From ed399a69e2a0fc40418c3bc955e5cb2787aa93fa Mon Sep 17 00:00:00 2001 From: Reid Kleckner Date: Thu, 15 Aug 2019 19:45:28 +0000 Subject: [Sema] Implement DR2386 for C++17 structured binding Allow implementations to provide complete definitions of std::tuple_size, but to omit the 'value' member to signal that T is not tuple-like. The Microsoft standard library implements std::tuple_size this way. If the value member exists, clang still validates that it is an ICE, but if it does not, then the type is considered to not be tuple-like. Fixes PR33236 Reviewers: rsmith Differential Revision: https://reviews.llvm.org/D66040 llvm-svn: 369043 --- clang/lib/Sema/SemaDeclCXX.cpp | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) (limited to 'clang/lib/Sema/SemaDeclCXX.cpp') diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp index b5d46681b57..2442986eff3 100644 --- a/clang/lib/Sema/SemaDeclCXX.cpp +++ b/clang/lib/Sema/SemaDeclCXX.cpp @@ -1030,8 +1030,10 @@ static IsTupleLike isTupleLike(Sema &S, SourceLocation Loc, QualType T, TemplateArgumentListInfo Args(Loc, Loc); Args.addArgument(getTrivialTypeTemplateArgument(S, Loc, T)); - // If there's no tuple_size specialization, it's not tuple-like. - if (lookupStdTypeTraitMember(S, R, Loc, "tuple_size", Args, /*DiagID*/0)) + // If there's no tuple_size specialization or the lookup of 'value' is empty, + // it's not tuple-like. + if (lookupStdTypeTraitMember(S, R, Loc, "tuple_size", Args, /*DiagID*/ 0) || + R.empty()) return IsTupleLike::NotTupleLike; // If we get this far, we've committed to the tuple interpretation, but @@ -1048,11 +1050,6 @@ static IsTupleLike isTupleLike(Sema &S, SourceLocation Loc, QualType T, } } Diagnoser(R, Args); - if (R.empty()) { - Diagnoser.diagnoseNotICE(S, Loc, SourceRange()); - return IsTupleLike::Error; - } - ExprResult E = S.BuildDeclarationNameExpr(CXXScopeSpec(), R, /*NeedsADL*/false); if (E.isInvalid()) -- cgit v1.2.3