https://github.com/danielcm585 updated https://github.com/llvm/llvm-project/pull/206629
>From 644978c7e0629638c4cce14aa6b284620538cf0b Mon Sep 17 00:00:00 2001 From: danielcm585 <[email protected]> Date: Tue, 30 Jun 2026 09:43:04 +0800 Subject: [PATCH 1/2] [sema] Fix recursive concept detection --- clang/include/clang/Sema/Sema.h | 2 ++ clang/lib/Sema/SemaConcept.cpp | 12 +++++++++++- clang/test/SemaCXX/recursive-concept-alias.cpp | 3 +++ 3 files changed, 16 insertions(+), 1 deletion(-) create mode 100644 clang/test/SemaCXX/recursive-concept-alias.cpp diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h index 2cf16fac83282..f8dfc06d2dc1a 100644 --- a/clang/include/clang/Sema/Sema.h +++ b/clang/include/clang/Sema/Sema.h @@ -918,6 +918,8 @@ class Sema final : public SemaBase { CodeCompleteConsumer *CompletionConsumer = nullptr); ~Sema(); + llvm::SmallPtrSet<const NamedDecl *, 8> ActiveConcepts; + /// Perform initialization that occurs after the parser has been /// initialized but before it parses anything. void Initialize(); diff --git a/clang/lib/Sema/SemaConcept.cpp b/clang/lib/Sema/SemaConcept.cpp index f41f37b8a3d19..b558480d526b5 100644 --- a/clang/lib/Sema/SemaConcept.cpp +++ b/clang/lib/Sema/SemaConcept.cpp @@ -1051,6 +1051,16 @@ ExprResult ConstraintSatisfactionChecker::Evaluate( const MultiLevelTemplateArgumentList &MLTAL) { const ConceptReference *ConceptId = Constraint.getConceptId(); + const NamedDecl *ConceptDecl = cast<clang::NamedDecl>(ConceptId->getNamedConcept()->getCanonicalDecl()); + + if (S.ActiveConcepts.contains(ConceptDecl)) { + S.Diag(ConceptId->getBeginLoc(), diag::err_recursive_concept) + << ConceptId->getNamedConcept()->getName(); + Satisfaction.IsSatisfied = false; + Satisfaction.ContainsErrors = true; + return ExprError(); + } + Sema::InstantiatingTemplate InstTemplate( S, ConceptId->getBeginLoc(), Sema::InstantiatingTemplate::ConstraintsCheck{}, @@ -1069,7 +1079,7 @@ ExprResult ConstraintSatisfactionChecker::Evaluate( unsigned Size = Satisfaction.Details.size(); llvm::SaveAndRestore PushConceptDecl( - ParentConcept, cast<ConceptDecl>(ConceptId->getNamedConcept())); + ParentConcept, cast<clang::ConceptDecl>(ConceptId->getNamedConcept())); ExprResult E = Evaluate(Constraint.getNormalizedConstraint(), MLTAL); diff --git a/clang/test/SemaCXX/recursive-concept-alias.cpp b/clang/test/SemaCXX/recursive-concept-alias.cpp new file mode 100644 index 0000000000000..f97889afb02e9 --- /dev/null +++ b/clang/test/SemaCXX/recursive-concept-alias.cpp @@ -0,0 +1,3 @@ +// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify %s + +template<typename T> concept C1 = C1<T>; // expected-error {{a concept definition cannot refer to itself}} expected-note {{here}} \ No newline at end of file >From 06716f457538f187495c1e834a27357b70a78b2f Mon Sep 17 00:00:00 2001 From: danielcm585 <[email protected]> Date: Tue, 30 Jun 2026 09:50:16 +0800 Subject: [PATCH 2/2] fix formatting --- clang/lib/Sema/SemaConcept.cpp | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/clang/lib/Sema/SemaConcept.cpp b/clang/lib/Sema/SemaConcept.cpp index b558480d526b5..b71bb461d680a 100644 --- a/clang/lib/Sema/SemaConcept.cpp +++ b/clang/lib/Sema/SemaConcept.cpp @@ -1051,7 +1051,8 @@ ExprResult ConstraintSatisfactionChecker::Evaluate( const MultiLevelTemplateArgumentList &MLTAL) { const ConceptReference *ConceptId = Constraint.getConceptId(); - const NamedDecl *ConceptDecl = cast<clang::NamedDecl>(ConceptId->getNamedConcept()->getCanonicalDecl()); + const NamedDecl *ConceptDecl = + cast<clang::NamedDecl>(ConceptId->getNamedConcept()->getCanonicalDecl()); if (S.ActiveConcepts.contains(ConceptDecl)) { S.Diag(ConceptId->getBeginLoc(), diag::err_recursive_concept) _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
