On 17 February 2017 at 18:03, Richard Smith <rich...@metafoo.co.uk> wrote:
> On 22 July 2016 at 21:05, Faisal Vali via cfe-commits < > cfe-commits@lists.llvm.org> wrote: > >> Author: faisalv >> Date: Fri Jul 22 23:05:19 2016 >> New Revision: 276514 >> >> URL: http://llvm.org/viewvc/llvm-project?rev=276514&view=rev >> Log: >> [cxx1z-constexpr-lambda] Make a lambda's closure type eligible as a >> literal-type in C++1z >> >> >> Additionally, for pre-C++1z, instead of forbidding a lambda's closure >> type from being a literal type through circumlocutorily setting >> HasNonLiteralTypeFieldsOrBases falsely to true -- handle lambda's more >> directly in CXXRecordDecl::isLiteral(). >> >> One additional small step towards implementing constexpr-lambdas. >> > > I don't know if this problem started with this change, but we now accept > this invalid code in C++14 mode: > > constexpr auto a = [] {}; > This was a result of two separate bugs. I've fixed one of them, but another remains, and can be observed in this example: constexpr int f() { return ([]{}, 0); } constexpr int n = f(); This is ill-formed before C++17, and yet we accept it in C++11 mode. > Thanks to Richard Smith for his review! >> https://reviews.llvm.org/D22662 >> >> >> Modified: >> cfe/trunk/include/clang/AST/DeclCXX.h >> cfe/trunk/test/SemaCXX/cxx1z-constexpr-lambdas.cpp >> >> Modified: cfe/trunk/include/clang/AST/DeclCXX.h >> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/ >> AST/DeclCXX.h?rev=276514&r1=276513&r2=276514&view=diff >> ============================================================ >> ================== >> --- cfe/trunk/include/clang/AST/DeclCXX.h (original) >> +++ cfe/trunk/include/clang/AST/DeclCXX.h Fri Jul 22 23:05:19 2016 >> @@ -535,11 +535,10 @@ class CXXRecordDecl : public RecordDecl >> MethodTyInfo(Info) { >> IsLambda = true; >> >> - // C++11 [expr.prim.lambda]p3: >> - // This class type is neither an aggregate nor a literal type. >> + // C++1z [expr.prim.lambda]p4: >> + // This class type is not an aggregate type. >> Aggregate = false; >> PlainOldData = false; >> - HasNonLiteralTypeFieldsOrBases = true; >> } >> >> /// \brief Whether this lambda is known to be dependent, even if its >> @@ -1338,11 +1337,15 @@ public: >> /// >> /// We resolve DR1361 by ignoring the second bullet. We resolve DR1452 >> by >> /// treating types with trivial default constructors as literal types. >> + /// >> + /// Only in C++1z and beyond, are lambdas literal types. >> bool isLiteral() const { >> return hasTrivialDestructor() && >> - (isAggregate() || hasConstexprNonCopyMoveConstructor() || >> - hasTrivialDefaultConstructor()) && >> - !hasNonLiteralTypeFieldsOrBases(); >> + (!isLambda() || getASTContext().getLangOpts().CPlusPlus1z) && >> + !hasNonLiteralTypeFieldsOrBases() && >> + (isAggregate() || isLambda() || >> + hasConstexprNonCopyMoveConstructor() || >> + hasTrivialDefaultConstructor()); >> } >> >> /// \brief If this record is an instantiation of a member class, >> >> Modified: cfe/trunk/test/SemaCXX/cxx1z-constexpr-lambdas.cpp >> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/ >> cxx1z-constexpr-lambdas.cpp?rev=276514&r1=276513&r2=276514&view=diff >> ============================================================ >> ================== >> --- cfe/trunk/test/SemaCXX/cxx1z-constexpr-lambdas.cpp (original) >> +++ cfe/trunk/test/SemaCXX/cxx1z-constexpr-lambdas.cpp Fri Jul 22 >> 23:05:19 2016 >> @@ -1,8 +1,8 @@ >> // RUN: %clang_cc1 -std=c++1z -verify -fsyntax-only -fblocks %s >> // RUN: %clang_cc1 -std=c++1z -verify -fsyntax-only -fblocks >> -fdelayed-template-parsing %s >> -// RUN: %clang_cc1 -std=c++1z -verify -fsyntax-only -fblocks >> -fms-extensions %s >> -// RUN: %clang_cc1 -std=c++1z -verify -fsyntax-only -fblocks >> -fdelayed-template-parsing -fms-extensions %s >> +// RUN: %clang_cc1 -std=c++14 -verify -fsyntax-only -fblocks %s >> -DCPP14_AND_EARLIER >> >> +#ifndef CPP14_AND_EARLIER >> namespace test_constexpr_checking { >> >> namespace ns1 { >> @@ -33,4 +33,16 @@ namespace ns3 { >> L(3); //expected-note{{non-constexpr function}} >> } >> >> -} // end ns test_constexpr_call >> \ No newline at end of file >> +} // end ns test_constexpr_call >> + >> +#endif >> + >> +namespace test_lambda_is_literal { >> +#ifdef CPP14_AND_EARLIER >> +//expected-error@+4{{not a literal type}} >> +//expected-note@+2{{not an aggregate and has no constexpr constructors}} >> +#endif >> +auto L = [] { }; >> +constexpr int foo(decltype(L) l) { return 0; } >> + >> +} >> \ No newline at end of file >> >> >> _______________________________________________ >> cfe-commits mailing list >> cfe-commits@lists.llvm.org >> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits >> > >
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