1 //===--- ExprClassification.cpp - Expression AST Node Implementation ------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements Expr::classify.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Support/ErrorHandling.h"
15 #include "clang/AST/Expr.h"
16 #include "clang/AST/ExprCXX.h"
17 #include "clang/AST/ExprObjC.h"
18 #include "clang/AST/ASTContext.h"
19 #include "clang/AST/DeclObjC.h"
20 #include "clang/AST/DeclCXX.h"
21 #include "clang/AST/DeclTemplate.h"
22 using namespace clang;
24 typedef Expr::Classification Cl;
26 static Cl::Kinds ClassifyInternal(ASTContext &Ctx, const Expr *E);
27 static Cl::Kinds ClassifyDecl(ASTContext &Ctx, const Decl *D);
28 static Cl::Kinds ClassifyUnnamed(ASTContext &Ctx, QualType T);
29 static Cl::Kinds ClassifyMemberExpr(ASTContext &Ctx, const MemberExpr *E);
30 static Cl::Kinds ClassifyBinaryOp(ASTContext &Ctx, const BinaryOperator *E);
31 static Cl::Kinds ClassifyConditional(ASTContext &Ctx,
33 const Expr *falseExpr);
34 static Cl::ModifiableType IsModifiable(ASTContext &Ctx, const Expr *E,
35 Cl::Kinds Kind, SourceLocation &Loc);
37 static Cl::Kinds ClassifyExprValueKind(const LangOptions &Lang,
42 return Lang.CPlusPlus && E->getType()->isRecordType() ?
43 Cl::CL_ClassTemporary : Cl::CL_PRValue;
49 llvm_unreachable("Invalid value category of implicit cast.");
50 return Cl::CL_PRValue;
53 Cl Expr::ClassifyImpl(ASTContext &Ctx, SourceLocation *Loc) const {
54 assert(!TR->isReferenceType() && "Expressions can't have reference type.");
56 Cl::Kinds kind = ClassifyInternal(Ctx, this);
57 // C99 6.3.2.1: An lvalue is an expression with an object type or an
58 // incomplete type other than void.
59 if (!Ctx.getLangOptions().CPlusPlus) {
60 // Thus, no functions.
61 if (TR->isFunctionType() || TR == Ctx.OverloadTy)
62 kind = Cl::CL_Function;
63 // No void either, but qualified void is OK because it is "other than void".
64 // Void "lvalues" are classified as addressable void values, which are void
65 // expressions whose address can be taken.
66 else if (TR->isVoidType() && !TR.hasQualifiers())
67 kind = (kind == Cl::CL_LValue ? Cl::CL_AddressableVoid : Cl::CL_Void);
70 // Enable this assertion for testing.
72 case Cl::CL_LValue: assert(getValueKind() == VK_LValue); break;
73 case Cl::CL_XValue: assert(getValueKind() == VK_XValue); break;
76 case Cl::CL_AddressableVoid:
77 case Cl::CL_DuplicateVectorComponents:
78 case Cl::CL_MemberFunction:
79 case Cl::CL_SubObjCPropertySetting:
80 case Cl::CL_ClassTemporary:
81 case Cl::CL_ObjCMessageRValue:
82 case Cl::CL_PRValue: assert(getValueKind() == VK_RValue); break;
85 Cl::ModifiableType modifiable = Cl::CM_Untested;
87 modifiable = IsModifiable(Ctx, this, kind, *Loc);
88 return Classification(kind, modifiable);
91 static Cl::Kinds ClassifyInternal(ASTContext &Ctx, const Expr *E) {
92 // This function takes the first stab at classifying expressions.
93 const LangOptions &Lang = Ctx.getLangOptions();
95 switch (E->getStmtClass()) {
96 // First come the expressions that are always lvalues, unconditionally.
97 case Stmt::NoStmtClass:
98 #define ABSTRACT_STMT(Kind)
99 #define STMT(Kind, Base) case Expr::Kind##Class:
100 #define EXPR(Kind, Base)
101 #include "clang/AST/StmtNodes.inc"
102 llvm_unreachable("cannot classify a statement");
104 case Expr::ObjCIsaExprClass:
105 // C++ [expr.prim.general]p1: A string literal is an lvalue.
106 case Expr::StringLiteralClass:
107 // @encode is equivalent to its string
108 case Expr::ObjCEncodeExprClass:
109 // __func__ and friends are too.
110 case Expr::PredefinedExprClass:
111 // Property references are lvalues
112 case Expr::ObjCPropertyRefExprClass:
113 // C++ [expr.typeid]p1: The result of a typeid expression is an lvalue of...
114 case Expr::CXXTypeidExprClass:
115 // Unresolved lookups get classified as lvalues.
116 // FIXME: Is this wise? Should they get their own kind?
117 case Expr::UnresolvedLookupExprClass:
118 case Expr::UnresolvedMemberExprClass:
119 case Expr::CXXDependentScopeMemberExprClass:
120 case Expr::DependentScopeDeclRefExprClass:
121 // ObjC instance variables are lvalues
122 // FIXME: ObjC++0x might have different rules
123 case Expr::ObjCIvarRefExprClass:
124 return Cl::CL_LValue;
125 // C99 6.5.2.5p5 says that compound literals are lvalues.
126 // In C++, they're class temporaries.
127 case Expr::CompoundLiteralExprClass:
128 return Ctx.getLangOptions().CPlusPlus? Cl::CL_ClassTemporary
131 // Expressions that are prvalues.
132 case Expr::CXXBoolLiteralExprClass:
133 case Expr::CXXPseudoDestructorExprClass:
134 case Expr::UnaryExprOrTypeTraitExprClass:
135 case Expr::CXXNewExprClass:
136 case Expr::CXXThisExprClass:
137 case Expr::CXXNullPtrLiteralExprClass:
138 case Expr::ImaginaryLiteralClass:
139 case Expr::GNUNullExprClass:
140 case Expr::OffsetOfExprClass:
141 case Expr::CXXThrowExprClass:
142 case Expr::ShuffleVectorExprClass:
143 case Expr::IntegerLiteralClass:
144 case Expr::CharacterLiteralClass:
145 case Expr::AddrLabelExprClass:
146 case Expr::CXXDeleteExprClass:
147 case Expr::ImplicitValueInitExprClass:
148 case Expr::BlockExprClass:
149 case Expr::FloatingLiteralClass:
150 case Expr::CXXNoexceptExprClass:
151 case Expr::CXXScalarValueInitExprClass:
152 case Expr::UnaryTypeTraitExprClass:
153 case Expr::BinaryTypeTraitExprClass:
154 case Expr::ArrayTypeTraitExprClass:
155 case Expr::ExpressionTraitExprClass:
156 case Expr::ObjCSelectorExprClass:
157 case Expr::ObjCProtocolExprClass:
158 case Expr::ObjCStringLiteralClass:
159 case Expr::ParenListExprClass:
160 case Expr::InitListExprClass:
161 case Expr::SizeOfPackExprClass:
162 case Expr::SubstNonTypeTemplateParmPackExprClass:
163 case Expr::AsTypeExprClass:
164 case Expr::ObjCIndirectCopyRestoreExprClass:
165 case Expr::AtomicExprClass:
166 return Cl::CL_PRValue;
168 // Next come the complicated cases.
169 case Expr::SubstNonTypeTemplateParmExprClass:
170 return ClassifyInternal(Ctx,
171 cast<SubstNonTypeTemplateParmExpr>(E)->getReplacement());
173 // C++ [expr.sub]p1: The result is an lvalue of type "T".
174 // However, subscripting vector types is more like member access.
175 case Expr::ArraySubscriptExprClass:
176 if (cast<ArraySubscriptExpr>(E)->getBase()->getType()->isVectorType())
177 return ClassifyInternal(Ctx, cast<ArraySubscriptExpr>(E)->getBase());
178 return Cl::CL_LValue;
180 // C++ [expr.prim.general]p3: The result is an lvalue if the entity is a
181 // function or variable and a prvalue otherwise.
182 case Expr::DeclRefExprClass:
183 if (E->getType() == Ctx.UnknownAnyTy)
184 return isa<FunctionDecl>(cast<DeclRefExpr>(E)->getDecl())
185 ? Cl::CL_PRValue : Cl::CL_LValue;
186 return ClassifyDecl(Ctx, cast<DeclRefExpr>(E)->getDecl());
187 // We deal with names referenced from blocks the same way.
188 case Expr::BlockDeclRefExprClass:
189 return ClassifyDecl(Ctx, cast<BlockDeclRefExpr>(E)->getDecl());
191 // Member access is complex.
192 case Expr::MemberExprClass:
193 return ClassifyMemberExpr(Ctx, cast<MemberExpr>(E));
195 case Expr::UnaryOperatorClass:
196 switch (cast<UnaryOperator>(E)->getOpcode()) {
197 // C++ [expr.unary.op]p1: The unary * operator performs indirection:
198 // [...] the result is an lvalue referring to the object or function
199 // to which the expression points.
201 return Cl::CL_LValue;
203 // GNU extensions, simply look through them.
205 return ClassifyInternal(Ctx, cast<UnaryOperator>(E)->getSubExpr());
207 // Treat _Real and _Imag basically as if they were member
208 // expressions: l-value only if the operand is a true l-value.
211 const Expr *Op = cast<UnaryOperator>(E)->getSubExpr()->IgnoreParens();
212 Cl::Kinds K = ClassifyInternal(Ctx, Op);
213 if (K != Cl::CL_LValue) return K;
215 if (isa<ObjCPropertyRefExpr>(Op))
216 return Cl::CL_SubObjCPropertySetting;
217 return Cl::CL_LValue;
220 // C++ [expr.pre.incr]p1: The result is the updated operand; it is an
225 return Lang.CPlusPlus ? Cl::CL_LValue : Cl::CL_PRValue;
228 return Cl::CL_PRValue;
231 case Expr::OpaqueValueExprClass:
232 return ClassifyExprValueKind(Lang, E,
233 cast<OpaqueValueExpr>(E)->getValueKind());
235 // Implicit casts are lvalues if they're lvalue casts. Other than that, we
236 // only specifically record class temporaries.
237 case Expr::ImplicitCastExprClass:
238 return ClassifyExprValueKind(Lang, E,
239 cast<ImplicitCastExpr>(E)->getValueKind());
241 // C++ [expr.prim.general]p4: The presence of parentheses does not affect
242 // whether the expression is an lvalue.
243 case Expr::ParenExprClass:
244 return ClassifyInternal(Ctx, cast<ParenExpr>(E)->getSubExpr());
246 // C1X 6.5.1.1p4: [A generic selection] is an lvalue, a function designator,
247 // or a void expression if its result expression is, respectively, an
248 // lvalue, a function designator, or a void expression.
249 case Expr::GenericSelectionExprClass:
250 if (cast<GenericSelectionExpr>(E)->isResultDependent())
251 return Cl::CL_PRValue;
252 return ClassifyInternal(Ctx,cast<GenericSelectionExpr>(E)->getResultExpr());
254 case Expr::BinaryOperatorClass:
255 case Expr::CompoundAssignOperatorClass:
256 // C doesn't have any binary expressions that are lvalues.
258 return ClassifyBinaryOp(Ctx, cast<BinaryOperator>(E));
259 return Cl::CL_PRValue;
261 case Expr::CallExprClass:
262 case Expr::CXXOperatorCallExprClass:
263 case Expr::CXXMemberCallExprClass:
264 case Expr::CUDAKernelCallExprClass:
265 return ClassifyUnnamed(Ctx, cast<CallExpr>(E)->getCallReturnType());
267 // __builtin_choose_expr is equivalent to the chosen expression.
268 case Expr::ChooseExprClass:
269 return ClassifyInternal(Ctx, cast<ChooseExpr>(E)->getChosenSubExpr(Ctx));
271 // Extended vector element access is an lvalue unless there are duplicates
272 // in the shuffle expression.
273 case Expr::ExtVectorElementExprClass:
274 return cast<ExtVectorElementExpr>(E)->containsDuplicateElements() ?
275 Cl::CL_DuplicateVectorComponents : Cl::CL_LValue;
277 // Simply look at the actual default argument.
278 case Expr::CXXDefaultArgExprClass:
279 return ClassifyInternal(Ctx, cast<CXXDefaultArgExpr>(E)->getExpr());
281 // Same idea for temporary binding.
282 case Expr::CXXBindTemporaryExprClass:
283 return ClassifyInternal(Ctx, cast<CXXBindTemporaryExpr>(E)->getSubExpr());
285 // And the cleanups guard.
286 case Expr::ExprWithCleanupsClass:
287 return ClassifyInternal(Ctx, cast<ExprWithCleanups>(E)->getSubExpr());
289 // Casts depend completely on the target type. All casts work the same.
290 case Expr::CStyleCastExprClass:
291 case Expr::CXXFunctionalCastExprClass:
292 case Expr::CXXStaticCastExprClass:
293 case Expr::CXXDynamicCastExprClass:
294 case Expr::CXXReinterpretCastExprClass:
295 case Expr::CXXConstCastExprClass:
296 case Expr::ObjCBridgedCastExprClass:
297 // Only in C++ can casts be interesting at all.
298 if (!Lang.CPlusPlus) return Cl::CL_PRValue;
299 return ClassifyUnnamed(Ctx, cast<ExplicitCastExpr>(E)->getTypeAsWritten());
301 case Expr::CXXUnresolvedConstructExprClass:
302 return ClassifyUnnamed(Ctx,
303 cast<CXXUnresolvedConstructExpr>(E)->getTypeAsWritten());
305 case Expr::BinaryConditionalOperatorClass: {
306 if (!Lang.CPlusPlus) return Cl::CL_PRValue;
307 const BinaryConditionalOperator *co = cast<BinaryConditionalOperator>(E);
308 return ClassifyConditional(Ctx, co->getTrueExpr(), co->getFalseExpr());
311 case Expr::ConditionalOperatorClass: {
312 // Once again, only C++ is interesting.
313 if (!Lang.CPlusPlus) return Cl::CL_PRValue;
314 const ConditionalOperator *co = cast<ConditionalOperator>(E);
315 return ClassifyConditional(Ctx, co->getTrueExpr(), co->getFalseExpr());
318 // ObjC message sends are effectively function calls, if the target function
320 case Expr::ObjCMessageExprClass:
321 if (const ObjCMethodDecl *Method =
322 cast<ObjCMessageExpr>(E)->getMethodDecl()) {
323 Cl::Kinds kind = ClassifyUnnamed(Ctx, Method->getResultType());
324 return (kind == Cl::CL_PRValue) ? Cl::CL_ObjCMessageRValue : kind;
326 return Cl::CL_PRValue;
328 // Some C++ expressions are always class temporaries.
329 case Expr::CXXConstructExprClass:
330 case Expr::CXXTemporaryObjectExprClass:
331 return Cl::CL_ClassTemporary;
333 case Expr::VAArgExprClass:
334 return ClassifyUnnamed(Ctx, E->getType());
336 case Expr::DesignatedInitExprClass:
337 return ClassifyInternal(Ctx, cast<DesignatedInitExpr>(E)->getInit());
339 case Expr::StmtExprClass: {
340 const CompoundStmt *S = cast<StmtExpr>(E)->getSubStmt();
341 if (const Expr *LastExpr = dyn_cast_or_null<Expr>(S->body_back()))
342 return ClassifyUnnamed(Ctx, LastExpr->getType());
343 return Cl::CL_PRValue;
346 case Expr::CXXUuidofExprClass:
347 return Cl::CL_LValue;
349 case Expr::PackExpansionExprClass:
350 return ClassifyInternal(Ctx, cast<PackExpansionExpr>(E)->getPattern());
352 case Expr::MaterializeTemporaryExprClass:
353 return cast<MaterializeTemporaryExpr>(E)->isBoundToLvalueReference()
358 llvm_unreachable("unhandled expression kind in classification");
359 return Cl::CL_LValue;
362 /// ClassifyDecl - Return the classification of an expression referencing the
363 /// given declaration.
364 static Cl::Kinds ClassifyDecl(ASTContext &Ctx, const Decl *D) {
365 // C++ [expr.prim.general]p6: The result is an lvalue if the entity is a
366 // function, variable, or data member and a prvalue otherwise.
367 // In C, functions are not lvalues.
368 // In addition, NonTypeTemplateParmDecl derives from VarDecl but isn't an
369 // lvalue unless it's a reference type (C++ [temp.param]p6), so we need to
370 // special-case this.
372 if (isa<CXXMethodDecl>(D) && cast<CXXMethodDecl>(D)->isInstance())
373 return Cl::CL_MemberFunction;
376 if (const NonTypeTemplateParmDecl *NTTParm =
377 dyn_cast<NonTypeTemplateParmDecl>(D))
378 islvalue = NTTParm->getType()->isReferenceType();
380 islvalue = isa<VarDecl>(D) || isa<FieldDecl>(D) ||
381 isa<IndirectFieldDecl>(D) ||
382 (Ctx.getLangOptions().CPlusPlus &&
383 (isa<FunctionDecl>(D) || isa<FunctionTemplateDecl>(D)));
385 return islvalue ? Cl::CL_LValue : Cl::CL_PRValue;
388 /// ClassifyUnnamed - Return the classification of an expression yielding an
389 /// unnamed value of the given type. This applies in particular to function
391 static Cl::Kinds ClassifyUnnamed(ASTContext &Ctx, QualType T) {
392 // In C, function calls are always rvalues.
393 if (!Ctx.getLangOptions().CPlusPlus) return Cl::CL_PRValue;
395 // C++ [expr.call]p10: A function call is an lvalue if the result type is an
396 // lvalue reference type or an rvalue reference to function type, an xvalue
397 // if the result type is an rvalue reference to object type, and a prvalue
399 if (T->isLValueReferenceType())
400 return Cl::CL_LValue;
401 const RValueReferenceType *RV = T->getAs<RValueReferenceType>();
402 if (!RV) // Could still be a class temporary, though.
403 return T->isRecordType() ? Cl::CL_ClassTemporary : Cl::CL_PRValue;
405 return RV->getPointeeType()->isFunctionType() ? Cl::CL_LValue : Cl::CL_XValue;
408 static Cl::Kinds ClassifyMemberExpr(ASTContext &Ctx, const MemberExpr *E) {
409 if (E->getType() == Ctx.UnknownAnyTy)
410 return (isa<FunctionDecl>(E->getMemberDecl())
411 ? Cl::CL_PRValue : Cl::CL_LValue);
413 // Handle C first, it's easier.
414 if (!Ctx.getLangOptions().CPlusPlus) {
416 // For dot access, the expression is an lvalue if the first part is. For
417 // arrow access, it always is an lvalue.
419 return Cl::CL_LValue;
420 // ObjC property accesses are not lvalues, but get special treatment.
421 Expr *Base = E->getBase()->IgnoreParens();
422 if (isa<ObjCPropertyRefExpr>(Base))
423 return Cl::CL_SubObjCPropertySetting;
424 return ClassifyInternal(Ctx, Base);
427 NamedDecl *Member = E->getMemberDecl();
428 // C++ [expr.ref]p3: E1->E2 is converted to the equivalent form (*(E1)).E2.
429 // C++ [expr.ref]p4: If E2 is declared to have type "reference to T", then
430 // E1.E2 is an lvalue.
431 if (ValueDecl *Value = dyn_cast<ValueDecl>(Member))
432 if (Value->getType()->isReferenceType())
433 return Cl::CL_LValue;
435 // Otherwise, one of the following rules applies.
436 // -- If E2 is a static member [...] then E1.E2 is an lvalue.
437 if (isa<VarDecl>(Member) && Member->getDeclContext()->isRecord())
438 return Cl::CL_LValue;
440 // -- If E2 is a non-static data member [...]. If E1 is an lvalue, then
441 // E1.E2 is an lvalue; if E1 is an xvalue, then E1.E2 is an xvalue;
442 // otherwise, it is a prvalue.
443 if (isa<FieldDecl>(Member)) {
446 return Cl::CL_LValue;
447 Expr *Base = E->getBase()->IgnoreParenImpCasts();
448 if (isa<ObjCPropertyRefExpr>(Base))
449 return Cl::CL_SubObjCPropertySetting;
450 return ClassifyInternal(Ctx, E->getBase());
453 // -- If E2 is a [...] member function, [...]
454 // -- If it refers to a static member function [...], then E1.E2 is an
456 // -- Otherwise [...] E1.E2 is a prvalue.
457 if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Member))
458 return Method->isStatic() ? Cl::CL_LValue : Cl::CL_MemberFunction;
460 // -- If E2 is a member enumerator [...], the expression E1.E2 is a prvalue.
461 // So is everything else we haven't handled yet.
462 return Cl::CL_PRValue;
465 static Cl::Kinds ClassifyBinaryOp(ASTContext &Ctx, const BinaryOperator *E) {
466 assert(Ctx.getLangOptions().CPlusPlus &&
467 "This is only relevant for C++.");
468 // C++ [expr.ass]p1: All [...] return an lvalue referring to the left operand.
469 // Except we override this for writes to ObjC properties.
470 if (E->isAssignmentOp())
471 return (E->getLHS()->getObjectKind() == OK_ObjCProperty
472 ? Cl::CL_PRValue : Cl::CL_LValue);
474 // C++ [expr.comma]p1: the result is of the same value category as its right
476 if (E->getOpcode() == BO_Comma)
477 return ClassifyInternal(Ctx, E->getRHS());
479 // C++ [expr.mptr.oper]p6: The result of a .* expression whose second operand
480 // is a pointer to a data member is of the same value category as its first
482 if (E->getOpcode() == BO_PtrMemD)
483 return (E->getType()->isFunctionType() || E->getType() == Ctx.BoundMemberTy)
484 ? Cl::CL_MemberFunction
485 : ClassifyInternal(Ctx, E->getLHS());
487 // C++ [expr.mptr.oper]p6: The result of an ->* expression is an lvalue if its
488 // second operand is a pointer to data member and a prvalue otherwise.
489 if (E->getOpcode() == BO_PtrMemI)
490 return (E->getType()->isFunctionType() || E->getType() == Ctx.BoundMemberTy)
491 ? Cl::CL_MemberFunction
494 // All other binary operations are prvalues.
495 return Cl::CL_PRValue;
498 static Cl::Kinds ClassifyConditional(ASTContext &Ctx, const Expr *True,
500 assert(Ctx.getLangOptions().CPlusPlus &&
501 "This is only relevant for C++.");
504 // If either the second or the third operand has type (cv) void, [...]
505 // the result [...] is a prvalue.
506 if (True->getType()->isVoidType() || False->getType()->isVoidType())
507 return Cl::CL_PRValue;
509 // Note that at this point, we have already performed all conversions
510 // according to [expr.cond]p3.
511 // C++ [expr.cond]p4: If the second and third operands are glvalues of the
512 // same value category [...], the result is of that [...] value category.
513 // C++ [expr.cond]p5: Otherwise, the result is a prvalue.
514 Cl::Kinds LCl = ClassifyInternal(Ctx, True),
515 RCl = ClassifyInternal(Ctx, False);
516 return LCl == RCl ? LCl : Cl::CL_PRValue;
519 static Cl::ModifiableType IsModifiable(ASTContext &Ctx, const Expr *E,
520 Cl::Kinds Kind, SourceLocation &Loc) {
521 // As a general rule, we only care about lvalues. But there are some rvalues
522 // for which we want to generate special results.
523 if (Kind == Cl::CL_PRValue) {
524 // For the sake of better diagnostics, we want to specifically recognize
525 // use of the GCC cast-as-lvalue extension.
526 if (const ExplicitCastExpr *CE =
527 dyn_cast<ExplicitCastExpr>(E->IgnoreParens())) {
528 if (CE->getSubExpr()->IgnoreParenImpCasts()->isLValue()) {
529 Loc = CE->getExprLoc();
530 return Cl::CM_LValueCast;
534 if (Kind != Cl::CL_LValue)
535 return Cl::CM_RValue;
537 // This is the lvalue case.
538 // Functions are lvalues in C++, but not modifiable. (C++ [basic.lval]p6)
539 if (Ctx.getLangOptions().CPlusPlus && E->getType()->isFunctionType())
540 return Cl::CM_Function;
542 // You cannot assign to a variable outside a block from within the block if
543 // it is not marked __block, e.g.
544 // void takeclosure(void (^C)(void));
545 // void func() { int x = 1; takeclosure(^{ x = 7; }); }
546 if (const BlockDeclRefExpr *BDR = dyn_cast<BlockDeclRefExpr>(E)) {
547 if (!BDR->isByRef() && isa<VarDecl>(BDR->getDecl()))
548 return Cl::CM_NotBlockQualified;
551 // Assignment to a property in ObjC is an implicit setter access. But a
552 // setter might not exist.
553 if (const ObjCPropertyRefExpr *Expr = dyn_cast<ObjCPropertyRefExpr>(E)) {
554 if (Expr->isImplicitProperty() && Expr->getImplicitPropertySetter() == 0)
555 return Cl::CM_NoSetterProperty;
558 CanQualType CT = Ctx.getCanonicalType(E->getType());
559 // Const stuff is obviously not modifiable.
560 if (CT.isConstQualified())
561 return Cl::CM_ConstQualified;
562 // Arrays are not modifiable, only their elements are.
563 if (CT->isArrayType())
564 return Cl::CM_ArrayType;
565 // Incomplete types are not modifiable.
566 if (CT->isIncompleteType())
567 return Cl::CM_IncompleteType;
569 // Records with any const fields (recursively) are not modifiable.
570 if (const RecordType *R = CT->getAs<RecordType>()) {
571 assert((E->getObjectKind() == OK_ObjCProperty ||
572 !Ctx.getLangOptions().CPlusPlus) &&
573 "C++ struct assignment should be resolved by the "
574 "copy assignment operator.");
575 if (R->hasConstFields())
576 return Cl::CM_ConstQualified;
579 return Cl::CM_Modifiable;
582 Expr::LValueClassification Expr::ClassifyLValue(ASTContext &Ctx) const {
583 Classification VC = Classify(Ctx);
584 switch (VC.getKind()) {
585 case Cl::CL_LValue: return LV_Valid;
586 case Cl::CL_XValue: return LV_InvalidExpression;
587 case Cl::CL_Function: return LV_NotObjectType;
588 case Cl::CL_Void: return LV_InvalidExpression;
589 case Cl::CL_AddressableVoid: return LV_IncompleteVoidType;
590 case Cl::CL_DuplicateVectorComponents: return LV_DuplicateVectorComponents;
591 case Cl::CL_MemberFunction: return LV_MemberFunction;
592 case Cl::CL_SubObjCPropertySetting: return LV_SubObjCPropertySetting;
593 case Cl::CL_ClassTemporary: return LV_ClassTemporary;
594 case Cl::CL_ObjCMessageRValue: return LV_InvalidMessageExpression;
595 case Cl::CL_PRValue: return LV_InvalidExpression;
597 llvm_unreachable("Unhandled kind");
600 Expr::isModifiableLvalueResult
601 Expr::isModifiableLvalue(ASTContext &Ctx, SourceLocation *Loc) const {
602 SourceLocation dummy;
603 Classification VC = ClassifyModifiable(Ctx, Loc ? *Loc : dummy);
604 switch (VC.getKind()) {
605 case Cl::CL_LValue: break;
606 case Cl::CL_XValue: return MLV_InvalidExpression;
607 case Cl::CL_Function: return MLV_NotObjectType;
608 case Cl::CL_Void: return MLV_InvalidExpression;
609 case Cl::CL_AddressableVoid: return MLV_IncompleteVoidType;
610 case Cl::CL_DuplicateVectorComponents: return MLV_DuplicateVectorComponents;
611 case Cl::CL_MemberFunction: return MLV_MemberFunction;
612 case Cl::CL_SubObjCPropertySetting: return MLV_SubObjCPropertySetting;
613 case Cl::CL_ClassTemporary: return MLV_ClassTemporary;
614 case Cl::CL_ObjCMessageRValue: return MLV_InvalidMessageExpression;
616 return VC.getModifiable() == Cl::CM_LValueCast ?
617 MLV_LValueCast : MLV_InvalidExpression;
619 assert(VC.getKind() == Cl::CL_LValue && "Unhandled kind");
620 switch (VC.getModifiable()) {
621 case Cl::CM_Untested: llvm_unreachable("Did not test modifiability");
622 case Cl::CM_Modifiable: return MLV_Valid;
623 case Cl::CM_RValue: llvm_unreachable("CM_RValue and CL_LValue don't match");
624 case Cl::CM_Function: return MLV_NotObjectType;
625 case Cl::CM_LValueCast:
626 llvm_unreachable("CM_LValueCast and CL_LValue don't match");
627 case Cl::CM_NotBlockQualified: return MLV_NotBlockQualified;
628 case Cl::CM_NoSetterProperty: return MLV_NoSetterProperty;
629 case Cl::CM_ConstQualified: return MLV_ConstQualified;
630 case Cl::CM_ArrayType: return MLV_ArrayType;
631 case Cl::CM_IncompleteType: return MLV_IncompleteType;
633 llvm_unreachable("Unhandled modifiable type");