[Clang] Bugfixes and improved support for AttributedTypes in lambdas (#85325)

Sirraide · yuxuanchen1997 · Doug Wyatt · web-flow · commit f4fa16f14b3e · 2024-09-26T03:24:53.000+02:00
This fixes a crash when we attempt to instantiate a lambda with an `AnnotatedType`, refactors the code that handles transforming the function type of a lambda, and improves source fidelity for lambda function types. This fixes #85120 and fixes #85154. --------- Co-authored-by: Yuxuan Chen <ych@meta.com> Co-authored-by: Doug Wyatt <dwyatt@apple.com>
diff --git a/clang/include/clang/AST/ASTContext.h b/clang/include/clang/AST/ASTContext.h
@@ -253,7 +253,7 @@ class ASTContext : public RefCountedBase<ASTContext> {
   mutable llvm::FoldingSet<BitIntType> BitIntTypes;
   mutable llvm::ContextualFoldingSet<DependentBitIntType, ASTContext &>
       DependentBitIntTypes;
-  llvm::FoldingSet<BTFTagAttributedType> BTFTagAttributedTypes;
+  mutable llvm::FoldingSet<BTFTagAttributedType> BTFTagAttributedTypes;
   llvm::FoldingSet<HLSLAttributedResourceType> HLSLAttributedResourceTypes;
 
   mutable llvm::FoldingSet<CountAttributedType> CountAttributedTypes;
@@ -1369,10 +1369,21 @@ class ASTContext : public RefCountedBase<ASTContext> {
   /// calling T.withConst().
   QualType getConstType(QualType T) const { return T.withConst(); }
 
+  /// Rebuild a type, preserving any existing type sugar. For function types,
+  /// you probably want to just use \c adjustFunctionResultType and friends
+  /// instead.
+  QualType adjustType(QualType OldType,
+                      llvm::function_ref<QualType(QualType)> Adjust) const;
+
   /// Change the ExtInfo on a function type.
   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;
 
@@ -1702,7 +1713,7 @@ class ASTContext : public RefCountedBase<ASTContext> {
                              QualType equivalentType) const;
 
   QualType getBTFTagAttributedType(const BTFTypeTagAttr *BTFAttr,
-                                   QualType Wrapped);
+                                   QualType Wrapped) const;
 
   QualType getHLSLAttributedResourceType(
       QualType Wrapped, QualType Contained,
diff --git a/clang/include/clang/Sema/Template.h b/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
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
@@ -3535,6 +3535,50 @@ QualType ASTContext::getCountAttributedType(
   return QualType(CATy, 0);
 }
 
+QualType
+ASTContext::adjustType(QualType Orig,
+                       llvm::function_ref<QualType(QualType)> Adjust) const {
+  switch (Orig->getTypeClass()) {
+  case Type::Attributed: {
+    const auto *AT = dyn_cast<AttributedType>(Orig);
+    return getAttributedType(AT->getAttrKind(),
+                             adjustType(AT->getModifiedType(), Adjust),
+                             adjustType(AT->getEquivalentType(), Adjust));
+  }
+
+  case Type::BTFTagAttributed: {
+    const auto *BTFT = dyn_cast<BTFTagAttributedType>(Orig);
+    return getBTFTagAttributedType(BTFT->getAttr(),
+                                   adjustType(BTFT->getWrappedType(), Adjust));
+  }
+
+  case Type::Elaborated: {
+    const auto *ET = cast<ElaboratedType>(Orig);
+    return getElaboratedType(ET->getKeyword(), ET->getQualifier(),
+                             adjustType(ET->getNamedType(), Adjust));
+  }
+
+  case Type::Paren:
+    return getParenType(
+        adjustType(cast<ParenType>(Orig)->getInnerType(), Adjust));
+
+  case Type::Adjusted: {
+    const auto *AT = cast<AdjustedType>(Orig);
+    return getAdjustedType(AT->getOriginalType(),
+                           adjustType(AT->getAdjustedType(), Adjust));
+  }
+
+  case Type::MacroQualified: {
+    const auto *MQT = cast<MacroQualifiedType>(Orig);
+    return getMacroQualifiedType(adjustType(MQT->getUnderlyingType(), Adjust),
+                                 MQT->getMacroIdentifier());
+  }
+
+  default:
+    return Adjust(Orig);
+  }
+}
+
 const FunctionType *ASTContext::adjustFunctionType(const FunctionType *T,
                                                    FunctionType::ExtInfo Info) {
   if (T->getExtInfo() == Info)
@@ -3553,13 +3597,23 @@ const FunctionType *ASTContext::adjustFunctionType(const FunctionType *T,
   return cast<FunctionType>(Result.getTypePtr());
 }
 
+QualType ASTContext::adjustFunctionResultType(QualType FunctionType,
+                                              QualType ResultType) {
+  return adjustType(FunctionType, [&](QualType Orig) {
+    if (const auto *FNPT = Orig->getAs<FunctionNoProtoType>())
+      return getFunctionNoProtoType(ResultType, FNPT->getExtInfo());
+
+    const auto *FPT = Orig->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
@@ -3575,30 +3629,11 @@ void ASTContext::adjustDeducedFunctionResultType(FunctionDecl *FD,
 /// and preserved. Other type sugar (for instance, typedefs) is not.
 QualType ASTContext::getFunctionTypeWithExceptionSpec(
     QualType Orig, const FunctionProtoType::ExceptionSpecInfo &ESI) const {
-  // Might have some parens.
-  if (const auto *PT = dyn_cast<ParenType>(Orig))
-    return getParenType(
-        getFunctionTypeWithExceptionSpec(PT->getInnerType(), ESI));
-
-  // Might be wrapped in a macro qualified type.
-  if (const auto *MQT = dyn_cast<MacroQualifiedType>(Orig))
-    return getMacroQualifiedType(
-        getFunctionTypeWithExceptionSpec(MQT->getUnderlyingType(), ESI),
-        MQT->getMacroIdentifier());
-
-  // Might have a calling-convention attribute.
-  if (const auto *AT = dyn_cast<AttributedType>(Orig))
-    return getAttributedType(
-        AT->getAttrKind(),
-        getFunctionTypeWithExceptionSpec(AT->getModifiedType(), ESI),
-        getFunctionTypeWithExceptionSpec(AT->getEquivalentType(), ESI));
-
-  // Anything else must be a function type. Rebuild it with the new exception
-  // specification.
-  const auto *Proto = Orig->castAs<FunctionProtoType>();
-  return getFunctionType(
-      Proto->getReturnType(), Proto->getParamTypes(),
-      Proto->getExtProtoInfo().withExceptionSpec(ESI));
+  return adjustType(Orig, [&](QualType Ty) {
+    const auto *Proto = Ty->castAs<FunctionProtoType>();
+    return getFunctionType(Proto->getReturnType(), Proto->getParamTypes(),
+                           Proto->getExtProtoInfo().withExceptionSpec(ESI));
+  });
 }
 
 bool ASTContext::hasSameFunctionTypeIgnoringExceptionSpec(QualType T,
@@ -5165,7 +5200,7 @@ QualType ASTContext::getAttributedType(attr::Kind attrKind,
 }
 
 QualType ASTContext::getBTFTagAttributedType(const BTFTypeTagAttr *BTFAttr,
-                                             QualType Wrapped) {
+                                             QualType Wrapped) const {
   llvm::FoldingSetNodeID ID;
   BTFTagAttributedType::Profile(ID, Wrapped, BTFAttr);
 
diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -1677,7 +1677,8 @@ namespace {
       // Lambdas have already been processed inside their eval contexts.
       if (SemaRef.RebuildingImmediateInvocation)
         return E;
-      LocalInstantiationScope Scope(SemaRef, /*CombineWithOuterScope=*/true);
+      LocalInstantiationScope Scope(SemaRef, /*CombineWithOuterScope=*/true,
+                                    /*InstantiatingLambda=*/true);
       Sema::ConstraintEvalRAII<TemplateInstantiator> RAII(*this);
 
       return inherited::TransformLambdaExpr(E);
@@ -2432,8 +2433,18 @@ 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, the transformation MUST be done in the
+  // CurrentInstantiationScope since it introduces a mapping of
+  // the original to the newly created transformed parameters.
+  //
+  // In that case, TemplateInstantiator::TransformLambdaExpr will
+  // have already pushed a scope for this prototype, so don't create
+  // a second one.
+  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);
 }
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
@@ -684,10 +684,6 @@ 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,
@@ -7373,11 +7369,10 @@ 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();
 
@@ -7392,12 +7387,27 @@ 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();
+    // If the equivalent type is equal to the modified type, we don't want to
+    // transform it as well because:
+    //
+    //   1. The transformation would yield the same result and is therefore
+    //      superfluous, and
+    //
+    //   2. Transforming the same type twice can cause problems, e.g. if it
+    //      is a FunctionProtoType, we may end up instantiating the function
+    //      parameters twice, which causes an assertion since the parameters
+    //      are already bound to their counterparts in the template for this
+    //      instantiation.
+    //
+    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.
@@ -7421,15 +7431,6 @@ 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>::TransformCountAttributedType(
     TypeLocBuilder &TLB, CountAttributedTypeLoc TL) {
@@ -14774,63 +14775,29 @@ TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) {
         TPL->containsUnexpandedParameterPack();
   }
 
-  // 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);
-    }
-
-    if (NewCallOpType.isNull())
-      return ExprError();
-    LSI->ContainsUnexpandedParameterPack |=
-        NewCallOpType->containsUnexpandedParameterPack();
-    NewCallOpTSI =
-        NewCallOpTLBuilder.getTypeSourceInfo(getSema().Context, NewCallOpType);
-  }
+  TypeLocBuilder NewCallOpTLBuilder;
+  TypeLoc OldCallOpTypeLoc =
+      E->getCallOperator()->getTypeSourceInfo()->getTypeLoc();
+  QualType NewCallOpType =
+      getDerived().TransformType(NewCallOpTLBuilder, OldCallOpTypeLoc);
+  if (NewCallOpType.isNull())
+    return ExprError();
+  LSI->ContainsUnexpandedParameterPack |=
+      NewCallOpType->containsUnexpandedParameterPack();
+  TypeSourceInfo *NewCallOpTSI =
+      NewCallOpTLBuilder.getTypeSourceInfo(getSema().Context, NewCallOpType);
 
-  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();
-  }
+  // The type may be an AttributedType or some other kind of sugar;
+  // get the actual underlying FunctionProtoType.
+  auto FPTL = NewCallOpTSI->getTypeLoc().getAsAdjusted<FunctionProtoTypeLoc>();
+  assert(FPTL && "Not a FunctionProtoType?");
 
   getSema().CompleteLambdaCallOperator(
       NewCallOperator, E->getCallOperator()->getLocation(),
       E->getCallOperator()->getInnerLocStart(),
       E->getCallOperator()->getTrailingRequiresClause(), NewCallOpTSI,
       E->getCallOperator()->getConstexprKind(),
-      E->getCallOperator()->getStorageClass(), Params,
+      E->getCallOperator()->getStorageClass(), FPTL.getParams(),
       E->hasExplicitResultType());
 
   getDerived().transformAttrs(E->getCallOperator(), NewCallOperator);
diff --git a/clang/test/SemaCXX/lambda-attributes.cpp b/clang/test/SemaCXX/lambda-attributes.cpp
diff --git a/clang/test/SemaCXX/lambda-conversion-op-cc.cpp b/clang/test/SemaCXX/lambda-conversion-op-cc.cpp
