forked from OSchip/llvm-project
704 lines
28 KiB
C++
704 lines
28 KiB
C++
//===--- ExprClassification.cpp - Expression AST Node Implementation ------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements Expr::classify.
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//
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//===----------------------------------------------------------------------===//
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#include "clang/AST/Expr.h"
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#include "clang/AST/ASTContext.h"
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#include "clang/AST/DeclCXX.h"
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#include "clang/AST/DeclObjC.h"
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#include "clang/AST/DeclTemplate.h"
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#include "clang/AST/ExprCXX.h"
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#include "clang/AST/ExprObjC.h"
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#include "llvm/Support/ErrorHandling.h"
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using namespace clang;
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typedef Expr::Classification Cl;
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static Cl::Kinds ClassifyInternal(ASTContext &Ctx, const Expr *E);
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static Cl::Kinds ClassifyDecl(ASTContext &Ctx, const Decl *D);
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static Cl::Kinds ClassifyUnnamed(ASTContext &Ctx, QualType T);
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static Cl::Kinds ClassifyMemberExpr(ASTContext &Ctx, const MemberExpr *E);
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static Cl::Kinds ClassifyBinaryOp(ASTContext &Ctx, const BinaryOperator *E);
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static Cl::Kinds ClassifyConditional(ASTContext &Ctx,
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const Expr *trueExpr,
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const Expr *falseExpr);
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static Cl::ModifiableType IsModifiable(ASTContext &Ctx, const Expr *E,
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Cl::Kinds Kind, SourceLocation &Loc);
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Cl Expr::ClassifyImpl(ASTContext &Ctx, SourceLocation *Loc) const {
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assert(!TR->isReferenceType() && "Expressions can't have reference type.");
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Cl::Kinds kind = ClassifyInternal(Ctx, this);
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// C99 6.3.2.1: An lvalue is an expression with an object type or an
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// incomplete type other than void.
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if (!Ctx.getLangOpts().CPlusPlus) {
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// Thus, no functions.
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if (TR->isFunctionType() || TR == Ctx.OverloadTy)
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kind = Cl::CL_Function;
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// No void either, but qualified void is OK because it is "other than void".
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// Void "lvalues" are classified as addressable void values, which are void
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// expressions whose address can be taken.
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else if (TR->isVoidType() && !TR.hasQualifiers())
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kind = (kind == Cl::CL_LValue ? Cl::CL_AddressableVoid : Cl::CL_Void);
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}
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// Enable this assertion for testing.
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switch (kind) {
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case Cl::CL_LValue: assert(getValueKind() == VK_LValue); break;
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case Cl::CL_XValue: assert(getValueKind() == VK_XValue); break;
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case Cl::CL_Function:
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case Cl::CL_Void:
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case Cl::CL_AddressableVoid:
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case Cl::CL_DuplicateVectorComponents:
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case Cl::CL_MemberFunction:
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case Cl::CL_SubObjCPropertySetting:
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case Cl::CL_ClassTemporary:
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case Cl::CL_ArrayTemporary:
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case Cl::CL_ObjCMessageRValue:
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case Cl::CL_PRValue: assert(getValueKind() == VK_RValue); break;
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}
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Cl::ModifiableType modifiable = Cl::CM_Untested;
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if (Loc)
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modifiable = IsModifiable(Ctx, this, kind, *Loc);
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return Classification(kind, modifiable);
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}
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/// Classify an expression which creates a temporary, based on its type.
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static Cl::Kinds ClassifyTemporary(QualType T) {
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if (T->isRecordType())
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return Cl::CL_ClassTemporary;
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if (T->isArrayType())
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return Cl::CL_ArrayTemporary;
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// No special classification: these don't behave differently from normal
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// prvalues.
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return Cl::CL_PRValue;
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}
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static Cl::Kinds ClassifyExprValueKind(const LangOptions &Lang,
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const Expr *E,
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ExprValueKind Kind) {
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switch (Kind) {
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case VK_RValue:
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return Lang.CPlusPlus ? ClassifyTemporary(E->getType()) : Cl::CL_PRValue;
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case VK_LValue:
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return Cl::CL_LValue;
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case VK_XValue:
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return Cl::CL_XValue;
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}
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llvm_unreachable("Invalid value category of implicit cast.");
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}
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static Cl::Kinds ClassifyInternal(ASTContext &Ctx, const Expr *E) {
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// This function takes the first stab at classifying expressions.
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const LangOptions &Lang = Ctx.getLangOpts();
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switch (E->getStmtClass()) {
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case Stmt::NoStmtClass:
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#define ABSTRACT_STMT(Kind)
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#define STMT(Kind, Base) case Expr::Kind##Class:
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#define EXPR(Kind, Base)
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#include "clang/AST/StmtNodes.inc"
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llvm_unreachable("cannot classify a statement");
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// First come the expressions that are always lvalues, unconditionally.
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case Expr::ObjCIsaExprClass:
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// C++ [expr.prim.general]p1: A string literal is an lvalue.
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case Expr::StringLiteralClass:
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// @encode is equivalent to its string
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case Expr::ObjCEncodeExprClass:
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// __func__ and friends are too.
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case Expr::PredefinedExprClass:
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// Property references are lvalues
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case Expr::ObjCSubscriptRefExprClass:
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case Expr::ObjCPropertyRefExprClass:
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// C++ [expr.typeid]p1: The result of a typeid expression is an lvalue of...
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case Expr::CXXTypeidExprClass:
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// Unresolved lookups and uncorrected typos get classified as lvalues.
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// FIXME: Is this wise? Should they get their own kind?
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case Expr::UnresolvedLookupExprClass:
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case Expr::UnresolvedMemberExprClass:
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case Expr::TypoExprClass:
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case Expr::DependentCoawaitExprClass:
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case Expr::CXXDependentScopeMemberExprClass:
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case Expr::DependentScopeDeclRefExprClass:
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// ObjC instance variables are lvalues
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// FIXME: ObjC++0x might have different rules
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case Expr::ObjCIvarRefExprClass:
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case Expr::FunctionParmPackExprClass:
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case Expr::MSPropertyRefExprClass:
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case Expr::MSPropertySubscriptExprClass:
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case Expr::OMPArraySectionExprClass:
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return Cl::CL_LValue;
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// C99 6.5.2.5p5 says that compound literals are lvalues.
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// In C++, they're prvalue temporaries, except for file-scope arrays.
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case Expr::CompoundLiteralExprClass:
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return !E->isLValue() ? ClassifyTemporary(E->getType()) : Cl::CL_LValue;
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// Expressions that are prvalues.
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case Expr::CXXBoolLiteralExprClass:
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case Expr::CXXPseudoDestructorExprClass:
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case Expr::UnaryExprOrTypeTraitExprClass:
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case Expr::CXXNewExprClass:
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case Expr::CXXThisExprClass:
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case Expr::CXXNullPtrLiteralExprClass:
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case Expr::ImaginaryLiteralClass:
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case Expr::GNUNullExprClass:
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case Expr::OffsetOfExprClass:
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case Expr::CXXThrowExprClass:
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case Expr::ShuffleVectorExprClass:
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case Expr::ConvertVectorExprClass:
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case Expr::IntegerLiteralClass:
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case Expr::CharacterLiteralClass:
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case Expr::AddrLabelExprClass:
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case Expr::CXXDeleteExprClass:
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case Expr::ImplicitValueInitExprClass:
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case Expr::BlockExprClass:
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case Expr::FloatingLiteralClass:
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case Expr::CXXNoexceptExprClass:
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case Expr::CXXScalarValueInitExprClass:
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case Expr::TypeTraitExprClass:
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case Expr::ArrayTypeTraitExprClass:
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case Expr::ExpressionTraitExprClass:
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case Expr::ObjCSelectorExprClass:
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case Expr::ObjCProtocolExprClass:
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case Expr::ObjCStringLiteralClass:
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case Expr::ObjCBoxedExprClass:
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case Expr::ObjCArrayLiteralClass:
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case Expr::ObjCDictionaryLiteralClass:
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case Expr::ObjCBoolLiteralExprClass:
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case Expr::ObjCAvailabilityCheckExprClass:
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case Expr::ParenListExprClass:
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case Expr::SizeOfPackExprClass:
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case Expr::SubstNonTypeTemplateParmPackExprClass:
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case Expr::AsTypeExprClass:
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case Expr::ObjCIndirectCopyRestoreExprClass:
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case Expr::AtomicExprClass:
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case Expr::CXXFoldExprClass:
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case Expr::ArrayInitLoopExprClass:
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case Expr::ArrayInitIndexExprClass:
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case Expr::NoInitExprClass:
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case Expr::DesignatedInitUpdateExprClass:
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return Cl::CL_PRValue;
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// Next come the complicated cases.
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case Expr::SubstNonTypeTemplateParmExprClass:
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return ClassifyInternal(Ctx,
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cast<SubstNonTypeTemplateParmExpr>(E)->getReplacement());
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// C, C++98 [expr.sub]p1: The result is an lvalue of type "T".
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// C++11 (DR1213): in the case of an array operand, the result is an lvalue
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// if that operand is an lvalue and an xvalue otherwise.
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// Subscripting vector types is more like member access.
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case Expr::ArraySubscriptExprClass:
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if (cast<ArraySubscriptExpr>(E)->getBase()->getType()->isVectorType())
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return ClassifyInternal(Ctx, cast<ArraySubscriptExpr>(E)->getBase());
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if (Lang.CPlusPlus11) {
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// Step over the array-to-pointer decay if present, but not over the
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// temporary materialization.
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auto *Base = cast<ArraySubscriptExpr>(E)->getBase()->IgnoreImpCasts();
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if (Base->getType()->isArrayType())
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return ClassifyInternal(Ctx, Base);
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}
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return Cl::CL_LValue;
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// C++ [expr.prim.general]p3: The result is an lvalue if the entity is a
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// function or variable and a prvalue otherwise.
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case Expr::DeclRefExprClass:
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if (E->getType() == Ctx.UnknownAnyTy)
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return isa<FunctionDecl>(cast<DeclRefExpr>(E)->getDecl())
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? Cl::CL_PRValue : Cl::CL_LValue;
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return ClassifyDecl(Ctx, cast<DeclRefExpr>(E)->getDecl());
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// Member access is complex.
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case Expr::MemberExprClass:
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return ClassifyMemberExpr(Ctx, cast<MemberExpr>(E));
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case Expr::UnaryOperatorClass:
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switch (cast<UnaryOperator>(E)->getOpcode()) {
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// C++ [expr.unary.op]p1: The unary * operator performs indirection:
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// [...] the result is an lvalue referring to the object or function
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// to which the expression points.
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case UO_Deref:
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return Cl::CL_LValue;
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// GNU extensions, simply look through them.
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case UO_Extension:
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return ClassifyInternal(Ctx, cast<UnaryOperator>(E)->getSubExpr());
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// Treat _Real and _Imag basically as if they were member
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// expressions: l-value only if the operand is a true l-value.
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case UO_Real:
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case UO_Imag: {
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const Expr *Op = cast<UnaryOperator>(E)->getSubExpr()->IgnoreParens();
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Cl::Kinds K = ClassifyInternal(Ctx, Op);
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if (K != Cl::CL_LValue) return K;
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if (isa<ObjCPropertyRefExpr>(Op))
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return Cl::CL_SubObjCPropertySetting;
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return Cl::CL_LValue;
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}
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// C++ [expr.pre.incr]p1: The result is the updated operand; it is an
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// lvalue, [...]
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// Not so in C.
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case UO_PreInc:
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case UO_PreDec:
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return Lang.CPlusPlus ? Cl::CL_LValue : Cl::CL_PRValue;
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default:
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return Cl::CL_PRValue;
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}
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case Expr::OpaqueValueExprClass:
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return ClassifyExprValueKind(Lang, E, E->getValueKind());
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// Pseudo-object expressions can produce l-values with reference magic.
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case Expr::PseudoObjectExprClass:
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return ClassifyExprValueKind(Lang, E,
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cast<PseudoObjectExpr>(E)->getValueKind());
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// Implicit casts are lvalues if they're lvalue casts. Other than that, we
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// only specifically record class temporaries.
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case Expr::ImplicitCastExprClass:
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return ClassifyExprValueKind(Lang, E, E->getValueKind());
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// C++ [expr.prim.general]p4: The presence of parentheses does not affect
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// whether the expression is an lvalue.
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case Expr::ParenExprClass:
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return ClassifyInternal(Ctx, cast<ParenExpr>(E)->getSubExpr());
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// C11 6.5.1.1p4: [A generic selection] is an lvalue, a function designator,
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// or a void expression if its result expression is, respectively, an
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// lvalue, a function designator, or a void expression.
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case Expr::GenericSelectionExprClass:
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if (cast<GenericSelectionExpr>(E)->isResultDependent())
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return Cl::CL_PRValue;
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return ClassifyInternal(Ctx,cast<GenericSelectionExpr>(E)->getResultExpr());
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case Expr::BinaryOperatorClass:
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case Expr::CompoundAssignOperatorClass:
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// C doesn't have any binary expressions that are lvalues.
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if (Lang.CPlusPlus)
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return ClassifyBinaryOp(Ctx, cast<BinaryOperator>(E));
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return Cl::CL_PRValue;
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case Expr::CallExprClass:
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case Expr::CXXOperatorCallExprClass:
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case Expr::CXXMemberCallExprClass:
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case Expr::UserDefinedLiteralClass:
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case Expr::CUDAKernelCallExprClass:
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return ClassifyUnnamed(Ctx, cast<CallExpr>(E)->getCallReturnType(Ctx));
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// __builtin_choose_expr is equivalent to the chosen expression.
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case Expr::ChooseExprClass:
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return ClassifyInternal(Ctx, cast<ChooseExpr>(E)->getChosenSubExpr());
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// Extended vector element access is an lvalue unless there are duplicates
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// in the shuffle expression.
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case Expr::ExtVectorElementExprClass:
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if (cast<ExtVectorElementExpr>(E)->containsDuplicateElements())
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return Cl::CL_DuplicateVectorComponents;
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if (cast<ExtVectorElementExpr>(E)->isArrow())
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return Cl::CL_LValue;
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return ClassifyInternal(Ctx, cast<ExtVectorElementExpr>(E)->getBase());
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// Simply look at the actual default argument.
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case Expr::CXXDefaultArgExprClass:
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return ClassifyInternal(Ctx, cast<CXXDefaultArgExpr>(E)->getExpr());
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// Same idea for default initializers.
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case Expr::CXXDefaultInitExprClass:
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return ClassifyInternal(Ctx, cast<CXXDefaultInitExpr>(E)->getExpr());
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// Same idea for temporary binding.
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case Expr::CXXBindTemporaryExprClass:
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return ClassifyInternal(Ctx, cast<CXXBindTemporaryExpr>(E)->getSubExpr());
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// And the cleanups guard.
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case Expr::ExprWithCleanupsClass:
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return ClassifyInternal(Ctx, cast<ExprWithCleanups>(E)->getSubExpr());
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// Casts depend completely on the target type. All casts work the same.
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case Expr::CStyleCastExprClass:
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case Expr::CXXFunctionalCastExprClass:
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case Expr::CXXStaticCastExprClass:
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case Expr::CXXDynamicCastExprClass:
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case Expr::CXXReinterpretCastExprClass:
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case Expr::CXXConstCastExprClass:
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case Expr::ObjCBridgedCastExprClass:
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// Only in C++ can casts be interesting at all.
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if (!Lang.CPlusPlus) return Cl::CL_PRValue;
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return ClassifyUnnamed(Ctx, cast<ExplicitCastExpr>(E)->getTypeAsWritten());
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case Expr::CXXUnresolvedConstructExprClass:
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return ClassifyUnnamed(Ctx,
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cast<CXXUnresolvedConstructExpr>(E)->getTypeAsWritten());
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case Expr::BinaryConditionalOperatorClass: {
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if (!Lang.CPlusPlus) return Cl::CL_PRValue;
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const BinaryConditionalOperator *co = cast<BinaryConditionalOperator>(E);
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return ClassifyConditional(Ctx, co->getTrueExpr(), co->getFalseExpr());
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}
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case Expr::ConditionalOperatorClass: {
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// Once again, only C++ is interesting.
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if (!Lang.CPlusPlus) return Cl::CL_PRValue;
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const ConditionalOperator *co = cast<ConditionalOperator>(E);
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return ClassifyConditional(Ctx, co->getTrueExpr(), co->getFalseExpr());
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}
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// ObjC message sends are effectively function calls, if the target function
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// is known.
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case Expr::ObjCMessageExprClass:
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if (const ObjCMethodDecl *Method =
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cast<ObjCMessageExpr>(E)->getMethodDecl()) {
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Cl::Kinds kind = ClassifyUnnamed(Ctx, Method->getReturnType());
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return (kind == Cl::CL_PRValue) ? Cl::CL_ObjCMessageRValue : kind;
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}
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return Cl::CL_PRValue;
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// Some C++ expressions are always class temporaries.
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case Expr::CXXConstructExprClass:
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case Expr::CXXInheritedCtorInitExprClass:
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case Expr::CXXTemporaryObjectExprClass:
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case Expr::LambdaExprClass:
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case Expr::CXXStdInitializerListExprClass:
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return Cl::CL_ClassTemporary;
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case Expr::VAArgExprClass:
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return ClassifyUnnamed(Ctx, E->getType());
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case Expr::DesignatedInitExprClass:
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return ClassifyInternal(Ctx, cast<DesignatedInitExpr>(E)->getInit());
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case Expr::StmtExprClass: {
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const CompoundStmt *S = cast<StmtExpr>(E)->getSubStmt();
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if (const Expr *LastExpr = dyn_cast_or_null<Expr>(S->body_back()))
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return ClassifyUnnamed(Ctx, LastExpr->getType());
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return Cl::CL_PRValue;
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}
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case Expr::CXXUuidofExprClass:
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return Cl::CL_LValue;
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case Expr::PackExpansionExprClass:
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return ClassifyInternal(Ctx, cast<PackExpansionExpr>(E)->getPattern());
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case Expr::MaterializeTemporaryExprClass:
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return cast<MaterializeTemporaryExpr>(E)->isBoundToLvalueReference()
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? Cl::CL_LValue
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: Cl::CL_XValue;
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case Expr::InitListExprClass:
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// An init list can be an lvalue if it is bound to a reference and
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// contains only one element. In that case, we look at that element
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// for an exact classification. Init list creation takes care of the
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// value kind for us, so we only need to fine-tune.
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if (E->isRValue())
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return ClassifyExprValueKind(Lang, E, E->getValueKind());
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assert(cast<InitListExpr>(E)->getNumInits() == 1 &&
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"Only 1-element init lists can be glvalues.");
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return ClassifyInternal(Ctx, cast<InitListExpr>(E)->getInit(0));
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case Expr::CoawaitExprClass:
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case Expr::CoyieldExprClass:
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return ClassifyInternal(Ctx, cast<CoroutineSuspendExpr>(E)->getResumeExpr());
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}
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llvm_unreachable("unhandled expression kind in classification");
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}
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/// ClassifyDecl - Return the classification of an expression referencing the
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/// given declaration.
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static Cl::Kinds ClassifyDecl(ASTContext &Ctx, const Decl *D) {
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// C++ [expr.prim.general]p6: The result is an lvalue if the entity is a
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// function, variable, or data member and a prvalue otherwise.
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// In C, functions are not lvalues.
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// In addition, NonTypeTemplateParmDecl derives from VarDecl but isn't an
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// lvalue unless it's a reference type (C++ [temp.param]p6), so we need to
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// special-case this.
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if (isa<CXXMethodDecl>(D) && cast<CXXMethodDecl>(D)->isInstance())
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return Cl::CL_MemberFunction;
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bool islvalue;
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if (const NonTypeTemplateParmDecl *NTTParm =
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dyn_cast<NonTypeTemplateParmDecl>(D))
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islvalue = NTTParm->getType()->isReferenceType();
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else
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islvalue = isa<VarDecl>(D) || isa<FieldDecl>(D) ||
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isa<IndirectFieldDecl>(D) ||
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isa<BindingDecl>(D) ||
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(Ctx.getLangOpts().CPlusPlus &&
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(isa<FunctionDecl>(D) || isa<MSPropertyDecl>(D) ||
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isa<FunctionTemplateDecl>(D)));
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return islvalue ? Cl::CL_LValue : Cl::CL_PRValue;
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}
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/// 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 RValueReferenceType *RV = T->getAs<RValueReferenceType>();
|
|
if (!RV) // Could still be a class temporary, though.
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|
return ClassifyTemporary(T);
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|
|
|
return RV->getPointeeType()->isFunctionType() ? Cl::CL_LValue : Cl::CL_XValue;
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|
}
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|
|
|
static Cl::Kinds ClassifyMemberExpr(ASTContext &Ctx, const MemberExpr *E) {
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|
if (E->getType() == Ctx.UnknownAnyTy)
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|
return (isa<FunctionDecl>(E->getMemberDecl())
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|
? Cl::CL_PRValue : Cl::CL_LValue);
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|
|
|
// Handle C first, it's easier.
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|
if (!Ctx.getLangOpts().CPlusPlus) {
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|
// C99 6.5.2.3p3
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|
// For dot access, the expression is an lvalue if the first part is. For
|
|
// arrow access, it always is an lvalue.
|
|
if (E->isArrow())
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|
return Cl::CL_LValue;
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|
// ObjC property accesses are not lvalues, but get special treatment.
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|
Expr *Base = E->getBase()->IgnoreParens();
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|
if (isa<ObjCPropertyRefExpr>(Base))
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|
return Cl::CL_SubObjCPropertySetting;
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|
return ClassifyInternal(Ctx, Base);
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|
}
|
|
|
|
NamedDecl *Member = E->getMemberDecl();
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|
// C++ [expr.ref]p3: E1->E2 is converted to the equivalent form (*(E1)).E2.
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|
// C++ [expr.ref]p4: If E2 is declared to have type "reference to T", then
|
|
// E1.E2 is an lvalue.
|
|
if (ValueDecl *Value = dyn_cast<ValueDecl>(Member))
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|
if (Value->getType()->isReferenceType())
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|
return Cl::CL_LValue;
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|
|
|
// Otherwise, one of the following rules applies.
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|
// -- If E2 is a static member [...] then E1.E2 is an lvalue.
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|
if (isa<VarDecl>(Member) && Member->getDeclContext()->isRecord())
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|
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<FieldDecl>(Member)) {
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|
// *E1 is an lvalue
|
|
if (E->isArrow())
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|
return Cl::CL_LValue;
|
|
Expr *Base = E->getBase()->IgnoreParenImpCasts();
|
|
if (isa<ObjCPropertyRefExpr>(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 (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(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<CXXThrowExpr>(True->IgnoreParenImpCasts());
|
|
bool FalseIsThrow = isa<CXXThrowExpr>(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 ExplicitCastExpr *CE =
|
|
dyn_cast<ExplicitCastExpr>(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 ObjCPropertyRefExpr *Expr = dyn_cast<ObjCPropertyRefExpr>(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<RecordType>())
|
|
if (R->hasConstFields())
|
|
return Cl::CM_ConstQualified;
|
|
|
|
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_ConstAddrSpace: return MLV_ConstAddrSpace;
|
|
case Cl::CM_ArrayType: return MLV_ArrayType;
|
|
case Cl::CM_IncompleteType: return MLV_IncompleteType;
|
|
}
|
|
llvm_unreachable("Unhandled modifiable type");
|
|
}
|