Author: Younan Zhang Date: 2025-07-10T16:17:34+08:00 New Revision: adcd1bb32a050ced58584882b405f04f42c6009b
URL: https://github.com/llvm/llvm-project/commit/adcd1bb32a050ced58584882b405f04f42c6009b DIFF: https://github.com/llvm/llvm-project/commit/adcd1bb32a050ced58584882b405f04f42c6009b.diff LOG: [Clang] Fix the template argument collection after CWG2369 (#147894) Since the function template isn't instantiated before constraint checking, we'll not be able to find the outer template arguments through function specialization when evaluating the inner constraint that is nested within a larger constraint expression. The only practical solution is to get them back through the code synthesis context, which also allows us to eliminate an overload of getTemplateInstantiationArgs. No release note because it's a regression on trunk. Fixes https://github.com/llvm/llvm-project/issues/147772 Added: Modified: clang/include/clang/Sema/Sema.h clang/lib/Sema/SemaConcept.cpp clang/lib/Sema/SemaTemplateInstantiate.cpp clang/test/SemaTemplate/concepts-lambda.cpp Removed: ################################################################################ diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h index a21836dffb0e6..dbba13df3dbe8 100644 --- a/clang/include/clang/Sema/Sema.h +++ b/clang/include/clang/Sema/Sema.h @@ -13318,18 +13318,6 @@ class Sema final : public SemaBase { /// \param ForDefaultArgumentSubstitution indicates we should continue looking /// when encountering a specialized member function template, rather than /// returning immediately. - void getTemplateInstantiationArgs( - MultiLevelTemplateArgumentList &Result, const NamedDecl *D, - const DeclContext *DC = nullptr, bool Final = false, - std::optional<ArrayRef<TemplateArgument>> Innermost = std::nullopt, - bool RelativeToPrimary = false, const FunctionDecl *Pattern = nullptr, - bool ForConstraintInstantiation = false, - bool SkipForSpecialization = false, - bool ForDefaultArgumentSubstitution = false); - - /// This creates a new \p MultiLevelTemplateArgumentList and invokes the other - /// overload with it as the first parameter. Prefer this overload in most - /// situations. MultiLevelTemplateArgumentList getTemplateInstantiationArgs( const NamedDecl *D, const DeclContext *DC = nullptr, bool Final = false, std::optional<ArrayRef<TemplateArgument>> Innermost = std::nullopt, diff --git a/clang/lib/Sema/SemaConcept.cpp b/clang/lib/Sema/SemaConcept.cpp index 4a16412a5b04b..834417f8e15ac 100644 --- a/clang/lib/Sema/SemaConcept.cpp +++ b/clang/lib/Sema/SemaConcept.cpp @@ -1078,15 +1078,23 @@ static bool CheckFunctionConstraintsWithoutInstantiation( // template. We need the entire list, since the constraint is completely // uninstantiated at this point. - // FIXME: Add TemplateArgs through the 'Innermost' parameter once - // the refactoring of getTemplateInstantiationArgs() relands. MultiLevelTemplateArgumentList MLTAL; - MLTAL.addOuterTemplateArguments(Template, {}, /*Final=*/false); - SemaRef.getTemplateInstantiationArgs( - MLTAL, /*D=*/FD, FD, - /*Final=*/false, /*Innermost=*/{}, /*RelativeToPrimary=*/true, - /*Pattern=*/nullptr, /*ForConstraintInstantiation=*/true); - MLTAL.replaceInnermostTemplateArguments(Template, TemplateArgs); + { + // getTemplateInstantiationArgs uses this instantiation context to find out + // template arguments for uninstantiated functions. + // We don't want this RAII object to persist, because there would be + // otherwise duplicate diagnostic notes. + Sema::InstantiatingTemplate Inst( + SemaRef, PointOfInstantiation, + Sema::InstantiatingTemplate::ConstraintsCheck{}, Template, TemplateArgs, + PointOfInstantiation); + if (Inst.isInvalid()) + return true; + MLTAL = SemaRef.getTemplateInstantiationArgs( + /*D=*/FD, FD, + /*Final=*/false, /*Innermost=*/{}, /*RelativeToPrimary=*/true, + /*Pattern=*/nullptr, /*ForConstraintInstantiation=*/true); + } Sema::ContextRAII SavedContext(SemaRef, FD); std::optional<Sema::CXXThisScopeRAII> ThisScope; diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp index 9140f00fcd740..f04b01f64b960 100644 --- a/clang/lib/Sema/SemaTemplateInstantiate.cpp +++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp @@ -309,10 +309,24 @@ Response HandleFunction(Sema &SemaRef, const FunctionDecl *Function, isGenericLambdaCallOperatorOrStaticInvokerSpecialization(Function)) return Response::Done(); - } else if (Function->getDescribedFunctionTemplate()) { + } else if (auto *Template = Function->getDescribedFunctionTemplate()) { assert( (ForConstraintInstantiation || Result.getNumSubstitutedLevels() == 0) && "Outer template not instantiated?"); + if (ForConstraintInstantiation) { + for (auto &Inst : llvm::reverse(SemaRef.CodeSynthesisContexts)) { + if (Inst.Kind == Sema::CodeSynthesisContext::ConstraintsCheck && + Inst.Entity == Template) { + // After CWG2369, the outer templates are not instantiated when + // checking its associated constraints. So add them back through the + // synthesis context; this is useful for e.g. nested constraints + // involving lambdas. + Result.addOuterTemplateArguments(Template, Inst.template_arguments(), + /*Final=*/false); + break; + } + } + } } // If this is a friend or local declaration and it declares an entity at // namespace scope, take arguments from its lexical parent @@ -474,21 +488,6 @@ MultiLevelTemplateArgumentList Sema::getTemplateInstantiationArgs( assert((ND || DC) && "Can't find arguments for a decl if one isn't provided"); // Accumulate the set of template argument lists in this structure. MultiLevelTemplateArgumentList Result; - getTemplateInstantiationArgs( - Result, ND, DC, Final, Innermost, RelativeToPrimary, Pattern, - ForConstraintInstantiation, SkipForSpecialization, - ForDefaultArgumentSubstitution); - return Result; -} - -void Sema::getTemplateInstantiationArgs( - MultiLevelTemplateArgumentList &Result, const NamedDecl *ND, - const DeclContext *DC, bool Final, - std::optional<ArrayRef<TemplateArgument>> Innermost, bool RelativeToPrimary, - const FunctionDecl *Pattern, bool ForConstraintInstantiation, - bool SkipForSpecialization, bool ForDefaultArgumentSubstitution) { - assert((ND || DC) && "Can't find arguments for a decl if one isn't provided"); - // Accumulate the set of template argument lists in this structure. using namespace TemplateInstArgsHelpers; const Decl *CurDecl = ND; @@ -548,12 +547,13 @@ void Sema::getTemplateInstantiationArgs( } if (R.IsDone) - return; + return Result; if (R.ClearRelativeToPrimary) RelativeToPrimary = false; assert(R.NextDecl); CurDecl = R.NextDecl; } + return Result; } bool Sema::CodeSynthesisContext::isInstantiationRecord() const { diff --git a/clang/test/SemaTemplate/concepts-lambda.cpp b/clang/test/SemaTemplate/concepts-lambda.cpp index f5b1c2277f601..ddee39b162c63 100644 --- a/clang/test/SemaTemplate/concepts-lambda.cpp +++ b/clang/test/SemaTemplate/concepts-lambda.cpp @@ -341,6 +341,23 @@ void foo() { } +namespace GH147772 { + +template<int...> +struct seq {}; + +using arr = char[1]; + +struct foo { + template<int... i> + constexpr foo(seq<i...>) requires requires { + arr { [](auto) requires(i, true) { return 0; }(i)... }; + } {} +}; + +constexpr auto bar = foo(seq<0>()); +} + namespace GH147650 { template <int> int b; template <int b> _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
