Author: Haojian Wu Date: 2024-03-13T09:02:05+01:00 New Revision: 0be9592b0077dc63596ce46379cf7b3bd4a405c8
URL: https://github.com/llvm/llvm-project/commit/0be9592b0077dc63596ce46379cf7b3bd4a405c8 DIFF: https://github.com/llvm/llvm-project/commit/0be9592b0077dc63596ce46379cf7b3bd4a405c8.diff LOG: [clang] CTAD: Respect requires-clause of the original function template for the synthesized deduction guide (#84913) We ignored the require-clause of the original template when building the deduction guide for type-alias CTAD, this resulted in accepting code which should be rejected (see the test case). This patch fixes it, part of #84492. Added: Modified: clang/lib/Sema/SemaTemplate.cpp clang/test/SemaCXX/cxx20-ctad-type-alias.cpp Removed: ################################################################################ diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp index d8c9a5c09944c4..51e8db2dfbaac8 100644 --- a/clang/lib/Sema/SemaTemplate.cpp +++ b/clang/lib/Sema/SemaTemplate.cpp @@ -2906,18 +2906,27 @@ void DeclareImplicitDeductionGuidesForTypeAlias( Context.getCanonicalTemplateArgument( Context.getInjectedTemplateArg(NewParam)); } - // FIXME: implement the associated constraint per C++ + // Substitute new template parameters into requires-clause if present. + Expr *RequiresClause = nullptr; + if (Expr *InnerRC = F->getTemplateParameters()->getRequiresClause()) { + MultiLevelTemplateArgumentList Args; + Args.setKind(TemplateSubstitutionKind::Rewrite); + Args.addOuterTemplateArguments(TemplateArgsForBuildingFPrime); + ExprResult E = SemaRef.SubstExpr(InnerRC, Args); + if (E.isInvalid()) + return; + RequiresClause = E.getAs<Expr>(); + } + // FIXME: implement the is_deducible constraint per C++ // [over.match.class.deduct]p3.3: - // The associated constraints ([temp.constr.decl]) are the - // conjunction of the associated constraints of g and a - // constraint that is satisfied if and only if the arguments + // ... and a constraint that is satisfied if and only if the arguments // of A are deducible (see below) from the return type. auto *FPrimeTemplateParamList = TemplateParameterList::Create( Context, AliasTemplate->getTemplateParameters()->getTemplateLoc(), AliasTemplate->getTemplateParameters()->getLAngleLoc(), FPrimeTemplateParams, AliasTemplate->getTemplateParameters()->getRAngleLoc(), - /*RequiresClause=*/nullptr); + /*RequiresClause=*/RequiresClause); // To form a deduction guide f' from f, we leverage clang's instantiation // mechanism, we construct a template argument list where the template diff --git a/clang/test/SemaCXX/cxx20-ctad-type-alias.cpp b/clang/test/SemaCXX/cxx20-ctad-type-alias.cpp index 794496ed418489..3ce26c8fcd984e 100644 --- a/clang/test/SemaCXX/cxx20-ctad-type-alias.cpp +++ b/clang/test/SemaCXX/cxx20-ctad-type-alias.cpp @@ -230,3 +230,20 @@ using AFoo = Foo<U>*; // expected-note {{template is declared here}} AFoo s = {1}; // expected-error {{alias template 'AFoo' requires template arguments; argument deduction only allowed for}} } // namespace test17 + +namespace test18 { +template<typename T> +concept False = false; // expected-note {{because 'false' evaluated to false}} + +template <typename T> struct Foo { T t; }; + +template<typename T> requires False<T> // expected-note {{because 'int' does not satisfy 'False'}} +Foo(T) -> Foo<int>; + +template <typename U> +using Bar = Foo<U>; // expected-note {{could not match 'Foo<type-parameter-0-0>' against 'int'}} \ + // expected-note {{candidate template ignored: constraints not satisfied}} \ + // expected-note {{candidate function template not viable}} + +Bar s = {1}; // expected-error {{no viable constructor or deduction guide for deduction of template arguments}} +} // namespace test18 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
