//===- ExprClassification.cpp - Expression AST Node Implementation --------===// // // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // //===----------------------------------------------------------------------===// // // This file implements Expr::classify. // //===----------------------------------------------------------------------===// #include "clang/AST/Expr.h" #include "clang/AST/ASTContext.h" #include "clang/AST/DeclCXX.h" #include "clang/AST/DeclObjC.h" #include "clang/AST/DeclTemplate.h" #include "clang/AST/ExprCXX.h" #include "clang/AST/ExprObjC.h" #include "llvm/Support/ErrorHandling.h" using namespace clang; using Cl = Expr::Classification; static Cl::Kinds ClassifyInternal(ASTContext &Ctx, const Expr *E); static Cl::Kinds ClassifyDecl(ASTContext &Ctx, const Decl *D); static Cl::Kinds ClassifyUnnamed(ASTContext &Ctx, QualType T); static Cl::Kinds ClassifyMemberExpr(ASTContext &Ctx, const MemberExpr *E); static Cl::Kinds ClassifyBinaryOp(ASTContext &Ctx, const BinaryOperator *E); static Cl::Kinds ClassifyConditional(ASTContext &Ctx, const Expr *trueExpr, const Expr *falseExpr); static Cl::ModifiableType IsModifiable(ASTContext &Ctx, const Expr *E, Cl::Kinds Kind, SourceLocation &Loc); Cl Expr::ClassifyImpl(ASTContext &Ctx, SourceLocation *Loc) const { assert(!TR->isReferenceType() && "Expressions can't have reference type."); Cl::Kinds kind = ClassifyInternal(Ctx, this); // C99 6.3.2.1: An lvalue is an expression with an object type or an // incomplete type other than void. if (!Ctx.getLangOpts().CPlusPlus) { // Thus, no functions. if (TR->isFunctionType() || TR == Ctx.OverloadTy) kind = Cl::CL_Function; // No void either, but qualified void is OK because it is "other than void". // Void "lvalues" are classified as addressable void values, which are void // expressions whose address can be taken. else if (TR->isVoidType() && !TR.hasQualifiers()) kind = (kind == Cl::CL_LValue ? Cl::CL_AddressableVoid : Cl::CL_Void); } // Enable this assertion for testing. switch (kind) { case Cl::CL_LValue: assert(getValueKind() == VK_LValue); break; case Cl::CL_XValue: assert(getValueKind() == VK_XValue); break; case Cl::CL_Function: case Cl::CL_Void: case Cl::CL_AddressableVoid: case Cl::CL_DuplicateVectorComponents: case Cl::CL_MemberFunction: case Cl::CL_SubObjCPropertySetting: case Cl::CL_ClassTemporary: case Cl::CL_ArrayTemporary: case Cl::CL_ObjCMessageRValue: case Cl::CL_PRValue: assert(getValueKind() == VK_RValue); break; } Cl::ModifiableType modifiable = Cl::CM_Untested; if (Loc) modifiable = IsModifiable(Ctx, this, kind, *Loc); return Classification(kind, modifiable); } /// Classify an expression which creates a temporary, based on its type. static Cl::Kinds ClassifyTemporary(QualType T) { if (T->isRecordType()) return Cl::CL_ClassTemporary; if (T->isArrayType()) return Cl::CL_ArrayTemporary; // No special classification: these don't behave differently from normal // prvalues. return Cl::CL_PRValue; } static Cl::Kinds ClassifyExprValueKind(const LangOptions &Lang, const Expr *E, ExprValueKind Kind) { switch (Kind) { case VK_RValue: return Lang.CPlusPlus ? ClassifyTemporary(E->getType()) : Cl::CL_PRValue; case VK_LValue: return Cl::CL_LValue; case VK_XValue: return Cl::CL_XValue; } llvm_unreachable("Invalid value category of implicit cast."); } static Cl::Kinds ClassifyInternal(ASTContext &Ctx, const Expr *E) { // This function takes the first stab at classifying expressions. const LangOptions &Lang = Ctx.getLangOpts(); switch (E->getStmtClass()) { case Stmt::NoStmtClass: #define ABSTRACT_STMT(Kind) #define STMT(Kind, Base) case Expr::Kind##Class: #define EXPR(Kind, Base) #include "clang/AST/StmtNodes.inc" llvm_unreachable("cannot classify a statement"); // First come the expressions that are always lvalues, unconditionally. case Expr::ObjCIsaExprClass: // C++ [expr.prim.general]p1: A string literal is an lvalue. case Expr::StringLiteralClass: // @encode is equivalent to its string case Expr::ObjCEncodeExprClass: // __func__ and friends are too. case Expr::PredefinedExprClass: // Property references are lvalues case Expr::ObjCSubscriptRefExprClass: case Expr::ObjCPropertyRefExprClass: // C++ [expr.typeid]p1: The result of a typeid expression is an lvalue of... case Expr::CXXTypeidExprClass: case Expr::CXXUuidofExprClass: // Unresolved lookups and uncorrected typos get classified as lvalues. // FIXME: Is this wise? Should they get their own kind? case Expr::UnresolvedLookupExprClass: case Expr::UnresolvedMemberExprClass: case Expr::TypoExprClass: case Expr::DependentCoawaitExprClass: case Expr::CXXDependentScopeMemberExprClass: case Expr::DependentScopeDeclRefExprClass: // ObjC instance variables are lvalues // FIXME: ObjC++0x might have different rules case Expr::ObjCIvarRefExprClass: case Expr::FunctionParmPackExprClass: case Expr::MSPropertyRefExprClass: case Expr::MSPropertySubscriptExprClass: case Expr::OMPArraySectionExprClass: case Expr::OMPArrayShapingExprClass: case Expr::OMPIteratorExprClass: return Cl::CL_LValue; // C99 6.5.2.5p5 says that compound literals are lvalues. // In C++, they're prvalue temporaries, except for file-scope arrays. case Expr::CompoundLiteralExprClass: return !E->isLValue() ? ClassifyTemporary(E->getType()) : Cl::CL_LValue; // Expressions that are prvalues. case Expr::CXXBoolLiteralExprClass: case Expr::CXXPseudoDestructorExprClass: case Expr::UnaryExprOrTypeTraitExprClass: case Expr::CXXNewExprClass: case Expr::CXXThisExprClass: case Expr::CXXNullPtrLiteralExprClass: case Expr::ImaginaryLiteralClass: case Expr::GNUNullExprClass: case Expr::OffsetOfExprClass: case Expr::CXXThrowExprClass: case Expr::ShuffleVectorExprClass: case Expr::ConvertVectorExprClass: case Expr::IntegerLiteralClass: case Expr::FixedPointLiteralClass: case Expr::CharacterLiteralClass: case Expr::AddrLabelExprClass: case Expr::CXXDeleteExprClass: case Expr::ImplicitValueInitExprClass: case Expr::BlockExprClass: case Expr::FloatingLiteralClass: case Expr::CXXNoexceptExprClass: case Expr::CXXScalarValueInitExprClass: case Expr::TypeTraitExprClass: case Expr::ArrayTypeTraitExprClass: case Expr::ExpressionTraitExprClass: case Expr::ObjCSelectorExprClass: case Expr::ObjCProtocolExprClass: case Expr::ObjCStringLiteralClass: case Expr::ObjCBoxedExprClass: case Expr::ObjCArrayLiteralClass: case Expr::ObjCDictionaryLiteralClass: case Expr::ObjCBoolLiteralExprClass: case Expr::ObjCAvailabilityCheckExprClass: case Expr::ParenListExprClass: case Expr::SizeOfPackExprClass: case Expr::SubstNonTypeTemplateParmPackExprClass: case Expr::AsTypeExprClass: case Expr::ObjCIndirectCopyRestoreExprClass: case Expr::AtomicExprClass: case Expr::CXXFoldExprClass: case Expr::ArrayInitLoopExprClass: case Expr::ArrayInitIndexExprClass: case Expr::NoInitExprClass: case Expr::DesignatedInitUpdateExprClass: case Expr::SourceLocExprClass: case Expr::ConceptSpecializationExprClass: case Expr::RequiresExprClass: return Cl::CL_PRValue; case Expr::ConstantExprClass: return ClassifyInternal(Ctx, cast(E)->getSubExpr()); // Next come the complicated cases. case Expr::SubstNonTypeTemplateParmExprClass: return ClassifyInternal(Ctx, cast(E)->getReplacement()); // C, C++98 [expr.sub]p1: The result is an lvalue of type "T". // C++11 (DR1213): in the case of an array operand, the result is an lvalue // if that operand is an lvalue and an xvalue otherwise. // Subscripting vector types is more like member access. case Expr::ArraySubscriptExprClass: if (cast(E)->getBase()->getType()->isVectorType()) return ClassifyInternal(Ctx, cast(E)->getBase()); if (Lang.CPlusPlus11) { // Step over the array-to-pointer decay if present, but not over the // temporary materialization. auto *Base = cast(E)->getBase()->IgnoreImpCasts(); if (Base->getType()->isArrayType()) return ClassifyInternal(Ctx, Base); } return Cl::CL_LValue; // Subscripting matrix types behaves like member accesses. case Expr::MatrixSubscriptExprClass: return ClassifyInternal(Ctx, cast(E)->getBase()); // C++ [expr.prim.general]p3: The result is an lvalue if the entity is a // function or variable and a prvalue otherwise. case Expr::DeclRefExprClass: if (E->getType() == Ctx.UnknownAnyTy) return isa(cast(E)->getDecl()) ? Cl::CL_PRValue : Cl::CL_LValue; return ClassifyDecl(Ctx, cast(E)->getDecl()); // Member access is complex. case Expr::MemberExprClass: return ClassifyMemberExpr(Ctx, cast(E)); case Expr::UnaryOperatorClass: switch (cast(E)->getOpcode()) { // C++ [expr.unary.op]p1: The unary * operator performs indirection: // [...] the result is an lvalue referring to the object or function // to which the expression points. case UO_Deref: return Cl::CL_LValue; // GNU extensions, simply look through them. case UO_Extension: return ClassifyInternal(Ctx, cast(E)->getSubExpr()); // Treat _Real and _Imag basically as if they were member // expressions: l-value only if the operand is a true l-value. case UO_Real: case UO_Imag: { const Expr *Op = cast(E)->getSubExpr()->IgnoreParens(); Cl::Kinds K = ClassifyInternal(Ctx, Op); if (K != Cl::CL_LValue) return K; if (isa(Op)) return Cl::CL_SubObjCPropertySetting; return Cl::CL_LValue; } // C++ [expr.pre.incr]p1: The result is the updated operand; it is an // lvalue, [...] // Not so in C. case UO_PreInc: case UO_PreDec: return Lang.CPlusPlus ? Cl::CL_LValue : Cl::CL_PRValue; default: return Cl::CL_PRValue; } case Expr::RecoveryExprClass: case Expr::OpaqueValueExprClass: return ClassifyExprValueKind(Lang, E, E->getValueKind()); // Pseudo-object expressions can produce l-values with reference magic. case Expr::PseudoObjectExprClass: return ClassifyExprValueKind(Lang, E, cast(E)->getValueKind()); // Implicit casts are lvalues if they're lvalue casts. Other than that, we // only specifically record class temporaries. case Expr::ImplicitCastExprClass: return ClassifyExprValueKind(Lang, E, E->getValueKind()); // C++ [expr.prim.general]p4: The presence of parentheses does not affect // whether the expression is an lvalue. case Expr::ParenExprClass: return ClassifyInternal(Ctx, cast(E)->getSubExpr()); // C11 6.5.1.1p4: [A generic selection] is an lvalue, a function designator, // or a void expression if its result expression is, respectively, an // lvalue, a function designator, or a void expression. case Expr::GenericSelectionExprClass: if (cast(E)->isResultDependent()) return Cl::CL_PRValue; return ClassifyInternal(Ctx,cast(E)->getResultExpr()); case Expr::BinaryOperatorClass: case Expr::CompoundAssignOperatorClass: // C doesn't have any binary expressions that are lvalues. if (Lang.CPlusPlus) return ClassifyBinaryOp(Ctx, cast(E)); return Cl::CL_PRValue; case Expr::CallExprClass: case Expr::CXXOperatorCallExprClass: case Expr::CXXMemberCallExprClass: case Expr::UserDefinedLiteralClass: case Expr::CUDAKernelCallExprClass: return ClassifyUnnamed(Ctx, cast(E)->getCallReturnType(Ctx)); case Expr::CXXRewrittenBinaryOperatorClass: return ClassifyInternal( Ctx, cast(E)->getSemanticForm()); // __builtin_choose_expr is equivalent to the chosen expression. case Expr::ChooseExprClass: return ClassifyInternal(Ctx, cast(E)->getChosenSubExpr()); // Extended vector element access is an lvalue unless there are duplicates // in the shuffle expression. case Expr::ExtVectorElementExprClass: if (cast(E)->containsDuplicateElements()) return Cl::CL_DuplicateVectorComponents; if (cast(E)->isArrow()) return Cl::CL_LValue; return ClassifyInternal(Ctx, cast(E)->getBase()); // Simply look at the actual default argument. case Expr::CXXDefaultArgExprClass: return ClassifyInternal(Ctx, cast(E)->getExpr()); // Same idea for default initializers. case Expr::CXXDefaultInitExprClass: return ClassifyInternal(Ctx, cast(E)->getExpr()); // Same idea for temporary binding. case Expr::CXXBindTemporaryExprClass: return ClassifyInternal(Ctx, cast(E)->getSubExpr()); // And the cleanups guard. case Expr::ExprWithCleanupsClass: return ClassifyInternal(Ctx, cast(E)->getSubExpr()); // Casts depend completely on the target type. All casts work the same. case Expr::CStyleCastExprClass: case Expr::CXXFunctionalCastExprClass: case Expr::CXXStaticCastExprClass: case Expr::CXXDynamicCastExprClass: case Expr::CXXReinterpretCastExprClass: case Expr::CXXConstCastExprClass: case Expr::CXXAddrspaceCastExprClass: case Expr::ObjCBridgedCastExprClass: case Expr::BuiltinBitCastExprClass: // Only in C++ can casts be interesting at all. if (!Lang.CPlusPlus) return Cl::CL_PRValue; return ClassifyUnnamed(Ctx, cast(E)->getTypeAsWritten()); case Expr::CXXUnresolvedConstructExprClass: return ClassifyUnnamed(Ctx, cast(E)->getTypeAsWritten()); case Expr::BinaryConditionalOperatorClass: { if (!Lang.CPlusPlus) return Cl::CL_PRValue; const auto *co = cast(E); return ClassifyConditional(Ctx, co->getTrueExpr(), co->getFalseExpr()); } case Expr::ConditionalOperatorClass: { // Once again, only C++ is interesting. if (!Lang.CPlusPlus) return Cl::CL_PRValue; const auto *co = cast(E); return ClassifyConditional(Ctx, co->getTrueExpr(), co->getFalseExpr()); } // ObjC message sends are effectively function calls, if the target function // is known. case Expr::ObjCMessageExprClass: if (const ObjCMethodDecl *Method = cast(E)->getMethodDecl()) { Cl::Kinds kind = ClassifyUnnamed(Ctx, Method->getReturnType()); return (kind == Cl::CL_PRValue) ? Cl::CL_ObjCMessageRValue : kind; } return Cl::CL_PRValue; // Some C++ expressions are always class temporaries. case Expr::CXXConstructExprClass: case Expr::CXXInheritedCtorInitExprClass: case Expr::CXXTemporaryObjectExprClass: case Expr::LambdaExprClass: case Expr::CXXStdInitializerListExprClass: return Cl::CL_ClassTemporary; case Expr::VAArgExprClass: return ClassifyUnnamed(Ctx, E->getType()); case Expr::DesignatedInitExprClass: return ClassifyInternal(Ctx, cast(E)->getInit()); case Expr::StmtExprClass: { const CompoundStmt *S = cast(E)->getSubStmt(); if (const auto *LastExpr = dyn_cast_or_null(S->body_back())) return ClassifyUnnamed(Ctx, LastExpr->getType()); return Cl::CL_PRValue; } case Expr::PackExpansionExprClass: return ClassifyInternal(Ctx, cast(E)->getPattern()); case Expr::MaterializeTemporaryExprClass: return cast(E)->isBoundToLvalueReference() ? Cl::CL_LValue : Cl::CL_XValue; case Expr::InitListExprClass: // An init list can be an lvalue if it is bound to a reference and // contains only one element. In that case, we look at that element // for an exact classification. Init list creation takes care of the // value kind for us, so we only need to fine-tune. if (E->isRValue()) return ClassifyExprValueKind(Lang, E, E->getValueKind()); assert(cast(E)->getNumInits() == 1 && "Only 1-element init lists can be glvalues."); return ClassifyInternal(Ctx, cast(E)->getInit(0)); case Expr::CoawaitExprClass: case Expr::CoyieldExprClass: return ClassifyInternal(Ctx, cast(E)->getResumeExpr()); } llvm_unreachable("unhandled expression kind in classification"); } /// ClassifyDecl - Return the classification of an expression referencing the /// given declaration. static Cl::Kinds ClassifyDecl(ASTContext &Ctx, const Decl *D) { // C++ [expr.prim.general]p6: The result is an lvalue if the entity is a // function, variable, or data member and a prvalue otherwise. // In C, functions are not lvalues. // In addition, NonTypeTemplateParmDecl derives from VarDecl but isn't an // lvalue unless it's a reference type (C++ [temp.param]p6), so we need to // special-case this. if (isa(D) && cast(D)->isInstance()) return Cl::CL_MemberFunction; bool islvalue; if (const auto *NTTParm = dyn_cast(D)) islvalue = NTTParm->getType()->isReferenceType(); else islvalue = isa(D) || isa(D) || isa(D) || isa(D) || isa(D) || (Ctx.getLangOpts().CPlusPlus && (isa(D) || isa(D) || isa(D))); return islvalue ? Cl::CL_LValue : Cl::CL_PRValue; } /// ClassifyUnnamed - Return the classification of an expression yielding an /// unnamed value of the given type. This applies in particular to function /// calls and casts. static Cl::Kinds ClassifyUnnamed(ASTContext &Ctx, QualType T) { // In C, function calls are always rvalues. if (!Ctx.getLangOpts().CPlusPlus) return Cl::CL_PRValue; // C++ [expr.call]p10: A function call is an lvalue if the result type is an // lvalue reference type or an rvalue reference to function type, an xvalue // if the result type is an rvalue reference to object type, and a prvalue // otherwise. if (T->isLValueReferenceType()) return Cl::CL_LValue; const auto *RV = T->getAs(); if (!RV) // Could still be a class temporary, though. return ClassifyTemporary(T); return RV->getPointeeType()->isFunctionType() ? Cl::CL_LValue : Cl::CL_XValue; } static Cl::Kinds ClassifyMemberExpr(ASTContext &Ctx, const MemberExpr *E) { if (E->getType() == Ctx.UnknownAnyTy) return (isa(E->getMemberDecl()) ? Cl::CL_PRValue : Cl::CL_LValue); // Handle C first, it's easier. if (!Ctx.getLangOpts().CPlusPlus) { // C99 6.5.2.3p3 // For dot access, the expression is an lvalue if the first part is. For // arrow access, it always is an lvalue. if (E->isArrow()) return Cl::CL_LValue; // ObjC property accesses are not lvalues, but get special treatment. Expr *Base = E->getBase()->IgnoreParens(); if (isa(Base)) return Cl::CL_SubObjCPropertySetting; return ClassifyInternal(Ctx, Base); } NamedDecl *Member = E->getMemberDecl(); // C++ [expr.ref]p3: E1->E2 is converted to the equivalent form (*(E1)).E2. // C++ [expr.ref]p4: If E2 is declared to have type "reference to T", then // E1.E2 is an lvalue. if (const auto *Value = dyn_cast(Member)) if (Value->getType()->isReferenceType()) return Cl::CL_LValue; // Otherwise, one of the following rules applies. // -- If E2 is a static member [...] then E1.E2 is an lvalue. if (isa(Member) && Member->getDeclContext()->isRecord()) return Cl::CL_LValue; // -- If E2 is a non-static data member [...]. If E1 is an lvalue, then // E1.E2 is an lvalue; if E1 is an xvalue, then E1.E2 is an xvalue; // otherwise, it is a prvalue. if (isa(Member)) { // *E1 is an lvalue if (E->isArrow()) return Cl::CL_LValue; Expr *Base = E->getBase()->IgnoreParenImpCasts(); if (isa(Base)) return Cl::CL_SubObjCPropertySetting; return ClassifyInternal(Ctx, E->getBase()); } // -- If E2 is a [...] member function, [...] // -- If it refers to a static member function [...], then E1.E2 is an // lvalue; [...] // -- Otherwise [...] E1.E2 is a prvalue. if (const auto *Method = dyn_cast(Member)) return Method->isStatic() ? Cl::CL_LValue : Cl::CL_MemberFunction; // -- If E2 is a member enumerator [...], the expression E1.E2 is a prvalue. // So is everything else we haven't handled yet. return Cl::CL_PRValue; } static Cl::Kinds ClassifyBinaryOp(ASTContext &Ctx, const BinaryOperator *E) { assert(Ctx.getLangOpts().CPlusPlus && "This is only relevant for C++."); // C++ [expr.ass]p1: All [...] return an lvalue referring to the left operand. // Except we override this for writes to ObjC properties. if (E->isAssignmentOp()) return (E->getLHS()->getObjectKind() == OK_ObjCProperty ? Cl::CL_PRValue : Cl::CL_LValue); // C++ [expr.comma]p1: the result is of the same value category as its right // operand, [...]. if (E->getOpcode() == BO_Comma) return ClassifyInternal(Ctx, E->getRHS()); // C++ [expr.mptr.oper]p6: The result of a .* expression whose second operand // is a pointer to a data member is of the same value category as its first // operand. if (E->getOpcode() == BO_PtrMemD) return (E->getType()->isFunctionType() || E->hasPlaceholderType(BuiltinType::BoundMember)) ? Cl::CL_MemberFunction : ClassifyInternal(Ctx, E->getLHS()); // C++ [expr.mptr.oper]p6: The result of an ->* expression is an lvalue if its // second operand is a pointer to data member and a prvalue otherwise. if (E->getOpcode() == BO_PtrMemI) return (E->getType()->isFunctionType() || E->hasPlaceholderType(BuiltinType::BoundMember)) ? Cl::CL_MemberFunction : Cl::CL_LValue; // All other binary operations are prvalues. return Cl::CL_PRValue; } static Cl::Kinds ClassifyConditional(ASTContext &Ctx, const Expr *True, const Expr *False) { assert(Ctx.getLangOpts().CPlusPlus && "This is only relevant for C++."); // C++ [expr.cond]p2 // If either the second or the third operand has type (cv) void, // one of the following shall hold: if (True->getType()->isVoidType() || False->getType()->isVoidType()) { // The second or the third operand (but not both) is a (possibly // parenthesized) throw-expression; the result is of the [...] value // category of the other. bool TrueIsThrow = isa(True->IgnoreParenImpCasts()); bool FalseIsThrow = isa(False->IgnoreParenImpCasts()); if (const Expr *NonThrow = TrueIsThrow ? (FalseIsThrow ? nullptr : False) : (FalseIsThrow ? True : nullptr)) return ClassifyInternal(Ctx, NonThrow); // [Otherwise] the result [...] is a prvalue. return Cl::CL_PRValue; } // Note that at this point, we have already performed all conversions // according to [expr.cond]p3. // C++ [expr.cond]p4: If the second and third operands are glvalues of the // same value category [...], the result is of that [...] value category. // C++ [expr.cond]p5: Otherwise, the result is a prvalue. Cl::Kinds LCl = ClassifyInternal(Ctx, True), RCl = ClassifyInternal(Ctx, False); return LCl == RCl ? LCl : Cl::CL_PRValue; } static Cl::ModifiableType IsModifiable(ASTContext &Ctx, const Expr *E, Cl::Kinds Kind, SourceLocation &Loc) { // As a general rule, we only care about lvalues. But there are some rvalues // for which we want to generate special results. if (Kind == Cl::CL_PRValue) { // For the sake of better diagnostics, we want to specifically recognize // use of the GCC cast-as-lvalue extension. if (const auto *CE = dyn_cast(E->IgnoreParens())) { if (CE->getSubExpr()->IgnoreParenImpCasts()->isLValue()) { Loc = CE->getExprLoc(); return Cl::CM_LValueCast; } } } if (Kind != Cl::CL_LValue) return Cl::CM_RValue; // This is the lvalue case. // Functions are lvalues in C++, but not modifiable. (C++ [basic.lval]p6) if (Ctx.getLangOpts().CPlusPlus && E->getType()->isFunctionType()) return Cl::CM_Function; // Assignment to a property in ObjC is an implicit setter access. But a // setter might not exist. if (const auto *Expr = dyn_cast(E)) { if (Expr->isImplicitProperty() && Expr->getImplicitPropertySetter() == nullptr) return Cl::CM_NoSetterProperty; } CanQualType CT = Ctx.getCanonicalType(E->getType()); // Const stuff is obviously not modifiable. if (CT.isConstQualified()) return Cl::CM_ConstQualified; if (Ctx.getLangOpts().OpenCL && CT.getQualifiers().getAddressSpace() == LangAS::opencl_constant) return Cl::CM_ConstAddrSpace; // Arrays are not modifiable, only their elements are. if (CT->isArrayType()) return Cl::CM_ArrayType; // Incomplete types are not modifiable. if (CT->isIncompleteType()) return Cl::CM_IncompleteType; // Records with any const fields (recursively) are not modifiable. if (const RecordType *R = CT->getAs()) if (R->hasConstFields()) return Cl::CM_ConstQualifiedField; return Cl::CM_Modifiable; } Expr::LValueClassification Expr::ClassifyLValue(ASTContext &Ctx) const { Classification VC = Classify(Ctx); switch (VC.getKind()) { case Cl::CL_LValue: return LV_Valid; case Cl::CL_XValue: return LV_InvalidExpression; case Cl::CL_Function: return LV_NotObjectType; case Cl::CL_Void: return LV_InvalidExpression; case Cl::CL_AddressableVoid: return LV_IncompleteVoidType; case Cl::CL_DuplicateVectorComponents: return LV_DuplicateVectorComponents; case Cl::CL_MemberFunction: return LV_MemberFunction; case Cl::CL_SubObjCPropertySetting: return LV_SubObjCPropertySetting; case Cl::CL_ClassTemporary: return LV_ClassTemporary; case Cl::CL_ArrayTemporary: return LV_ArrayTemporary; case Cl::CL_ObjCMessageRValue: return LV_InvalidMessageExpression; case Cl::CL_PRValue: return LV_InvalidExpression; } llvm_unreachable("Unhandled kind"); } Expr::isModifiableLvalueResult Expr::isModifiableLvalue(ASTContext &Ctx, SourceLocation *Loc) const { SourceLocation dummy; Classification VC = ClassifyModifiable(Ctx, Loc ? *Loc : dummy); switch (VC.getKind()) { case Cl::CL_LValue: break; case Cl::CL_XValue: return MLV_InvalidExpression; case Cl::CL_Function: return MLV_NotObjectType; case Cl::CL_Void: return MLV_InvalidExpression; case Cl::CL_AddressableVoid: return MLV_IncompleteVoidType; case Cl::CL_DuplicateVectorComponents: return MLV_DuplicateVectorComponents; case Cl::CL_MemberFunction: return MLV_MemberFunction; case Cl::CL_SubObjCPropertySetting: return MLV_SubObjCPropertySetting; case Cl::CL_ClassTemporary: return MLV_ClassTemporary; case Cl::CL_ArrayTemporary: return MLV_ArrayTemporary; case Cl::CL_ObjCMessageRValue: return MLV_InvalidMessageExpression; case Cl::CL_PRValue: return VC.getModifiable() == Cl::CM_LValueCast ? MLV_LValueCast : MLV_InvalidExpression; } assert(VC.getKind() == Cl::CL_LValue && "Unhandled kind"); switch (VC.getModifiable()) { case Cl::CM_Untested: llvm_unreachable("Did not test modifiability"); case Cl::CM_Modifiable: return MLV_Valid; case Cl::CM_RValue: llvm_unreachable("CM_RValue and CL_LValue don't match"); case Cl::CM_Function: return MLV_NotObjectType; case Cl::CM_LValueCast: llvm_unreachable("CM_LValueCast and CL_LValue don't match"); case Cl::CM_NoSetterProperty: return MLV_NoSetterProperty; case Cl::CM_ConstQualified: return MLV_ConstQualified; case Cl::CM_ConstQualifiedField: return MLV_ConstQualifiedField; case Cl::CM_ConstAddrSpace: return MLV_ConstAddrSpace; case Cl::CM_ArrayType: return MLV_ArrayType; case Cl::CM_IncompleteType: return MLV_IncompleteType; } llvm_unreachable("Unhandled modifiable type"); }