https://github.com/usx95 created https://github.com/llvm/llvm-project/pull/68999
We associated conversion seq for args (when reversed) to the wrong index. This lead to clang believing reversed `operator==` a worse overload candidate than the `operator==` without reversed args when both these candidate were ambiguous. Fixes https://github.com/llvm/llvm-project/issues/53954 >From 01ba05ec9349c7b93239b7e6196e3fa6c7fc1f82 Mon Sep 17 00:00:00 2001 From: Utkarsh Saxena <u...@google.com> Date: Fri, 13 Oct 2023 17:17:32 +0200 Subject: [PATCH] Correctly compute conversion seq for args to fn with reveresed param order --- clang/docs/ReleaseNotes.rst | 2 ++ clang/lib/Sema/SemaOverload.cpp | 4 +-- .../over.match.oper/p3-2a.cpp | 35 +++++++++++++++++++ 3 files changed, 39 insertions(+), 2 deletions(-) diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 2d918967e7f0b02..07cedeabcdbd9b7 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -113,6 +113,8 @@ C++ Language Changes C++20 Feature Support ^^^^^^^^^^^^^^^^^^^^^ +- Fix a bug in conversion sequence of arguments to a function with reversed parameter order. + Fixes `GH <https://github.com/llvm/llvm-project/issues/53954>`_. C++23 Feature Support ^^^^^^^^^^^^^^^^^^^^^ diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp index ce78994e6553814..b00adb00eab01aa 100644 --- a/clang/lib/Sema/SemaOverload.cpp +++ b/clang/lib/Sema/SemaOverload.cpp @@ -7688,7 +7688,7 @@ bool Sema::CheckNonDependentConversions( QualType ParamType = ParamTypes[I + Offset]; if (!ParamType->isDependentType()) { unsigned ConvIdx = PO == OverloadCandidateParamOrder::Reversed - ? 0 + ? Args.size() - 1 - (ThisConversions + I) : (ThisConversions + I); Conversions[ConvIdx] = TryCopyInitialization(*this, Args[I], ParamType, @@ -10631,7 +10631,7 @@ OverloadCandidateSet::BestViableFunction(Sema &S, SourceLocation Loc, // Find the best viable function. Best = end(); for (auto *Cand : Candidates) { - Cand->Best = false; + Cand->Best = false; if (Cand->Viable) { if (Best == end() || isBetterOverloadCandidate(S, *Cand, *Best, Loc, Kind)) diff --git a/clang/test/CXX/over/over.match/over.match.funcs/over.match.oper/p3-2a.cpp b/clang/test/CXX/over/over.match/over.match.funcs/over.match.oper/p3-2a.cpp index 5c6804eb7726b5f..8975706e721cff1 100644 --- a/clang/test/CXX/over/over.match/over.match.funcs/over.match.oper/p3-2a.cpp +++ b/clang/test/CXX/over/over.match/over.match.funcs/over.match.oper/p3-2a.cpp @@ -324,6 +324,41 @@ bool x = X() == X(); // expected-warning {{ambiguous}} } } // namespace P2468R2 +namespace GH53954{ +namespace test1 { +struct P { + template <class S> + friend bool operator==(const P &, const S &); // expected-note {{candidate}} \ + // expected-note {{reversed parameter order}} +}; +struct A : public P {}; +struct B : public P {}; +bool check(A a, B b) { return a == b; } // expected-error {{ '==' is ambiguous}} +} + +namespace test2 { +struct P { + template <class S> + friend bool operator==(const S &, const P &); // expected-note {{candidate}} \ + // expected-note {{reversed parameter order}} +}; +struct A : public P {}; +struct B : public P {}; +bool check(A a, B b) { return a == b; } // expected-error {{ '==' is ambiguous}} +} + +namespace test3 { +struct P { + template<class S> + bool operator==(const S &) const; // expected-note {{candidate}} \ + // expected-note {{reversed parameter order}} +}; +struct A : public P {}; +struct B : public P {}; +bool check(A a, B b) { return a == b; } // expected-error {{ '==' is ambiguous}} +} +} + #else // NO_ERRORS namespace problem_cases { _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
