//===--- SemaStmt.cpp - Semantic Analysis for Statements ------------------===// // // 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 semantic analysis for statements. // //===----------------------------------------------------------------------===// #include "clang/AST/ASTContext.h" #include "clang/AST/ASTDiagnostic.h" #include "clang/AST/ASTLambda.h" #include "clang/AST/CXXInheritance.h" #include "clang/AST/CharUnits.h" #include "clang/AST/DeclObjC.h" #include "clang/AST/EvaluatedExprVisitor.h" #include "clang/AST/ExprCXX.h" #include "clang/AST/ExprObjC.h" #include "clang/AST/IgnoreExpr.h" #include "clang/AST/RecursiveASTVisitor.h" #include "clang/AST/StmtCXX.h" #include "clang/AST/StmtObjC.h" #include "clang/AST/TypeLoc.h" #include "clang/AST/TypeOrdering.h" #include "clang/Basic/TargetInfo.h" #include "clang/Lex/Preprocessor.h" #include "clang/Sema/Initialization.h" #include "clang/Sema/Lookup.h" #include "clang/Sema/Ownership.h" #include "clang/Sema/Scope.h" #include "clang/Sema/ScopeInfo.h" #include "clang/Sema/SemaInternal.h" #include "llvm/ADT/ArrayRef.h" #include "llvm/ADT/DenseMap.h" #include "llvm/ADT/STLExtras.h" #include "llvm/ADT/SmallPtrSet.h" #include "llvm/ADT/SmallString.h" #include "llvm/ADT/SmallVector.h" using namespace clang; using namespace sema; StmtResult Sema::ActOnExprStmt(ExprResult FE, bool DiscardedValue) { if (FE.isInvalid()) return StmtError(); FE = ActOnFinishFullExpr(FE.get(), FE.get()->getExprLoc(), DiscardedValue); if (FE.isInvalid()) return StmtError(); // C99 6.8.3p2: The expression in an expression statement is evaluated as a // void expression for its side effects. Conversion to void allows any // operand, even incomplete types. // Same thing in for stmt first clause (when expr) and third clause. return StmtResult(FE.getAs()); } StmtResult Sema::ActOnExprStmtError() { DiscardCleanupsInEvaluationContext(); return StmtError(); } StmtResult Sema::ActOnNullStmt(SourceLocation SemiLoc, bool HasLeadingEmptyMacro) { return new (Context) NullStmt(SemiLoc, HasLeadingEmptyMacro); } StmtResult Sema::ActOnDeclStmt(DeclGroupPtrTy dg, SourceLocation StartLoc, SourceLocation EndLoc) { DeclGroupRef DG = dg.get(); // If we have an invalid decl, just return an error. if (DG.isNull()) return StmtError(); return new (Context) DeclStmt(DG, StartLoc, EndLoc); } void Sema::ActOnForEachDeclStmt(DeclGroupPtrTy dg) { DeclGroupRef DG = dg.get(); // If we don't have a declaration, or we have an invalid declaration, // just return. if (DG.isNull() || !DG.isSingleDecl()) return; Decl *decl = DG.getSingleDecl(); if (!decl || decl->isInvalidDecl()) return; // Only variable declarations are permitted. VarDecl *var = dyn_cast(decl); if (!var) { Diag(decl->getLocation(), diag::err_non_variable_decl_in_for); decl->setInvalidDecl(); return; } // foreach variables are never actually initialized in the way that // the parser came up with. var->setInit(nullptr); // In ARC, we don't need to retain the iteration variable of a fast // enumeration loop. Rather than actually trying to catch that // during declaration processing, we remove the consequences here. if (getLangOpts().ObjCAutoRefCount) { QualType type = var->getType(); // Only do this if we inferred the lifetime. Inferred lifetime // will show up as a local qualifier because explicit lifetime // should have shown up as an AttributedType instead. if (type.getLocalQualifiers().getObjCLifetime() == Qualifiers::OCL_Strong) { // Add 'const' and mark the variable as pseudo-strong. var->setType(type.withConst()); var->setARCPseudoStrong(true); } } } /// Diagnose unused comparisons, both builtin and overloaded operators. /// For '==' and '!=', suggest fixits for '=' or '|='. /// /// Adding a cast to void (or other expression wrappers) will prevent the /// warning from firing. static bool DiagnoseUnusedComparison(Sema &S, const Expr *E) { SourceLocation Loc; bool CanAssign; enum { Equality, Inequality, Relational, ThreeWay } Kind; if (const BinaryOperator *Op = dyn_cast(E)) { if (!Op->isComparisonOp()) return false; if (Op->getOpcode() == BO_EQ) Kind = Equality; else if (Op->getOpcode() == BO_NE) Kind = Inequality; else if (Op->getOpcode() == BO_Cmp) Kind = ThreeWay; else { assert(Op->isRelationalOp()); Kind = Relational; } Loc = Op->getOperatorLoc(); CanAssign = Op->getLHS()->IgnoreParenImpCasts()->isLValue(); } else if (const CXXOperatorCallExpr *Op = dyn_cast(E)) { switch (Op->getOperator()) { case OO_EqualEqual: Kind = Equality; break; case OO_ExclaimEqual: Kind = Inequality; break; case OO_Less: case OO_Greater: case OO_GreaterEqual: case OO_LessEqual: Kind = Relational; break; case OO_Spaceship: Kind = ThreeWay; break; default: return false; } Loc = Op->getOperatorLoc(); CanAssign = Op->getArg(0)->IgnoreParenImpCasts()->isLValue(); } else { // Not a typo-prone comparison. return false; } // Suppress warnings when the operator, suspicious as it may be, comes from // a macro expansion. if (S.SourceMgr.isMacroBodyExpansion(Loc)) return false; S.Diag(Loc, diag::warn_unused_comparison) << (unsigned)Kind << E->getSourceRange(); // If the LHS is a plausible entity to assign to, provide a fixit hint to // correct common typos. if (CanAssign) { if (Kind == Inequality) S.Diag(Loc, diag::note_inequality_comparison_to_or_assign) << FixItHint::CreateReplacement(Loc, "|="); else if (Kind == Equality) S.Diag(Loc, diag::note_equality_comparison_to_assign) << FixItHint::CreateReplacement(Loc, "="); } return true; } static bool DiagnoseNoDiscard(Sema &S, const WarnUnusedResultAttr *A, SourceLocation Loc, SourceRange R1, SourceRange R2, bool IsCtor) { if (!A) return false; StringRef Msg = A->getMessage(); if (Msg.empty()) { if (IsCtor) return S.Diag(Loc, diag::warn_unused_constructor) << A << R1 << R2; return S.Diag(Loc, diag::warn_unused_result) << A << R1 << R2; } if (IsCtor) return S.Diag(Loc, diag::warn_unused_constructor_msg) << A << Msg << R1 << R2; return S.Diag(Loc, diag::warn_unused_result_msg) << A << Msg << R1 << R2; } void Sema::DiagnoseUnusedExprResult(const Stmt *S) { if (const LabelStmt *Label = dyn_cast_or_null(S)) return DiagnoseUnusedExprResult(Label->getSubStmt()); const Expr *E = dyn_cast_or_null(S); if (!E) return; // If we are in an unevaluated expression context, then there can be no unused // results because the results aren't expected to be used in the first place. if (isUnevaluatedContext()) return; SourceLocation ExprLoc = E->IgnoreParenImpCasts()->getExprLoc(); // In most cases, we don't want to warn if the expression is written in a // macro body, or if the macro comes from a system header. If the offending // expression is a call to a function with the warn_unused_result attribute, // we warn no matter the location. Because of the order in which the various // checks need to happen, we factor out the macro-related test here. bool ShouldSuppress = SourceMgr.isMacroBodyExpansion(ExprLoc) || SourceMgr.isInSystemMacro(ExprLoc); const Expr *WarnExpr; SourceLocation Loc; SourceRange R1, R2; if (!E->isUnusedResultAWarning(WarnExpr, Loc, R1, R2, Context)) return; // If this is a GNU statement expression expanded from a macro, it is probably // unused because it is a function-like macro that can be used as either an // expression or statement. Don't warn, because it is almost certainly a // false positive. if (isa(E) && Loc.isMacroID()) return; // Check if this is the UNREFERENCED_PARAMETER from the Microsoft headers. // That macro is frequently used to suppress "unused parameter" warnings, // but its implementation makes clang's -Wunused-value fire. Prevent this. if (isa(E->IgnoreImpCasts()) && Loc.isMacroID()) { SourceLocation SpellLoc = Loc; if (findMacroSpelling(SpellLoc, "UNREFERENCED_PARAMETER")) return; } // Okay, we have an unused result. Depending on what the base expression is, // we might want to make a more specific diagnostic. Check for one of these // cases now. unsigned DiagID = diag::warn_unused_expr; if (const FullExpr *Temps = dyn_cast(E)) E = Temps->getSubExpr(); if (const CXXBindTemporaryExpr *TempExpr = dyn_cast(E)) E = TempExpr->getSubExpr(); if (DiagnoseUnusedComparison(*this, E)) return; E = WarnExpr; if (const auto *Cast = dyn_cast(E)) if (Cast->getCastKind() == CK_NoOp || Cast->getCastKind() == CK_ConstructorConversion) E = Cast->getSubExpr()->IgnoreImpCasts(); if (const CallExpr *CE = dyn_cast(E)) { if (E->getType()->isVoidType()) return; if (DiagnoseNoDiscard(*this, cast_or_null( CE->getUnusedResultAttr(Context)), Loc, R1, R2, /*isCtor=*/false)) return; // If the callee has attribute pure, const, or warn_unused_result, warn with // a more specific message to make it clear what is happening. If the call // is written in a macro body, only warn if it has the warn_unused_result // attribute. if (const Decl *FD = CE->getCalleeDecl()) { if (ShouldSuppress) return; if (FD->hasAttr()) { Diag(Loc, diag::warn_unused_call) << R1 << R2 << "pure"; return; } if (FD->hasAttr()) { Diag(Loc, diag::warn_unused_call) << R1 << R2 << "const"; return; } } } else if (const auto *CE = dyn_cast(E)) { if (const CXXConstructorDecl *Ctor = CE->getConstructor()) { const auto *A = Ctor->getAttr(); A = A ? A : Ctor->getParent()->getAttr(); if (DiagnoseNoDiscard(*this, A, Loc, R1, R2, /*isCtor=*/true)) return; } } else if (const auto *ILE = dyn_cast(E)) { if (const TagDecl *TD = ILE->getType()->getAsTagDecl()) { if (DiagnoseNoDiscard(*this, TD->getAttr(), Loc, R1, R2, /*isCtor=*/false)) return; } } else if (ShouldSuppress) return; E = WarnExpr; if (const ObjCMessageExpr *ME = dyn_cast(E)) { if (getLangOpts().ObjCAutoRefCount && ME->isDelegateInitCall()) { Diag(Loc, diag::err_arc_unused_init_message) << R1; return; } const ObjCMethodDecl *MD = ME->getMethodDecl(); if (MD) { if (DiagnoseNoDiscard(*this, MD->getAttr(), Loc, R1, R2, /*isCtor=*/false)) return; } } else if (const PseudoObjectExpr *POE = dyn_cast(E)) { const Expr *Source = POE->getSyntacticForm(); // Handle the actually selected call of an OpenMP specialized call. if (LangOpts.OpenMP && isa(Source) && POE->getNumSemanticExprs() == 1 && isa(POE->getSemanticExpr(0))) return DiagnoseUnusedExprResult(POE->getSemanticExpr(0)); if (isa(Source)) DiagID = diag::warn_unused_container_subscript_expr; else DiagID = diag::warn_unused_property_expr; } else if (const CXXFunctionalCastExpr *FC = dyn_cast(E)) { const Expr *E = FC->getSubExpr(); if (const CXXBindTemporaryExpr *TE = dyn_cast(E)) E = TE->getSubExpr(); if (isa(E)) return; if (const CXXConstructExpr *CE = dyn_cast(E)) if (const CXXRecordDecl *RD = CE->getType()->getAsCXXRecordDecl()) if (!RD->getAttr()) return; } // Diagnose "(void*) blah" as a typo for "(void) blah". else if (const CStyleCastExpr *CE = dyn_cast(E)) { TypeSourceInfo *TI = CE->getTypeInfoAsWritten(); QualType T = TI->getType(); // We really do want to use the non-canonical type here. if (T == Context.VoidPtrTy) { PointerTypeLoc TL = TI->getTypeLoc().castAs(); Diag(Loc, diag::warn_unused_voidptr) << FixItHint::CreateRemoval(TL.getStarLoc()); return; } } // Tell the user to assign it into a variable to force a volatile load if this // isn't an array. if (E->isGLValue() && E->getType().isVolatileQualified() && !E->getType()->isArrayType()) { Diag(Loc, diag::warn_unused_volatile) << R1 << R2; return; } DiagRuntimeBehavior(Loc, nullptr, PDiag(DiagID) << R1 << R2); } void Sema::ActOnStartOfCompoundStmt(bool IsStmtExpr) { PushCompoundScope(IsStmtExpr); } void Sema::ActOnAfterCompoundStatementLeadingPragmas() { if (getCurFPFeatures().isFPConstrained()) { FunctionScopeInfo *FSI = getCurFunction(); assert(FSI); FSI->setUsesFPIntrin(); } } void Sema::ActOnFinishOfCompoundStmt() { PopCompoundScope(); } sema::CompoundScopeInfo &Sema::getCurCompoundScope() const { return getCurFunction()->CompoundScopes.back(); } StmtResult Sema::ActOnCompoundStmt(SourceLocation L, SourceLocation R, ArrayRef Elts, bool isStmtExpr) { const unsigned NumElts = Elts.size(); // If we're in C89 mode, check that we don't have any decls after stmts. If // so, emit an extension diagnostic. if (!getLangOpts().C99 && !getLangOpts().CPlusPlus) { // Note that __extension__ can be around a decl. unsigned i = 0; // Skip over all declarations. for (; i != NumElts && isa(Elts[i]); ++i) /*empty*/; // We found the end of the list or a statement. Scan for another declstmt. for (; i != NumElts && !isa(Elts[i]); ++i) /*empty*/; if (i != NumElts) { Decl *D = *cast(Elts[i])->decl_begin(); Diag(D->getLocation(), diag::ext_mixed_decls_code); } } // Check for suspicious empty body (null statement) in `for' and `while' // statements. Don't do anything for template instantiations, this just adds // noise. if (NumElts != 0 && !CurrentInstantiationScope && getCurCompoundScope().HasEmptyLoopBodies) { for (unsigned i = 0; i != NumElts - 1; ++i) DiagnoseEmptyLoopBody(Elts[i], Elts[i + 1]); } return CompoundStmt::Create(Context, Elts, L, R); } ExprResult Sema::ActOnCaseExpr(SourceLocation CaseLoc, ExprResult Val) { if (!Val.get()) return Val; if (DiagnoseUnexpandedParameterPack(Val.get())) return ExprError(); // If we're not inside a switch, let the 'case' statement handling diagnose // this. Just clean up after the expression as best we can. if (getCurFunction()->SwitchStack.empty()) return ActOnFinishFullExpr(Val.get(), Val.get()->getExprLoc(), false, getLangOpts().CPlusPlus11); Expr *CondExpr = getCurFunction()->SwitchStack.back().getPointer()->getCond(); if (!CondExpr) return ExprError(); QualType CondType = CondExpr->getType(); auto CheckAndFinish = [&](Expr *E) { if (CondType->isDependentType() || E->isTypeDependent()) return ExprResult(E); if (getLangOpts().CPlusPlus11) { // C++11 [stmt.switch]p2: the constant-expression shall be a converted // constant expression of the promoted type of the switch condition. llvm::APSInt TempVal; return CheckConvertedConstantExpression(E, CondType, TempVal, CCEK_CaseValue); } ExprResult ER = E; if (!E->isValueDependent()) ER = VerifyIntegerConstantExpression(E, AllowFold); if (!ER.isInvalid()) ER = DefaultLvalueConversion(ER.get()); if (!ER.isInvalid()) ER = ImpCastExprToType(ER.get(), CondType, CK_IntegralCast); if (!ER.isInvalid()) ER = ActOnFinishFullExpr(ER.get(), ER.get()->getExprLoc(), false); return ER; }; ExprResult Converted = CorrectDelayedTyposInExpr( Val, /*InitDecl=*/nullptr, /*RecoverUncorrectedTypos=*/false, CheckAndFinish); if (Converted.get() == Val.get()) Converted = CheckAndFinish(Val.get()); return Converted; } StmtResult Sema::ActOnCaseStmt(SourceLocation CaseLoc, ExprResult LHSVal, SourceLocation DotDotDotLoc, ExprResult RHSVal, SourceLocation ColonLoc) { assert((LHSVal.isInvalid() || LHSVal.get()) && "missing LHS value"); assert((DotDotDotLoc.isInvalid() ? RHSVal.isUnset() : RHSVal.isInvalid() || RHSVal.get()) && "missing RHS value"); if (getCurFunction()->SwitchStack.empty()) { Diag(CaseLoc, diag::err_case_not_in_switch); return StmtError(); } if (LHSVal.isInvalid() || RHSVal.isInvalid()) { getCurFunction()->SwitchStack.back().setInt(true); return StmtError(); } auto *CS = CaseStmt::Create(Context, LHSVal.get(), RHSVal.get(), CaseLoc, DotDotDotLoc, ColonLoc); getCurFunction()->SwitchStack.back().getPointer()->addSwitchCase(CS); return CS; } /// ActOnCaseStmtBody - This installs a statement as the body of a case. void Sema::ActOnCaseStmtBody(Stmt *S, Stmt *SubStmt) { cast(S)->setSubStmt(SubStmt); } StmtResult Sema::ActOnDefaultStmt(SourceLocation DefaultLoc, SourceLocation ColonLoc, Stmt *SubStmt, Scope *CurScope) { if (getCurFunction()->SwitchStack.empty()) { Diag(DefaultLoc, diag::err_default_not_in_switch); return SubStmt; } DefaultStmt *DS = new (Context) DefaultStmt(DefaultLoc, ColonLoc, SubStmt); getCurFunction()->SwitchStack.back().getPointer()->addSwitchCase(DS); return DS; } StmtResult Sema::ActOnLabelStmt(SourceLocation IdentLoc, LabelDecl *TheDecl, SourceLocation ColonLoc, Stmt *SubStmt) { // If the label was multiply defined, reject it now. if (TheDecl->getStmt()) { Diag(IdentLoc, diag::err_redefinition_of_label) << TheDecl->getDeclName(); Diag(TheDecl->getLocation(), diag::note_previous_definition); return SubStmt; } ReservedIdentifierStatus Status = TheDecl->isReserved(getLangOpts()); if (Status != ReservedIdentifierStatus::NotReserved && !Context.getSourceManager().isInSystemHeader(IdentLoc)) Diag(IdentLoc, diag::warn_reserved_extern_symbol) << TheDecl << static_cast(Status); // Otherwise, things are good. Fill in the declaration and return it. LabelStmt *LS = new (Context) LabelStmt(IdentLoc, TheDecl, SubStmt); TheDecl->setStmt(LS); if (!TheDecl->isGnuLocal()) { TheDecl->setLocStart(IdentLoc); if (!TheDecl->isMSAsmLabel()) { // Don't update the location of MS ASM labels. These will result in // a diagnostic, and changing the location here will mess that up. TheDecl->setLocation(IdentLoc); } } return LS; } StmtResult Sema::BuildAttributedStmt(SourceLocation AttrsLoc, ArrayRef Attrs, Stmt *SubStmt) { // FIXME: this code should move when a planned refactoring around statement // attributes lands. for (const auto *A : Attrs) { if (A->getKind() == attr::MustTail) { if (!checkAndRewriteMustTailAttr(SubStmt, *A)) { return SubStmt; } setFunctionHasMustTail(); } } return AttributedStmt::Create(Context, AttrsLoc, Attrs, SubStmt); } StmtResult Sema::ActOnAttributedStmt(const ParsedAttributesWithRange &Attrs, Stmt *SubStmt) { SmallVector SemanticAttrs; ProcessStmtAttributes(SubStmt, Attrs, SemanticAttrs); if (!SemanticAttrs.empty()) return BuildAttributedStmt(Attrs.Range.getBegin(), SemanticAttrs, SubStmt); // If none of the attributes applied, that's fine, we can recover by // returning the substatement directly instead of making an AttributedStmt // with no attributes on it. return SubStmt; } bool Sema::checkAndRewriteMustTailAttr(Stmt *St, const Attr &MTA) { ReturnStmt *R = cast(St); Expr *E = R->getRetValue(); if (CurContext->isDependentContext() || (E && E->isInstantiationDependent())) // We have to suspend our check until template instantiation time. return true; if (!checkMustTailAttr(St, MTA)) return false; // FIXME: Replace Expr::IgnoreImplicitAsWritten() with this function. // Currently it does not skip implicit constructors in an initialization // context. auto IgnoreImplicitAsWritten = [](Expr *E) -> Expr * { return IgnoreExprNodes(E, IgnoreImplicitAsWrittenSingleStep, IgnoreElidableImplicitConstructorSingleStep); }; // Now that we have verified that 'musttail' is valid here, rewrite the // return value to remove all implicit nodes, but retain parentheses. R->setRetValue(IgnoreImplicitAsWritten(E)); return true; } bool Sema::checkMustTailAttr(const Stmt *St, const Attr &MTA) { assert(!CurContext->isDependentContext() && "musttail cannot be checked from a dependent context"); // FIXME: Add Expr::IgnoreParenImplicitAsWritten() with this definition. auto IgnoreParenImplicitAsWritten = [](const Expr *E) -> const Expr * { return IgnoreExprNodes(const_cast(E), IgnoreParensSingleStep, IgnoreImplicitAsWrittenSingleStep, IgnoreElidableImplicitConstructorSingleStep); }; const Expr *E = cast(St)->getRetValue(); const auto *CE = dyn_cast_or_null(IgnoreParenImplicitAsWritten(E)); if (!CE) { Diag(St->getBeginLoc(), diag::err_musttail_needs_call) << &MTA; return false; } if (const auto *EWC = dyn_cast(E)) { if (EWC->cleanupsHaveSideEffects()) { Diag(St->getBeginLoc(), diag::err_musttail_needs_trivial_args) << &MTA; return false; } } // We need to determine the full function type (including "this" type, if any) // for both caller and callee. struct FuncType { enum { ft_non_member, ft_static_member, ft_non_static_member, ft_pointer_to_member, } MemberType = ft_non_member; QualType This; const FunctionProtoType *Func; const CXXMethodDecl *Method = nullptr; } CallerType, CalleeType; auto GetMethodType = [this, St, MTA](const CXXMethodDecl *CMD, FuncType &Type, bool IsCallee) -> bool { if (isa(CMD)) { Diag(St->getBeginLoc(), diag::err_musttail_structors_forbidden) << IsCallee << isa(CMD); if (IsCallee) Diag(CMD->getBeginLoc(), diag::note_musttail_structors_forbidden) << isa(CMD); Diag(MTA.getLocation(), diag::note_tail_call_required) << &MTA; return false; } if (CMD->isStatic()) Type.MemberType = FuncType::ft_static_member; else { Type.This = CMD->getThisType()->getPointeeType(); Type.MemberType = FuncType::ft_non_static_member; } Type.Func = CMD->getType()->castAs(); return true; }; const auto *CallerDecl = dyn_cast(CurContext); // Find caller function signature. if (!CallerDecl) { int ContextType; if (isa(CurContext)) ContextType = 0; else if (isa(CurContext)) ContextType = 1; else ContextType = 2; Diag(St->getBeginLoc(), diag::err_musttail_forbidden_from_this_context) << &MTA << ContextType; return false; } else if (const auto *CMD = dyn_cast(CurContext)) { // Caller is a class/struct method. if (!GetMethodType(CMD, CallerType, false)) return false; } else { // Caller is a non-method function. CallerType.Func = CallerDecl->getType()->getAs(); } const Expr *CalleeExpr = CE->getCallee()->IgnoreParens(); const auto *CalleeBinOp = dyn_cast(CalleeExpr); SourceLocation CalleeLoc = CE->getCalleeDecl() ? CE->getCalleeDecl()->getBeginLoc() : St->getBeginLoc(); // Find callee function signature. if (const CXXMethodDecl *CMD = dyn_cast_or_null(CE->getCalleeDecl())) { // Call is: obj.method(), obj->method(), functor(), etc. if (!GetMethodType(CMD, CalleeType, true)) return false; } else if (CalleeBinOp && CalleeBinOp->isPtrMemOp()) { // Call is: obj->*method_ptr or obj.*method_ptr const auto *MPT = CalleeBinOp->getRHS()->getType()->castAs(); CalleeType.This = QualType(MPT->getClass(), 0); CalleeType.Func = MPT->getPointeeType()->castAs(); CalleeType.MemberType = FuncType::ft_pointer_to_member; } else if (isa(CalleeExpr)) { Diag(St->getBeginLoc(), diag::err_musttail_structors_forbidden) << /* IsCallee = */ 1 << /* IsDestructor = */ 1; Diag(MTA.getLocation(), diag::note_tail_call_required) << &MTA; return false; } else { // Non-method function. CalleeType.Func = CalleeExpr->getType()->getPointeeType()->getAs(); } // Both caller and callee must have a prototype (no K&R declarations). if (!CalleeType.Func || !CallerType.Func) { Diag(St->getBeginLoc(), diag::err_musttail_needs_prototype) << &MTA; if (!CalleeType.Func && CE->getDirectCallee()) { Diag(CE->getDirectCallee()->getBeginLoc(), diag::note_musttail_fix_non_prototype); } if (!CallerType.Func) Diag(CallerDecl->getBeginLoc(), diag::note_musttail_fix_non_prototype); return false; } // Caller and callee must have matching calling conventions. // // Some calling conventions are physically capable of supporting tail calls // even if the function types don't perfectly match. LLVM is currently too // strict to allow this, but if LLVM added support for this in the future, we // could exit early here and skip the remaining checks if the functions are // using such a calling convention. if (CallerType.Func->getCallConv() != CalleeType.Func->getCallConv()) { if (const auto *ND = dyn_cast_or_null(CE->getCalleeDecl())) Diag(St->getBeginLoc(), diag::err_musttail_callconv_mismatch) << true << ND->getDeclName(); else Diag(St->getBeginLoc(), diag::err_musttail_callconv_mismatch) << false; Diag(CalleeLoc, diag::note_musttail_callconv_mismatch) << FunctionType::getNameForCallConv(CallerType.Func->getCallConv()) << FunctionType::getNameForCallConv(CalleeType.Func->getCallConv()); Diag(MTA.getLocation(), diag::note_tail_call_required) << &MTA; return false; } if (CalleeType.Func->isVariadic() || CallerType.Func->isVariadic()) { Diag(St->getBeginLoc(), diag::err_musttail_no_variadic) << &MTA; return false; } // Caller and callee must match in whether they have a "this" parameter. if (CallerType.This.isNull() != CalleeType.This.isNull()) { if (const auto *ND = dyn_cast_or_null(CE->getCalleeDecl())) { Diag(St->getBeginLoc(), diag::err_musttail_member_mismatch) << CallerType.MemberType << CalleeType.MemberType << true << ND->getDeclName(); Diag(CalleeLoc, diag::note_musttail_callee_defined_here) << ND->getDeclName(); } else Diag(St->getBeginLoc(), diag::err_musttail_member_mismatch) << CallerType.MemberType << CalleeType.MemberType << false; Diag(MTA.getLocation(), diag::note_tail_call_required) << &MTA; return false; } auto CheckTypesMatch = [this](FuncType CallerType, FuncType CalleeType, PartialDiagnostic &PD) -> bool { enum { ft_different_class, ft_parameter_arity, ft_parameter_mismatch, ft_return_type, }; auto DoTypesMatch = [this, &PD](QualType A, QualType B, unsigned Select) -> bool { if (!Context.hasSimilarType(A, B)) { PD << Select << A.getUnqualifiedType() << B.getUnqualifiedType(); return false; } return true; }; if (!CallerType.This.isNull() && !DoTypesMatch(CallerType.This, CalleeType.This, ft_different_class)) return false; if (!DoTypesMatch(CallerType.Func->getReturnType(), CalleeType.Func->getReturnType(), ft_return_type)) return false; if (CallerType.Func->getNumParams() != CalleeType.Func->getNumParams()) { PD << ft_parameter_arity << CallerType.Func->getNumParams() << CalleeType.Func->getNumParams(); return false; } ArrayRef CalleeParams = CalleeType.Func->getParamTypes(); ArrayRef CallerParams = CallerType.Func->getParamTypes(); size_t N = CallerType.Func->getNumParams(); for (size_t I = 0; I < N; I++) { if (!DoTypesMatch(CalleeParams[I], CallerParams[I], ft_parameter_mismatch)) { PD << static_cast(I) + 1; return false; } } return true; }; PartialDiagnostic PD = PDiag(diag::note_musttail_mismatch); if (!CheckTypesMatch(CallerType, CalleeType, PD)) { if (const auto *ND = dyn_cast_or_null(CE->getCalleeDecl())) Diag(St->getBeginLoc(), diag::err_musttail_mismatch) << true << ND->getDeclName(); else Diag(St->getBeginLoc(), diag::err_musttail_mismatch) << false; Diag(CalleeLoc, PD); Diag(MTA.getLocation(), diag::note_tail_call_required) << &MTA; return false; } return true; } namespace { class CommaVisitor : public EvaluatedExprVisitor { typedef EvaluatedExprVisitor Inherited; Sema &SemaRef; public: CommaVisitor(Sema &SemaRef) : Inherited(SemaRef.Context), SemaRef(SemaRef) {} void VisitBinaryOperator(BinaryOperator *E) { if (E->getOpcode() == BO_Comma) SemaRef.DiagnoseCommaOperator(E->getLHS(), E->getExprLoc()); EvaluatedExprVisitor::VisitBinaryOperator(E); } }; } StmtResult Sema::ActOnIfStmt(SourceLocation IfLoc, bool IsConstexpr, SourceLocation LParenLoc, Stmt *InitStmt, ConditionResult Cond, SourceLocation RParenLoc, Stmt *thenStmt, SourceLocation ElseLoc, Stmt *elseStmt) { if (Cond.isInvalid()) Cond = ConditionResult( *this, nullptr, MakeFullExpr(new (Context) OpaqueValueExpr(SourceLocation(), Context.BoolTy, VK_RValue), IfLoc), false); Expr *CondExpr = Cond.get().second; // Only call the CommaVisitor when not C89 due to differences in scope flags. if ((getLangOpts().C99 || getLangOpts().CPlusPlus) && !Diags.isIgnored(diag::warn_comma_operator, CondExpr->getExprLoc())) CommaVisitor(*this).Visit(CondExpr); if (!elseStmt) DiagnoseEmptyStmtBody(CondExpr->getEndLoc(), thenStmt, diag::warn_empty_if_body); if (IsConstexpr) { auto DiagnoseLikelihood = [&](const Stmt *S) { if (const Attr *A = Stmt::getLikelihoodAttr(S)) { Diags.Report(A->getLocation(), diag::warn_attribute_has_no_effect_on_if_constexpr) << A << A->getRange(); Diags.Report(IfLoc, diag::note_attribute_has_no_effect_on_if_constexpr_here) << SourceRange(IfLoc, LParenLoc.getLocWithOffset(-1)); } }; DiagnoseLikelihood(thenStmt); DiagnoseLikelihood(elseStmt); } else { std::tuple LHC = Stmt::determineLikelihoodConflict(thenStmt, elseStmt); if (std::get<0>(LHC)) { const Attr *ThenAttr = std::get<1>(LHC); const Attr *ElseAttr = std::get<2>(LHC); Diags.Report(ThenAttr->getLocation(), diag::warn_attributes_likelihood_ifstmt_conflict) << ThenAttr << ThenAttr->getRange(); Diags.Report(ElseAttr->getLocation(), diag::note_conflicting_attribute) << ElseAttr << ElseAttr->getRange(); } } return BuildIfStmt(IfLoc, IsConstexpr, LParenLoc, InitStmt, Cond, RParenLoc, thenStmt, ElseLoc, elseStmt); } StmtResult Sema::BuildIfStmt(SourceLocation IfLoc, bool IsConstexpr, SourceLocation LParenLoc, Stmt *InitStmt, ConditionResult Cond, SourceLocation RParenLoc, Stmt *thenStmt, SourceLocation ElseLoc, Stmt *elseStmt) { if (Cond.isInvalid()) return StmtError(); if (IsConstexpr || isa(Cond.get().second)) setFunctionHasBranchProtectedScope(); return IfStmt::Create(Context, IfLoc, IsConstexpr, InitStmt, Cond.get().first, Cond.get().second, LParenLoc, RParenLoc, thenStmt, ElseLoc, elseStmt); } namespace { struct CaseCompareFunctor { bool operator()(const std::pair &LHS, const llvm::APSInt &RHS) { return LHS.first < RHS; } bool operator()(const std::pair &LHS, const std::pair &RHS) { return LHS.first < RHS.first; } bool operator()(const llvm::APSInt &LHS, const std::pair &RHS) { return LHS < RHS.first; } }; } /// CmpCaseVals - Comparison predicate for sorting case values. /// static bool CmpCaseVals(const std::pair& lhs, const std::pair& rhs) { if (lhs.first < rhs.first) return true; if (lhs.first == rhs.first && lhs.second->getCaseLoc() < rhs.second->getCaseLoc()) return true; return false; } /// CmpEnumVals - Comparison predicate for sorting enumeration values. /// static bool CmpEnumVals(const std::pair& lhs, const std::pair& rhs) { return lhs.first < rhs.first; } /// EqEnumVals - Comparison preficate for uniqing enumeration values. /// static bool EqEnumVals(const std::pair& lhs, const std::pair& rhs) { return lhs.first == rhs.first; } /// GetTypeBeforeIntegralPromotion - Returns the pre-promotion type of /// potentially integral-promoted expression @p expr. static QualType GetTypeBeforeIntegralPromotion(const Expr *&E) { if (const auto *FE = dyn_cast(E)) E = FE->getSubExpr(); while (const auto *ImpCast = dyn_cast(E)) { if (ImpCast->getCastKind() != CK_IntegralCast) break; E = ImpCast->getSubExpr(); } return E->getType(); } ExprResult Sema::CheckSwitchCondition(SourceLocation SwitchLoc, Expr *Cond) { class SwitchConvertDiagnoser : public ICEConvertDiagnoser { Expr *Cond; public: SwitchConvertDiagnoser(Expr *Cond) : ICEConvertDiagnoser(/*AllowScopedEnumerations*/true, false, true), Cond(Cond) {} SemaDiagnosticBuilder diagnoseNotInt(Sema &S, SourceLocation Loc, QualType T) override { return S.Diag(Loc, diag::err_typecheck_statement_requires_integer) << T; } SemaDiagnosticBuilder diagnoseIncomplete( Sema &S, SourceLocation Loc, QualType T) override { return S.Diag(Loc, diag::err_switch_incomplete_class_type) << T << Cond->getSourceRange(); } SemaDiagnosticBuilder diagnoseExplicitConv( Sema &S, SourceLocation Loc, QualType T, QualType ConvTy) override { return S.Diag(Loc, diag::err_switch_explicit_conversion) << T << ConvTy; } SemaDiagnosticBuilder noteExplicitConv( Sema &S, CXXConversionDecl *Conv, QualType ConvTy) override { return S.Diag(Conv->getLocation(), diag::note_switch_conversion) << ConvTy->isEnumeralType() << ConvTy; } SemaDiagnosticBuilder diagnoseAmbiguous(Sema &S, SourceLocation Loc, QualType T) override { return S.Diag(Loc, diag::err_switch_multiple_conversions) << T; } SemaDiagnosticBuilder noteAmbiguous( Sema &S, CXXConversionDecl *Conv, QualType ConvTy) override { return S.Diag(Conv->getLocation(), diag::note_switch_conversion) << ConvTy->isEnumeralType() << ConvTy; } SemaDiagnosticBuilder diagnoseConversion( Sema &S, SourceLocation Loc, QualType T, QualType ConvTy) override { llvm_unreachable("conversion functions are permitted"); } } SwitchDiagnoser(Cond); ExprResult CondResult = PerformContextualImplicitConversion(SwitchLoc, Cond, SwitchDiagnoser); if (CondResult.isInvalid()) return ExprError(); // FIXME: PerformContextualImplicitConversion doesn't always tell us if it // failed and produced a diagnostic. Cond = CondResult.get(); if (!Cond->isTypeDependent() && !Cond->getType()->isIntegralOrEnumerationType()) return ExprError(); // C99 6.8.4.2p5 - Integer promotions are performed on the controlling expr. return UsualUnaryConversions(Cond); } StmtResult Sema::ActOnStartOfSwitchStmt(SourceLocation SwitchLoc, SourceLocation LParenLoc, Stmt *InitStmt, ConditionResult Cond, SourceLocation RParenLoc) { Expr *CondExpr = Cond.get().second; assert((Cond.isInvalid() || CondExpr) && "switch with no condition"); if (CondExpr && !CondExpr->isTypeDependent()) { // We have already converted the expression to an integral or enumeration // type, when we parsed the switch condition. There are cases where we don't // have an appropriate type, e.g. a typo-expr Cond was corrected to an // inappropriate-type expr, we just return an error. if (!CondExpr->getType()->isIntegralOrEnumerationType()) return StmtError(); if (CondExpr->isKnownToHaveBooleanValue()) { // switch(bool_expr) {...} is often a programmer error, e.g. // switch(n && mask) { ... } // Doh - should be "n & mask". // One can always use an if statement instead of switch(bool_expr). Diag(SwitchLoc, diag::warn_bool_switch_condition) << CondExpr->getSourceRange(); } } setFunctionHasBranchIntoScope(); auto *SS = SwitchStmt::Create(Context, InitStmt, Cond.get().first, CondExpr, LParenLoc, RParenLoc); getCurFunction()->SwitchStack.push_back( FunctionScopeInfo::SwitchInfo(SS, false)); return SS; } static void AdjustAPSInt(llvm::APSInt &Val, unsigned BitWidth, bool IsSigned) { Val = Val.extOrTrunc(BitWidth); Val.setIsSigned(IsSigned); } /// Check the specified case value is in range for the given unpromoted switch /// type. static void checkCaseValue(Sema &S, SourceLocation Loc, const llvm::APSInt &Val, unsigned UnpromotedWidth, bool UnpromotedSign) { // In C++11 onwards, this is checked by the language rules. if (S.getLangOpts().CPlusPlus11) return; // If the case value was signed and negative and the switch expression is // unsigned, don't bother to warn: this is implementation-defined behavior. // FIXME: Introduce a second, default-ignored warning for this case? if (UnpromotedWidth < Val.getBitWidth()) { llvm::APSInt ConvVal(Val); AdjustAPSInt(ConvVal, UnpromotedWidth, UnpromotedSign); AdjustAPSInt(ConvVal, Val.getBitWidth(), Val.isSigned()); // FIXME: Use different diagnostics for overflow in conversion to promoted // type versus "switch expression cannot have this value". Use proper // IntRange checking rather than just looking at the unpromoted type here. if (ConvVal != Val) S.Diag(Loc, diag::warn_case_value_overflow) << Val.toString(10) << ConvVal.toString(10); } } typedef SmallVector, 64> EnumValsTy; /// Returns true if we should emit a diagnostic about this case expression not /// being a part of the enum used in the switch controlling expression. static bool ShouldDiagnoseSwitchCaseNotInEnum(const Sema &S, const EnumDecl *ED, const Expr *CaseExpr, EnumValsTy::iterator &EI, EnumValsTy::iterator &EIEnd, const llvm::APSInt &Val) { if (!ED->isClosed()) return false; if (const DeclRefExpr *DRE = dyn_cast(CaseExpr->IgnoreParenImpCasts())) { if (const VarDecl *VD = dyn_cast(DRE->getDecl())) { QualType VarType = VD->getType(); QualType EnumType = S.Context.getTypeDeclType(ED); if (VD->hasGlobalStorage() && VarType.isConstQualified() && S.Context.hasSameUnqualifiedType(EnumType, VarType)) return false; } } if (ED->hasAttr()) return !S.IsValueInFlagEnum(ED, Val, false); while (EI != EIEnd && EI->first < Val) EI++; if (EI != EIEnd && EI->first == Val) return false; return true; } static void checkEnumTypesInSwitchStmt(Sema &S, const Expr *Cond, const Expr *Case) { QualType CondType = Cond->getType(); QualType CaseType = Case->getType(); const EnumType *CondEnumType = CondType->getAs(); const EnumType *CaseEnumType = CaseType->getAs(); if (!CondEnumType || !CaseEnumType) return; // Ignore anonymous enums. if (!CondEnumType->getDecl()->getIdentifier() && !CondEnumType->getDecl()->getTypedefNameForAnonDecl()) return; if (!CaseEnumType->getDecl()->getIdentifier() && !CaseEnumType->getDecl()->getTypedefNameForAnonDecl()) return; if (S.Context.hasSameUnqualifiedType(CondType, CaseType)) return; S.Diag(Case->getExprLoc(), diag::warn_comparison_of_mixed_enum_types_switch) << CondType << CaseType << Cond->getSourceRange() << Case->getSourceRange(); } StmtResult Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch, Stmt *BodyStmt) { SwitchStmt *SS = cast(Switch); bool CaseListIsIncomplete = getCurFunction()->SwitchStack.back().getInt(); assert(SS == getCurFunction()->SwitchStack.back().getPointer() && "switch stack missing push/pop!"); getCurFunction()->SwitchStack.pop_back(); if (!BodyStmt) return StmtError(); SS->setBody(BodyStmt, SwitchLoc); Expr *CondExpr = SS->getCond(); if (!CondExpr) return StmtError(); QualType CondType = CondExpr->getType(); // C++ 6.4.2.p2: // Integral promotions are performed (on the switch condition). // // A case value unrepresentable by the original switch condition // type (before the promotion) doesn't make sense, even when it can // be represented by the promoted type. Therefore we need to find // the pre-promotion type of the switch condition. const Expr *CondExprBeforePromotion = CondExpr; QualType CondTypeBeforePromotion = GetTypeBeforeIntegralPromotion(CondExprBeforePromotion); // Get the bitwidth of the switched-on value after promotions. We must // convert the integer case values to this width before comparison. bool HasDependentValue = CondExpr->isTypeDependent() || CondExpr->isValueDependent(); unsigned CondWidth = HasDependentValue ? 0 : Context.getIntWidth(CondType); bool CondIsSigned = CondType->isSignedIntegerOrEnumerationType(); // Get the width and signedness that the condition might actually have, for // warning purposes. // FIXME: Grab an IntRange for the condition rather than using the unpromoted // type. unsigned CondWidthBeforePromotion = HasDependentValue ? 0 : Context.getIntWidth(CondTypeBeforePromotion); bool CondIsSignedBeforePromotion = CondTypeBeforePromotion->isSignedIntegerOrEnumerationType(); // Accumulate all of the case values in a vector so that we can sort them // and detect duplicates. This vector contains the APInt for the case after // it has been converted to the condition type. typedef SmallVector, 64> CaseValsTy; CaseValsTy CaseVals; // Keep track of any GNU case ranges we see. The APSInt is the low value. typedef std::vector > CaseRangesTy; CaseRangesTy CaseRanges; DefaultStmt *TheDefaultStmt = nullptr; bool CaseListIsErroneous = false; for (SwitchCase *SC = SS->getSwitchCaseList(); SC && !HasDependentValue; SC = SC->getNextSwitchCase()) { if (DefaultStmt *DS = dyn_cast(SC)) { if (TheDefaultStmt) { Diag(DS->getDefaultLoc(), diag::err_multiple_default_labels_defined); Diag(TheDefaultStmt->getDefaultLoc(), diag::note_duplicate_case_prev); // FIXME: Remove the default statement from the switch block so that // we'll return a valid AST. This requires recursing down the AST and // finding it, not something we are set up to do right now. For now, // just lop the entire switch stmt out of the AST. CaseListIsErroneous = true; } TheDefaultStmt = DS; } else { CaseStmt *CS = cast(SC); Expr *Lo = CS->getLHS(); if (Lo->isValueDependent()) { HasDependentValue = true; break; } // We already verified that the expression has a constant value; // get that value (prior to conversions). const Expr *LoBeforePromotion = Lo; GetTypeBeforeIntegralPromotion(LoBeforePromotion); llvm::APSInt LoVal = LoBeforePromotion->EvaluateKnownConstInt(Context); // Check the unconverted value is within the range of possible values of // the switch expression. checkCaseValue(*this, Lo->getBeginLoc(), LoVal, CondWidthBeforePromotion, CondIsSignedBeforePromotion); // FIXME: This duplicates the check performed for warn_not_in_enum below. checkEnumTypesInSwitchStmt(*this, CondExprBeforePromotion, LoBeforePromotion); // Convert the value to the same width/sign as the condition. AdjustAPSInt(LoVal, CondWidth, CondIsSigned); // If this is a case range, remember it in CaseRanges, otherwise CaseVals. if (CS->getRHS()) { if (CS->getRHS()->isValueDependent()) { HasDependentValue = true; break; } CaseRanges.push_back(std::make_pair(LoVal, CS)); } else CaseVals.push_back(std::make_pair(LoVal, CS)); } } if (!HasDependentValue) { // If we don't have a default statement, check whether the // condition is constant. llvm::APSInt ConstantCondValue; bool HasConstantCond = false; if (!TheDefaultStmt) { Expr::EvalResult Result; HasConstantCond = CondExpr->EvaluateAsInt(Result, Context, Expr::SE_AllowSideEffects); if (Result.Val.isInt()) ConstantCondValue = Result.Val.getInt(); assert(!HasConstantCond || (ConstantCondValue.getBitWidth() == CondWidth && ConstantCondValue.isSigned() == CondIsSigned)); } bool ShouldCheckConstantCond = HasConstantCond; // Sort all the scalar case values so we can easily detect duplicates. llvm::stable_sort(CaseVals, CmpCaseVals); if (!CaseVals.empty()) { for (unsigned i = 0, e = CaseVals.size(); i != e; ++i) { if (ShouldCheckConstantCond && CaseVals[i].first == ConstantCondValue) ShouldCheckConstantCond = false; if (i != 0 && CaseVals[i].first == CaseVals[i-1].first) { // If we have a duplicate, report it. // First, determine if either case value has a name StringRef PrevString, CurrString; Expr *PrevCase = CaseVals[i-1].second->getLHS()->IgnoreParenCasts(); Expr *CurrCase = CaseVals[i].second->getLHS()->IgnoreParenCasts(); if (DeclRefExpr *DeclRef = dyn_cast(PrevCase)) { PrevString = DeclRef->getDecl()->getName(); } if (DeclRefExpr *DeclRef = dyn_cast(CurrCase)) { CurrString = DeclRef->getDecl()->getName(); } SmallString<16> CaseValStr; CaseVals[i-1].first.toString(CaseValStr); if (PrevString == CurrString) Diag(CaseVals[i].second->getLHS()->getBeginLoc(), diag::err_duplicate_case) << (PrevString.empty() ? StringRef(CaseValStr) : PrevString); else Diag(CaseVals[i].second->getLHS()->getBeginLoc(), diag::err_duplicate_case_differing_expr) << (PrevString.empty() ? StringRef(CaseValStr) : PrevString) << (CurrString.empty() ? StringRef(CaseValStr) : CurrString) << CaseValStr; Diag(CaseVals[i - 1].second->getLHS()->getBeginLoc(), diag::note_duplicate_case_prev); // FIXME: We really want to remove the bogus case stmt from the // substmt, but we have no way to do this right now. CaseListIsErroneous = true; } } } // Detect duplicate case ranges, which usually don't exist at all in // the first place. if (!CaseRanges.empty()) { // Sort all the case ranges by their low value so we can easily detect // overlaps between ranges. llvm::stable_sort(CaseRanges); // Scan the ranges, computing the high values and removing empty ranges. std::vector HiVals; for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) { llvm::APSInt &LoVal = CaseRanges[i].first; CaseStmt *CR = CaseRanges[i].second; Expr *Hi = CR->getRHS(); const Expr *HiBeforePromotion = Hi; GetTypeBeforeIntegralPromotion(HiBeforePromotion); llvm::APSInt HiVal = HiBeforePromotion->EvaluateKnownConstInt(Context); // Check the unconverted value is within the range of possible values of // the switch expression. checkCaseValue(*this, Hi->getBeginLoc(), HiVal, CondWidthBeforePromotion, CondIsSignedBeforePromotion); // Convert the value to the same width/sign as the condition. AdjustAPSInt(HiVal, CondWidth, CondIsSigned); // If the low value is bigger than the high value, the case is empty. if (LoVal > HiVal) { Diag(CR->getLHS()->getBeginLoc(), diag::warn_case_empty_range) << SourceRange(CR->getLHS()->getBeginLoc(), Hi->getEndLoc()); CaseRanges.erase(CaseRanges.begin()+i); --i; --e; continue; } if (ShouldCheckConstantCond && LoVal <= ConstantCondValue && ConstantCondValue <= HiVal) ShouldCheckConstantCond = false; HiVals.push_back(HiVal); } // Rescan the ranges, looking for overlap with singleton values and other // ranges. Since the range list is sorted, we only need to compare case // ranges with their neighbors. for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) { llvm::APSInt &CRLo = CaseRanges[i].first; llvm::APSInt &CRHi = HiVals[i]; CaseStmt *CR = CaseRanges[i].second; // Check to see whether the case range overlaps with any // singleton cases. CaseStmt *OverlapStmt = nullptr; llvm::APSInt OverlapVal(32); // Find the smallest value >= the lower bound. If I is in the // case range, then we have overlap. CaseValsTy::iterator I = llvm::lower_bound(CaseVals, CRLo, CaseCompareFunctor()); if (I != CaseVals.end() && I->first < CRHi) { OverlapVal = I->first; // Found overlap with scalar. OverlapStmt = I->second; } // Find the smallest value bigger than the upper bound. I = std::upper_bound(I, CaseVals.end(), CRHi, CaseCompareFunctor()); if (I != CaseVals.begin() && (I-1)->first >= CRLo) { OverlapVal = (I-1)->first; // Found overlap with scalar. OverlapStmt = (I-1)->second; } // Check to see if this case stmt overlaps with the subsequent // case range. if (i && CRLo <= HiVals[i-1]) { OverlapVal = HiVals[i-1]; // Found overlap with range. OverlapStmt = CaseRanges[i-1].second; } if (OverlapStmt) { // If we have a duplicate, report it. Diag(CR->getLHS()->getBeginLoc(), diag::err_duplicate_case) << OverlapVal.toString(10); Diag(OverlapStmt->getLHS()->getBeginLoc(), diag::note_duplicate_case_prev); // FIXME: We really want to remove the bogus case stmt from the // substmt, but we have no way to do this right now. CaseListIsErroneous = true; } } } // Complain if we have a constant condition and we didn't find a match. if (!CaseListIsErroneous && !CaseListIsIncomplete && ShouldCheckConstantCond) { // TODO: it would be nice if we printed enums as enums, chars as // chars, etc. Diag(CondExpr->getExprLoc(), diag::warn_missing_case_for_condition) << ConstantCondValue.toString(10) << CondExpr->getSourceRange(); } // Check to see if switch is over an Enum and handles all of its // values. We only issue a warning if there is not 'default:', but // we still do the analysis to preserve this information in the AST // (which can be used by flow-based analyes). // const EnumType *ET = CondTypeBeforePromotion->getAs(); // If switch has default case, then ignore it. if (!CaseListIsErroneous && !CaseListIsIncomplete && !HasConstantCond && ET && ET->getDecl()->isCompleteDefinition()) { const EnumDecl *ED = ET->getDecl(); EnumValsTy EnumVals; // Gather all enum values, set their type and sort them, // allowing easier comparison with CaseVals. for (auto *EDI : ED->enumerators()) { llvm::APSInt Val = EDI->getInitVal(); AdjustAPSInt(Val, CondWidth, CondIsSigned); EnumVals.push_back(std::make_pair(Val, EDI)); } llvm::stable_sort(EnumVals, CmpEnumVals); auto EI = EnumVals.begin(), EIEnd = std::unique(EnumVals.begin(), EnumVals.end(), EqEnumVals); // See which case values aren't in enum. for (CaseValsTy::const_iterator CI = CaseVals.begin(); CI != CaseVals.end(); CI++) { Expr *CaseExpr = CI->second->getLHS(); if (ShouldDiagnoseSwitchCaseNotInEnum(*this, ED, CaseExpr, EI, EIEnd, CI->first)) Diag(CaseExpr->getExprLoc(), diag::warn_not_in_enum) << CondTypeBeforePromotion; } // See which of case ranges aren't in enum EI = EnumVals.begin(); for (CaseRangesTy::const_iterator RI = CaseRanges.begin(); RI != CaseRanges.end(); RI++) { Expr *CaseExpr = RI->second->getLHS(); if (ShouldDiagnoseSwitchCaseNotInEnum(*this, ED, CaseExpr, EI, EIEnd, RI->first)) Diag(CaseExpr->getExprLoc(), diag::warn_not_in_enum) << CondTypeBeforePromotion; llvm::APSInt Hi = RI->second->getRHS()->EvaluateKnownConstInt(Context); AdjustAPSInt(Hi, CondWidth, CondIsSigned); CaseExpr = RI->second->getRHS(); if (ShouldDiagnoseSwitchCaseNotInEnum(*this, ED, CaseExpr, EI, EIEnd, Hi)) Diag(CaseExpr->getExprLoc(), diag::warn_not_in_enum) << CondTypeBeforePromotion; } // Check which enum vals aren't in switch auto CI = CaseVals.begin(); auto RI = CaseRanges.begin(); bool hasCasesNotInSwitch = false; SmallVector UnhandledNames; for (EI = EnumVals.begin(); EI != EIEnd; EI++) { // Don't warn about omitted unavailable EnumConstantDecls. switch (EI->second->getAvailability()) { case AR_Deprecated: // Omitting a deprecated constant is ok; it should never materialize. case AR_Unavailable: continue; case AR_NotYetIntroduced: // Partially available enum constants should be present. Note that we // suppress -Wunguarded-availability diagnostics for such uses. case AR_Available: break; } if (EI->second->hasAttr()) continue; // Drop unneeded case values while (CI != CaseVals.end() && CI->first < EI->first) CI++; if (CI != CaseVals.end() && CI->first == EI->first) continue; // Drop unneeded case ranges for (; RI != CaseRanges.end(); RI++) { llvm::APSInt Hi = RI->second->getRHS()->EvaluateKnownConstInt(Context); AdjustAPSInt(Hi, CondWidth, CondIsSigned); if (EI->first <= Hi) break; } if (RI == CaseRanges.end() || EI->first < RI->first) { hasCasesNotInSwitch = true; UnhandledNames.push_back(EI->second->getDeclName()); } } if (TheDefaultStmt && UnhandledNames.empty() && ED->isClosedNonFlag()) Diag(TheDefaultStmt->getDefaultLoc(), diag::warn_unreachable_default); // Produce a nice diagnostic if multiple values aren't handled. if (!UnhandledNames.empty()) { auto DB = Diag(CondExpr->getExprLoc(), TheDefaultStmt ? diag::warn_def_missing_case : diag::warn_missing_case) << (int)UnhandledNames.size(); for (size_t I = 0, E = std::min(UnhandledNames.size(), (size_t)3); I != E; ++I) DB << UnhandledNames[I]; } if (!hasCasesNotInSwitch) SS->setAllEnumCasesCovered(); } } if (BodyStmt) DiagnoseEmptyStmtBody(CondExpr->getEndLoc(), BodyStmt, diag::warn_empty_switch_body); // FIXME: If the case list was broken is some way, we don't have a good system // to patch it up. Instead, just return the whole substmt as broken. if (CaseListIsErroneous) return StmtError(); return SS; } void Sema::DiagnoseAssignmentEnum(QualType DstType, QualType SrcType, Expr *SrcExpr) { if (Diags.isIgnored(diag::warn_not_in_enum_assignment, SrcExpr->getExprLoc())) return; if (const EnumType *ET = DstType->getAs()) if (!Context.hasSameUnqualifiedType(SrcType, DstType) && SrcType->isIntegerType()) { if (!SrcExpr->isTypeDependent() && !SrcExpr->isValueDependent() && SrcExpr->isIntegerConstantExpr(Context)) { // Get the bitwidth of the enum value before promotions. unsigned DstWidth = Context.getIntWidth(DstType); bool DstIsSigned = DstType->isSignedIntegerOrEnumerationType(); llvm::APSInt RhsVal = SrcExpr->EvaluateKnownConstInt(Context); AdjustAPSInt(RhsVal, DstWidth, DstIsSigned); const EnumDecl *ED = ET->getDecl(); if (!ED->isClosed()) return; if (ED->hasAttr()) { if (!IsValueInFlagEnum(ED, RhsVal, true)) Diag(SrcExpr->getExprLoc(), diag::warn_not_in_enum_assignment) << DstType.getUnqualifiedType(); } else { typedef SmallVector, 64> EnumValsTy; EnumValsTy EnumVals; // Gather all enum values, set their type and sort them, // allowing easier comparison with rhs constant. for (auto *EDI : ED->enumerators()) { llvm::APSInt Val = EDI->getInitVal(); AdjustAPSInt(Val, DstWidth, DstIsSigned); EnumVals.push_back(std::make_pair(Val, EDI)); } if (EnumVals.empty()) return; llvm::stable_sort(EnumVals, CmpEnumVals); EnumValsTy::iterator EIend = std::unique(EnumVals.begin(), EnumVals.end(), EqEnumVals); // See which values aren't in the enum. EnumValsTy::const_iterator EI = EnumVals.begin(); while (EI != EIend && EI->first < RhsVal) EI++; if (EI == EIend || EI->first != RhsVal) { Diag(SrcExpr->getExprLoc(), diag::warn_not_in_enum_assignment) << DstType.getUnqualifiedType(); } } } } } StmtResult Sema::ActOnWhileStmt(SourceLocation WhileLoc, SourceLocation LParenLoc, ConditionResult Cond, SourceLocation RParenLoc, Stmt *Body) { if (Cond.isInvalid()) return StmtError(); auto CondVal = Cond.get(); CheckBreakContinueBinding(CondVal.second); if (CondVal.second && !Diags.isIgnored(diag::warn_comma_operator, CondVal.second->getExprLoc())) CommaVisitor(*this).Visit(CondVal.second); if (isa(Body)) getCurCompoundScope().setHasEmptyLoopBodies(); return WhileStmt::Create(Context, CondVal.first, CondVal.second, Body, WhileLoc, LParenLoc, RParenLoc); } StmtResult Sema::ActOnDoStmt(SourceLocation DoLoc, Stmt *Body, SourceLocation WhileLoc, SourceLocation CondLParen, Expr *Cond, SourceLocation CondRParen) { assert(Cond && "ActOnDoStmt(): missing expression"); CheckBreakContinueBinding(Cond); ExprResult CondResult = CheckBooleanCondition(DoLoc, Cond); if (CondResult.isInvalid()) return StmtError(); Cond = CondResult.get(); CondResult = ActOnFinishFullExpr(Cond, DoLoc, /*DiscardedValue*/ false); if (CondResult.isInvalid()) return StmtError(); Cond = CondResult.get(); // Only call the CommaVisitor for C89 due to differences in scope flags. if (Cond && !getLangOpts().C99 && !getLangOpts().CPlusPlus && !Diags.isIgnored(diag::warn_comma_operator, Cond->getExprLoc())) CommaVisitor(*this).Visit(Cond); return new (Context) DoStmt(Body, Cond, DoLoc, WhileLoc, CondRParen); } namespace { // Use SetVector since the diagnostic cares about the ordering of the Decl's. using DeclSetVector = llvm::SetVector, llvm::SmallPtrSet>; // This visitor will traverse a conditional statement and store all // the evaluated decls into a vector. Simple is set to true if none // of the excluded constructs are used. class DeclExtractor : public EvaluatedExprVisitor { DeclSetVector &Decls; SmallVectorImpl &Ranges; bool Simple; public: typedef EvaluatedExprVisitor Inherited; DeclExtractor(Sema &S, DeclSetVector &Decls, SmallVectorImpl &Ranges) : Inherited(S.Context), Decls(Decls), Ranges(Ranges), Simple(true) {} bool isSimple() { return Simple; } // Replaces the method in EvaluatedExprVisitor. void VisitMemberExpr(MemberExpr* E) { Simple = false; } // Any Stmt not explicitly listed will cause the condition to be marked // complex. void VisitStmt(Stmt *S) { Simple = false; } void VisitBinaryOperator(BinaryOperator *E) { Visit(E->getLHS()); Visit(E->getRHS()); } void VisitCastExpr(CastExpr *E) { Visit(E->getSubExpr()); } void VisitUnaryOperator(UnaryOperator *E) { // Skip checking conditionals with derefernces. if (E->getOpcode() == UO_Deref) Simple = false; else Visit(E->getSubExpr()); } void VisitConditionalOperator(ConditionalOperator *E) { Visit(E->getCond()); Visit(E->getTrueExpr()); Visit(E->getFalseExpr()); } void VisitParenExpr(ParenExpr *E) { Visit(E->getSubExpr()); } void VisitBinaryConditionalOperator(BinaryConditionalOperator *E) { Visit(E->getOpaqueValue()->getSourceExpr()); Visit(E->getFalseExpr()); } void VisitIntegerLiteral(IntegerLiteral *E) { } void VisitFloatingLiteral(FloatingLiteral *E) { } void VisitCXXBoolLiteralExpr(CXXBoolLiteralExpr *E) { } void VisitCharacterLiteral(CharacterLiteral *E) { } void VisitGNUNullExpr(GNUNullExpr *E) { } void VisitImaginaryLiteral(ImaginaryLiteral *E) { } void VisitDeclRefExpr(DeclRefExpr *E) { VarDecl *VD = dyn_cast(E->getDecl()); if (!VD) { // Don't allow unhandled Decl types. Simple = false; return; } Ranges.push_back(E->getSourceRange()); Decls.insert(VD); } }; // end class DeclExtractor // DeclMatcher checks to see if the decls are used in a non-evaluated // context. class DeclMatcher : public EvaluatedExprVisitor { DeclSetVector &Decls; bool FoundDecl; public: typedef EvaluatedExprVisitor Inherited; DeclMatcher(Sema &S, DeclSetVector &Decls, Stmt *Statement) : Inherited(S.Context), Decls(Decls), FoundDecl(false) { if (!Statement) return; Visit(Statement); } void VisitReturnStmt(ReturnStmt *S) { FoundDecl = true; } void VisitBreakStmt(BreakStmt *S) { FoundDecl = true; } void VisitGotoStmt(GotoStmt *S) { FoundDecl = true; } void VisitCastExpr(CastExpr *E) { if (E->getCastKind() == CK_LValueToRValue) CheckLValueToRValueCast(E->getSubExpr()); else Visit(E->getSubExpr()); } void CheckLValueToRValueCast(Expr *E) { E = E->IgnoreParenImpCasts(); if (isa(E)) { return; } if (ConditionalOperator *CO = dyn_cast(E)) { Visit(CO->getCond()); CheckLValueToRValueCast(CO->getTrueExpr()); CheckLValueToRValueCast(CO->getFalseExpr()); return; } if (BinaryConditionalOperator *BCO = dyn_cast(E)) { CheckLValueToRValueCast(BCO->getOpaqueValue()->getSourceExpr()); CheckLValueToRValueCast(BCO->getFalseExpr()); return; } Visit(E); } void VisitDeclRefExpr(DeclRefExpr *E) { if (VarDecl *VD = dyn_cast(E->getDecl())) if (Decls.count(VD)) FoundDecl = true; } void VisitPseudoObjectExpr(PseudoObjectExpr *POE) { // Only need to visit the semantics for POE. // SyntaticForm doesn't really use the Decal. for (auto *S : POE->semantics()) { if (auto *OVE = dyn_cast(S)) // Look past the OVE into the expression it binds. Visit(OVE->getSourceExpr()); else Visit(S); } } bool FoundDeclInUse() { return FoundDecl; } }; // end class DeclMatcher void CheckForLoopConditionalStatement(Sema &S, Expr *Second, Expr *Third, Stmt *Body) { // Condition is empty if (!Second) return; if (S.Diags.isIgnored(diag::warn_variables_not_in_loop_body, Second->getBeginLoc())) return; PartialDiagnostic PDiag = S.PDiag(diag::warn_variables_not_in_loop_body); DeclSetVector Decls; SmallVector Ranges; DeclExtractor DE(S, Decls, Ranges); DE.Visit(Second); // Don't analyze complex conditionals. if (!DE.isSimple()) return; // No decls found. if (Decls.size() == 0) return; // Don't warn on volatile, static, or global variables. for (auto *VD : Decls) if (VD->getType().isVolatileQualified() || VD->hasGlobalStorage()) return; if (DeclMatcher(S, Decls, Second).FoundDeclInUse() || DeclMatcher(S, Decls, Third).FoundDeclInUse() || DeclMatcher(S, Decls, Body).FoundDeclInUse()) return; // Load decl names into diagnostic. if (Decls.size() > 4) { PDiag << 0; } else { PDiag << (unsigned)Decls.size(); for (auto *VD : Decls) PDiag << VD->getDeclName(); } for (auto Range : Ranges) PDiag << Range; S.Diag(Ranges.begin()->getBegin(), PDiag); } // If Statement is an incemement or decrement, return true and sets the // variables Increment and DRE. bool ProcessIterationStmt(Sema &S, Stmt* Statement, bool &Increment, DeclRefExpr *&DRE) { if (auto Cleanups = dyn_cast(Statement)) if (!Cleanups->cleanupsHaveSideEffects()) Statement = Cleanups->getSubExpr(); if (UnaryOperator *UO = dyn_cast(Statement)) { switch (UO->getOpcode()) { default: return false; case UO_PostInc: case UO_PreInc: Increment = true; break; case UO_PostDec: case UO_PreDec: Increment = false; break; } DRE = dyn_cast(UO->getSubExpr()); return DRE; } if (CXXOperatorCallExpr *Call = dyn_cast(Statement)) { FunctionDecl *FD = Call->getDirectCallee(); if (!FD || !FD->isOverloadedOperator()) return false; switch (FD->getOverloadedOperator()) { default: return false; case OO_PlusPlus: Increment = true; break; case OO_MinusMinus: Increment = false; break; } DRE = dyn_cast(Call->getArg(0)); return DRE; } return false; } // A visitor to determine if a continue or break statement is a // subexpression. class BreakContinueFinder : public ConstEvaluatedExprVisitor { SourceLocation BreakLoc; SourceLocation ContinueLoc; bool InSwitch = false; public: BreakContinueFinder(Sema &S, const Stmt* Body) : Inherited(S.Context) { Visit(Body); } typedef ConstEvaluatedExprVisitor Inherited; void VisitContinueStmt(const ContinueStmt* E) { ContinueLoc = E->getContinueLoc(); } void VisitBreakStmt(const BreakStmt* E) { if (!InSwitch) BreakLoc = E->getBreakLoc(); } void VisitSwitchStmt(const SwitchStmt* S) { if (const Stmt *Init = S->getInit()) Visit(Init); if (const Stmt *CondVar = S->getConditionVariableDeclStmt()) Visit(CondVar); if (const Stmt *Cond = S->getCond()) Visit(Cond); // Don't return break statements from the body of a switch. InSwitch = true; if (const Stmt *Body = S->getBody()) Visit(Body); InSwitch = false; } void VisitForStmt(const ForStmt *S) { // Only visit the init statement of a for loop; the body // has a different break/continue scope. if (const Stmt *Init = S->getInit()) Visit(Init); } void VisitWhileStmt(const WhileStmt *) { // Do nothing; the children of a while loop have a different // break/continue scope. } void VisitDoStmt(const DoStmt *) { // Do nothing; the children of a while loop have a different // break/continue scope. } void VisitCXXForRangeStmt(const CXXForRangeStmt *S) { // Only visit the initialization of a for loop; the body // has a different break/continue scope. if (const Stmt *Init = S->getInit()) Visit(Init); if (const Stmt *Range = S->getRangeStmt()) Visit(Range); if (const Stmt *Begin = S->getBeginStmt()) Visit(Begin); if (const Stmt *End = S->getEndStmt()) Visit(End); } void VisitObjCForCollectionStmt(const ObjCForCollectionStmt *S) { // Only visit the initialization of a for loop; the body // has a different break/continue scope. if (const Stmt *Element = S->getElement()) Visit(Element); if (const Stmt *Collection = S->getCollection()) Visit(Collection); } bool ContinueFound() { return ContinueLoc.isValid(); } bool BreakFound() { return BreakLoc.isValid(); } SourceLocation GetContinueLoc() { return ContinueLoc; } SourceLocation GetBreakLoc() { return BreakLoc; } }; // end class BreakContinueFinder // Emit a warning when a loop increment/decrement appears twice per loop // iteration. The conditions which trigger this warning are: // 1) The last statement in the loop body and the third expression in the // for loop are both increment or both decrement of the same variable // 2) No continue statements in the loop body. void CheckForRedundantIteration(Sema &S, Expr *Third, Stmt *Body) { // Return when there is nothing to check. if (!Body || !Third) return; if (S.Diags.isIgnored(diag::warn_redundant_loop_iteration, Third->getBeginLoc())) return; // Get the last statement from the loop body. CompoundStmt *CS = dyn_cast(Body); if (!CS || CS->body_empty()) return; Stmt *LastStmt = CS->body_back(); if (!LastStmt) return; bool LoopIncrement, LastIncrement; DeclRefExpr *LoopDRE, *LastDRE; if (!ProcessIterationStmt(S, Third, LoopIncrement, LoopDRE)) return; if (!ProcessIterationStmt(S, LastStmt, LastIncrement, LastDRE)) return; // Check that the two statements are both increments or both decrements // on the same variable. if (LoopIncrement != LastIncrement || LoopDRE->getDecl() != LastDRE->getDecl()) return; if (BreakContinueFinder(S, Body).ContinueFound()) return; S.Diag(LastDRE->getLocation(), diag::warn_redundant_loop_iteration) << LastDRE->getDecl() << LastIncrement; S.Diag(LoopDRE->getLocation(), diag::note_loop_iteration_here) << LoopIncrement; } } // end namespace void Sema::CheckBreakContinueBinding(Expr *E) { if (!E || getLangOpts().CPlusPlus) return; BreakContinueFinder BCFinder(*this, E); Scope *BreakParent = CurScope->getBreakParent(); if (BCFinder.BreakFound() && BreakParent) { if (BreakParent->getFlags() & Scope::SwitchScope) { Diag(BCFinder.GetBreakLoc(), diag::warn_break_binds_to_switch); } else { Diag(BCFinder.GetBreakLoc(), diag::warn_loop_ctrl_binds_to_inner) << "break"; } } else if (BCFinder.ContinueFound() && CurScope->getContinueParent()) { Diag(BCFinder.GetContinueLoc(), diag::warn_loop_ctrl_binds_to_inner) << "continue"; } } StmtResult Sema::ActOnForStmt(SourceLocation ForLoc, SourceLocation LParenLoc, Stmt *First, ConditionResult Second, FullExprArg third, SourceLocation RParenLoc, Stmt *Body) { if (Second.isInvalid()) return StmtError(); if (!getLangOpts().CPlusPlus) { if (DeclStmt *DS = dyn_cast_or_null(First)) { // C99 6.8.5p3: The declaration part of a 'for' statement shall only // declare identifiers for objects having storage class 'auto' or // 'register'. const Decl *NonVarSeen = nullptr; bool VarDeclSeen = false; for (auto *DI : DS->decls()) { if (VarDecl *VD = dyn_cast(DI)) { VarDeclSeen = true; if (VD->isLocalVarDecl() && !VD->hasLocalStorage()) { Diag(DI->getLocation(), diag::err_non_local_variable_decl_in_for); DI->setInvalidDecl(); } } else if (!NonVarSeen) { // Keep track of the first non-variable declaration we saw so that // we can diagnose if we don't see any variable declarations. This // covers a case like declaring a typedef, function, or structure // type rather than a variable. NonVarSeen = DI; } } // Diagnose if we saw a non-variable declaration but no variable // declarations. if (NonVarSeen && !VarDeclSeen) Diag(NonVarSeen->getLocation(), diag::err_non_variable_decl_in_for); } } CheckBreakContinueBinding(Second.get().second); CheckBreakContinueBinding(third.get()); if (!Second.get().first) CheckForLoopConditionalStatement(*this, Second.get().second, third.get(), Body); CheckForRedundantIteration(*this, third.get(), Body); if (Second.get().second && !Diags.isIgnored(diag::warn_comma_operator, Second.get().second->getExprLoc())) CommaVisitor(*this).Visit(Second.get().second); Expr *Third = third.release().getAs(); if (isa(Body)) getCurCompoundScope().setHasEmptyLoopBodies(); return new (Context) ForStmt(Context, First, Second.get().second, Second.get().first, Third, Body, ForLoc, LParenLoc, RParenLoc); } /// In an Objective C collection iteration statement: /// for (x in y) /// x can be an arbitrary l-value expression. Bind it up as a /// full-expression. StmtResult Sema::ActOnForEachLValueExpr(Expr *E) { // Reduce placeholder expressions here. Note that this rejects the // use of pseudo-object l-values in this position. ExprResult result = CheckPlaceholderExpr(E); if (result.isInvalid()) return StmtError(); E = result.get(); ExprResult FullExpr = ActOnFinishFullExpr(E, /*DiscardedValue*/ false); if (FullExpr.isInvalid()) return StmtError(); return StmtResult(static_cast(FullExpr.get())); } ExprResult Sema::CheckObjCForCollectionOperand(SourceLocation forLoc, Expr *collection) { if (!collection) return ExprError(); ExprResult result = CorrectDelayedTyposInExpr(collection); if (!result.isUsable()) return ExprError(); collection = result.get(); // Bail out early if we've got a type-dependent expression. if (collection->isTypeDependent()) return collection; // Perform normal l-value conversion. result = DefaultFunctionArrayLvalueConversion(collection); if (result.isInvalid()) return ExprError(); collection = result.get(); // The operand needs to have object-pointer type. // TODO: should we do a contextual conversion? const ObjCObjectPointerType *pointerType = collection->getType()->getAs(); if (!pointerType) return Diag(forLoc, diag::err_collection_expr_type) << collection->getType() << collection->getSourceRange(); // Check that the operand provides // - countByEnumeratingWithState:objects:count: const ObjCObjectType *objectType = pointerType->getObjectType(); ObjCInterfaceDecl *iface = objectType->getInterface(); // If we have a forward-declared type, we can't do this check. // Under ARC, it is an error not to have a forward-declared class. if (iface && (getLangOpts().ObjCAutoRefCount ? RequireCompleteType(forLoc, QualType(objectType, 0), diag::err_arc_collection_forward, collection) : !isCompleteType(forLoc, QualType(objectType, 0)))) { // Otherwise, if we have any useful type information, check that // the type declares the appropriate method. } else if (iface || !objectType->qual_empty()) { IdentifierInfo *selectorIdents[] = { &Context.Idents.get("countByEnumeratingWithState"), &Context.Idents.get("objects"), &Context.Idents.get("count") }; Selector selector = Context.Selectors.getSelector(3, &selectorIdents[0]); ObjCMethodDecl *method = nullptr; // If there's an interface, look in both the public and private APIs. if (iface) { method = iface->lookupInstanceMethod(selector); if (!method) method = iface->lookupPrivateMethod(selector); } // Also check protocol qualifiers. if (!method) method = LookupMethodInQualifiedType(selector, pointerType, /*instance*/ true); // If we didn't find it anywhere, give up. if (!method) { Diag(forLoc, diag::warn_collection_expr_type) << collection->getType() << selector << collection->getSourceRange(); } // TODO: check for an incompatible signature? } // Wrap up any cleanups in the expression. return collection; } StmtResult Sema::ActOnObjCForCollectionStmt(SourceLocation ForLoc, Stmt *First, Expr *collection, SourceLocation RParenLoc) { setFunctionHasBranchProtectedScope(); ExprResult CollectionExprResult = CheckObjCForCollectionOperand(ForLoc, collection); if (First) { QualType FirstType; if (DeclStmt *DS = dyn_cast(First)) { if (!DS->isSingleDecl()) return StmtError(Diag((*DS->decl_begin())->getLocation(), diag::err_toomany_element_decls)); VarDecl *D = dyn_cast(DS->getSingleDecl()); if (!D || D->isInvalidDecl()) return StmtError(); FirstType = D->getType(); // C99 6.8.5p3: The declaration part of a 'for' statement shall only // declare identifiers for objects having storage class 'auto' or // 'register'. if (!D->hasLocalStorage()) return StmtError(Diag(D->getLocation(), diag::err_non_local_variable_decl_in_for)); // If the type contained 'auto', deduce the 'auto' to 'id'. if (FirstType->getContainedAutoType()) { OpaqueValueExpr OpaqueId(D->getLocation(), Context.getObjCIdType(), VK_RValue); Expr *DeducedInit = &OpaqueId; if (DeduceAutoType(D->getTypeSourceInfo(), DeducedInit, FirstType) == DAR_Failed) DiagnoseAutoDeductionFailure(D, DeducedInit); if (FirstType.isNull()) { D->setInvalidDecl(); return StmtError(); } D->setType(FirstType); if (!inTemplateInstantiation()) { SourceLocation Loc = D->getTypeSourceInfo()->getTypeLoc().getBeginLoc(); Diag(Loc, diag::warn_auto_var_is_id) << D->getDeclName(); } } } else { Expr *FirstE = cast(First); if (!FirstE->isTypeDependent() && !FirstE->isLValue()) return StmtError( Diag(First->getBeginLoc(), diag::err_selector_element_not_lvalue) << First->getSourceRange()); FirstType = static_cast(First)->getType(); if (FirstType.isConstQualified()) Diag(ForLoc, diag::err_selector_element_const_type) << FirstType << First->getSourceRange(); } if (!FirstType->isDependentType() && !FirstType->isObjCObjectPointerType() && !FirstType->isBlockPointerType()) return StmtError(Diag(ForLoc, diag::err_selector_element_type) << FirstType << First->getSourceRange()); } if (CollectionExprResult.isInvalid()) return StmtError(); CollectionExprResult = ActOnFinishFullExpr(CollectionExprResult.get(), /*DiscardedValue*/ false); if (CollectionExprResult.isInvalid()) return StmtError(); return new (Context) ObjCForCollectionStmt(First, CollectionExprResult.get(), nullptr, ForLoc, RParenLoc); } /// Finish building a variable declaration for a for-range statement. /// \return true if an error occurs. static bool FinishForRangeVarDecl(Sema &SemaRef, VarDecl *Decl, Expr *Init, SourceLocation Loc, int DiagID) { if (Decl->getType()->isUndeducedType()) { ExprResult Res = SemaRef.CorrectDelayedTyposInExpr(Init); if (!Res.isUsable()) { Decl->setInvalidDecl(); return true; } Init = Res.get(); } // Deduce the type for the iterator variable now rather than leaving it to // AddInitializerToDecl, so we can produce a more suitable diagnostic. QualType InitType; if ((!isa(Init) && Init->getType()->isVoidType()) || SemaRef.DeduceAutoType(Decl->getTypeSourceInfo(), Init, InitType) == Sema::DAR_Failed) SemaRef.Diag(Loc, DiagID) << Init->getType(); if (InitType.isNull()) { Decl->setInvalidDecl(); return true; } Decl->setType(InitType); // In ARC, infer lifetime. // FIXME: ARC may want to turn this into 'const __unsafe_unretained' if // we're doing the equivalent of fast iteration. if (SemaRef.getLangOpts().ObjCAutoRefCount && SemaRef.inferObjCARCLifetime(Decl)) Decl->setInvalidDecl(); SemaRef.AddInitializerToDecl(Decl, Init, /*DirectInit=*/false); SemaRef.FinalizeDeclaration(Decl); SemaRef.CurContext->addHiddenDecl(Decl); return false; } namespace { // An enum to represent whether something is dealing with a call to begin() // or a call to end() in a range-based for loop. enum BeginEndFunction { BEF_begin, BEF_end }; /// Produce a note indicating which begin/end function was implicitly called /// by a C++11 for-range statement. This is often not obvious from the code, /// nor from the diagnostics produced when analysing the implicit expressions /// required in a for-range statement. void NoteForRangeBeginEndFunction(Sema &SemaRef, Expr *E, BeginEndFunction BEF) { CallExpr *CE = dyn_cast(E); if (!CE) return; FunctionDecl *D = dyn_cast(CE->getCalleeDecl()); if (!D) return; SourceLocation Loc = D->getLocation(); std::string Description; bool IsTemplate = false; if (FunctionTemplateDecl *FunTmpl = D->getPrimaryTemplate()) { Description = SemaRef.getTemplateArgumentBindingsText( FunTmpl->getTemplateParameters(), *D->getTemplateSpecializationArgs()); IsTemplate = true; } SemaRef.Diag(Loc, diag::note_for_range_begin_end) << BEF << IsTemplate << Description << E->getType(); } /// Build a variable declaration for a for-range statement. VarDecl *BuildForRangeVarDecl(Sema &SemaRef, SourceLocation Loc, QualType Type, StringRef Name) { DeclContext *DC = SemaRef.CurContext; IdentifierInfo *II = &SemaRef.PP.getIdentifierTable().get(Name); TypeSourceInfo *TInfo = SemaRef.Context.getTrivialTypeSourceInfo(Type, Loc); VarDecl *Decl = VarDecl::Create(SemaRef.Context, DC, Loc, Loc, II, Type, TInfo, SC_None); Decl->setImplicit(); return Decl; } } static bool ObjCEnumerationCollection(Expr *Collection) { return !Collection->isTypeDependent() && Collection->getType()->getAs() != nullptr; } /// ActOnCXXForRangeStmt - Check and build a C++11 for-range statement. /// /// C++11 [stmt.ranged]: /// A range-based for statement is equivalent to /// /// { /// auto && __range = range-init; /// for ( auto __begin = begin-expr, /// __end = end-expr; /// __begin != __end; /// ++__begin ) { /// for-range-declaration = *__begin; /// statement /// } /// } /// /// The body of the loop is not available yet, since it cannot be analysed until /// we have determined the type of the for-range-declaration. StmtResult Sema::ActOnCXXForRangeStmt(Scope *S, SourceLocation ForLoc, SourceLocation CoawaitLoc, Stmt *InitStmt, Stmt *First, SourceLocation ColonLoc, Expr *Range, SourceLocation RParenLoc, BuildForRangeKind Kind) { if (!First) return StmtError(); if (Range && ObjCEnumerationCollection(Range)) { // FIXME: Support init-statements in Objective-C++20 ranged for statement. if (InitStmt) return Diag(InitStmt->getBeginLoc(), diag::err_objc_for_range_init_stmt) << InitStmt->getSourceRange(); return ActOnObjCForCollectionStmt(ForLoc, First, Range, RParenLoc); } DeclStmt *DS = dyn_cast(First); assert(DS && "first part of for range not a decl stmt"); if (!DS->isSingleDecl()) { Diag(DS->getBeginLoc(), diag::err_type_defined_in_for_range); return StmtError(); } // This function is responsible for attaching an initializer to LoopVar. We // must call ActOnInitializerError if we fail to do so. Decl *LoopVar = DS->getSingleDecl(); if (LoopVar->isInvalidDecl() || !Range || DiagnoseUnexpandedParameterPack(Range, UPPC_Expression)) { ActOnInitializerError(LoopVar); return StmtError(); } // Build the coroutine state immediately and not later during template // instantiation if (!CoawaitLoc.isInvalid()) { if (!ActOnCoroutineBodyStart(S, CoawaitLoc, "co_await")) { ActOnInitializerError(LoopVar); return StmtError(); } } // Build auto && __range = range-init // Divide by 2, since the variables are in the inner scope (loop body). const auto DepthStr = std::to_string(S->getDepth() / 2); SourceLocation RangeLoc = Range->getBeginLoc(); VarDecl *RangeVar = BuildForRangeVarDecl(*this, RangeLoc, Context.getAutoRRefDeductType(), std::string("__range") + DepthStr); if (FinishForRangeVarDecl(*this, RangeVar, Range, RangeLoc, diag::err_for_range_deduction_failure)) { ActOnInitializerError(LoopVar); return StmtError(); } // Claim the type doesn't contain auto: we've already done the checking. DeclGroupPtrTy RangeGroup = BuildDeclaratorGroup(MutableArrayRef((Decl **)&RangeVar, 1)); StmtResult RangeDecl = ActOnDeclStmt(RangeGroup, RangeLoc, RangeLoc); if (RangeDecl.isInvalid()) { ActOnInitializerError(LoopVar); return StmtError(); } StmtResult R = BuildCXXForRangeStmt( ForLoc, CoawaitLoc, InitStmt, ColonLoc, RangeDecl.get(), /*BeginStmt=*/nullptr, /*EndStmt=*/nullptr, /*Cond=*/nullptr, /*Inc=*/nullptr, DS, RParenLoc, Kind); if (R.isInvalid()) { ActOnInitializerError(LoopVar); return StmtError(); } return R; } /// Create the initialization, compare, and increment steps for /// the range-based for loop expression. /// This function does not handle array-based for loops, /// which are created in Sema::BuildCXXForRangeStmt. /// /// \returns a ForRangeStatus indicating success or what kind of error occurred. /// BeginExpr and EndExpr are set and FRS_Success is returned on success; /// CandidateSet and BEF are set and some non-success value is returned on /// failure. static Sema::ForRangeStatus BuildNonArrayForRange(Sema &SemaRef, Expr *BeginRange, Expr *EndRange, QualType RangeType, VarDecl *BeginVar, VarDecl *EndVar, SourceLocation ColonLoc, SourceLocation CoawaitLoc, OverloadCandidateSet *CandidateSet, ExprResult *BeginExpr, ExprResult *EndExpr, BeginEndFunction *BEF) { DeclarationNameInfo BeginNameInfo( &SemaRef.PP.getIdentifierTable().get("begin"), ColonLoc); DeclarationNameInfo EndNameInfo(&SemaRef.PP.getIdentifierTable().get("end"), ColonLoc); LookupResult BeginMemberLookup(SemaRef, BeginNameInfo, Sema::LookupMemberName); LookupResult EndMemberLookup(SemaRef, EndNameInfo, Sema::LookupMemberName); auto BuildBegin = [&] { *BEF = BEF_begin; Sema::ForRangeStatus RangeStatus = SemaRef.BuildForRangeBeginEndCall(ColonLoc, ColonLoc, BeginNameInfo, BeginMemberLookup, CandidateSet, BeginRange, BeginExpr); if (RangeStatus != Sema::FRS_Success) { if (RangeStatus == Sema::FRS_DiagnosticIssued) SemaRef.Diag(BeginRange->getBeginLoc(), diag::note_in_for_range) << ColonLoc << BEF_begin << BeginRange->getType(); return RangeStatus; } if (!CoawaitLoc.isInvalid()) { // FIXME: getCurScope() should not be used during template instantiation. // We should pick up the set of unqualified lookup results for operator // co_await during the initial parse. *BeginExpr = SemaRef.ActOnCoawaitExpr(SemaRef.getCurScope(), ColonLoc, BeginExpr->get()); if (BeginExpr->isInvalid()) return Sema::FRS_DiagnosticIssued; } if (FinishForRangeVarDecl(SemaRef, BeginVar, BeginExpr->get(), ColonLoc, diag::err_for_range_iter_deduction_failure)) { NoteForRangeBeginEndFunction(SemaRef, BeginExpr->get(), *BEF); return Sema::FRS_DiagnosticIssued; } return Sema::FRS_Success; }; auto BuildEnd = [&] { *BEF = BEF_end; Sema::ForRangeStatus RangeStatus = SemaRef.BuildForRangeBeginEndCall(ColonLoc, ColonLoc, EndNameInfo, EndMemberLookup, CandidateSet, EndRange, EndExpr); if (RangeStatus != Sema::FRS_Success) { if (RangeStatus == Sema::FRS_DiagnosticIssued) SemaRef.Diag(EndRange->getBeginLoc(), diag::note_in_for_range) << ColonLoc << BEF_end << EndRange->getType(); return RangeStatus; } if (FinishForRangeVarDecl(SemaRef, EndVar, EndExpr->get(), ColonLoc, diag::err_for_range_iter_deduction_failure)) { NoteForRangeBeginEndFunction(SemaRef, EndExpr->get(), *BEF); return Sema::FRS_DiagnosticIssued; } return Sema::FRS_Success; }; if (CXXRecordDecl *D = RangeType->getAsCXXRecordDecl()) { // - if _RangeT is a class type, the unqualified-ids begin and end are // looked up in the scope of class _RangeT as if by class member access // lookup (3.4.5), and if either (or both) finds at least one // declaration, begin-expr and end-expr are __range.begin() and // __range.end(), respectively; SemaRef.LookupQualifiedName(BeginMemberLookup, D); if (BeginMemberLookup.isAmbiguous()) return Sema::FRS_DiagnosticIssued; SemaRef.LookupQualifiedName(EndMemberLookup, D); if (EndMemberLookup.isAmbiguous()) return Sema::FRS_DiagnosticIssued; if (BeginMemberLookup.empty() != EndMemberLookup.empty()) { // Look up the non-member form of the member we didn't find, first. // This way we prefer a "no viable 'end'" diagnostic over a "i found // a 'begin' but ignored it because there was no member 'end'" // diagnostic. auto BuildNonmember = [&]( BeginEndFunction BEFFound, LookupResult &Found, llvm::function_ref BuildFound, llvm::function_ref BuildNotFound) { LookupResult OldFound = std::move(Found); Found.clear(); if (Sema::ForRangeStatus Result = BuildNotFound()) return Result; switch (BuildFound()) { case Sema::FRS_Success: return Sema::FRS_Success; case Sema::FRS_NoViableFunction: CandidateSet->NoteCandidates( PartialDiagnosticAt(BeginRange->getBeginLoc(), SemaRef.PDiag(diag::err_for_range_invalid) << BeginRange->getType() << BEFFound), SemaRef, OCD_AllCandidates, BeginRange); LLVM_FALLTHROUGH; case Sema::FRS_DiagnosticIssued: for (NamedDecl *D : OldFound) { SemaRef.Diag(D->getLocation(), diag::note_for_range_member_begin_end_ignored) << BeginRange->getType() << BEFFound; } return Sema::FRS_DiagnosticIssued; } llvm_unreachable("unexpected ForRangeStatus"); }; if (BeginMemberLookup.empty()) return BuildNonmember(BEF_end, EndMemberLookup, BuildEnd, BuildBegin); return BuildNonmember(BEF_begin, BeginMemberLookup, BuildBegin, BuildEnd); } } else { // - otherwise, begin-expr and end-expr are begin(__range) and // end(__range), respectively, where begin and end are looked up with // argument-dependent lookup (3.4.2). For the purposes of this name // lookup, namespace std is an associated namespace. } if (Sema::ForRangeStatus Result = BuildBegin()) return Result; return BuildEnd(); } /// Speculatively attempt to dereference an invalid range expression. /// If the attempt fails, this function will return a valid, null StmtResult /// and emit no diagnostics. static StmtResult RebuildForRangeWithDereference(Sema &SemaRef, Scope *S, SourceLocation ForLoc, SourceLocation CoawaitLoc, Stmt *InitStmt, Stmt *LoopVarDecl, SourceLocation ColonLoc, Expr *Range, SourceLocation RangeLoc, SourceLocation RParenLoc) { // Determine whether we can rebuild the for-range statement with a // dereferenced range expression. ExprResult AdjustedRange; { Sema::SFINAETrap Trap(SemaRef); AdjustedRange = SemaRef.BuildUnaryOp(S, RangeLoc, UO_Deref, Range); if (AdjustedRange.isInvalid()) return StmtResult(); StmtResult SR = SemaRef.ActOnCXXForRangeStmt( S, ForLoc, CoawaitLoc, InitStmt, LoopVarDecl, ColonLoc, AdjustedRange.get(), RParenLoc, Sema::BFRK_Check); if (SR.isInvalid()) return StmtResult(); } // The attempt to dereference worked well enough that it could produce a valid // loop. Produce a fixit, and rebuild the loop with diagnostics enabled, in // case there are any other (non-fatal) problems with it. SemaRef.Diag(RangeLoc, diag::err_for_range_dereference) << Range->getType() << FixItHint::CreateInsertion(RangeLoc, "*"); return SemaRef.ActOnCXXForRangeStmt( S, ForLoc, CoawaitLoc, InitStmt, LoopVarDecl, ColonLoc, AdjustedRange.get(), RParenLoc, Sema::BFRK_Rebuild); } /// BuildCXXForRangeStmt - Build or instantiate a C++11 for-range statement. StmtResult Sema::BuildCXXForRangeStmt(SourceLocation ForLoc, SourceLocation CoawaitLoc, Stmt *InitStmt, SourceLocation ColonLoc, Stmt *RangeDecl, Stmt *Begin, Stmt *End, Expr *Cond, Expr *Inc, Stmt *LoopVarDecl, SourceLocation RParenLoc, BuildForRangeKind Kind) { // FIXME: This should not be used during template instantiation. We should // pick up the set of unqualified lookup results for the != and + operators // in the initial parse. // // Testcase (accepts-invalid): // template void f() { for (auto x : T()) {} } // namespace N { struct X { X begin(); X end(); int operator*(); }; } // bool operator!=(N::X, N::X); void operator++(N::X); // void g() { f(); } Scope *S = getCurScope(); DeclStmt *RangeDS = cast(RangeDecl); VarDecl *RangeVar = cast(RangeDS->getSingleDecl()); QualType RangeVarType = RangeVar->getType(); DeclStmt *LoopVarDS = cast(LoopVarDecl); VarDecl *LoopVar = cast(LoopVarDS->getSingleDecl()); StmtResult BeginDeclStmt = Begin; StmtResult EndDeclStmt = End; ExprResult NotEqExpr = Cond, IncrExpr = Inc; if (RangeVarType->isDependentType()) { // The range is implicitly used as a placeholder when it is dependent. RangeVar->markUsed(Context); // Deduce any 'auto's in the loop variable as 'DependentTy'. We'll fill // them in properly when we instantiate the loop. if (!LoopVar->isInvalidDecl() && Kind != BFRK_Check) { if (auto *DD = dyn_cast(LoopVar)) for (auto *Binding : DD->bindings()) Binding->setType(Context.DependentTy); LoopVar->setType(SubstAutoType(LoopVar->getType(), Context.DependentTy)); } } else if (!BeginDeclStmt.get()) { SourceLocation RangeLoc = RangeVar->getLocation(); const QualType RangeVarNonRefType = RangeVarType.getNonReferenceType(); ExprResult BeginRangeRef = BuildDeclRefExpr(RangeVar, RangeVarNonRefType, VK_LValue, ColonLoc); if (BeginRangeRef.isInvalid()) return StmtError(); ExprResult EndRangeRef = BuildDeclRefExpr(RangeVar, RangeVarNonRefType, VK_LValue, ColonLoc); if (EndRangeRef.isInvalid()) return StmtError(); QualType AutoType = Context.getAutoDeductType(); Expr *Range = RangeVar->getInit(); if (!Range) return StmtError(); QualType RangeType = Range->getType(); if (RequireCompleteType(RangeLoc, RangeType, diag::err_for_range_incomplete_type)) return StmtError(); // Build auto __begin = begin-expr, __end = end-expr. // Divide by 2, since the variables are in the inner scope (loop body). const auto DepthStr = std::to_string(S->getDepth() / 2); VarDecl *BeginVar = BuildForRangeVarDecl(*this, ColonLoc, AutoType, std::string("__begin") + DepthStr); VarDecl *EndVar = BuildForRangeVarDecl(*this, ColonLoc, AutoType, std::string("__end") + DepthStr); // Build begin-expr and end-expr and attach to __begin and __end variables. ExprResult BeginExpr, EndExpr; if (const ArrayType *UnqAT = RangeType->getAsArrayTypeUnsafe()) { // - if _RangeT is an array type, begin-expr and end-expr are __range and // __range + __bound, respectively, where __bound is the array bound. If // _RangeT is an array of unknown size or an array of incomplete type, // the program is ill-formed; // begin-expr is __range. BeginExpr = BeginRangeRef; if (!CoawaitLoc.isInvalid()) { BeginExpr = ActOnCoawaitExpr(S, ColonLoc, BeginExpr.get()); if (BeginExpr.isInvalid()) return StmtError(); } if (FinishForRangeVarDecl(*this, BeginVar, BeginRangeRef.get(), ColonLoc, diag::err_for_range_iter_deduction_failure)) { NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin); return StmtError(); } // Find the array bound. ExprResult BoundExpr; if (const ConstantArrayType *CAT = dyn_cast(UnqAT)) BoundExpr = IntegerLiteral::Create( Context, CAT->getSize(), Context.getPointerDiffType(), RangeLoc); else if (const VariableArrayType *VAT = dyn_cast(UnqAT)) { // For a variably modified type we can't just use the expression within // the array bounds, since we don't want that to be re-evaluated here. // Rather, we need to determine what it was when the array was first // created - so we resort to using sizeof(vla)/sizeof(element). // For e.g. // void f(int b) { // int vla[b]; // b = -1; <-- This should not affect the num of iterations below // for (int &c : vla) { .. } // } // FIXME: This results in codegen generating IR that recalculates the // run-time number of elements (as opposed to just using the IR Value // that corresponds to the run-time value of each bound that was // generated when the array was created.) If this proves too embarrassing // even for unoptimized IR, consider passing a magic-value/cookie to // codegen that then knows to simply use that initial llvm::Value (that // corresponds to the bound at time of array creation) within // getelementptr. But be prepared to pay the price of increasing a // customized form of coupling between the two components - which could // be hard to maintain as the codebase evolves. ExprResult SizeOfVLAExprR = ActOnUnaryExprOrTypeTraitExpr( EndVar->getLocation(), UETT_SizeOf, /*IsType=*/true, CreateParsedType(VAT->desugar(), Context.getTrivialTypeSourceInfo( VAT->desugar(), RangeLoc)) .getAsOpaquePtr(), EndVar->getSourceRange()); if (SizeOfVLAExprR.isInvalid()) return StmtError(); ExprResult SizeOfEachElementExprR = ActOnUnaryExprOrTypeTraitExpr( EndVar->getLocation(), UETT_SizeOf, /*IsType=*/true, CreateParsedType(VAT->desugar(), Context.getTrivialTypeSourceInfo( VAT->getElementType(), RangeLoc)) .getAsOpaquePtr(), EndVar->getSourceRange()); if (SizeOfEachElementExprR.isInvalid()) return StmtError(); BoundExpr = ActOnBinOp(S, EndVar->getLocation(), tok::slash, SizeOfVLAExprR.get(), SizeOfEachElementExprR.get()); if (BoundExpr.isInvalid()) return StmtError(); } else { // Can't be a DependentSizedArrayType or an IncompleteArrayType since // UnqAT is not incomplete and Range is not type-dependent. llvm_unreachable("Unexpected array type in for-range"); } // end-expr is __range + __bound. EndExpr = ActOnBinOp(S, ColonLoc, tok::plus, EndRangeRef.get(), BoundExpr.get()); if (EndExpr.isInvalid()) return StmtError(); if (FinishForRangeVarDecl(*this, EndVar, EndExpr.get(), ColonLoc, diag::err_for_range_iter_deduction_failure)) { NoteForRangeBeginEndFunction(*this, EndExpr.get(), BEF_end); return StmtError(); } } else { OverloadCandidateSet CandidateSet(RangeLoc, OverloadCandidateSet::CSK_Normal); BeginEndFunction BEFFailure; ForRangeStatus RangeStatus = BuildNonArrayForRange( *this, BeginRangeRef.get(), EndRangeRef.get(), RangeType, BeginVar, EndVar, ColonLoc, CoawaitLoc, &CandidateSet, &BeginExpr, &EndExpr, &BEFFailure); if (Kind == BFRK_Build && RangeStatus == FRS_NoViableFunction && BEFFailure == BEF_begin) { // If the range is being built from an array parameter, emit a // a diagnostic that it is being treated as a pointer. if (DeclRefExpr *DRE = dyn_cast(Range)) { if (ParmVarDecl *PVD = dyn_cast(DRE->getDecl())) { QualType ArrayTy = PVD->getOriginalType(); QualType PointerTy = PVD->getType(); if (PointerTy->isPointerType() && ArrayTy->isArrayType()) { Diag(Range->getBeginLoc(), diag::err_range_on_array_parameter) << RangeLoc << PVD << ArrayTy << PointerTy; Diag(PVD->getLocation(), diag::note_declared_at); return StmtError(); } } } // If building the range failed, try dereferencing the range expression // unless a diagnostic was issued or the end function is problematic. StmtResult SR = RebuildForRangeWithDereference(*this, S, ForLoc, CoawaitLoc, InitStmt, LoopVarDecl, ColonLoc, Range, RangeLoc, RParenLoc); if (SR.isInvalid() || SR.isUsable()) return SR; } // Otherwise, emit diagnostics if we haven't already. if (RangeStatus == FRS_NoViableFunction) { Expr *Range = BEFFailure ? EndRangeRef.get() : BeginRangeRef.get(); CandidateSet.NoteCandidates( PartialDiagnosticAt(Range->getBeginLoc(), PDiag(diag::err_for_range_invalid) << RangeLoc << Range->getType() << BEFFailure), *this, OCD_AllCandidates, Range); } // Return an error if no fix was discovered. if (RangeStatus != FRS_Success) return StmtError(); } assert(!BeginExpr.isInvalid() && !EndExpr.isInvalid() && "invalid range expression in for loop"); // C++11 [dcl.spec.auto]p7: BeginType and EndType must be the same. // C++1z removes this restriction. QualType BeginType = BeginVar->getType(), EndType = EndVar->getType(); if (!Context.hasSameType(BeginType, EndType)) { Diag(RangeLoc, getLangOpts().CPlusPlus17 ? diag::warn_for_range_begin_end_types_differ : diag::ext_for_range_begin_end_types_differ) << BeginType << EndType; NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin); NoteForRangeBeginEndFunction(*this, EndExpr.get(), BEF_end); } BeginDeclStmt = ActOnDeclStmt(ConvertDeclToDeclGroup(BeginVar), ColonLoc, ColonLoc); EndDeclStmt = ActOnDeclStmt(ConvertDeclToDeclGroup(EndVar), ColonLoc, ColonLoc); const QualType BeginRefNonRefType = BeginType.getNonReferenceType(); ExprResult BeginRef = BuildDeclRefExpr(BeginVar, BeginRefNonRefType, VK_LValue, ColonLoc); if (BeginRef.isInvalid()) return StmtError(); ExprResult EndRef = BuildDeclRefExpr(EndVar, EndType.getNonReferenceType(), VK_LValue, ColonLoc); if (EndRef.isInvalid()) return StmtError(); // Build and check __begin != __end expression. NotEqExpr = ActOnBinOp(S, ColonLoc, tok::exclaimequal, BeginRef.get(), EndRef.get()); if (!NotEqExpr.isInvalid()) NotEqExpr = CheckBooleanCondition(ColonLoc, NotEqExpr.get()); if (!NotEqExpr.isInvalid()) NotEqExpr = ActOnFinishFullExpr(NotEqExpr.get(), /*DiscardedValue*/ false); if (NotEqExpr.isInvalid()) { Diag(RangeLoc, diag::note_for_range_invalid_iterator) << RangeLoc << 0 << BeginRangeRef.get()->getType(); NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin); if (!Context.hasSameType(BeginType, EndType)) NoteForRangeBeginEndFunction(*this, EndExpr.get(), BEF_end); return StmtError(); } // Build and check ++__begin expression. BeginRef = BuildDeclRefExpr(BeginVar, BeginRefNonRefType, VK_LValue, ColonLoc); if (BeginRef.isInvalid()) return StmtError(); IncrExpr = ActOnUnaryOp(S, ColonLoc, tok::plusplus, BeginRef.get()); if (!IncrExpr.isInvalid() && CoawaitLoc.isValid()) // FIXME: getCurScope() should not be used during template instantiation. // We should pick up the set of unqualified lookup results for operator // co_await during the initial parse. IncrExpr = ActOnCoawaitExpr(S, CoawaitLoc, IncrExpr.get()); if (!IncrExpr.isInvalid()) IncrExpr = ActOnFinishFullExpr(IncrExpr.get(), /*DiscardedValue*/ false); if (IncrExpr.isInvalid()) { Diag(RangeLoc, diag::note_for_range_invalid_iterator) << RangeLoc << 2 << BeginRangeRef.get()->getType() ; NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin); return StmtError(); } // Build and check *__begin expression. BeginRef = BuildDeclRefExpr(BeginVar, BeginRefNonRefType, VK_LValue, ColonLoc); if (BeginRef.isInvalid()) return StmtError(); ExprResult DerefExpr = ActOnUnaryOp(S, ColonLoc, tok::star, BeginRef.get()); if (DerefExpr.isInvalid()) { Diag(RangeLoc, diag::note_for_range_invalid_iterator) << RangeLoc << 1 << BeginRangeRef.get()->getType(); NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin); return StmtError(); } // Attach *__begin as initializer for VD. Don't touch it if we're just // trying to determine whether this would be a valid range. if (!LoopVar->isInvalidDecl() && Kind != BFRK_Check) { AddInitializerToDecl(LoopVar, DerefExpr.get(), /*DirectInit=*/false); if (LoopVar->isInvalidDecl() || (LoopVar->getInit() && LoopVar->getInit()->containsErrors())) NoteForRangeBeginEndFunction(*this, BeginExpr.get(), BEF_begin); } } // Don't bother to actually allocate the result if we're just trying to // determine whether it would be valid. if (Kind == BFRK_Check) return StmtResult(); // In OpenMP loop region loop control variable must be private. Perform // analysis of first part (if any). if (getLangOpts().OpenMP >= 50 && BeginDeclStmt.isUsable()) ActOnOpenMPLoopInitialization(ForLoc, BeginDeclStmt.get()); return new (Context) CXXForRangeStmt( InitStmt, RangeDS, cast_or_null(BeginDeclStmt.get()), cast_or_null(EndDeclStmt.get()), NotEqExpr.get(), IncrExpr.get(), LoopVarDS, /*Body=*/nullptr, ForLoc, CoawaitLoc, ColonLoc, RParenLoc); } /// FinishObjCForCollectionStmt - Attach the body to a objective-C foreach /// statement. StmtResult Sema::FinishObjCForCollectionStmt(Stmt *S, Stmt *B) { if (!S || !B) return StmtError(); ObjCForCollectionStmt * ForStmt = cast(S); ForStmt->setBody(B); return S; } // Warn when the loop variable is a const reference that creates a copy. // Suggest using the non-reference type for copies. If a copy can be prevented // suggest the const reference type that would do so. // For instance, given "for (const &Foo : Range)", suggest // "for (const Foo : Range)" to denote a copy is made for the loop. If // possible, also suggest "for (const &Bar : Range)" if this type prevents // the copy altogether. static void DiagnoseForRangeReferenceVariableCopies(Sema &SemaRef, const VarDecl *VD, QualType RangeInitType) { const Expr *InitExpr = VD->getInit(); if (!InitExpr) return; QualType VariableType = VD->getType(); if (auto Cleanups = dyn_cast(InitExpr)) if (!Cleanups->cleanupsHaveSideEffects()) InitExpr = Cleanups->getSubExpr(); const MaterializeTemporaryExpr *MTE = dyn_cast(InitExpr); // No copy made. if (!MTE) return; const Expr *E = MTE->getSubExpr()->IgnoreImpCasts(); // Searching for either UnaryOperator for dereference of a pointer or // CXXOperatorCallExpr for handling iterators. while (!isa(E) && !isa(E)) { if (const CXXConstructExpr *CCE = dyn_cast(E)) { E = CCE->getArg(0); } else if (const CXXMemberCallExpr *Call = dyn_cast(E)) { const MemberExpr *ME = cast(Call->getCallee()); E = ME->getBase(); } else { const MaterializeTemporaryExpr *MTE = cast(E); E = MTE->getSubExpr(); } E = E->IgnoreImpCasts(); } QualType ReferenceReturnType; if (isa(E)) { ReferenceReturnType = SemaRef.Context.getLValueReferenceType(E->getType()); } else { const CXXOperatorCallExpr *Call = cast(E); const FunctionDecl *FD = Call->getDirectCallee(); QualType ReturnType = FD->getReturnType(); if (ReturnType->isReferenceType()) ReferenceReturnType = ReturnType; } if (!ReferenceReturnType.isNull()) { // Loop variable creates a temporary. Suggest either to go with // non-reference loop variable to indicate a copy is made, or // the correct type to bind a const reference. SemaRef.Diag(VD->getLocation(), diag::warn_for_range_const_ref_binds_temp_built_from_ref) << VD << VariableType << ReferenceReturnType; QualType NonReferenceType = VariableType.getNonReferenceType(); NonReferenceType.removeLocalConst(); QualType NewReferenceType = SemaRef.Context.getLValueReferenceType(E->getType().withConst()); SemaRef.Diag(VD->getBeginLoc(), diag::note_use_type_or_non_reference) << NonReferenceType << NewReferenceType << VD->getSourceRange() << FixItHint::CreateRemoval(VD->getTypeSpecEndLoc()); } else if (!VariableType->isRValueReferenceType()) { // The range always returns a copy, so a temporary is always created. // Suggest removing the reference from the loop variable. // If the type is a rvalue reference do not warn since that changes the // semantic of the code. SemaRef.Diag(VD->getLocation(), diag::warn_for_range_ref_binds_ret_temp) << VD << RangeInitType; QualType NonReferenceType = VariableType.getNonReferenceType(); NonReferenceType.removeLocalConst(); SemaRef.Diag(VD->getBeginLoc(), diag::note_use_non_reference_type) << NonReferenceType << VD->getSourceRange() << FixItHint::CreateRemoval(VD->getTypeSpecEndLoc()); } } /// Determines whether the @p VariableType's declaration is a record with the /// clang::trivial_abi attribute. static bool hasTrivialABIAttr(QualType VariableType) { if (CXXRecordDecl *RD = VariableType->getAsCXXRecordDecl()) return RD->hasAttr(); return false; } // Warns when the loop variable can be changed to a reference type to // prevent a copy. For instance, if given "for (const Foo x : Range)" suggest // "for (const Foo &x : Range)" if this form does not make a copy. static void DiagnoseForRangeConstVariableCopies(Sema &SemaRef, const VarDecl *VD) { const Expr *InitExpr = VD->getInit(); if (!InitExpr) return; QualType VariableType = VD->getType(); if (const CXXConstructExpr *CE = dyn_cast(InitExpr)) { if (!CE->getConstructor()->isCopyConstructor()) return; } else if (const CastExpr *CE = dyn_cast(InitExpr)) { if (CE->getCastKind() != CK_LValueToRValue) return; } else { return; } // Small trivially copyable types are cheap to copy. Do not emit the // diagnostic for these instances. 64 bytes is a common size of a cache line. // (The function `getTypeSize` returns the size in bits.) ASTContext &Ctx = SemaRef.Context; if (Ctx.getTypeSize(VariableType) <= 64 * 8 && (VariableType.isTriviallyCopyableType(Ctx) || hasTrivialABIAttr(VariableType))) return; // Suggest changing from a const variable to a const reference variable // if doing so will prevent a copy. SemaRef.Diag(VD->getLocation(), diag::warn_for_range_copy) << VD << VariableType; SemaRef.Diag(VD->getBeginLoc(), diag::note_use_reference_type) << SemaRef.Context.getLValueReferenceType(VariableType) << VD->getSourceRange() << FixItHint::CreateInsertion(VD->getLocation(), "&"); } /// DiagnoseForRangeVariableCopies - Diagnose three cases and fixes for them. /// 1) for (const foo &x : foos) where foos only returns a copy. Suggest /// using "const foo x" to show that a copy is made /// 2) for (const bar &x : foos) where bar is a temporary initialized by bar. /// Suggest either "const bar x" to keep the copying or "const foo& x" to /// prevent the copy. /// 3) for (const foo x : foos) where x is constructed from a reference foo. /// Suggest "const foo &x" to prevent the copy. static void DiagnoseForRangeVariableCopies(Sema &SemaRef, const CXXForRangeStmt *ForStmt) { if (SemaRef.inTemplateInstantiation()) return; if (SemaRef.Diags.isIgnored( diag::warn_for_range_const_ref_binds_temp_built_from_ref, ForStmt->getBeginLoc()) && SemaRef.Diags.isIgnored(diag::warn_for_range_ref_binds_ret_temp, ForStmt->getBeginLoc()) && SemaRef.Diags.isIgnored(diag::warn_for_range_copy, ForStmt->getBeginLoc())) { return; } const VarDecl *VD = ForStmt->getLoopVariable(); if (!VD) return; QualType VariableType = VD->getType(); if (VariableType->isIncompleteType()) return; const Expr *InitExpr = VD->getInit(); if (!InitExpr) return; if (InitExpr->getExprLoc().isMacroID()) return; if (VariableType->isReferenceType()) { DiagnoseForRangeReferenceVariableCopies(SemaRef, VD, ForStmt->getRangeInit()->getType()); } else if (VariableType.isConstQualified()) { DiagnoseForRangeConstVariableCopies(SemaRef, VD); } } /// FinishCXXForRangeStmt - Attach the body to a C++0x for-range statement. /// This is a separate step from ActOnCXXForRangeStmt because analysis of the /// body cannot be performed until after the type of the range variable is /// determined. StmtResult Sema::FinishCXXForRangeStmt(Stmt *S, Stmt *B) { if (!S || !B) return StmtError(); if (isa(S)) return FinishObjCForCollectionStmt(S, B); CXXForRangeStmt *ForStmt = cast(S); ForStmt->setBody(B); DiagnoseEmptyStmtBody(ForStmt->getRParenLoc(), B, diag::warn_empty_range_based_for_body); DiagnoseForRangeVariableCopies(*this, ForStmt); return S; } StmtResult Sema::ActOnGotoStmt(SourceLocation GotoLoc, SourceLocation LabelLoc, LabelDecl *TheDecl) { setFunctionHasBranchIntoScope(); TheDecl->markUsed(Context); return new (Context) GotoStmt(TheDecl, GotoLoc, LabelLoc); } StmtResult Sema::ActOnIndirectGotoStmt(SourceLocation GotoLoc, SourceLocation StarLoc, Expr *E) { // Convert operand to void* if (!E->isTypeDependent()) { QualType ETy = E->getType(); QualType DestTy = Context.getPointerType(Context.VoidTy.withConst()); ExprResult ExprRes = E; AssignConvertType ConvTy = CheckSingleAssignmentConstraints(DestTy, ExprRes); if (ExprRes.isInvalid()) return StmtError(); E = ExprRes.get(); if (DiagnoseAssignmentResult(ConvTy, StarLoc, DestTy, ETy, E, AA_Passing)) return StmtError(); } ExprResult ExprRes = ActOnFinishFullExpr(E, /*DiscardedValue*/ false); if (ExprRes.isInvalid()) return StmtError(); E = ExprRes.get(); setFunctionHasIndirectGoto(); return new (Context) IndirectGotoStmt(GotoLoc, StarLoc, E); } static void CheckJumpOutOfSEHFinally(Sema &S, SourceLocation Loc, const Scope &DestScope) { if (!S.CurrentSEHFinally.empty() && DestScope.Contains(*S.CurrentSEHFinally.back())) { S.Diag(Loc, diag::warn_jump_out_of_seh_finally); } } StmtResult Sema::ActOnContinueStmt(SourceLocation ContinueLoc, Scope *CurScope) { Scope *S = CurScope->getContinueParent(); if (!S) { // C99 6.8.6.2p1: A break shall appear only in or as a loop body. return StmtError(Diag(ContinueLoc, diag::err_continue_not_in_loop)); } if (S->getFlags() & Scope::ConditionVarScope) { // We cannot 'continue;' from within a statement expression in the // initializer of a condition variable because we would jump past the // initialization of that variable. return StmtError(Diag(ContinueLoc, diag::err_continue_from_cond_var_init)); } CheckJumpOutOfSEHFinally(*this, ContinueLoc, *S); return new (Context) ContinueStmt(ContinueLoc); } StmtResult Sema::ActOnBreakStmt(SourceLocation BreakLoc, Scope *CurScope) { Scope *S = CurScope->getBreakParent(); if (!S) { // C99 6.8.6.3p1: A break shall appear only in or as a switch/loop body. return StmtError(Diag(BreakLoc, diag::err_break_not_in_loop_or_switch)); } if (S->isOpenMPLoopScope()) return StmtError(Diag(BreakLoc, diag::err_omp_loop_cannot_use_stmt) << "break"); CheckJumpOutOfSEHFinally(*this, BreakLoc, *S); return new (Context) BreakStmt(BreakLoc); } /// Determine whether the given expression is a candidate for /// copy elision in either a return statement or a throw expression. /// /// \param ReturnType If we're determining the copy elision candidate for /// a return statement, this is the return type of the function. If we're /// determining the copy elision candidate for a throw expression, this will /// be a NULL type. /// /// \param E The expression being returned from the function or block, or /// being thrown. /// /// \param CESK Whether we allow function parameters or /// id-expressions that could be moved out of the function to be considered NRVO /// candidates. C++ prohibits these for NRVO itself, but we re-use this logic to /// determine whether we should try to move as part of a return or throw (which /// does allow function parameters). /// /// \returns The NRVO candidate variable, if the return statement may use the /// NRVO, or NULL if there is no such candidate. VarDecl *Sema::getCopyElisionCandidate(QualType ReturnType, Expr *E, CopyElisionSemanticsKind CESK) { // - in a return statement in a function [where] ... // ... the expression is the name of a non-volatile automatic object ... DeclRefExpr *DR = dyn_cast(E->IgnoreParens()); if (!DR || DR->refersToEnclosingVariableOrCapture()) return nullptr; VarDecl *VD = dyn_cast(DR->getDecl()); if (!VD) return nullptr; if (isCopyElisionCandidate(ReturnType, VD, CESK)) return VD; return nullptr; } bool Sema::isCopyElisionCandidate(QualType ReturnType, const VarDecl *VD, CopyElisionSemanticsKind CESK) { QualType VDType = VD->getType(); // - in a return statement in a function with ... // ... a class return type ... if (!ReturnType.isNull() && !ReturnType->isDependentType()) { if (!ReturnType->isRecordType()) return false; // ... the same cv-unqualified type as the function return type ... // When considering moving this expression out, allow dissimilar types. if (!(CESK & CES_AllowDifferentTypes) && !VDType->isDependentType() && !Context.hasSameUnqualifiedType(ReturnType, VDType)) return false; } // ...object (other than a function or catch-clause parameter)... if (VD->getKind() != Decl::Var && !((CESK & CES_AllowParameters) && VD->getKind() == Decl::ParmVar)) return false; if (!(CESK & CES_AllowExceptionVariables) && VD->isExceptionVariable()) return false; // ...automatic... if (!VD->hasLocalStorage()) return false; // Return false if VD is a __block variable. We don't want to implicitly move // out of a __block variable during a return because we cannot assume the // variable will no longer be used. if (VD->hasAttr()) return false; if (VDType->isObjectType()) { // C++17 [class.copy.elision]p3: // ...non-volatile automatic object... if (VDType.isVolatileQualified()) return false; } else if (VDType->isRValueReferenceType()) { // C++20 [class.copy.elision]p3: // ...either a non-volatile object or an rvalue reference to a non-volatile object type... if (!(CESK & CES_AllowRValueReferenceType)) return false; QualType VDReferencedType = VDType.getNonReferenceType(); if (VDReferencedType.isVolatileQualified() || !VDReferencedType->isObjectType()) return false; } else { return false; } if (CESK & CES_AllowDifferentTypes) return true; // Variables with higher required alignment than their type's ABI // alignment cannot use NRVO. if (!VDType->isDependentType() && VD->hasAttr() && Context.getDeclAlign(VD) > Context.getTypeAlignInChars(VDType)) return false; return true; } /// Try to perform the initialization of a potentially-movable value, /// which is the operand to a return or throw statement. /// /// This routine implements C++20 [class.copy.elision]p3, which attempts to /// treat returned lvalues as rvalues in certain cases (to prefer move /// construction), then falls back to treating them as lvalues if that failed. /// /// \param ConvertingConstructorsOnly If true, follow [class.copy.elision]p3 and /// reject resolutions that find non-constructors, such as derived-to-base /// conversions or `operator T()&&` member functions. If false, do consider such /// conversion sequences. /// /// \param Res We will fill this in if move-initialization was possible. /// If move-initialization is not possible, such that we must fall back to /// treating the operand as an lvalue, we will leave Res in its original /// invalid state. /// /// \returns Whether we need to do the second overload resolution. If the first /// overload resolution fails, or if the first overload resolution succeeds but /// the selected constructor/operator doesn't match the additional criteria, we /// need to do the second overload resolution. static bool TryMoveInitialization(Sema &S, const InitializedEntity &Entity, const VarDecl *NRVOCandidate, QualType ResultType, Expr *&Value, bool ConvertingConstructorsOnly, bool IsDiagnosticsCheck, ExprResult &Res) { ImplicitCastExpr AsRvalue(ImplicitCastExpr::OnStack, Value->getType(), CK_NoOp, Value, VK_XValue, FPOptionsOverride()); Expr *InitExpr = &AsRvalue; InitializationKind Kind = InitializationKind::CreateCopy( Value->getBeginLoc(), Value->getBeginLoc()); InitializationSequence Seq(S, Entity, Kind, InitExpr); bool NeedSecondOverloadResolution = true; if (!Seq && (IsDiagnosticsCheck || Seq.getFailedOverloadResult() != OR_Deleted)) { return NeedSecondOverloadResolution; } for (const InitializationSequence::Step &Step : Seq.steps()) { if (Step.Kind != InitializationSequence::SK_ConstructorInitialization && Step.Kind != InitializationSequence::SK_UserConversion) continue; FunctionDecl *FD = Step.Function.Function; if (ConvertingConstructorsOnly) { if (isa(FD)) { // C++11 [class.copy]p32: // C++14 [class.copy]p32: // C++17 [class.copy.elision]p3: // [...] if the type of the first parameter of the selected constructor // is not an rvalue reference to the object's type (possibly // cv-qualified), overload resolution is performed again, considering // the object as an lvalue. const RValueReferenceType *RRefType = FD->getParamDecl(0)->getType()->getAs(); if (!RRefType) break; if (!S.Context.hasSameUnqualifiedType(RRefType->getPointeeType(), NRVOCandidate->getType())) break; } else { continue; } } else { if (isa(FD)) { // Check that overload resolution selected a constructor taking an // rvalue reference. If it selected an lvalue reference, then we // didn't need to cast this thing to an rvalue in the first place. if (IsDiagnosticsCheck && !isa(FD->getParamDecl(0)->getType())) break; } else if (isa(FD)) { // Check that overload resolution selected a conversion operator // taking an rvalue reference. if (cast(FD)->getRefQualifier() != RQ_RValue) break; } else { continue; } } NeedSecondOverloadResolution = false; // Promote "AsRvalue" to the heap, since we now need this // expression node to persist. Value = ImplicitCastExpr::Create(S.Context, Value->getType(), CK_NoOp, Value, nullptr, VK_XValue, FPOptionsOverride()); // Complete type-checking the initialization of the return type // using the constructor we found. Res = Seq.Perform(S, Entity, Kind, Value); } return NeedSecondOverloadResolution; } /// Perform the initialization of a potentially-movable value, which /// is the result of return value. /// /// This routine implements C++20 [class.copy.elision]p3, which attempts to /// treat returned lvalues as rvalues in certain cases (to prefer move /// construction), then falls back to treating them as lvalues if that failed. ExprResult Sema::PerformMoveOrCopyInitialization( const InitializedEntity &Entity, const VarDecl *NRVOCandidate, QualType ResultType, Expr *Value, bool AllowNRVO) { ExprResult Res = ExprError(); bool NeedSecondOverloadResolution = true; if (AllowNRVO) { CopyElisionSemanticsKind CESK = CES_Strict; if (getLangOpts().CPlusPlus20) { CESK = CES_ImplicitlyMovableCXX20; } else if (getLangOpts().CPlusPlus11) { CESK = CES_ImplicitlyMovableCXX11CXX14CXX17; } if (!NRVOCandidate) { NRVOCandidate = getCopyElisionCandidate(ResultType, Value, CESK); } if (NRVOCandidate) { NeedSecondOverloadResolution = TryMoveInitialization(*this, Entity, NRVOCandidate, ResultType, Value, !getLangOpts().CPlusPlus20, false, Res); } if (!getLangOpts().CPlusPlus20 && NeedSecondOverloadResolution && !getDiagnostics().isIgnored(diag::warn_return_std_move, Value->getExprLoc())) { const VarDecl *FakeNRVOCandidate = getCopyElisionCandidate( QualType(), Value, CES_ImplicitlyMovableCXX20); if (FakeNRVOCandidate) { QualType QT = FakeNRVOCandidate->getType(); if (QT->isLValueReferenceType()) { // Adding 'std::move' around an lvalue reference variable's name is // dangerous. Don't suggest it. } else if (QT.getNonReferenceType() .getUnqualifiedType() .isTriviallyCopyableType(Context)) { // Adding 'std::move' around a trivially copyable variable is probably // pointless. Don't suggest it. } else { ExprResult FakeRes = ExprError(); Expr *FakeValue = Value; TryMoveInitialization(*this, Entity, FakeNRVOCandidate, ResultType, FakeValue, false, true, FakeRes); if (!FakeRes.isInvalid()) { bool IsThrow = (Entity.getKind() == InitializedEntity::EK_Exception); SmallString<32> Str; Str += "std::move("; Str += FakeNRVOCandidate->getDeclName().getAsString(); Str += ")"; Diag(Value->getExprLoc(), diag::warn_return_std_move) << Value->getSourceRange() << FakeNRVOCandidate->getDeclName() << IsThrow; Diag(Value->getExprLoc(), diag::note_add_std_move) << FixItHint::CreateReplacement(Value->getSourceRange(), Str); } } } } } // Either we didn't meet the criteria for treating an lvalue as an rvalue, // above, or overload resolution failed. Either way, we need to try // (again) now with the return value expression as written. if (NeedSecondOverloadResolution) Res = PerformCopyInitialization(Entity, SourceLocation(), Value); return Res; } /// Determine whether the declared return type of the specified function /// contains 'auto'. static bool hasDeducedReturnType(FunctionDecl *FD) { const FunctionProtoType *FPT = FD->getTypeSourceInfo()->getType()->castAs(); return FPT->getReturnType()->isUndeducedType(); } /// ActOnCapScopeReturnStmt - Utility routine to type-check return statements /// for capturing scopes. /// StmtResult Sema::ActOnCapScopeReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) { // If this is the first return we've seen, infer the return type. // [expr.prim.lambda]p4 in C++11; block literals follow the same rules. CapturingScopeInfo *CurCap = cast(getCurFunction()); QualType FnRetType = CurCap->ReturnType; LambdaScopeInfo *CurLambda = dyn_cast(CurCap); bool HasDeducedReturnType = CurLambda && hasDeducedReturnType(CurLambda->CallOperator); if (ExprEvalContexts.back().Context == ExpressionEvaluationContext::DiscardedStatement && (HasDeducedReturnType || CurCap->HasImplicitReturnType)) { if (RetValExp) { ExprResult ER = ActOnFinishFullExpr(RetValExp, ReturnLoc, /*DiscardedValue*/ false); if (ER.isInvalid()) return StmtError(); RetValExp = ER.get(); } return ReturnStmt::Create(Context, ReturnLoc, RetValExp, /* NRVOCandidate=*/nullptr); } if (HasDeducedReturnType) { FunctionDecl *FD = CurLambda->CallOperator; // If we've already decided this lambda is invalid, e.g. because // we saw a `return` whose expression had an error, don't keep // trying to deduce its return type. if (FD->isInvalidDecl()) return StmtError(); // In C++1y, the return type may involve 'auto'. // FIXME: Blocks might have a return type of 'auto' explicitly specified. if (CurCap->ReturnType.isNull()) CurCap->ReturnType = FD->getReturnType(); AutoType *AT = CurCap->ReturnType->getContainedAutoType(); assert(AT && "lost auto type from lambda return type"); if (DeduceFunctionTypeFromReturnExpr(FD, ReturnLoc, RetValExp, AT)) { FD->setInvalidDecl(); // FIXME: preserve the ill-formed return expression. return StmtError(); } CurCap->ReturnType = FnRetType = FD->getReturnType(); } else if (CurCap->HasImplicitReturnType) { // For blocks/lambdas with implicit return types, we check each return // statement individually, and deduce the common return type when the block // or lambda is completed. // FIXME: Fold this into the 'auto' codepath above. if (RetValExp && !isa(RetValExp)) { ExprResult Result = DefaultFunctionArrayLvalueConversion(RetValExp); if (Result.isInvalid()) return StmtError(); RetValExp = Result.get(); // DR1048: even prior to C++14, we should use the 'auto' deduction rules // when deducing a return type for a lambda-expression (or by extension // for a block). These rules differ from the stated C++11 rules only in // that they remove top-level cv-qualifiers. if (!CurContext->isDependentContext()) FnRetType = RetValExp->getType().getUnqualifiedType(); else FnRetType = CurCap->ReturnType = Context.DependentTy; } else { if (RetValExp) { // C++11 [expr.lambda.prim]p4 bans inferring the result from an // initializer list, because it is not an expression (even // though we represent it as one). We still deduce 'void'. Diag(ReturnLoc, diag::err_lambda_return_init_list) << RetValExp->getSourceRange(); } FnRetType = Context.VoidTy; } // Although we'll properly infer the type of the block once it's completed, // make sure we provide a return type now for better error recovery. if (CurCap->ReturnType.isNull()) CurCap->ReturnType = FnRetType; } assert(!FnRetType.isNull()); if (auto *CurBlock = dyn_cast(CurCap)) { if (CurBlock->FunctionType->castAs()->getNoReturnAttr()) { Diag(ReturnLoc, diag::err_noreturn_block_has_return_expr); return StmtError(); } } else if (auto *CurRegion = dyn_cast(CurCap)) { Diag(ReturnLoc, diag::err_return_in_captured_stmt) << CurRegion->getRegionName(); return StmtError(); } else { assert(CurLambda && "unknown kind of captured scope"); if (CurLambda->CallOperator->getType() ->castAs() ->getNoReturnAttr()) { Diag(ReturnLoc, diag::err_noreturn_lambda_has_return_expr); return StmtError(); } } // Otherwise, verify that this result type matches the previous one. We are // pickier with blocks than for normal functions because we don't have GCC // compatibility to worry about here. const VarDecl *NRVOCandidate = nullptr; if (FnRetType->isDependentType()) { // Delay processing for now. TODO: there are lots of dependent // types we can conclusively prove aren't void. } else if (FnRetType->isVoidType()) { if (RetValExp && !isa(RetValExp) && !(getLangOpts().CPlusPlus && (RetValExp->isTypeDependent() || RetValExp->getType()->isVoidType()))) { if (!getLangOpts().CPlusPlus && RetValExp->getType()->isVoidType()) Diag(ReturnLoc, diag::ext_return_has_void_expr) << "literal" << 2; else { Diag(ReturnLoc, diag::err_return_block_has_expr); RetValExp = nullptr; } } } else if (!RetValExp) { return StmtError(Diag(ReturnLoc, diag::err_block_return_missing_expr)); } else if (!RetValExp->isTypeDependent()) { // we have a non-void block with an expression, continue checking // C99 6.8.6.4p3(136): The return statement is not an assignment. The // overlap restriction of subclause 6.5.16.1 does not apply to the case of // function return. // In C++ the return statement is handled via a copy initialization. // the C version of which boils down to CheckSingleAssignmentConstraints. NRVOCandidate = getCopyElisionCandidate(FnRetType, RetValExp, CES_Strict); InitializedEntity Entity = InitializedEntity::InitializeResult(ReturnLoc, FnRetType, NRVOCandidate != nullptr); ExprResult Res = PerformMoveOrCopyInitialization(Entity, NRVOCandidate, FnRetType, RetValExp); if (Res.isInvalid()) { // FIXME: Cleanup temporaries here, anyway? return StmtError(); } RetValExp = Res.get(); CheckReturnValExpr(RetValExp, FnRetType, ReturnLoc); } else { NRVOCandidate = getCopyElisionCandidate(FnRetType, RetValExp, CES_Strict); } if (RetValExp) { ExprResult ER = ActOnFinishFullExpr(RetValExp, ReturnLoc, /*DiscardedValue*/ false); if (ER.isInvalid()) return StmtError(); RetValExp = ER.get(); } auto *Result = ReturnStmt::Create(Context, ReturnLoc, RetValExp, NRVOCandidate); // If we need to check for the named return value optimization, // or if we need to infer the return type, // save the return statement in our scope for later processing. if (CurCap->HasImplicitReturnType || NRVOCandidate) FunctionScopes.back()->Returns.push_back(Result); if (FunctionScopes.back()->FirstReturnLoc.isInvalid()) FunctionScopes.back()->FirstReturnLoc = ReturnLoc; return Result; } namespace { /// Marks all typedefs in all local classes in a type referenced. /// /// In a function like /// auto f() { /// struct S { typedef int a; }; /// return S(); /// } /// /// the local type escapes and could be referenced in some TUs but not in /// others. Pretend that all local typedefs are always referenced, to not warn /// on this. This isn't necessary if f has internal linkage, or the typedef /// is private. class LocalTypedefNameReferencer : public RecursiveASTVisitor { public: LocalTypedefNameReferencer(Sema &S) : S(S) {} bool VisitRecordType(const RecordType *RT); private: Sema &S; }; bool LocalTypedefNameReferencer::VisitRecordType(const RecordType *RT) { auto *R = dyn_cast(RT->getDecl()); if (!R || !R->isLocalClass() || !R->isLocalClass()->isExternallyVisible() || R->isDependentType()) return true; for (auto *TmpD : R->decls()) if (auto *T = dyn_cast(TmpD)) if (T->getAccess() != AS_private || R->hasFriends()) S.MarkAnyDeclReferenced(T->getLocation(), T, /*OdrUse=*/false); return true; } } TypeLoc Sema::getReturnTypeLoc(FunctionDecl *FD) const { return FD->getTypeSourceInfo() ->getTypeLoc() .getAsAdjusted() .getReturnLoc(); } /// Deduce the return type for a function from a returned expression, per /// C++1y [dcl.spec.auto]p6. bool Sema::DeduceFunctionTypeFromReturnExpr(FunctionDecl *FD, SourceLocation ReturnLoc, Expr *&RetExpr, AutoType *AT) { // If this is the conversion function for a lambda, we choose to deduce it // type from the corresponding call operator, not from the synthesized return // statement within it. See Sema::DeduceReturnType. if (isLambdaConversionOperator(FD)) return false; TypeLoc OrigResultType = getReturnTypeLoc(FD); QualType Deduced; if (RetExpr && isa(RetExpr)) { // If the deduction is for a return statement and the initializer is // a braced-init-list, the program is ill-formed. Diag(RetExpr->getExprLoc(), getCurLambda() ? diag::err_lambda_return_init_list : diag::err_auto_fn_return_init_list) << RetExpr->getSourceRange(); return true; } if (FD->isDependentContext()) { // C++1y [dcl.spec.auto]p12: // Return type deduction [...] occurs when the definition is // instantiated even if the function body contains a return // statement with a non-type-dependent operand. assert(AT->isDeduced() && "should have deduced to dependent type"); return false; } if (RetExpr) { // Otherwise, [...] deduce a value for U using the rules of template // argument deduction. DeduceAutoResult DAR = DeduceAutoType(OrigResultType, RetExpr, Deduced); if (DAR == DAR_Failed && !FD->isInvalidDecl()) Diag(RetExpr->getExprLoc(), diag::err_auto_fn_deduction_failure) << OrigResultType.getType() << RetExpr->getType(); if (DAR != DAR_Succeeded) return true; // If a local type is part of the returned type, mark its fields as // referenced. LocalTypedefNameReferencer Referencer(*this); Referencer.TraverseType(RetExpr->getType()); } else { // In the case of a return with no operand, the initializer is considered // to be void(). // // Deduction here can only succeed if the return type is exactly 'cv auto' // or 'decltype(auto)', so just check for that case directly. if (!OrigResultType.getType()->getAs()) { Diag(ReturnLoc, diag::err_auto_fn_return_void_but_not_auto) << OrigResultType.getType(); return true; } // We always deduce U = void in this case. Deduced = SubstAutoType(OrigResultType.getType(), Context.VoidTy); if (Deduced.isNull()) return true; } // CUDA: Kernel function must have 'void' return type. if (getLangOpts().CUDA) if (FD->hasAttr() && !Deduced->isVoidType()) { Diag(FD->getLocation(), diag::err_kern_type_not_void_return) << FD->getType() << FD->getSourceRange(); return true; } // If a function with a declared return type that contains a placeholder type // has multiple return statements, the return type is deduced for each return // statement. [...] if the type deduced is not the same in each deduction, // the program is ill-formed. QualType DeducedT = AT->getDeducedType(); if (!DeducedT.isNull() && !FD->isInvalidDecl()) { AutoType *NewAT = Deduced->getContainedAutoType(); // It is possible that NewAT->getDeducedType() is null. When that happens, // we should not crash, instead we ignore this deduction. if (NewAT->getDeducedType().isNull()) return false; CanQualType OldDeducedType = Context.getCanonicalFunctionResultType( DeducedT); CanQualType NewDeducedType = Context.getCanonicalFunctionResultType( NewAT->getDeducedType()); if (!FD->isDependentContext() && OldDeducedType != NewDeducedType) { const LambdaScopeInfo *LambdaSI = getCurLambda(); if (LambdaSI && LambdaSI->HasImplicitReturnType) { Diag(ReturnLoc, diag::err_typecheck_missing_return_type_incompatible) << NewAT->getDeducedType() << DeducedT << true /*IsLambda*/; } else { Diag(ReturnLoc, diag::err_auto_fn_different_deductions) << (AT->isDecltypeAuto() ? 1 : 0) << NewAT->getDeducedType() << DeducedT; } return true; } } else if (!FD->isInvalidDecl()) { // Update all declarations of the function to have the deduced return type. Context.adjustDeducedFunctionResultType(FD, Deduced); } return false; } StmtResult Sema::ActOnReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp, Scope *CurScope) { // Correct typos, in case the containing function returns 'auto' and // RetValExp should determine the deduced type. ExprResult RetVal = CorrectDelayedTyposInExpr( RetValExp, nullptr, /*RecoverUncorrectedTypos=*/true); if (RetVal.isInvalid()) return StmtError(); StmtResult R = BuildReturnStmt(ReturnLoc, RetVal.get()); if (R.isInvalid() || ExprEvalContexts.back().Context == ExpressionEvaluationContext::DiscardedStatement) return R; if (VarDecl *VD = const_cast(cast(R.get())->getNRVOCandidate())) { CurScope->addNRVOCandidate(VD); } else { CurScope->setNoNRVO(); } CheckJumpOutOfSEHFinally(*this, ReturnLoc, *CurScope->getFnParent()); return R; } StmtResult Sema::BuildReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) { // Check for unexpanded parameter packs. if (RetValExp && DiagnoseUnexpandedParameterPack(RetValExp)) return StmtError(); if (isa(getCurFunction())) return ActOnCapScopeReturnStmt(ReturnLoc, RetValExp); QualType FnRetType; QualType RelatedRetType; const AttrVec *Attrs = nullptr; bool isObjCMethod = false; if (const FunctionDecl *FD = getCurFunctionDecl()) { FnRetType = FD->getReturnType(); if (FD->hasAttrs()) Attrs = &FD->getAttrs(); if (FD->isNoReturn()) Diag(ReturnLoc, diag::warn_noreturn_function_has_return_expr) << FD; if (FD->isMain() && RetValExp) if (isa(RetValExp)) Diag(ReturnLoc, diag::warn_main_returns_bool_literal) << RetValExp->getSourceRange(); if (FD->hasAttr() && RetValExp) { if (const auto *RT = dyn_cast(FnRetType.getCanonicalType())) { if (RT->getDecl()->isOrContainsUnion()) Diag(RetValExp->getBeginLoc(), diag::warn_cmse_nonsecure_union) << 1; } } } else if (ObjCMethodDecl *MD = getCurMethodDecl()) { FnRetType = MD->getReturnType(); isObjCMethod = true; if (MD->hasAttrs()) Attrs = &MD->getAttrs(); if (MD->hasRelatedResultType() && MD->getClassInterface()) { // In the implementation of a method with a related return type, the // type used to type-check the validity of return statements within the // method body is a pointer to the type of the class being implemented. RelatedRetType = Context.getObjCInterfaceType(MD->getClassInterface()); RelatedRetType = Context.getObjCObjectPointerType(RelatedRetType); } } else // If we don't have a function/method context, bail. return StmtError(); // C++1z: discarded return statements are not considered when deducing a // return type. if (ExprEvalContexts.back().Context == ExpressionEvaluationContext::DiscardedStatement && FnRetType->getContainedAutoType()) { if (RetValExp) { ExprResult ER = ActOnFinishFullExpr(RetValExp, ReturnLoc, /*DiscardedValue*/ false); if (ER.isInvalid()) return StmtError(); RetValExp = ER.get(); } return ReturnStmt::Create(Context, ReturnLoc, RetValExp, /* NRVOCandidate=*/nullptr); } // FIXME: Add a flag to the ScopeInfo to indicate whether we're performing // deduction. if (getLangOpts().CPlusPlus14) { if (AutoType *AT = FnRetType->getContainedAutoType()) { FunctionDecl *FD = cast(CurContext); // If we've already decided this function is invalid, e.g. because // we saw a `return` whose expression had an error, don't keep // trying to deduce its return type. if (FD->isInvalidDecl()) return StmtError(); if (DeduceFunctionTypeFromReturnExpr(FD, ReturnLoc, RetValExp, AT)) { FD->setInvalidDecl(); return StmtError(); } else { FnRetType = FD->getReturnType(); } } } bool HasDependentReturnType = FnRetType->isDependentType(); ReturnStmt *Result = nullptr; if (FnRetType->isVoidType()) { if (RetValExp) { if (isa(RetValExp)) { // We simply never allow init lists as the return value of void // functions. This is compatible because this was never allowed before, // so there's no legacy code to deal with. NamedDecl *CurDecl = getCurFunctionOrMethodDecl(); int FunctionKind = 0; if (isa(CurDecl)) FunctionKind = 1; else if (isa(CurDecl)) FunctionKind = 2; else if (isa(CurDecl)) FunctionKind = 3; Diag(ReturnLoc, diag::err_return_init_list) << CurDecl << FunctionKind << RetValExp->getSourceRange(); // Drop the expression. RetValExp = nullptr; } else if (!RetValExp->isTypeDependent()) { // C99 6.8.6.4p1 (ext_ since GCC warns) unsigned D = diag::ext_return_has_expr; if (RetValExp->getType()->isVoidType()) { NamedDecl *CurDecl = getCurFunctionOrMethodDecl(); if (isa(CurDecl) || isa(CurDecl)) D = diag::err_ctor_dtor_returns_void; else D = diag::ext_return_has_void_expr; } else { ExprResult Result = RetValExp; Result = IgnoredValueConversions(Result.get()); if (Result.isInvalid()) return StmtError(); RetValExp = Result.get(); RetValExp = ImpCastExprToType(RetValExp, Context.VoidTy, CK_ToVoid).get(); } // return of void in constructor/destructor is illegal in C++. if (D == diag::err_ctor_dtor_returns_void) { NamedDecl *CurDecl = getCurFunctionOrMethodDecl(); Diag(ReturnLoc, D) << CurDecl << isa(CurDecl) << RetValExp->getSourceRange(); } // return (some void expression); is legal in C++. else if (D != diag::ext_return_has_void_expr || !getLangOpts().CPlusPlus) { NamedDecl *CurDecl = getCurFunctionOrMethodDecl(); int FunctionKind = 0; if (isa(CurDecl)) FunctionKind = 1; else if (isa(CurDecl)) FunctionKind = 2; else if (isa(CurDecl)) FunctionKind = 3; Diag(ReturnLoc, D) << CurDecl << FunctionKind << RetValExp->getSourceRange(); } } if (RetValExp) { ExprResult ER = ActOnFinishFullExpr(RetValExp, ReturnLoc, /*DiscardedValue*/ false); if (ER.isInvalid()) return StmtError(); RetValExp = ER.get(); } } Result = ReturnStmt::Create(Context, ReturnLoc, RetValExp, /* NRVOCandidate=*/nullptr); } else if (!RetValExp && !HasDependentReturnType) { FunctionDecl *FD = getCurFunctionDecl(); if (getLangOpts().CPlusPlus11 && FD && FD->isConstexpr()) { // C++11 [stmt.return]p2 Diag(ReturnLoc, diag::err_constexpr_return_missing_expr) << FD << FD->isConsteval(); FD->setInvalidDecl(); } else { // C99 6.8.6.4p1 (ext_ since GCC warns) // C90 6.6.6.4p4 unsigned DiagID = getLangOpts().C99 ? diag::ext_return_missing_expr : diag::warn_return_missing_expr; // Note that at this point one of getCurFunctionDecl() or // getCurMethodDecl() must be non-null (see above). assert((getCurFunctionDecl() || getCurMethodDecl()) && "Not in a FunctionDecl or ObjCMethodDecl?"); bool IsMethod = FD == nullptr; const NamedDecl *ND = IsMethod ? cast(getCurMethodDecl()) : cast(FD); Diag(ReturnLoc, DiagID) << ND << IsMethod; } Result = ReturnStmt::Create(Context, ReturnLoc, /* RetExpr=*/nullptr, /* NRVOCandidate=*/nullptr); } else { assert(RetValExp || HasDependentReturnType); const VarDecl *NRVOCandidate = nullptr; QualType RetType = RelatedRetType.isNull() ? FnRetType : RelatedRetType; // C99 6.8.6.4p3(136): The return statement is not an assignment. The // overlap restriction of subclause 6.5.16.1 does not apply to the case of // function return. // In C++ the return statement is handled via a copy initialization, // the C version of which boils down to CheckSingleAssignmentConstraints. if (RetValExp) NRVOCandidate = getCopyElisionCandidate(FnRetType, RetValExp, CES_Strict); if (!HasDependentReturnType && !RetValExp->isTypeDependent()) { // we have a non-void function with an expression, continue checking InitializedEntity Entity = InitializedEntity::InitializeResult(ReturnLoc, RetType, NRVOCandidate != nullptr); ExprResult Res = PerformMoveOrCopyInitialization(Entity, NRVOCandidate, RetType, RetValExp); if (Res.isInvalid()) { // FIXME: Clean up temporaries here anyway? return StmtError(); } RetValExp = Res.getAs(); // If we have a related result type, we need to implicitly // convert back to the formal result type. We can't pretend to // initialize the result again --- we might end double-retaining // --- so instead we initialize a notional temporary. if (!RelatedRetType.isNull()) { Entity = InitializedEntity::InitializeRelatedResult(getCurMethodDecl(), FnRetType); Res = PerformCopyInitialization(Entity, ReturnLoc, RetValExp); if (Res.isInvalid()) { // FIXME: Clean up temporaries here anyway? return StmtError(); } RetValExp = Res.getAs(); } CheckReturnValExpr(RetValExp, FnRetType, ReturnLoc, isObjCMethod, Attrs, getCurFunctionDecl()); } if (RetValExp) { ExprResult ER = ActOnFinishFullExpr(RetValExp, ReturnLoc, /*DiscardedValue*/ false); if (ER.isInvalid()) return StmtError(); RetValExp = ER.get(); } Result = ReturnStmt::Create(Context, ReturnLoc, RetValExp, NRVOCandidate); } // If we need to check for the named return value optimization, save the // return statement in our scope for later processing. if (Result->getNRVOCandidate()) FunctionScopes.back()->Returns.push_back(Result); if (FunctionScopes.back()->FirstReturnLoc.isInvalid()) FunctionScopes.back()->FirstReturnLoc = ReturnLoc; return Result; } StmtResult Sema::ActOnObjCAtCatchStmt(SourceLocation AtLoc, SourceLocation RParen, Decl *Parm, Stmt *Body) { VarDecl *Var = cast_or_null(Parm); if (Var && Var->isInvalidDecl()) return StmtError(); return new (Context) ObjCAtCatchStmt(AtLoc, RParen, Var, Body); } StmtResult Sema::ActOnObjCAtFinallyStmt(SourceLocation AtLoc, Stmt *Body) { return new (Context) ObjCAtFinallyStmt(AtLoc, Body); } StmtResult Sema::ActOnObjCAtTryStmt(SourceLocation AtLoc, Stmt *Try, MultiStmtArg CatchStmts, Stmt *Finally) { if (!getLangOpts().ObjCExceptions) Diag(AtLoc, diag::err_objc_exceptions_disabled) << "@try"; setFunctionHasBranchProtectedScope(); unsigned NumCatchStmts = CatchStmts.size(); return ObjCAtTryStmt::Create(Context, AtLoc, Try, CatchStmts.data(), NumCatchStmts, Finally); } StmtResult Sema::BuildObjCAtThrowStmt(SourceLocation AtLoc, Expr *Throw) { if (Throw) { ExprResult Result = DefaultLvalueConversion(Throw); if (Result.isInvalid()) return StmtError(); Result = ActOnFinishFullExpr(Result.get(), /*DiscardedValue*/ false); if (Result.isInvalid()) return StmtError(); Throw = Result.get(); QualType ThrowType = Throw->getType(); // Make sure the expression type is an ObjC pointer or "void *". if (!ThrowType->isDependentType() && !ThrowType->isObjCObjectPointerType()) { const PointerType *PT = ThrowType->getAs(); if (!PT || !PT->getPointeeType()->isVoidType()) return StmtError(Diag(AtLoc, diag::err_objc_throw_expects_object) << Throw->getType() << Throw->getSourceRange()); } } return new (Context) ObjCAtThrowStmt(AtLoc, Throw); } StmtResult Sema::ActOnObjCAtThrowStmt(SourceLocation AtLoc, Expr *Throw, Scope *CurScope) { if (!getLangOpts().ObjCExceptions) Diag(AtLoc, diag::err_objc_exceptions_disabled) << "@throw"; if (!Throw) { // @throw without an expression designates a rethrow (which must occur // in the context of an @catch clause). Scope *AtCatchParent = CurScope; while (AtCatchParent && !AtCatchParent->isAtCatchScope()) AtCatchParent = AtCatchParent->getParent(); if (!AtCatchParent) return StmtError(Diag(AtLoc, diag::err_rethrow_used_outside_catch)); } return BuildObjCAtThrowStmt(AtLoc, Throw); } ExprResult Sema::ActOnObjCAtSynchronizedOperand(SourceLocation atLoc, Expr *operand) { ExprResult result = DefaultLvalueConversion(operand); if (result.isInvalid()) return ExprError(); operand = result.get(); // Make sure the expression type is an ObjC pointer or "void *". QualType type = operand->getType(); if (!type->isDependentType() && !type->isObjCObjectPointerType()) { const PointerType *pointerType = type->getAs(); if (!pointerType || !pointerType->getPointeeType()->isVoidType()) { if (getLangOpts().CPlusPlus) { if (RequireCompleteType(atLoc, type, diag::err_incomplete_receiver_type)) return Diag(atLoc, diag::err_objc_synchronized_expects_object) << type << operand->getSourceRange(); ExprResult result = PerformContextuallyConvertToObjCPointer(operand); if (result.isInvalid()) return ExprError(); if (!result.isUsable()) return Diag(atLoc, diag::err_objc_synchronized_expects_object) << type << operand->getSourceRange(); operand = result.get(); } else { return Diag(atLoc, diag::err_objc_synchronized_expects_object) << type << operand->getSourceRange(); } } } // The operand to @synchronized is a full-expression. return ActOnFinishFullExpr(operand, /*DiscardedValue*/ false); } StmtResult Sema::ActOnObjCAtSynchronizedStmt(SourceLocation AtLoc, Expr *SyncExpr, Stmt *SyncBody) { // We can't jump into or indirect-jump out of a @synchronized block. setFunctionHasBranchProtectedScope(); return new (Context) ObjCAtSynchronizedStmt(AtLoc, SyncExpr, SyncBody); } /// ActOnCXXCatchBlock - Takes an exception declaration and a handler block /// and creates a proper catch handler from them. StmtResult Sema::ActOnCXXCatchBlock(SourceLocation CatchLoc, Decl *ExDecl, Stmt *HandlerBlock) { // There's nothing to test that ActOnExceptionDecl didn't already test. return new (Context) CXXCatchStmt(CatchLoc, cast_or_null(ExDecl), HandlerBlock); } StmtResult Sema::ActOnObjCAutoreleasePoolStmt(SourceLocation AtLoc, Stmt *Body) { setFunctionHasBranchProtectedScope(); return new (Context) ObjCAutoreleasePoolStmt(AtLoc, Body); } namespace { class CatchHandlerType { QualType QT; unsigned IsPointer : 1; // This is a special constructor to be used only with DenseMapInfo's // getEmptyKey() and getTombstoneKey() functions. friend struct llvm::DenseMapInfo; enum Unique { ForDenseMap }; CatchHandlerType(QualType QT, Unique) : QT(QT), IsPointer(false) {} public: /// Used when creating a CatchHandlerType from a handler type; will determine /// whether the type is a pointer or reference and will strip off the top /// level pointer and cv-qualifiers. CatchHandlerType(QualType Q) : QT(Q), IsPointer(false) { if (QT->isPointerType()) IsPointer = true; if (IsPointer || QT->isReferenceType()) QT = QT->getPointeeType(); QT = QT.getUnqualifiedType(); } /// Used when creating a CatchHandlerType from a base class type; pretends the /// type passed in had the pointer qualifier, does not need to get an /// unqualified type. CatchHandlerType(QualType QT, bool IsPointer) : QT(QT), IsPointer(IsPointer) {} QualType underlying() const { return QT; } bool isPointer() const { return IsPointer; } friend bool operator==(const CatchHandlerType &LHS, const CatchHandlerType &RHS) { // If the pointer qualification does not match, we can return early. if (LHS.IsPointer != RHS.IsPointer) return false; // Otherwise, check the underlying type without cv-qualifiers. return LHS.QT == RHS.QT; } }; } // namespace namespace llvm { template <> struct DenseMapInfo { static CatchHandlerType getEmptyKey() { return CatchHandlerType(DenseMapInfo::getEmptyKey(), CatchHandlerType::ForDenseMap); } static CatchHandlerType getTombstoneKey() { return CatchHandlerType(DenseMapInfo::getTombstoneKey(), CatchHandlerType::ForDenseMap); } static unsigned getHashValue(const CatchHandlerType &Base) { return DenseMapInfo::getHashValue(Base.underlying()); } static bool isEqual(const CatchHandlerType &LHS, const CatchHandlerType &RHS) { return LHS == RHS; } }; } namespace { class CatchTypePublicBases { ASTContext &Ctx; const llvm::DenseMap &TypesToCheck; const bool CheckAgainstPointer; CXXCatchStmt *FoundHandler; CanQualType FoundHandlerType; public: CatchTypePublicBases( ASTContext &Ctx, const llvm::DenseMap &T, bool C) : Ctx(Ctx), TypesToCheck(T), CheckAgainstPointer(C), FoundHandler(nullptr) {} CXXCatchStmt *getFoundHandler() const { return FoundHandler; } CanQualType getFoundHandlerType() const { return FoundHandlerType; } bool operator()(const CXXBaseSpecifier *S, CXXBasePath &) { if (S->getAccessSpecifier() == AccessSpecifier::AS_public) { CatchHandlerType Check(S->getType(), CheckAgainstPointer); const auto &M = TypesToCheck; auto I = M.find(Check); if (I != M.end()) { FoundHandler = I->second; FoundHandlerType = Ctx.getCanonicalType(S->getType()); return true; } } return false; } }; } /// ActOnCXXTryBlock - Takes a try compound-statement and a number of /// handlers and creates a try statement from them. StmtResult Sema::ActOnCXXTryBlock(SourceLocation TryLoc, Stmt *TryBlock, ArrayRef Handlers) { // Don't report an error if 'try' is used in system headers. if (!getLangOpts().CXXExceptions && !getSourceManager().isInSystemHeader(TryLoc) && !getLangOpts().CUDA) { // Delay error emission for the OpenMP device code. targetDiag(TryLoc, diag::err_exceptions_disabled) << "try"; } // Exceptions aren't allowed in CUDA device code. if (getLangOpts().CUDA) CUDADiagIfDeviceCode(TryLoc, diag::err_cuda_device_exceptions) << "try" << CurrentCUDATarget(); if (getCurScope() && getCurScope()->isOpenMPSimdDirectiveScope()) Diag(TryLoc, diag::err_omp_simd_region_cannot_use_stmt) << "try"; sema::FunctionScopeInfo *FSI = getCurFunction(); // C++ try is incompatible with SEH __try. if (!getLangOpts().Borland && FSI->FirstSEHTryLoc.isValid()) { Diag(TryLoc, diag::err_mixing_cxx_try_seh_try); Diag(FSI->FirstSEHTryLoc, diag::note_conflicting_try_here) << "'__try'"; } const unsigned NumHandlers = Handlers.size(); assert(!Handlers.empty() && "The parser shouldn't call this if there are no handlers."); llvm::DenseMap HandledTypes; for (unsigned i = 0; i < NumHandlers; ++i) { CXXCatchStmt *H = cast(Handlers[i]); // Diagnose when the handler is a catch-all handler, but it isn't the last // handler for the try block. [except.handle]p5. Also, skip exception // declarations that are invalid, since we can't usefully report on them. if (!H->getExceptionDecl()) { if (i < NumHandlers - 1) return StmtError(Diag(H->getBeginLoc(), diag::err_early_catch_all)); continue; } else if (H->getExceptionDecl()->isInvalidDecl()) continue; // Walk the type hierarchy to diagnose when this type has already been // handled (duplication), or cannot be handled (derivation inversion). We // ignore top-level cv-qualifiers, per [except.handle]p3 CatchHandlerType HandlerCHT = (QualType)Context.getCanonicalType(H->getCaughtType()); // We can ignore whether the type is a reference or a pointer; we need the // underlying declaration type in order to get at the underlying record // decl, if there is one. QualType Underlying = HandlerCHT.underlying(); if (auto *RD = Underlying->getAsCXXRecordDecl()) { if (!RD->hasDefinition()) continue; // Check that none of the public, unambiguous base classes are in the // map ([except.handle]p1). Give the base classes the same pointer // qualification as the original type we are basing off of. This allows // comparison against the handler type using the same top-level pointer // as the original type. CXXBasePaths Paths; Paths.setOrigin(RD); CatchTypePublicBases CTPB(Context, HandledTypes, HandlerCHT.isPointer()); if (RD->lookupInBases(CTPB, Paths)) { const CXXCatchStmt *Problem = CTPB.getFoundHandler(); if (!Paths.isAmbiguous(CTPB.getFoundHandlerType())) { Diag(H->getExceptionDecl()->getTypeSpecStartLoc(), diag::warn_exception_caught_by_earlier_handler) << H->getCaughtType(); Diag(Problem->getExceptionDecl()->getTypeSpecStartLoc(), diag::note_previous_exception_handler) << Problem->getCaughtType(); } } } // Add the type the list of ones we have handled; diagnose if we've already // handled it. auto R = HandledTypes.insert(std::make_pair(H->getCaughtType(), H)); if (!R.second) { const CXXCatchStmt *Problem = R.first->second; Diag(H->getExceptionDecl()->getTypeSpecStartLoc(), diag::warn_exception_caught_by_earlier_handler) << H->getCaughtType(); Diag(Problem->getExceptionDecl()->getTypeSpecStartLoc(), diag::note_previous_exception_handler) << Problem->getCaughtType(); } } FSI->setHasCXXTry(TryLoc); return CXXTryStmt::Create(Context, TryLoc, TryBlock, Handlers); } StmtResult Sema::ActOnSEHTryBlock(bool IsCXXTry, SourceLocation TryLoc, Stmt *TryBlock, Stmt *Handler) { assert(TryBlock && Handler); sema::FunctionScopeInfo *FSI = getCurFunction(); // SEH __try is incompatible with C++ try. Borland appears to support this, // however. if (!getLangOpts().Borland) { if (FSI->FirstCXXTryLoc.isValid()) { Diag(TryLoc, diag::err_mixing_cxx_try_seh_try); Diag(FSI->FirstCXXTryLoc, diag::note_conflicting_try_here) << "'try'"; } } FSI->setHasSEHTry(TryLoc); // Reject __try in Obj-C methods, blocks, and captured decls, since we don't // track if they use SEH. DeclContext *DC = CurContext; while (DC && !DC->isFunctionOrMethod()) DC = DC->getParent(); FunctionDecl *FD = dyn_cast_or_null(DC); if (FD) FD->setUsesSEHTry(true); else Diag(TryLoc, diag::err_seh_try_outside_functions); // Reject __try on unsupported targets. if (!Context.getTargetInfo().isSEHTrySupported()) Diag(TryLoc, diag::err_seh_try_unsupported); return SEHTryStmt::Create(Context, IsCXXTry, TryLoc, TryBlock, Handler); } StmtResult Sema::ActOnSEHExceptBlock(SourceLocation Loc, Expr *FilterExpr, Stmt *Block) { assert(FilterExpr && Block); QualType FTy = FilterExpr->getType(); if (!FTy->isIntegerType() && !FTy->isDependentType()) { return StmtError( Diag(FilterExpr->getExprLoc(), diag::err_filter_expression_integral) << FTy); } return SEHExceptStmt::Create(Context, Loc, FilterExpr, Block); } void Sema::ActOnStartSEHFinallyBlock() { CurrentSEHFinally.push_back(CurScope); } void Sema::ActOnAbortSEHFinallyBlock() { CurrentSEHFinally.pop_back(); } StmtResult Sema::ActOnFinishSEHFinallyBlock(SourceLocation Loc, Stmt *Block) { assert(Block); CurrentSEHFinally.pop_back(); return SEHFinallyStmt::Create(Context, Loc, Block); } StmtResult Sema::ActOnSEHLeaveStmt(SourceLocation Loc, Scope *CurScope) { Scope *SEHTryParent = CurScope; while (SEHTryParent && !SEHTryParent->isSEHTryScope()) SEHTryParent = SEHTryParent->getParent(); if (!SEHTryParent) return StmtError(Diag(Loc, diag::err_ms___leave_not_in___try)); CheckJumpOutOfSEHFinally(*this, Loc, *SEHTryParent); return new (Context) SEHLeaveStmt(Loc); } StmtResult Sema::BuildMSDependentExistsStmt(SourceLocation KeywordLoc, bool IsIfExists, NestedNameSpecifierLoc QualifierLoc, DeclarationNameInfo NameInfo, Stmt *Nested) { return new (Context) MSDependentExistsStmt(KeywordLoc, IsIfExists, QualifierLoc, NameInfo, cast(Nested)); } StmtResult Sema::ActOnMSDependentExistsStmt(SourceLocation KeywordLoc, bool IsIfExists, CXXScopeSpec &SS, UnqualifiedId &Name, Stmt *Nested) { return BuildMSDependentExistsStmt(KeywordLoc, IsIfExists, SS.getWithLocInContext(Context), GetNameFromUnqualifiedId(Name), Nested); } RecordDecl* Sema::CreateCapturedStmtRecordDecl(CapturedDecl *&CD, SourceLocation Loc, unsigned NumParams) { DeclContext *DC = CurContext; while (!(DC->isFunctionOrMethod() || DC->isRecord() || DC->isFileContext())) DC = DC->getParent(); RecordDecl *RD = nullptr; if (getLangOpts().CPlusPlus) RD = CXXRecordDecl::Create(Context, TTK_Struct, DC, Loc, Loc, /*Id=*/nullptr); else RD = RecordDecl::Create(Context, TTK_Struct, DC, Loc, Loc, /*Id=*/nullptr); RD->setCapturedRecord(); DC->addDecl(RD); RD->setImplicit(); RD->startDefinition(); assert(NumParams > 0 && "CapturedStmt requires context parameter"); CD = CapturedDecl::Create(Context, CurContext, NumParams); DC->addDecl(CD); return RD; } static bool buildCapturedStmtCaptureList(Sema &S, CapturedRegionScopeInfo *RSI, SmallVectorImpl &Captures, SmallVectorImpl &CaptureInits) { for (const sema::Capture &Cap : RSI->Captures) { if (Cap.isInvalid()) continue; // Form the initializer for the capture. ExprResult Init = S.BuildCaptureInit(Cap, Cap.getLocation(), RSI->CapRegionKind == CR_OpenMP); // FIXME: Bail out now if the capture is not used and the initializer has // no side-effects. // Create a field for this capture. FieldDecl *Field = S.BuildCaptureField(RSI->TheRecordDecl, Cap); // Add the capture to our list of captures. if (Cap.isThisCapture()) { Captures.push_back(CapturedStmt::Capture(Cap.getLocation(), CapturedStmt::VCK_This)); } else if (Cap.isVLATypeCapture()) { Captures.push_back( CapturedStmt::Capture(Cap.getLocation(), CapturedStmt::VCK_VLAType)); } else { assert(Cap.isVariableCapture() && "unknown kind of capture"); if (S.getLangOpts().OpenMP && RSI->CapRegionKind == CR_OpenMP) S.setOpenMPCaptureKind(Field, Cap.getVariable(), RSI->OpenMPLevel); Captures.push_back(CapturedStmt::Capture(Cap.getLocation(), Cap.isReferenceCapture() ? CapturedStmt::VCK_ByRef : CapturedStmt::VCK_ByCopy, Cap.getVariable())); } CaptureInits.push_back(Init.get()); } return false; } void Sema::ActOnCapturedRegionStart(SourceLocation Loc, Scope *CurScope, CapturedRegionKind Kind, unsigned NumParams) { CapturedDecl *CD = nullptr; RecordDecl *RD = CreateCapturedStmtRecordDecl(CD, Loc, NumParams); // Build the context parameter DeclContext *DC = CapturedDecl::castToDeclContext(CD); IdentifierInfo *ParamName = &Context.Idents.get("__context"); QualType ParamType = Context.getPointerType(Context.getTagDeclType(RD)); auto *Param = ImplicitParamDecl::Create(Context, DC, Loc, ParamName, ParamType, ImplicitParamDecl::CapturedContext); DC->addDecl(Param); CD->setContextParam(0, Param); // Enter the capturing scope for this captured region. PushCapturedRegionScope(CurScope, CD, RD, Kind); if (CurScope) PushDeclContext(CurScope, CD); else CurContext = CD; PushExpressionEvaluationContext( ExpressionEvaluationContext::PotentiallyEvaluated); } void Sema::ActOnCapturedRegionStart(SourceLocation Loc, Scope *CurScope, CapturedRegionKind Kind, ArrayRef Params, unsigned OpenMPCaptureLevel) { CapturedDecl *CD = nullptr; RecordDecl *RD = CreateCapturedStmtRecordDecl(CD, Loc, Params.size()); // Build the context parameter DeclContext *DC = CapturedDecl::castToDeclContext(CD); bool ContextIsFound = false; unsigned ParamNum = 0; for (ArrayRef::iterator I = Params.begin(), E = Params.end(); I != E; ++I, ++ParamNum) { if (I->second.isNull()) { assert(!ContextIsFound && "null type has been found already for '__context' parameter"); IdentifierInfo *ParamName = &Context.Idents.get("__context"); QualType ParamType = Context.getPointerType(Context.getTagDeclType(RD)) .withConst() .withRestrict(); auto *Param = ImplicitParamDecl::Create(Context, DC, Loc, ParamName, ParamType, ImplicitParamDecl::CapturedContext); DC->addDecl(Param); CD->setContextParam(ParamNum, Param); ContextIsFound = true; } else { IdentifierInfo *ParamName = &Context.Idents.get(I->first); auto *Param = ImplicitParamDecl::Create(Context, DC, Loc, ParamName, I->second, ImplicitParamDecl::CapturedContext); DC->addDecl(Param); CD->setParam(ParamNum, Param); } } assert(ContextIsFound && "no null type for '__context' parameter"); if (!ContextIsFound) { // Add __context implicitly if it is not specified. IdentifierInfo *ParamName = &Context.Idents.get("__context"); QualType ParamType = Context.getPointerType(Context.getTagDeclType(RD)); auto *Param = ImplicitParamDecl::Create(Context, DC, Loc, ParamName, ParamType, ImplicitParamDecl::CapturedContext); DC->addDecl(Param); CD->setContextParam(ParamNum, Param); } // Enter the capturing scope for this captured region. PushCapturedRegionScope(CurScope, CD, RD, Kind, OpenMPCaptureLevel); if (CurScope) PushDeclContext(CurScope, CD); else CurContext = CD; PushExpressionEvaluationContext( ExpressionEvaluationContext::PotentiallyEvaluated); } void Sema::ActOnCapturedRegionError() { DiscardCleanupsInEvaluationContext(); PopExpressionEvaluationContext(); PopDeclContext(); PoppedFunctionScopePtr ScopeRAII = PopFunctionScopeInfo(); CapturedRegionScopeInfo *RSI = cast(ScopeRAII.get()); RecordDecl *Record = RSI->TheRecordDecl; Record->setInvalidDecl(); SmallVector Fields(Record->fields()); ActOnFields(/*Scope=*/nullptr, Record->getLocation(), Record, Fields, SourceLocation(), SourceLocation(), ParsedAttributesView()); } StmtResult Sema::ActOnCapturedRegionEnd(Stmt *S) { // Leave the captured scope before we start creating captures in the // enclosing scope. DiscardCleanupsInEvaluationContext(); PopExpressionEvaluationContext(); PopDeclContext(); PoppedFunctionScopePtr ScopeRAII = PopFunctionScopeInfo(); CapturedRegionScopeInfo *RSI = cast(ScopeRAII.get()); SmallVector Captures; SmallVector CaptureInits; if (buildCapturedStmtCaptureList(*this, RSI, Captures, CaptureInits)) return StmtError(); CapturedDecl *CD = RSI->TheCapturedDecl; RecordDecl *RD = RSI->TheRecordDecl; CapturedStmt *Res = CapturedStmt::Create( getASTContext(), S, static_cast(RSI->CapRegionKind), Captures, CaptureInits, CD, RD); CD->setBody(Res->getCapturedStmt()); RD->completeDefinition(); return Res; }