Author: yronglin Date: 2024-05-13T01:16:36+08:00 New Revision: 17daa204feadf9c28fc13b7daa69c3cbe865b238
URL: https://github.com/llvm/llvm-project/commit/17daa204feadf9c28fc13b7daa69c3cbe865b238 DIFF: https://github.com/llvm/llvm-project/commit/17daa204feadf9c28fc13b7daa69c3cbe865b238.diff LOG: [Clang][CWG1815] Support lifetime extension of temporary created by aggregate initialization using a default member initializer (#87933) 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. --------- Signed-off-by: yronglin <yronglin...@gmail.com> Added: Modified: clang/include/clang/Basic/DiagnosticSemaKinds.td clang/lib/Sema/SemaExpr.cpp clang/lib/Sema/SemaInit.cpp clang/test/AST/ast-dump-default-init-json.cpp clang/test/AST/ast-dump-default-init.cpp clang/test/Analysis/lifetime-extended-regions.cpp clang/test/CXX/drs/cwg16xx.cpp clang/test/CXX/drs/cwg18xx.cpp clang/test/CXX/special/class.temporary/p6.cpp clang/test/SemaCXX/constexpr-default-arg.cpp clang/test/SemaCXX/eval-crashes.cpp clang/www/cxx_dr_status.html Removed: ################################################################################ diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td index d6863f90edb6e..9e82130c93609 100644 --- a/clang/include/clang/Basic/DiagnosticSemaKinds.td +++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td @@ -10035,12 +10035,6 @@ 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 c688cb21f2364..bb4b116fd73ca 100644 --- a/clang/lib/Sema/SemaExpr.cpp +++ b/clang/lib/Sema/SemaExpr.cpp @@ -5777,10 +5777,9 @@ 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(); @@ -5816,7 +5815,7 @@ ExprResult Sema::BuildCXXDefaultInitExpr(SourceLocation Loc, FieldDecl *Field) { Expr *Init = nullptr; bool NestedDefaultChecking = isCheckingDefaultArgumentOrInitializer(); - + bool InLifetimeExtendingContext = isInLifetimeExtendingContext(); EnterExpressionEvaluationContext EvalContext( *this, ExpressionEvaluationContext::PotentiallyEvaluated, Field); @@ -5851,19 +5850,35 @@ ExprResult Sema::BuildCXXDefaultInitExpr(SourceLocation Loc, FieldDecl *Field) { ImmediateCallVisitor V(getASTContext()); if (!NestedDefaultChecking) V.TraverseDecl(Field); - if (V.HasImmediateCalls) { + + // CWG1815 + // Support lifetime extension of temporary created by aggregate + // initialization using a default member initializer. We should always rebuild + // the initializer if it contains any temporaries (if the initializer + // expression is an ExprWithCleanups). Then make sure the normal lifetime + // extension code recurses into the default initializer and does lifetime + // extension when warranted. + bool ContainsAnyTemporaries = + isa_and_present<ExprWithCleanups>(Field->getInClassInitializer()); + if (V.HasImmediateCalls || InLifetimeExtendingContext || + ContainsAnyTemporaries) { 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; + + // Rebuild CXXDefaultInitExpr might cause diagnostics. + SFINAETrap Trap(*this); runWithSufficientStackSpace(Loc, [&] { 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 c8049ae581f84..fe4a698a612ea 100644 --- a/clang/lib/Sema/SemaInit.cpp +++ b/clang/lib/Sema/SemaInit.cpp @@ -8065,11 +8065,6 @@ static void visitLocalsRetainedByInitializer(IndirectLocalPath &Path, enum PathLifetimeKind { /// Lifetime-extend along this path. Extend, - /// We should lifetime-extend, but we don't because (due to technical - /// limitations) we can't. This happens for default member initializers, - /// which we don't clone for every use, so we don't have a unique - /// MaterializeTemporaryExpr to update. - ShouldExtend, /// Do not lifetime extend along this path. NoExtend }; @@ -8081,7 +8076,7 @@ shouldLifetimeExtendThroughPath(const IndirectLocalPath &Path) { PathLifetimeKind Kind = PathLifetimeKind::Extend; for (auto Elem : Path) { if (Elem.Kind == IndirectLocalPathEntry::DefaultInit) - Kind = PathLifetimeKind::ShouldExtend; + Kind = PathLifetimeKind::Extend; else if (Elem.Kind != IndirectLocalPathEntry::LambdaCaptureInit) return PathLifetimeKind::NoExtend; } @@ -8201,18 +8196,6 @@ 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/AST/ast-dump-default-init-json.cpp b/clang/test/AST/ast-dump-default-init-json.cpp index 1058b4e3ea4d9..f4949a9c9eedf 100644 --- a/clang/test/AST/ast-dump-default-init-json.cpp +++ b/clang/test/AST/ast-dump-default-init-json.cpp @@ -789,10 +789,10 @@ void test() { // CHECK-NEXT: "valueCategory": "lvalue", // CHECK-NEXT: "extendingDecl": { // CHECK-NEXT: "id": "0x{{.*}}", -// CHECK-NEXT: "kind": "FieldDecl", -// CHECK-NEXT: "name": "a", +// CHECK-NEXT: "kind": "VarDecl", +// CHECK-NEXT: "name": "b", // CHECK-NEXT: "type": { -// CHECK-NEXT: "qualType": "const A &" +// CHECK-NEXT: "qualType": "B" // CHECK-NEXT: } // CHECK-NEXT: }, // CHECK-NEXT: "storageDuration": "automatic", diff --git a/clang/test/AST/ast-dump-default-init.cpp b/clang/test/AST/ast-dump-default-init.cpp index 15b29f04bf21b..26864fbf15424 100644 --- a/clang/test/AST/ast-dump-default-init.cpp +++ b/clang/test/AST/ast-dump-default-init.cpp @@ -13,7 +13,7 @@ void test() { } // CHECK: -CXXDefaultInitExpr 0x{{[^ ]*}} <{{.*}}> 'const A' lvalue has rewritten init // CHECK-NEXT: `-ExprWithCleanups 0x{{[^ ]*}} <{{.*}}> 'const A' lvalue -// CHECK-NEXT: `-MaterializeTemporaryExpr 0x{{[^ ]*}} <{{.*}}> 'const A' lvalue extended by Field 0x{{[^ ]*}} 'a' 'const A &' +// CHECK-NEXT: `-MaterializeTemporaryExpr 0x{{[^ ]*}} <{{.*}}> 'const A' lvalue extended by Var 0x{{[^ ]*}} 'b' 'B' // CHECK-NEXT: `-ImplicitCastExpr 0x{{[^ ]*}} <{{.*}}> 'const A' <NoOp> // CHECK-NEXT: `-CXXFunctionalCastExpr 0x{{[^ ]*}} <{{.*}}> 'A' functional cast to A <NoOp> // CHECK-NEXT: `-InitListExpr 0x{{[^ ]*}} <{{.*}}> 'A' diff --git a/clang/test/Analysis/lifetime-extended-regions.cpp b/clang/test/Analysis/lifetime-extended-regions.cpp index 4e98bd4b0403e..4458ad294af7c 100644 --- a/clang/test/Analysis/lifetime-extended-regions.cpp +++ b/clang/test/Analysis/lifetime-extended-regions.cpp @@ -120,10 +120,11 @@ void aggregateWithReferences() { clang_analyzer_dump(viaReference); // expected-warning-re {{&lifetime_extended_object{RefAggregate, viaReference, S{{[0-9]+}}} }} clang_analyzer_dump(viaReference.rx); // expected-warning-re {{&lifetime_extended_object{int, viaReference, S{{[0-9]+}}} }} 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`) - RefAggregate defaultInitExtended{i}; // clang-bug does not extend `Composite` + + // FIXME: clang currently support extending lifetime of object bound to reference members of aggregates, + // that are created from default member initializer. But CFG and ExprEngine need to be updated to address this change. + // The following expect warning: {{&lifetime_extended_object{Composite, defaultInitExtended, S{{[0-9]+}}} }} + RefAggregate defaultInitExtended{i}; clang_analyzer_dump(defaultInitExtended.ry); // expected-warning {{Unknown }} } diff --git a/clang/test/CXX/drs/cwg16xx.cpp b/clang/test/CXX/drs/cwg16xx.cpp index cf6b45ceabf2c..82ef871939d2c 100644 --- a/clang/test/CXX/drs/cwg16xx.cpp +++ b/clang/test/CXX/drs/cwg16xx.cpp @@ -483,8 +483,6 @@ namespace cwg1696 { // cwg1696: 7 const A &a = A(); // #cwg1696-D1-a }; D1 d1 = {}; // #cwg1696-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@#cwg1696-D1-a {{initializing field 'a' with default member initializer}} struct D2 { const A &a = A(); // #cwg1696-D2-a diff --git a/clang/test/CXX/drs/cwg18xx.cpp b/clang/test/CXX/drs/cwg18xx.cpp index ea322ff4c8be1..9eb749153e57a 100644 --- a/clang/test/CXX/drs/cwg18xx.cpp +++ b/clang/test/CXX/drs/cwg18xx.cpp @@ -206,19 +206,28 @@ namespace cwg1814 { // cwg1814: yes #endif } -namespace cwg1815 { // cwg1815: no +namespace cwg1815 { // cwg1815: yes #if __cplusplus >= 201402L - // FIXME: needs codegen test - struct A { int &&r = 0; }; // #cwg1815-A + struct A { int &&r = 0; }; 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@#cwg1815-A {{initializing field 'r' with default member initializer}} struct B { int &&r = 0; }; // #cwg1815-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}} // since-cxx14-note@#cwg1815-B {{initializing field 'r' with default member initializer}} // since-cxx14-note@#cwg1815-b {{in implicit default constructor for 'cwg1815::B' first required here}} B b; // #cwg1815-b + +#if __cplusplus >= 201703L + struct C { const int &r = 0; }; + constexpr C c = {}; // OK, since cwg1815 + static_assert(c.r == 0); + + constexpr int f() { + A a = {}; // OK, since cwg1815 + return a.r; + } + static_assert(f() == 0); +#endif #endif } diff --git a/clang/test/CXX/special/class.temporary/p6.cpp b/clang/test/CXX/special/class.temporary/p6.cpp index 5554363cc69ab..a6d2adfd1fd2c 100644 --- a/clang/test/CXX/special/class.temporary/p6.cpp +++ b/clang/test/CXX/special/class.temporary/p6.cpp @@ -269,6 +269,40 @@ 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() {} + }; + B a = {}; + + // CHECK: call {{.*}}block_scope_begin_function + extern void block_scope_begin_function(); + extern void block_scope_end_function(); + block_scope_begin_function(); + { + // CHECK: call void @_ZZ12check_dr1815vEN1BD1Ev + // CHECK: call void @_ZZ12check_dr1815vEN1AD1Ev + B b = {}; + } + // CHECK: call {{.*}}block_scope_end_function + block_scope_end_function(); + + // CHECK: call {{.*}}some_other_function + extern void some_other_function(); + some_other_function(); + // CHECK: call void @_ZZ12check_dr1815vEN1BD1Ev + // CHECK: call void @_ZZ12check_dr1815vEN1AD1Ev +#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 ec9b2927880bd..901123bfb359f 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 017df977b26b7..a06f60f71e9c7 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 { diff --git a/clang/www/cxx_dr_status.html b/clang/www/cxx_dr_status.html index 12ab59224e82e..92fdcf5556ede 100755 --- a/clang/www/cxx_dr_status.html +++ b/clang/www/cxx_dr_status.html @@ -10698,7 +10698,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2> <td><a href="https://cplusplus.github.io/CWG/issues/1815.html";>1815</a></td> <td>CD4</td> <td>Lifetime extension in aggregate initialization</td> - <td class="none" align="center">No</td> + <td class="unreleased" align="center">Clang 19</td> </tr> <tr id="1816"> <td><a href="https://cplusplus.github.io/CWG/issues/1816.html";>1816</a></td> _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
