diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td index a92a3a6a7c331..208c885909b00 100644 --- a/clang/include/clang/Basic/DiagnosticSemaKinds.td +++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td @@ -3712,6 +3712,8 @@ def err_conflicting_codeseg_attribute : Error< def warn_duplicate_codeseg_attribute : Warning< "duplicate code segment specifiers">, InGroup
; +def err_expansion_stmt_invalid_init : Error< + "cannot expand expression of type %0">; def err_expansion_stmt_vla : Error< "cannot expand variable length array type %0">; def err_expansion_stmt_incomplete : Error< diff --git a/clang/lib/Sema/SemaExpand.cpp b/clang/lib/Sema/SemaExpand.cpp index 40891e96e97de..6fa1ad9856783 100644 --- a/clang/lib/Sema/SemaExpand.cpp +++ b/clang/lib/Sema/SemaExpand.cpp @@ -85,7 +85,7 @@ static bool HasDependentSize(const CXXExpansionStmtPattern *Pattern) { return true; case CXXExpansionStmtPattern::ExpansionStmtKind::Destructuring: - llvm_unreachable("TODO"); + return false; } llvm_unreachable("invalid pattern kind"); @@ -220,6 +220,52 @@ TryBuildIterableExpansionStmtInitializer(Sema &S, Expr *ExpansionInitializer, return Data; } +static StmtResult BuildDestructuringDecompositionDecl( + Sema &S, Expr *ExpansionInitializer, SourceLocation ColonLoc, + bool VarIsConstexpr, + ArrayRef LifetimeExtendTemps) { + auto Ctx = Sema::ExpressionEvaluationContext::PotentiallyEvaluated; + if (VarIsConstexpr) + Ctx = Sema::ExpressionEvaluationContext::ImmediateFunctionContext; + EnterExpressionEvaluationContext ExprEvalCtx(S, Ctx); + + // The declarations should be attached to the parent decl context. + Sema::ContextRAII CtxGuard( + S, S.CurContext->getEnclosingNonExpansionStatementContext(), + /*NewThis=*/false); + + UnsignedOrNone Arity = + S.GetDecompositionElementCount(ExpansionInitializer->getType(), ColonLoc); + + if (!Arity) { + S.Diag(ExpansionInitializer->getBeginLoc(), + diag::err_expansion_stmt_invalid_init) + << ExpansionInitializer->getType() + << ExpansionInitializer->getSourceRange(); + return StmtError(); + } + + QualType AutoRRef = S.Context.getAutoRRefDeductType(); + SmallVector Bindings; + for (unsigned I = 0; I < *Arity; ++I) + Bindings.push_back(BindingDecl::Create( + S.Context, S.CurContext, ColonLoc, + S.getPreprocessor().getIdentifierInfo("__u" + std::to_string(I)), + AutoRRef)); + + TypeSourceInfo *TSI = S.Context.getTrivialTypeSourceInfo(AutoRRef); + auto *DD = + DecompositionDecl::Create(S.Context, S.CurContext, ColonLoc, ColonLoc, + AutoRRef, TSI, SC_Auto, Bindings); + + if (VarIsConstexpr) + DD->setConstexpr(true); + + S.ApplyForRangeOrExpansionStatementLifetimeExtension(DD, LifetimeExtendTemps); + S.AddInitializerToDecl(DD, ExpansionInitializer, false); + return S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(DD), ColonLoc, ColonLoc); +} + CXXExpansionStmtDecl * Sema::ActOnCXXExpansionStmtDecl(unsigned TemplateDepth, SourceLocation TemplateKWLoc) { @@ -368,8 +414,43 @@ StmtResult Sema::BuildNonEnumeratingCXXExpansionStmtPattern( Data.EndDecl, LParenLoc, ColonLoc, RParenLoc); } - Diag(ESD->getLocation(), diag::err_expansion_statements_todo); - return StmtError(); + // If not, try destructuring. + StmtResult DecompDeclStmt = BuildDestructuringDecompositionDecl( + *this, ExpansionInitializer, ColonLoc, ExpansionVar->isConstexpr(), + LifetimeExtendTemps); + if (DecompDeclStmt.isInvalid()) { + ActOnInitializerError(ExpansionVar); + return StmtError(); + } + + auto *DS = DecompDeclStmt.getAs(); + auto *DD = cast(DS->getSingleDecl()); + if (DD->isInvalidDecl()) + return StmtError(); + + // Synthesise an InitListExpr to store the bindings; this essentially lets us + // desugar the expansion of a destructuring expansion statement to that of an + // enumerating expansion statement. + SmallVector Bindings; + for (BindingDecl *BD : DD->bindings()) { + auto *HVD = BD->getHoldingVar(); + Bindings.push_back(HVD ? HVD->getInit() : BD->getBinding()); + } + + ExprResult Select = BuildCXXExpansionSelectExpr( + new (Context) InitListExpr(Context, ColonLoc, Bindings, ColonLoc), + Index); + + if (Select.isInvalid()) { + ActOnInitializerError(ExpansionVar); + return StmtError(); + } + + if (FinaliseExpansionVar(*this, ExpansionVar, Select)) + return StmtError(); + + return CXXExpansionStmtPattern::CreateDestructuring( + Context, ESD, Init, ExpansionVarStmt, DS, LParenLoc, ColonLoc, RParenLoc); } StmtResult Sema::FinishCXXExpansionStmt(Stmt *Exp, Stmt *Body) { @@ -409,8 +490,10 @@ StmtResult Sema::FinishCXXExpansionStmt(Stmt *Exp, Stmt *Body) { Shared.push_back(Expansion->getRangeVarStmt()); Shared.push_back(Expansion->getBeginVarStmt()); Shared.push_back(Expansion->getEndVarStmt()); - } else { - assert(Expansion->isEnumerating() && "TODO"); + } else if (Expansion->isDestructuring()) { + Shared.push_back(Expansion->getDecompositionDeclStmt()); + MarkAnyDeclReferenced(Exp->getBeginLoc(), Expansion->getDecompositionDecl(), + true); } // Return an empty statement if the range is empty. @@ -663,5 +746,6 @@ Sema::ComputeExpansionSize(CXXExpansionStmtPattern *Expansion) { return ER.Val.getInt().getZExtValue(); } - llvm_unreachable("TODO"); + assert(Expansion->isDestructuring()); + return Expansion->getDecompositionDecl()->bindings().size(); } diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h index 58ba5fadd6f08..fc314c34a3065 100644 --- a/clang/lib/Sema/TreeTransform.h +++ b/clang/lib/Sema/TreeTransform.h @@ -9297,28 +9297,51 @@ TreeTransform::TransformCXXForRangeStmt(CXXForRangeStmt *S) { template StmtResult TreeTransform::TransformCXXExpansionStmtPattern( CXXExpansionStmtPattern *S) { + ExprResult ExpansionInitializer; + SmallVector LifetimeExtendTemps; CXXExpansionStmtDecl *NewESD = nullptr; Stmt *Init = nullptr; DeclStmt *ExpansionVarStmt = nullptr; - Decl *ESD = - getDerived().TransformDecl(S->getDecl()->getLocation(), S->getDecl()); - if (!ESD || ESD->isInvalidDecl()) - return StmtError(); - NewESD = cast(ESD); - Init = S->getInit(); - if (Init) { - StmtResult SR = getDerived().TransformStmt(Init); - if (SR.isInvalid()) + // Collect lifetime-extended temporaries in case this ends up being a + // destructuring expansion statement (for other kinds of expansion statements, + // this should make no difference since we ignore 'LifetimeExtendTemps' for + // those). + { + EnterExpressionEvaluationContext ExprEvalCtx( + SemaRef, SemaRef.currentEvaluationContext().Context); + SemaRef.currentEvaluationContext().InLifetimeExtendingContext = true; + SemaRef.currentEvaluationContext().RebuildDefaultArgOrDefaultInit = true; + Decl *ESD = + getDerived().TransformDecl(S->getDecl()->getLocation(), S->getDecl()); + if (!ESD || ESD->isInvalidDecl()) return StmtError(); - Init = SR.get(); - } + NewESD = cast(ESD); - StmtResult ExpansionVar = - getDerived().TransformStmt(S->getExpansionVarStmt()); - if (ExpansionVar.isInvalid()) - return StmtError(); - ExpansionVarStmt = cast(ExpansionVar.get()); + Init = S->getInit(); + if (Init) { + StmtResult SR = getDerived().TransformStmt(Init); + if (SR.isInvalid()) + return StmtError(); + Init = SR.get(); + } + + StmtResult ExpansionVar = + getDerived().TransformStmt(S->getExpansionVarStmt()); + if (ExpansionVar.isInvalid()) + return StmtError(); + ExpansionVarStmt = cast(ExpansionVar.get()); + + if (S->isDependent()) { + ExpansionInitializer = + getDerived().TransformExpr(S->getExpansionInitializer()); + if (ExpansionInitializer.isInvalid()) + return StmtError(); + + LifetimeExtendTemps = + SemaRef.currentEvaluationContext().ForRangeLifetimeExtendTemps; + } + } CXXExpansionStmtPattern *NewPattern = nullptr; if (S->isEnumerating()) { @@ -9340,22 +9363,22 @@ StmtResult TreeTransform::TransformCXXExpansionStmtPattern( Range.getAs(), Begin.getAs(), End.getAs(), S->getLParenLoc(), S->getColonLoc(), S->getRParenLoc()); } else if (S->isDependent()) { - ExprResult ExpansionInitializer = - getDerived().TransformExpr(S->getExpansionInitializer()); - if (ExpansionInitializer.isInvalid()) - return StmtError(); - StmtResult Res = SemaRef.BuildNonEnumeratingCXXExpansionStmtPattern( NewESD, Init, ExpansionVarStmt, ExpansionInitializer.get(), S->getLParenLoc(), S->getColonLoc(), S->getRParenLoc(), - /*LifetimeExtendTemps=*/{}); + LifetimeExtendTemps); if (Res.isInvalid()) return StmtError(); NewPattern = cast(Res.get()); } else { - llvm_unreachable("TODO"); + // The only time we instantiate an expansion statement is if its expansion + // size is dependent (otherwise, we only instantiate the expansions and + // leave the underlying CXXExpansionStmtPattern as-is). Since destructuring + // expansion statements never have a dependent size, we should never get + // here. + llvm_unreachable("destructuring pattern should never be instantiated"); } StmtResult Body = getDerived().TransformStmt(S->getBody()); @@ -9386,8 +9409,23 @@ StmtResult TreeTransform::TransformCXXExpansionStmtInstantiation( SmallVector SharedStmts; SmallVector Instantiations; - if (TransformStmts(SharedStmts, S->getSharedStmts())) - return StmtError(); + // Apply lifetime extension to the shared statements if this was a + // destructuring expansion statement. + { + EnterExpressionEvaluationContext ExprEvalCtx( + SemaRef, SemaRef.currentEvaluationContext().Context); + SemaRef.currentEvaluationContext().InLifetimeExtendingContext = true; + SemaRef.currentEvaluationContext().RebuildDefaultArgOrDefaultInit = true; + if (TransformStmts(SharedStmts, S->getSharedStmts())) + return StmtError(); + + if (S->shouldApplyLifetimeExtensionToSharedStmts()) { + auto *VD = + cast(cast(SharedStmts.front())->getSingleDecl()); + SemaRef.ApplyForRangeOrExpansionStatementLifetimeExtension( + VD, SemaRef.currentEvaluationContext().ForRangeLifetimeExtendTemps); + } + } if (TransformStmts(Instantiations, S->getInstantiations())) return StmtError();