From b368ea865f96071e827c6151073e153c4e45171d Mon Sep 17 00:00:00 2001 From: Richard Smith Date: Mon, 2 Jul 2018 23:25:22 +0000 Subject: [PATCH] Per C++ [over.match.copy]p1, direct-initialization of a reference can only invoke converting constructors of the reference's underlying type. llvm-svn: 336153 --- clang/lib/Sema/SemaInit.cpp | 10 ++++++---- clang/test/CXX/dcl.decl/dcl.init/dcl.init.ref/p5.cpp | 9 +++++++++ 2 files changed, 15 insertions(+), 4 deletions(-) diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp index b3f401e6..6e695ff 100644 --- a/clang/lib/Sema/SemaInit.cpp +++ b/clang/lib/Sema/SemaInit.cpp @@ -4224,9 +4224,11 @@ static OverloadingResult TryRefInitWithConversionFunction( OverloadCandidateSet &CandidateSet = Sequence.getFailedCandidateSet(); CandidateSet.clear(OverloadCandidateSet::CSK_InitByUserDefinedConversion); - // Determine whether we are allowed to call explicit constructors or - // explicit conversion operators. - bool AllowExplicit = Kind.AllowExplicit(); + // Determine whether we are allowed to call explicit conversion operators. + // Note that none of [over.match.copy], [over.match.conv], nor + // [over.match.ref] permit an explicit constructor to be chosen when + // initializing a reference, not even for direct-initialization. + bool AllowExplicitCtors = false; bool AllowExplicitConvs = Kind.allowExplicitConversionFunctionsInRefBinding(); const RecordType *T1RecordType = nullptr; @@ -4242,7 +4244,7 @@ static OverloadingResult TryRefInitWithConversionFunction( continue; if (!Info.Constructor->isInvalidDecl() && - Info.Constructor->isConvertingConstructor(AllowExplicit)) { + Info.Constructor->isConvertingConstructor(AllowExplicitCtors)) { if (Info.ConstructorTmpl) S.AddTemplateOverloadCandidate(Info.ConstructorTmpl, Info.FoundDecl, /*ExplicitArgs*/ nullptr, diff --git a/clang/test/CXX/dcl.decl/dcl.init/dcl.init.ref/p5.cpp b/clang/test/CXX/dcl.decl/dcl.init/dcl.init.ref/p5.cpp index e775e8f..869fc4f 100644 --- a/clang/test/CXX/dcl.decl/dcl.init/dcl.init.ref/p5.cpp +++ b/clang/test/CXX/dcl.decl/dcl.init/dcl.init.ref/p5.cpp @@ -61,3 +61,12 @@ namespace test3 { unsigned &t9 = (a->bitY += 3); // expected-error {{non-const reference cannot bind to bit-field 'bitY'}} } } + +namespace explicit_ctor { + struct A {}; + struct B { // expected-note 2{{candidate}} + explicit B(const A&); + }; + A a; + const B &b(a); // expected-error {{no viable conversion}} +} -- 2.7.4