Author: rsmith Date: Thu Sep 27 15:47:04 2018 New Revision: 343279 URL: http://llvm.org/viewvc/llvm-project?rev=343279&view=rev Log: [cxx2a] P0624R2: Lambdas with no capture-default are default-constructible and assignable.
Added: cfe/trunk/test/SemaCXX/cxx2a-lambda-default-ctor-assign.cpp Modified: cfe/trunk/include/clang/AST/DeclCXX.h cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td cfe/trunk/lib/AST/DeclCXX.cpp cfe/trunk/lib/Sema/SemaDeclCXX.cpp cfe/trunk/lib/Sema/SemaExpr.cpp cfe/trunk/test/SemaCXX/cxx17-compat.cpp cfe/trunk/www/cxx_status.html Modified: cfe/trunk/include/clang/AST/DeclCXX.h URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/DeclCXX.h?rev=343279&r1=343278&r2=343279&view=diff ============================================================================== --- cfe/trunk/include/clang/AST/DeclCXX.h (original) +++ cfe/trunk/include/clang/AST/DeclCXX.h Thu Sep 27 15:47:04 2018 @@ -974,10 +974,7 @@ public: bool needsImplicitDefaultConstructor() const { return !data().UserDeclaredConstructor && !(data().DeclaredSpecialMembers & SMF_DefaultConstructor) && - // C++14 [expr.prim.lambda]p20: - // The closure type associated with a lambda-expression has no - // default constructor. - !isLambda(); + (!isLambda() || lambdaIsDefaultConstructibleAndAssignable()); } /// Determine whether this class has any user-declared constructors. @@ -1167,10 +1164,7 @@ public: !hasUserDeclaredCopyAssignment() && !hasUserDeclaredMoveConstructor() && !hasUserDeclaredDestructor() && - // C++1z [expr.prim.lambda]p21: "the closure type has a deleted copy - // assignment operator". The intent is that this counts as a user - // declared copy assignment, but we do not model it that way. - !isLambda(); + (!isLambda() || lambdaIsDefaultConstructibleAndAssignable()); } /// Determine whether we need to eagerly declare a move assignment @@ -1210,6 +1204,10 @@ public: /// a template). bool isGenericLambda() const; + /// Determine whether this lambda should have an implicit default constructor + /// and copy and move assignment operators. + bool lambdaIsDefaultConstructibleAndAssignable() const; + /// Retrieve the lambda call operator of the closure type /// if this is a closure type. CXXMethodDecl *getLambdaCallOperator() const; Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=343279&r1=343278&r2=343279&view=diff ============================================================================== --- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original) +++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Thu Sep 27 15:47:04 2018 @@ -6633,6 +6633,11 @@ let CategoryName = "Lambda Issue" in { InGroup<DeprecatedThisCapture>, DefaultIgnore; def note_deprecated_this_capture : Note< "add an explicit capture of 'this' to capture '*this' by reference">; + + // C++2a default constructible / assignable lambdas. + def warn_cxx17_compat_lambda_def_ctor_assign : Warning< + "%select{default construction|assignment}0 of lambda is incompatible with " + "C++ standards before C++2a">, InGroup<CXXPre2aCompat>, DefaultIgnore; } def err_return_in_captured_stmt : Error< Modified: cfe/trunk/lib/AST/DeclCXX.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/DeclCXX.cpp?rev=343279&r1=343278&r2=343279&view=diff ============================================================================== --- cfe/trunk/lib/AST/DeclCXX.cpp (original) +++ cfe/trunk/lib/AST/DeclCXX.cpp Thu Sep 27 15:47:04 2018 @@ -628,6 +628,24 @@ bool CXXRecordDecl::hasSubobjectAtOffset return false; } +bool CXXRecordDecl::lambdaIsDefaultConstructibleAndAssignable() const { + assert(isLambda() && "not a lambda"); + + // C++2a [expr.prim.lambda.capture]p11: + // The closure type associated with a lambda-expression has no default + // constructor if the lambda-expression has a lambda-capture and a + // defaulted default constructor otherwise. It has a deleted copy + // assignment operator if the lambda-expression has a lambda-capture and + // defaulted copy and move assignment operators otherwise. + // + // C++17 [expr.prim.lambda]p21: + // The closure type associated with a lambda-expression has no default + // constructor and a deleted copy assignment operator. + if (getLambdaCaptureDefault() != LCD_None) + return false; + return getASTContext().getLangOpts().CPlusPlus2a; +} + void CXXRecordDecl::addedMember(Decl *D) { if (!D->isImplicit() && !isa<FieldDecl>(D) && Modified: cfe/trunk/lib/Sema/SemaDeclCXX.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDeclCXX.cpp?rev=343279&r1=343278&r2=343279&view=diff ============================================================================== --- cfe/trunk/lib/Sema/SemaDeclCXX.cpp (original) +++ cfe/trunk/lib/Sema/SemaDeclCXX.cpp Thu Sep 27 15:47:04 2018 @@ -7088,7 +7088,8 @@ bool Sema::ShouldDeleteSpecialMember(CXX // The closure type associated with a lambda-expression has a // deleted (8.4.3) default constructor and a deleted copy // assignment operator. - if (RD->isLambda() && + // C++2a adds back these operators if the lambda has no capture-default. + if (RD->isLambda() && !RD->lambdaIsDefaultConstructibleAndAssignable() && (CSM == CXXDefaultConstructor || CSM == CXXCopyAssignment)) { if (Diagnose) Diag(RD->getLocation(), diag::note_lambda_decl); Modified: cfe/trunk/lib/Sema/SemaExpr.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExpr.cpp?rev=343279&r1=343278&r2=343279&view=diff ============================================================================== --- cfe/trunk/lib/Sema/SemaExpr.cpp (original) +++ cfe/trunk/lib/Sema/SemaExpr.cpp Thu Sep 27 15:47:04 2018 @@ -266,6 +266,17 @@ bool Sema::DiagnoseUseOfDecl(NamedDecl * return true; } + if (auto *MD = dyn_cast<CXXMethodDecl>(D)) { + // Lambdas are only default-constructible or assignable in C++2a onwards. + if (MD->getParent()->isLambda() && + ((isa<CXXConstructorDecl>(MD) && + cast<CXXConstructorDecl>(MD)->isDefaultConstructor()) || + MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator())) { + Diag(Loc, diag::warn_cxx17_compat_lambda_def_ctor_assign) + << !isa<CXXConstructorDecl>(MD); + } + } + auto getReferencedObjCProp = [](const NamedDecl *D) -> const ObjCPropertyDecl * { if (const auto *MD = dyn_cast<ObjCMethodDecl>(D)) Modified: cfe/trunk/test/SemaCXX/cxx17-compat.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/cxx17-compat.cpp?rev=343279&r1=343278&r2=343279&view=diff ============================================================================== --- cfe/trunk/test/SemaCXX/cxx17-compat.cpp (original) +++ cfe/trunk/test/SemaCXX/cxx17-compat.cpp Thu Sep 27 15:47:04 2018 @@ -27,3 +27,18 @@ struct B { // expected-warning@-4 {{default member initializer for bit-field is incompatible with C++ standards before C++2a}} #endif }; + +auto Lambda = []{}; +decltype(Lambda) AnotherLambda; +#if __cplusplus <= 201703L + // expected-error@-2 {{no matching constructor}} expected-note@-3 2{{candidate}} +#else + // expected-warning@-4 {{default construction of lambda is incompatible with C++ standards before C++2a}} +#endif + +void copy_lambda() { Lambda = Lambda; } +#if __cplusplus <= 201703L + // expected-error@-2 {{deleted}} expected-note@-10 {{lambda}} +#else + // expected-warning@-4 {{assignment of lambda is incompatible with C++ standards before C++2a}} +#endif Added: cfe/trunk/test/SemaCXX/cxx2a-lambda-default-ctor-assign.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/cxx2a-lambda-default-ctor-assign.cpp?rev=343279&view=auto ============================================================================== --- cfe/trunk/test/SemaCXX/cxx2a-lambda-default-ctor-assign.cpp (added) +++ cfe/trunk/test/SemaCXX/cxx2a-lambda-default-ctor-assign.cpp Thu Sep 27 15:47:04 2018 @@ -0,0 +1,37 @@ +// RUN: %clang_cc1 -std=c++2a -verify %s + +auto a = []{}; +decltype(a) a2; +void f(decltype(a) x, decltype(a) y) { + x = y; + x = static_cast<decltype(a)&&>(y); +} + +template<typename T> +struct X { + constexpr X() { T::error; } // expected-error {{'::'}} + X(const X&); + constexpr X &operator=(const X&) { T::error; } // expected-error {{'::'}} + constexpr X &operator=(X&&) { T::error; } // expected-error {{'::'}} +}; +extern X<int> x; +auto b = [x = x]{}; // expected-note 3{{in instantiation of}} +decltype(b) b2; // expected-note {{in implicit default constructor}} +void f(decltype(b) x, decltype(b) y) { + x = y; // expected-note {{in implicit copy assignment}} + x = static_cast<decltype(b)&&>(y); // expected-note {{in implicit move assignment}} +} + +struct Y { + Y() = delete; // expected-note {{deleted}} + Y(const Y&); + Y &operator=(const Y&) = delete; // expected-note 2{{deleted}} + Y &operator=(Y&&) = delete; +}; +extern Y y; +auto c = [y = y]{}; // expected-note 3{{deleted because}} +decltype(c) c2; // expected-error {{deleted}} +void f(decltype(c) x, decltype(c) y) { + x = y; // expected-error {{deleted}} + x = static_cast<decltype(c)&&>(y); // expected-error {{deleted}} +} Modified: cfe/trunk/www/cxx_status.html URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/www/cxx_status.html?rev=343279&r1=343278&r2=343279&view=diff ============================================================================== --- cfe/trunk/www/cxx_status.html (original) +++ cfe/trunk/www/cxx_status.html Thu Sep 27 15:47:04 2018 @@ -905,7 +905,7 @@ as the draft C++2a standard evolves. <tr> <td>Default constructible and assignable stateless lambdas</td> <td><a href="http://wg21.link/p0624r2">P0624R2</a></td> - <td class="none" align="center">No</td> + <td class="svn" align="center">SVN</td> </tr> <tr> <td>Lambdas in unevaluated contexts</td> _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits