Author: Younan Zhang Date: 2024-08-26T14:30:26+08:00 New Revision: e6974daa7bc100c8b88057d50f3ec3eca7282243
URL: https://github.com/llvm/llvm-project/commit/e6974daa7bc100c8b88057d50f3ec3eca7282243 DIFF: https://github.com/llvm/llvm-project/commit/e6974daa7bc100c8b88057d50f3ec3eca7282243.diff LOG: [Clang][Concepts] Fix the constraint equivalence checking involving parameter packs (#102131) We established an instantiation scope in order for constraint equivalence checking to properly map the uninstantiated parameters. That mechanism mapped even packs to themselves. Consequently, parameter packs e.g. appearing in a function call, were not expanded. So they would end up becoming `SubstTemplateTypeParmPackType`s that circularly depend on the canonical declaration of the function template, which is not yet determined, hence the spurious error. No release note as I plan to backport it to 19. Fixes https://github.com/llvm/llvm-project/issues/101735 --------- Co-authored-by: cor3ntin <corentinja...@gmail.com> Added: Modified: clang/lib/Sema/SemaConcept.cpp clang/test/SemaTemplate/concepts-out-of-line-def.cpp Removed: ################################################################################ diff --git a/clang/lib/Sema/SemaConcept.cpp b/clang/lib/Sema/SemaConcept.cpp index de24bbe7eb99ce..86d6f308a51cc2 100644 --- a/clang/lib/Sema/SemaConcept.cpp +++ b/clang/lib/Sema/SemaConcept.cpp @@ -977,8 +977,30 @@ static const Expr *SubstituteConstraintExpressionWithoutSatisfaction( // equivalence. LocalInstantiationScope ScopeForParameters(S); if (auto *FD = DeclInfo.getDecl()->getAsFunction()) - for (auto *PVD : FD->parameters()) - ScopeForParameters.InstantiatedLocal(PVD, PVD); + for (auto *PVD : FD->parameters()) { + if (!PVD->isParameterPack()) { + ScopeForParameters.InstantiatedLocal(PVD, PVD); + continue; + } + // This is hacky: we're mapping the parameter pack to a size-of-1 argument + // to avoid building SubstTemplateTypeParmPackTypes for + // PackExpansionTypes. The SubstTemplateTypeParmPackType node would + // otherwise reference the AssociatedDecl of the template arguments, which + // is, in this case, the template declaration. + // + // However, as we are in the process of comparing potential + // re-declarations, the canonical declaration is the declaration itself at + // this point. So if we didn't expand these packs, we would end up with an + // incorrect profile diff erence because we will be profiling the + // canonical types! + // + // FIXME: Improve the "no-transform" machinery in FindInstantiatedDecl so + // that we can eliminate the Scope in the cases where the declarations are + // not necessarily instantiated. It would also benefit the noexcept + // specifier comparison. + ScopeForParameters.MakeInstantiatedLocalArgPack(PVD); + ScopeForParameters.InstantiatedLocalPackArg(PVD, PVD); + } std::optional<Sema::CXXThisScopeRAII> ThisScope; diff --git a/clang/test/SemaTemplate/concepts-out-of-line-def.cpp b/clang/test/SemaTemplate/concepts-out-of-line-def.cpp index 0142efcdc3ee86..333187b0d74ad6 100644 --- a/clang/test/SemaTemplate/concepts-out-of-line-def.cpp +++ b/clang/test/SemaTemplate/concepts-out-of-line-def.cpp @@ -599,3 +599,26 @@ template <class DerT> unsigned long DerivedCollection<DerTs...>::index() {} } // namespace GH72557 + +namespace GH101735 { + +template <class, class> +concept True = true; + +template <typename T> +class A { + template <typename... Ts> + void method(Ts&... ts) + requires requires (T t) { + { t.method(static_cast<Ts &&>(ts)...) } -> True<void>; + }; +}; + +template <typename T> +template <typename... Ts> +void A<T>::method(Ts&... ts) + requires requires (T t) { + { t.method(static_cast<Ts &&>(ts)...) } -> True<void>; + } {} + +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
