llvmorg-github-actions[bot] wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-clang Author: Daniel Christian Mandolang (danielcm585) <details> <summary>Changes</summary> This patch improves Clang's handling of recursive concept alias expansions in C++20 concepts. Previously, recursive concept definitions caused infinite recursion during semantic analysis, leading to compiler crashes or undefined behavior. Fixes #<!-- -->206336 --- Full diff: https://github.com/llvm/llvm-project/pull/206629.diff 3 Files Affected: - (modified) clang/include/clang/Sema/Sema.h (+2) - (modified) clang/lib/Sema/SemaConcept.cpp (+11-1) - (added) clang/test/SemaCXX/recursive-concept-alias.cpp (+3) ``````````diff 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 `````````` </details> https://github.com/llvm/llvm-project/pull/206629 _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
