Author: Younan Zhang Date: 2025-07-24T15:30:51+08:00 New Revision: 07faafe4a4d0a5bd82b648aa9717783f001ddfae
URL: https://github.com/llvm/llvm-project/commit/07faafe4a4d0a5bd82b648aa9717783f001ddfae DIFF: https://github.com/llvm/llvm-project/commit/07faafe4a4d0a5bd82b648aa9717783f001ddfae.diff LOG: [Clang] Fix a partial ordering bug involving CTAD injected template arguments (#149782) The synthesized deduction guides use injected template arguments for distinguishment of explicit and implicit deduction guides. In partial ordering, we may substitute into these injected types when checking consistency. Properly substituting them needs the instantiated class template specializations which isn't the case at that point. So instead, we check their template specialization types. No release note because I think we want a backport, after baking it for a couple of days. Fixes https://github.com/llvm/llvm-project/issues/134613 Added: Modified: clang/lib/Sema/SemaTemplateDeduction.cpp clang/test/SemaTemplate/deduction-guide.cpp Removed: ################################################################################ diff --git a/clang/lib/Sema/SemaTemplateDeduction.cpp b/clang/lib/Sema/SemaTemplateDeduction.cpp index e1a975bcfb3e1..9e56e6978ef7f 100644 --- a/clang/lib/Sema/SemaTemplateDeduction.cpp +++ b/clang/lib/Sema/SemaTemplateDeduction.cpp @@ -5523,6 +5523,15 @@ static TemplateDeductionResult CheckDeductionConsistency( // FIXME: A substitution can be incomplete on a non-structural part of the // type. Use the canonical type for now, until the TemplateInstantiator can // deal with that. + + // Workaround: Implicit deduction guides use InjectedClassNameTypes, whereas + // the explicit guides don't. The substitution doesn't transform these types, + // so let it transform their specializations instead. + bool IsDeductionGuide = isa<CXXDeductionGuideDecl>(FTD->getTemplatedDecl()); + if (IsDeductionGuide) { + if (auto *Injected = P->getAs<InjectedClassNameType>()) + P = Injected->getInjectedSpecializationType(); + } QualType InstP = S.SubstType(P.getCanonicalType(), MLTAL, FTD->getLocation(), FTD->getDeclName(), &IsIncompleteSubstitution); if (InstP.isNull() && !IsIncompleteSubstitution) @@ -5537,9 +5546,15 @@ static TemplateDeductionResult CheckDeductionConsistency( if (auto *PA = dyn_cast<PackExpansionType>(A); PA && !isa<PackExpansionType>(InstP)) A = PA->getPattern(); - if (!S.Context.hasSameType( - S.Context.getUnqualifiedArrayType(InstP.getNonReferenceType()), - S.Context.getUnqualifiedArrayType(A.getNonReferenceType()))) + auto T1 = S.Context.getUnqualifiedArrayType(InstP.getNonReferenceType()); + auto T2 = S.Context.getUnqualifiedArrayType(A.getNonReferenceType()); + if (IsDeductionGuide) { + if (auto *Injected = T1->getAs<InjectedClassNameType>()) + T1 = Injected->getInjectedSpecializationType(); + if (auto *Injected = T2->getAs<InjectedClassNameType>()) + T2 = Injected->getInjectedSpecializationType(); + } + if (!S.Context.hasSameType(T1, T2)) return TemplateDeductionResult::NonDeducedMismatch; return TemplateDeductionResult::Success; } diff --git a/clang/test/SemaTemplate/deduction-guide.cpp b/clang/test/SemaTemplate/deduction-guide.cpp index 0953f647426fa..f6bc6ee3673c2 100644 --- a/clang/test/SemaTemplate/deduction-guide.cpp +++ b/clang/test/SemaTemplate/deduction-guide.cpp @@ -966,3 +966,19 @@ Expand<Type, Invocable<>> _{}; // CHECK-NEXT: | `-ParmVarDecl {{.+}} 'T...' pack } + +namespace GH134613 { +template <typename R> struct Foo { + using value_type = R; + + Foo() = default; + Foo(Foo<Foo<R>> &&rhs) {} +}; + +void main() { + auto r1 = Foo(Foo<Foo<int>>{}); + + static_assert(__is_same(decltype(r1)::value_type, int)); +} + +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
