPartiallySubstitutedPack;
 
   public:
-    LocalInstantiationScope(Sema &SemaRef, bool CombineWithOuterScope = false)
+    LocalInstantiationScope(Sema &SemaRef, bool CombineWithOuterScope = false,
+                            bool InstantiatingLambda = false)
         : SemaRef(SemaRef), Outer(SemaRef.CurrentInstantiationScope),
-          CombineWithOuterScope(CombineWithOuterScope) {
+          CombineWithOuterScope(CombineWithOuterScope),
+          InstantiatingLambda(InstantiatingLambda) {
       SemaRef.CurrentInstantiationScope = this;
     }
 
@@ -553,6 +560,9 @@ enum class TemplateSubstitutionKind : char {
 
     /// Determine whether D is a pack expansion created in this scope.
     bool isLocalPackExpansion(const Decl *D);
+
+    /// Determine whether this scope is for instantiating a lambda.
+    bool isLambda() const { return InstantiatingLambda; }
   };
 
   class TemplateDeclInstantiator

clang/lib/AST/ASTContext.cpp

@@ -3140,13 +3140,35 @@ const FunctionType *ASTContext::adjustFunctionType(const FunctionType *T,
   return cast<FunctionType>(Result.getTypePtr());
 }
 
+QualType ASTContext::adjustFunctionResultType(QualType FunctionType,
+                                              QualType ResultType) {
+  // Might be wrapped in a macro qualified type.
+  if (const auto *MQT = dyn_cast<MacroQualifiedType>(FunctionType)) {
+    return getMacroQualifiedType(
+        adjustFunctionResultType(MQT->getUnderlyingType(), ResultType),
+        MQT->getMacroIdentifier());
+  }
+
+  // Might have a calling-convention attribute.
+  if (const auto *AT = dyn_cast<AttributedType>(FunctionType)) {
+    return getAttributedType(
+        AT->getAttrKind(),
+        adjustFunctionResultType(AT->getModifiedType(), ResultType),
+        adjustFunctionResultType(AT->getEquivalentType(), ResultType));
+  }
+
+  // Anything else must be a function type. Rebuild it with the new return
+  // value.
+  const auto *FPT = FunctionType->castAs<FunctionProtoType>();
+  return getFunctionType(ResultType, FPT->getParamTypes(),
+                         FPT->getExtProtoInfo());
+}
+
 void ASTContext::adjustDeducedFunctionResultType(FunctionDecl *FD,
                                                  QualType ResultType) {
   FD = FD->getMostRecentDecl();
   while (true) {
-    const auto *FPT = FD->getType()->castAs<FunctionProtoType>();
-    FunctionProtoType::ExtProtoInfo EPI = FPT->getExtProtoInfo();
-    FD->setType(getFunctionType(ResultType, FPT->getParamTypes(), EPI));
+    FD->setType(adjustFunctionResultType(FD->getType(), ResultType));
     if (FunctionDecl *Next = FD->getPreviousDecl())
       FD = Next;
     else

clang/lib/AST/ASTDumper.cpp

@@ -361,3 +361,11 @@ LLVM_DUMP_METHOD void ConceptReference::dump(raw_ostream &OS) const {
   ASTDumper P(OS, Ctx, Ctx.getDiagnostics().getShowColors());
   P.Visit(this);
 }
+
+//===----------------------------------------------------------------------===//
+// Attr method implementations
+//===----------------------------------------------------------------------===//
+LLVM_DUMP_METHOD void Attr::dump() const {
+  ASTDumper P(llvm::errs(), /*ShowColors=*/false);
+  P.Visit(this);
+}

clang/lib/Sema/SemaTemplateInstantiate.cpp

@@ -1535,7 +1535,8 @@ namespace {
                                            bool SuppressObjCLifetime);
 
     ExprResult TransformLambdaExpr(LambdaExpr *E) {
-      LocalInstantiationScope Scope(SemaRef, /*CombineWithOuterScope=*/true);
+      LocalInstantiationScope Scope(SemaRef, /*CombineWithOuterScope=*/true,
+                                    /*InstantiatingLambda=*/true);
       Sema::ConstraintEvalRAII<TemplateInstantiator> RAII(*this);
 
       ExprResult Result = inherited::TransformLambdaExpr(E);
@@ -2276,8 +2277,14 @@ QualType TemplateInstantiator::TransformFunctionProtoType(TypeLocBuilder &TLB,
                                  CXXRecordDecl *ThisContext,
                                  Qualifiers ThisTypeQuals,
                                  Fn TransformExceptionSpec) {
-  // We need a local instantiation scope for this function prototype.
-  LocalInstantiationScope Scope(SemaRef, /*CombineWithOuterScope=*/true);
+  // If this is a lambda, then TemplateInstantiator::TransformLambdaExpr will
+  // have already pushed a scope for this prototype, so don't create a second
+  // one. Otherwise, push a new instantiation scope.
+  LocalInstantiationScope *Current = getSema().CurrentInstantiationScope;
+  std::optional<LocalInstantiationScope> Scope;
+  if (!Current || !Current->isLambda())
+    Scope.emplace(SemaRef, /*CombineWithOuterScope=*/true);
+
   return inherited::TransformFunctionProtoType(
       TLB, TL, ThisContext, ThisTypeQuals, TransformExceptionSpec);
 }

clang/lib/Sema/TreeTransform.h

@@ -675,10 +675,6 @@ class TreeTransform {
                                       Qualifiers ThisTypeQuals,
                                       Fn TransformExceptionSpec);
 
-  template <typename Fn>
-  QualType TransformAttributedType(TypeLocBuilder &TLB, AttributedTypeLoc TL,
-                                   Fn TransformModifiedType);
-
   bool TransformExceptionSpec(SourceLocation Loc,
                               FunctionProtoType::ExceptionSpecInfo &ESI,
                               SmallVectorImpl<QualType> &Exceptions,
@@ -7212,11 +7208,10 @@ TreeTransform<Derived>::TransformElaboratedType(TypeLocBuilder &TLB,
 }
 
 template <typename Derived>
-template <typename Fn>
-QualType TreeTransform<Derived>::TransformAttributedType(
-    TypeLocBuilder &TLB, AttributedTypeLoc TL, Fn TransformModifiedTypeFn) {
+QualType TreeTransform<Derived>::TransformAttributedType(TypeLocBuilder &TLB,
+                                                         AttributedTypeLoc TL) {
   const AttributedType *oldType = TL.getTypePtr();
-  QualType modifiedType = TransformModifiedTypeFn(TLB, TL.getModifiedLoc());
+  QualType modifiedType = getDerived().TransformType(TLB, TL.getModifiedLoc());
   if (modifiedType.isNull())
     return QualType();
 
@@ -7231,12 +7226,16 @@ QualType TreeTransform<Derived>::TransformAttributedType(
   // FIXME: dependent operand expressions?
   if (getDerived().AlwaysRebuild() ||
       modifiedType != oldType->getModifiedType()) {
-    TypeLocBuilder AuxiliaryTLB;
-    AuxiliaryTLB.reserve(TL.getFullDataSize());
-    QualType equivalentType =
-        getDerived().TransformType(AuxiliaryTLB, TL.getEquivalentTypeLoc());
-    if (equivalentType.isNull())
-      return QualType();
+    // Do not transform the equivalent type if it is equal to the modified type.
+    QualType equivalentType = modifiedType;
+    if (TL.getModifiedLoc().getType() != TL.getEquivalentTypeLoc().getType()) {
+      TypeLocBuilder AuxiliaryTLB;
+      AuxiliaryTLB.reserve(TL.getFullDataSize());
+      equivalentType =
+          getDerived().TransformType(AuxiliaryTLB, TL.getEquivalentTypeLoc());
+      if (equivalentType.isNull())
+        return QualType();
+    }
 
     // Check whether we can add nullability; it is only represented as
     // type sugar, and therefore cannot be diagnosed in any other way.
@@ -7260,15 +7259,6 @@ QualType TreeTransform<Derived>::TransformAttributedType(
   return result;
 }
 
-template <typename Derived>
-QualType TreeTransform<Derived>::TransformAttributedType(TypeLocBuilder &TLB,
-                                                         AttributedTypeLoc TL) {
-  return getDerived().TransformAttributedType(
-      TLB, TL, [&](TypeLocBuilder &TLB, TypeLoc ModifiedLoc) -> QualType {
-        return getDerived().TransformType(TLB, ModifiedLoc);
-      });
-}
-
 template <typename Derived>
 QualType TreeTransform<Derived>::TransformBTFTagAttributedType(
     TypeLocBuilder &TLB, BTFTagAttributedTypeLoc TL) {
@@ -13830,62 +13820,40 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) {
     getSema().AddTemplateParametersToLambdaCallOperator(NewCallOperator, Class,
                                                         TPL);
 
-  // Transform the type of the original lambda's call operator.
-  // The transformation MUST be done in the CurrentInstantiationScope since
-  // it introduces a mapping of the original to the newly created
-  // transformed parameters.
   TypeSourceInfo *NewCallOpTSI = nullptr;
-  {
-    auto OldCallOpTypeLoc =
-        E->getCallOperator()->getTypeSourceInfo()->getTypeLoc();
-
-    auto TransformFunctionProtoTypeLoc =
-        [this](TypeLocBuilder &TLB, FunctionProtoTypeLoc FPTL) -> QualType {
-      SmallVector<QualType, 4> ExceptionStorage;
-      return this->TransformFunctionProtoType(
-          TLB, FPTL, nullptr, Qualifiers(),
-          [&](FunctionProtoType::ExceptionSpecInfo &ESI, bool &Changed) {
-            return TransformExceptionSpec(FPTL.getBeginLoc(), ESI,
-                                          ExceptionStorage, Changed);
-          });
-    };
-
-    QualType NewCallOpType;
-    TypeLocBuilder NewCallOpTLBuilder;
-
-    if (auto ATL = OldCallOpTypeLoc.getAs<AttributedTypeLoc>()) {
-      NewCallOpType = this->TransformAttributedType(
-          NewCallOpTLBuilder, ATL,
-          [&](TypeLocBuilder &TLB, TypeLoc TL) -> QualType {
-            return TransformFunctionProtoTypeLoc(
-                TLB, TL.castAs<FunctionProtoTypeLoc>());
-          });
-    } else {
-      auto FPTL = OldCallOpTypeLoc.castAs<FunctionProtoTypeLoc>();
-      NewCallOpType = TransformFunctionProtoTypeLoc(NewCallOpTLBuilder, FPTL);
-    }
+  auto OldCallOpTypeLoc =
+      E->getCallOperator()->getTypeSourceInfo()->getTypeLoc();
 
-    if (NewCallOpType.isNull())
-      return ExprError();
-    NewCallOpTSI =
-        NewCallOpTLBuilder.getTypeSourceInfo(getSema().Context, NewCallOpType);
-  }
+  QualType NewCallOpType;
+  TypeLocBuilder NewCallOpTLBuilder;
 
-  ArrayRef<ParmVarDecl *> Params;
-  if (auto ATL = NewCallOpTSI->getTypeLoc().getAs<AttributedTypeLoc>()) {
-    Params = ATL.getModifiedLoc().castAs<FunctionProtoTypeLoc>().getParams();
-  } else {
-    auto FPTL = NewCallOpTSI->getTypeLoc().castAs<FunctionProtoTypeLoc>();
-    Params = FPTL.getParams();
-  }
+  NewCallOpType =
+      getDerived().TransformType(NewCallOpTLBuilder, OldCallOpTypeLoc);
+  if (NewCallOpType.isNull())
+    return ExprError();
+  NewCallOpTSI =
+      NewCallOpTLBuilder.getTypeSourceInfo(getSema().Context, NewCallOpType);
+
+  auto ExtractParams = [](TypeLoc TL) {
+    auto Impl = [](auto Self, TypeLoc TL) -> ArrayRef<ParmVarDecl *> {
+      if (auto FPTL = TL.getAs<FunctionProtoTypeLoc>())
+        return FPTL.getParams();
+      if (auto ATL = TL.getAs<AttributedTypeLoc>())
+        return Self(Self, ATL.getModifiedLoc());
+      if (auto MQTL = TL.getAs<MacroQualifiedTypeLoc>())
+        return Self(Self, MQTL.getInnerLoc());
+      llvm_unreachable("Unhandled TypeLoc");
+    };
+    return Impl(Impl, TL);
+  };
 
   getSema().CompleteLambdaCallOperator(
       NewCallOperator, E->getCallOperator()->getLocation(),
       E->getCallOperator()->getInnerLocStart(),
       E->getCallOperator()->getTrailingRequiresClause(), NewCallOpTSI,
       E->getCallOperator()->getConstexprKind(),
-      E->getCallOperator()->getStorageClass(), Params,
-      E->hasExplicitResultType());
+      E->getCallOperator()->getStorageClass(),
+      ExtractParams(NewCallOpTSI->getTypeLoc()), E->hasExplicitResultType());
 
   getDerived().transformAttrs(E->getCallOperator(), NewCallOperator);
   getDerived().transformedLocalDecl(E->getCallOperator(), {NewCallOperator});

clang/test/SemaCXX/lambda-attributes.cpp

@@ -0,0 +1,62 @@
+// RUN: %clang_cc1 -std=c++23 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -std=c++23 -fsyntax-only -ast-dump %s | FileCheck %s
+// RUN: %clang_cc1 -std=c++23 -triple x86_64-pc-linux -emit-pch -o %t %s
+// RUN: %clang_cc1 -x c++ -std=c++23 -triple x86_64-pc-linux -include-pch %t -ast-dump-all /dev/null | FileCheck %s
+// expected-no-diagnostics
+
+// Check that we both don't crash on transforming FunctionProtoType's
+// wrapped in type sugar and that we don't drop it when performing
+// instantiations either.
+
+#define PRESERVE __attribute__((preserve_most))
+
+// Skip to the instantiation of f().
+// CHECK: FunctionDecl {{.*}} f 'void ()' implicit_instantiation
+template <typename T>
+void f() {
+  // CHECK: CXXMethodDecl {{.*}} operator() 'void (int) const __attribute__((preserve_most))':'void (int) __attribute__((preserve_most)) const' implicit_instantiation
+  (void) [] (T) __attribute__((preserve_most)) { };
+
+  // CHECK: CXXMethodDecl {{.*}} operator() 'void (int) const {{\[}}[clang::annotate_type(...)]]':'void (int) const' implicit_instantiation
+  (void) [] (T) [[clang::annotate_type("foo")]] { };
+
+  // CHECK: CXXMethodDecl {{.*}} operator() 'void (int) const {{\[}}[clang::annotate_type(...)]] {{\[}}[clang::annotate_type(...)]] {{\[}}[clang::annotate_type(...)]]':'void (int) const' implicit_instantiation
+  (void) [] (T) [[clang::annotate_type("foo")]]
+                [[clang::annotate_type("foo")]]
+                [[clang::annotate_type("foo")]] { };
+
+  // CHECK: CXXMethodDecl {{.*}} operator() 'void (int) const __attribute__((preserve_most)) {{\[}}[clang::annotate_type(...)]]':'void (int) __attribute__((preserve_most)) const' implicit_instantiation
+  (void) [] (T) __attribute__((preserve_most))
+                [[clang::annotate_type("foo")]] { };
+
+  // CHECK: CXXMethodDecl {{.*}} operator() 'void (int) const __attribute__((cdecl)) {{\[}}[clang::annotate_type(...)]]':'void (int) const' implicit_instantiation
+  (void) [] (T) __attribute__((cdecl))
+                [[clang::annotate_type("foo")]] { };
+
+  // CHECK: CXXMethodDecl {{.*}} operator() 'void (int) const {{\[}}[clang::annotate_type(...)]]':'void (int) const' implicit_instantiation
+  (void) [] (T t) [[clang::annotate_type("foo", t)]] { };
+
+  // CHECK: CXXMethodDecl {{.*}} operator() 'void (int) const __attribute__((preserve_most)) {{\[}}[clang::annotate_type(...)]]':'void (int) __attribute__((preserve_most)) const' implicit_instantiation
+  (void) [] (T t) __attribute__((preserve_most))
+                [[clang::annotate_type("foo", t, t, t, t)]] { };
+
+  // Check that the MacroQualifiedType is preserved.
+  // CHECK: CXXMethodDecl {{.*}} operator() 'PRESERVE void (int) __attribute__((preserve_most)) const':'void (int) __attribute__((preserve_most)) const' implicit_instantiation
+  (void) [] (T) PRESERVE { };
+
+  // CHECK: CXXMethodDecl {{.*}} operator() 'PRESERVE void (int) __attribute__((preserve_most)) const {{\[}}[clang::annotate_type(...)]]':'void (int) __attribute__((preserve_most)) const' implicit_instantiation
+  (void) [] (T) PRESERVE [[clang::annotate_type("foo")]] { };
+
+  // CHECK: CXXMethodDecl {{.*}} operator() 'void (int) const {{\[}}[clang::annotate_type(...)]]':'void (int) const' implicit_instantiation
+  (void) [] (T) [[clang::annotate_type("foo")]] {
+    // CHECK: CXXMethodDecl {{.*}} operator() 'PRESERVE void (int) __attribute__((preserve_most)) const {{\[}}[clang::annotate_type(...)]]':'void (int) __attribute__((preserve_most)) const' implicit_instantiation
+    auto l = []<typename U = T> (U u = {}) PRESERVE [[clang::annotate_type("foo", u)]] { };
+
+    // CHECK: DeclRefExpr {{.*}} 'PRESERVE void (int) __attribute__((preserve_most)) const {{\[}}[clang::annotate_type(...)]]':'void (int) __attribute__((preserve_most)) const' lvalue CXXMethod
+    l();
+  };
+}
+
+void g() {
+  f<int>();
+}

clang/test/SemaCXX/lambda-conversion-op-cc.cpp

@@ -44,19 +44,19 @@ void useage() {
 
   // CHECK: VarDecl {{.*}} vectorcall '
   // CHECK: LambdaExpr
-  // CHECK: CXXMethodDecl {{.*}} operator() 'void (int, float, double) __attribute__((vectorcall)) const'
+  // CHECK: CXXMethodDecl {{.*}} operator() 'void (int, float, double) const __attribute__((vectorcall))':'void (int, float, double) __attribute__((vectorcall)) const'
   // CHECK: CXXConversionDecl {{.*}} operator void (*)(int, float, double) __attribute__((vectorcall)) 'void
   // CHECK: CXXMethodDecl {{.*}} __invoke 'void (int, float, double) __attribute__((vectorcall))' static inline
 
   // WIN32: VarDecl {{.*}} thiscall '
   // WIN32: LambdaExpr
-  // WIN32: CXXMethodDecl {{.*}} operator() 'void (int, float, double) __attribute__((thiscall)) const'
+  // WIN32: CXXMethodDecl {{.*}} operator() 'void (int, float, double) const __attribute__((thiscall))':'void (int, float, double) __attribute__((thiscall)) const'
   // WIN32: CXXConversionDecl {{.*}} operator void (*)(int, float, double) 'void
   // WIN32: CXXMethodDecl {{.*}} __invoke 'void (int, float, double)' static inline
 
   // CHECK: VarDecl {{.*}} cdecl '
   // CHECK: LambdaExpr
-  // CHECK: CXXMethodDecl {{.*}} operator() 'void (int, float, double) const'
+  // CHECK: CXXMethodDecl {{.*}} operator() 'void (int, float, double) const __attribute__((cdecl))':'void (int, float, double) const'
   // NODEF: CXXConversionDecl {{.*}} operator void (*)(int, float, double) 'void
   // NODEF: CXXMethodDecl {{.*}} __invoke 'void (int, float, double)' static inline
   // VECTDEF: CXXConversionDecl {{.*}} operator void (*)(int, float, double) __attribute__((vectorcall)) 'void
@@ -108,8 +108,8 @@ void useage() {
   // CHECK: LambdaExpr
   // CHECK: FunctionTemplateDecl {{.*}} operator()
   // CHECK: CXXMethodDecl {{.*}} operator() 'auto (auto) __attribute__((vectorcall)) const' inline
-  // CHECK: CXXMethodDecl {{.*}} operator() 'void (char) __attribute__((vectorcall)) const' implicit_instantiation inline
-  // CHECK: CXXMethodDecl {{.*}} operator() 'void (int) __attribute__((vectorcall)) const' implicit_instantiation inline
+  // CHECK: CXXMethodDecl {{.*}} operator() 'void (char) const __attribute__((vectorcall))':'void (char) __attribute__((vectorcall)) const' implicit_instantiation inline
+  // CHECK: CXXMethodDecl {{.*}} operator() 'void (int) const __attribute__((vectorcall))':'void (int) __attribute__((vectorcall)) const' implicit_instantiation inline
   // CHECK: FunctionTemplateDecl {{.*}} operator auto (*)(type-parameter-0-0) __attribute__((vectorcall))
   // LIN64: CXXConversionDecl {{.*}} operator auto (*)(type-parameter-0-0) __attribute__((vectorcall)) 'auto (*() const noexcept)(auto) __attribute__((vectorcall))'
   // LIN64: CXXConversionDecl {{.*}} operator auto (*)(char) __attribute__((vectorcall)) 'void (*() const noexcept)(char) __attribute__((vectorcall))'