llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-clang Author: None (yronglin) <details> <summary>Changes</summary> This PR complete [DR1815](https://wg21.link/CWG1815) under the guidance of `FIXME` comments. And reuse `CXXDefaultInitExpr` rewrite machinery to clone the initializer expression on each use that would lifetime extend its temporaries. --- Full diff: https://github.com/llvm/llvm-project/pull/87933.diff 9 Files Affected: - (modified) clang/include/clang/Basic/DiagnosticSemaKinds.td (-6) - (modified) clang/lib/Sema/SemaExpr.cpp (+9-7) - (modified) clang/lib/Sema/SemaInit.cpp (+27-12) - (modified) clang/test/Analysis/lifetime-extended-regions.cpp (+1-1) - (modified) clang/test/CXX/drs/dr16xx.cpp (-2) - (modified) clang/test/CXX/drs/dr18xx.cpp (+1-4) - (modified) clang/test/CXX/special/class.temporary/p6.cpp (+20) - (modified) clang/test/SemaCXX/constexpr-default-arg.cpp (+2-2) - (modified) clang/test/SemaCXX/eval-crashes.cpp (+2-4) ``````````diff diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td index a1dda2d2461c31..ba779e83d2afd4 100644 --- a/clang/include/clang/Basic/DiagnosticSemaKinds.td +++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td @@ -10010,12 +10010,6 @@ def warn_new_dangling_initializer_list : Warning< "the allocated initializer list}0 " "will be destroyed at the end of the full-expression">, InGroup<DanglingInitializerList>; -def warn_unsupported_lifetime_extension : Warning< - "lifetime extension of " - "%select{temporary|backing array of initializer list}0 created " - "by aggregate initialization using a default member initializer " - "is not yet supported; lifetime of %select{temporary|backing array}0 " - "will end at the end of the full-expression">, InGroup<Dangling>; // For non-floating point, expressions of the form x == x or x != x // should result in a warning, since these always evaluate to a constant. diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp index 8db4fffeecfe35..b2e0f2a2a60113 100644 --- a/clang/lib/Sema/SemaExpr.cpp +++ b/clang/lib/Sema/SemaExpr.cpp @@ -6338,10 +6338,9 @@ ExprResult Sema::BuildCXXDefaultArgExpr(SourceLocation CallLoc, Res = Immediate.TransformInitializer(Param->getInit(), /*NotCopy=*/false); }); - if (Res.isInvalid()) - return ExprError(); - Res = ConvertParamDefaultArgument(Param, Res.get(), - Res.get()->getBeginLoc()); + if (Res.isUsable()) + Res = ConvertParamDefaultArgument(Param, Res.get(), + Res.get()->getBeginLoc()); if (Res.isInvalid()) return ExprError(); Init = Res.get(); @@ -6377,7 +6376,7 @@ ExprResult Sema::BuildCXXDefaultInitExpr(SourceLocation Loc, FieldDecl *Field) { Expr *Init = nullptr; bool NestedDefaultChecking = isCheckingDefaultArgumentOrInitializer(); - + bool InLifetimeExtendingContext = isInLifetimeExtendingContext(); EnterExpressionEvaluationContext EvalContext( *this, ExpressionEvaluationContext::PotentiallyEvaluated, Field); @@ -6412,11 +6411,14 @@ ExprResult Sema::BuildCXXDefaultInitExpr(SourceLocation Loc, FieldDecl *Field) { ImmediateCallVisitor V(getASTContext()); if (!NestedDefaultChecking) V.TraverseDecl(Field); - if (V.HasImmediateCalls) { + if (V.HasImmediateCalls || InLifetimeExtendingContext) { ExprEvalContexts.back().DelayedDefaultInitializationContext = {Loc, Field, CurContext}; ExprEvalContexts.back().IsCurrentlyCheckingDefaultArgumentOrInitializer = NestedDefaultChecking; + // Pass down lifetime extending flag, and collect temporaries in + // CreateMaterializeTemporaryExpr when we rewrite the call argument. + keepInLifetimeExtendingContext(); EnsureImmediateInvocationInDefaultArgs Immediate(*this); ExprResult Res; @@ -6424,7 +6426,7 @@ ExprResult Sema::BuildCXXDefaultInitExpr(SourceLocation Loc, FieldDecl *Field) { Res = Immediate.TransformInitializer(Field->getInClassInitializer(), /*CXXDirectInit=*/false); }); - if (!Res.isInvalid()) + if (Res.isUsable()) Res = ConvertMemberDefaultInitExpression(Field, Res.get(), Loc); if (Res.isInvalid()) { Field->setInvalidDecl(); diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp index a75e9925a43146..842412cd674d8c 100644 --- a/clang/lib/Sema/SemaInit.cpp +++ b/clang/lib/Sema/SemaInit.cpp @@ -710,6 +710,26 @@ void InitListChecker::FillInEmptyInitForField(unsigned Init, FieldDecl *Field, if (VerifyOnly) return; + // Enter a lifetime extension context, then we can support lifetime + // extension of temporary created by aggregate initialization using a + // default member initializer (DR1815 https://wg21.link/CWG1815). + // + // In a lifetime extension context, BuildCXXDefaultInitExpr will clone the + // initializer expression on each use that would lifetime extend its + // temporaries. + EnterExpressionEvaluationContext LifetimeExtensionContext( + SemaRef, Sema::ExpressionEvaluationContext::PotentiallyEvaluated, + /*LambdaContextDecl=*/nullptr, + Sema::ExpressionEvaluationContextRecord::EK_Other, true); + + // Lifetime extension in default-member-init. + auto &LastRecord = SemaRef.ExprEvalContexts.back(); + + // Just copy previous record, make sure we haven't forget anything. + LastRecord = + SemaRef.ExprEvalContexts[SemaRef.ExprEvalContexts.size() - 2]; + LastRecord.InLifetimeExtendingContext = true; + ExprResult DIE = SemaRef.BuildCXXDefaultInitExpr(Loc, Field); if (DIE.isInvalid()) { hadError = true; @@ -7699,6 +7719,8 @@ static void visitLocalsRetainedByReferenceBinding(IndirectLocalPath &Path, // Step into CXXDefaultInitExprs so we can diagnose cases where a // constructor inherits one as an implicit mem-initializer. if (auto *DIE = dyn_cast<CXXDefaultInitExpr>(Init)) { + assert(DIE->hasRewrittenInit() && + "CXXDefaultInitExpr must has rewritten init"); Path.push_back( {IndirectLocalPathEntry::DefaultInit, DIE, DIE->getField()}); Init = DIE->getExpr(); @@ -8193,6 +8215,11 @@ void Sema::checkInitializerLifetime(const InitializedEntity &Entity, } switch (shouldLifetimeExtendThroughPath(Path)) { + case PathLifetimeKind::ShouldExtend: + // We're supposed to lifetime-extend the temporary along this path (per + // the resolution of DR1815), we supported that by clone the initializer + // expression on each use that would lifetime extend its temporaries. + [[fallthrough]]; case PathLifetimeKind::Extend: // Update the storage duration of the materialized temporary. // FIXME: Rebuild the expression instead of mutating it. @@ -8200,18 +8227,6 @@ void Sema::checkInitializerLifetime(const InitializedEntity &Entity, ExtendingEntity->allocateManglingNumber()); // Also visit the temporaries lifetime-extended by this initializer. return true; - - case PathLifetimeKind::ShouldExtend: - // We're supposed to lifetime-extend the temporary along this path (per - // the resolution of DR1815), but we don't support that yet. - // - // FIXME: Properly handle this situation. Perhaps the easiest approach - // would be to clone the initializer expression on each use that would - // lifetime extend its temporaries. - Diag(DiagLoc, diag::warn_unsupported_lifetime_extension) - << RK << DiagRange; - break; - case PathLifetimeKind::NoExtend: // If the path goes through the initialization of a variable or field, // it can't possibly reach a temporary created in this full-expression. diff --git a/clang/test/Analysis/lifetime-extended-regions.cpp b/clang/test/Analysis/lifetime-extended-regions.cpp index 4e98bd4b0403eb..8df9b8a54a7e02 100644 --- a/clang/test/Analysis/lifetime-extended-regions.cpp +++ b/clang/test/Analysis/lifetime-extended-regions.cpp @@ -122,7 +122,7 @@ void aggregateWithReferences() { clang_analyzer_dump(viaReference.ry); // expected-warning-re {{&lifetime_extended_object{Composite, viaReference, S{{[0-9]+}}} }} // clang does not currently implement extending lifetime of object bound to reference members of aggregates, - // that are created from default member initializer (see `warn_unsupported_lifetime_extension` from `-Wdangling`) + // that are created from default member initializer (see `warn_unsupported_lifetime_extension` from `-Wdangling`) (Supported now). RefAggregate defaultInitExtended{i}; // clang-bug does not extend `Composite` clang_analyzer_dump(defaultInitExtended.ry); // expected-warning {{Unknown }} } diff --git a/clang/test/CXX/drs/dr16xx.cpp b/clang/test/CXX/drs/dr16xx.cpp index f4d6c04fb8e073..52002a7d0db002 100644 --- a/clang/test/CXX/drs/dr16xx.cpp +++ b/clang/test/CXX/drs/dr16xx.cpp @@ -484,8 +484,6 @@ namespace dr1696 { // dr1696: 7 const A &a = A(); // #dr1696-D1-a }; D1 d1 = {}; // #dr1696-d1 - // since-cxx14-warning@-1 {{lifetime extension of temporary created by aggregate initialization using a default member initializer is not yet supported; lifetime of temporary will end at the end of the full-expression}} - // since-cxx14-note@#dr1696-D1-a {{initializing field 'a' with default member initializer}} struct D2 { const A &a = A(); // #dr1696-D2-a diff --git a/clang/test/CXX/drs/dr18xx.cpp b/clang/test/CXX/drs/dr18xx.cpp index e78730e8992cf8..52a90ea3a05d26 100644 --- a/clang/test/CXX/drs/dr18xx.cpp +++ b/clang/test/CXX/drs/dr18xx.cpp @@ -206,13 +206,10 @@ namespace dr1814 { // dr1814: yes #endif } -namespace dr1815 { // dr1815: no +namespace dr1815 { // dr1815: yes #if __cplusplus >= 201402L - // FIXME: needs codegen test struct A { int &&r = 0; }; // #dr1815-A A a = {}; - // since-cxx14-warning@-1 {{lifetime extension of temporary created by aggregate initialization using a default member initializer is not yet supported; lifetime of temporary will end at the end of the full-expression}} FIXME - // since-cxx14-note@#dr1815-A {{initializing field 'r' with default member initializer}} struct B { int &&r = 0; }; // #dr1815-B // since-cxx14-error@-1 {{reference member 'r' binds to a temporary object whose lifetime would be shorter than the lifetime of the constructed object}} diff --git a/clang/test/CXX/special/class.temporary/p6.cpp b/clang/test/CXX/special/class.temporary/p6.cpp index 5554363cc69abb..002bf3e1c26740 100644 --- a/clang/test/CXX/special/class.temporary/p6.cpp +++ b/clang/test/CXX/special/class.temporary/p6.cpp @@ -269,6 +269,26 @@ void init_capture_init_list() { // CHECK: } } +void check_dr1815() { // dr1815: yes +#if __cplusplus >= 201402L + + struct A { + int &&r = 0; + ~A() {} + }; + + struct B { + A &&a = A{}; + ~B() {} + }; + + // CHECK: void @_Z12check_dr1815v() + // CHECK: call void @_ZZ12check_dr1815vEN1BD1Ev( + // CHECK: call void @_ZZ12check_dr1815vEN1AD1Ev( + B a = {}; +#endif +} + namespace P2718R0 { namespace basic { template <typename E> using T2 = std::list<E>; diff --git a/clang/test/SemaCXX/constexpr-default-arg.cpp b/clang/test/SemaCXX/constexpr-default-arg.cpp index 7c883692829548..8510a6ddc80399 100644 --- a/clang/test/SemaCXX/constexpr-default-arg.cpp +++ b/clang/test/SemaCXX/constexpr-default-arg.cpp @@ -32,8 +32,8 @@ void test_default_arg2() { } // Check that multiple CXXDefaultInitExprs don't cause an assertion failure. -struct A { int &&r = 0; }; // expected-note 2{{default member initializer}} +struct A { int &&r = 0; }; struct B { A x, y; }; -B b = {}; // expected-warning 2{{lifetime extension of temporary created by aggregate initialization using a default member initializer is not yet supported}} +B b = {}; // expected-no-diagnostics } diff --git a/clang/test/SemaCXX/eval-crashes.cpp b/clang/test/SemaCXX/eval-crashes.cpp index 017df977b26b7b..a06f60f71e9c7e 100644 --- a/clang/test/SemaCXX/eval-crashes.cpp +++ b/clang/test/SemaCXX/eval-crashes.cpp @@ -25,11 +25,9 @@ namespace pr33140_0b { } namespace pr33140_2 { - // FIXME: The declaration of 'b' below should lifetime-extend two int - // temporaries. - struct A { int &&r = 0; }; // expected-note 2{{initializing field 'r' with default member initializer}} + struct A { int &&r = 0; }; struct B { A x, y; }; - B b = {}; // expected-warning 2{{lifetime extension of temporary created by aggregate initialization using a default member initializer is not yet supported}} + B b = {}; } namespace pr33140_3 { `````````` </details> https://github.com/llvm/llvm-project/pull/87933 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
