Author: Ilya Biryukov Date: 2024-01-04T11:57:53+01:00 New Revision: f5efa74961560070a1e6f127214bcf6b570fef98
URL: https://github.com/llvm/llvm-project/commit/f5efa74961560070a1e6f127214bcf6b570fef98 DIFF: https://github.com/llvm/llvm-project/commit/f5efa74961560070a1e6f127214bcf6b570fef98.diff LOG: [Sema] When checking for constraint equivalence, do not calculate satisfaction (#74490) ... and only look at equivalence of substituted expressions, not results of constraint satisfaction. This is required by the standard when matching redeclarations. Fixes #74314. There is already some existing machinery for that in `TemplateInstantiator` and `Sema` exposed separate functions for substituting expressions with intention to do that: - `Sema::SubstExpr` should not evaluate constraints. - `Sema::SubstConstraintExpr` should. However, both functions used to be equivalent. Introduce a new function that does not evaluate constraint and use it when matching declarations. Also change implementation of `SubstConstraintExpr` to call `SubstExpr` directly so it's obvious they behave in the same way and add a FIXME to call out that we might need to revamp this approach in the future. Added: Modified: clang/include/clang/Sema/Sema.h clang/include/clang/Sema/Template.h clang/lib/Sema/SemaConcept.cpp clang/lib/Sema/SemaTemplateInstantiate.cpp clang/test/SemaTemplate/concepts-out-of-line-def.cpp Removed: ################################################################################ diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h index 5e3b57ea33220b..8f44adef38159e 100644 --- a/clang/include/clang/Sema/Sema.h +++ b/clang/include/clang/Sema/Sema.h @@ -10263,11 +10263,13 @@ class Sema final { ~ConstraintEvalRAII() { TI.setEvaluateConstraints(OldValue); } }; - // Unlike the above, this evaluates constraints, which should only happen at - // 'constraint checking' time. + // Must be used instead of SubstExpr at 'constraint checking' time. ExprResult SubstConstraintExpr(Expr *E, const MultiLevelTemplateArgumentList &TemplateArgs); + // Unlike the above, this does not evaluates constraints. + ExprResult SubstConstraintExprWithoutSatisfaction( + Expr *E, const MultiLevelTemplateArgumentList &TemplateArgs); /// Substitute the given template arguments into a list of /// expressions, expanding pack expansions if required. diff --git a/clang/include/clang/Sema/Template.h b/clang/include/clang/Sema/Template.h index 2a553054a0ce51..ce44aca797b0fb 100644 --- a/clang/include/clang/Sema/Template.h +++ b/clang/include/clang/Sema/Template.h @@ -564,6 +564,7 @@ enum class TemplateSubstitutionKind : char { const MultiLevelTemplateArgumentList &TemplateArgs; Sema::LateInstantiatedAttrVec* LateAttrs = nullptr; LocalInstantiationScope *StartingScope = nullptr; + // Whether to evaluate the C++20 constraints or simply substitute into them. bool EvaluateConstraints = true; /// A list of out-of-line class template partial diff --git a/clang/lib/Sema/SemaConcept.cpp b/clang/lib/Sema/SemaConcept.cpp index 719c6aab74e017..acfc00f4125407 100644 --- a/clang/lib/Sema/SemaConcept.cpp +++ b/clang/lib/Sema/SemaConcept.cpp @@ -771,10 +771,9 @@ namespace { }; } // namespace -static const Expr * -SubstituteConstraintExpression(Sema &S, - const Sema::TemplateCompareNewDeclInfo &DeclInfo, - const Expr *ConstrExpr) { +static const Expr *SubstituteConstraintExpressionWithoutSatisfaction( + Sema &S, const Sema::TemplateCompareNewDeclInfo &DeclInfo, + const Expr *ConstrExpr) { MultiLevelTemplateArgumentList MLTAL = S.getTemplateInstantiationArgs( DeclInfo.getDecl(), DeclInfo.getLexicalDeclContext(), /*Final=*/false, /*Innermost=*/nullptr, @@ -797,8 +796,8 @@ SubstituteConstraintExpression(Sema &S, std::optional<Sema::CXXThisScopeRAII> ThisScope; if (auto *RD = dyn_cast<CXXRecordDecl>(DeclInfo.getDeclContext())) ThisScope.emplace(S, const_cast<CXXRecordDecl *>(RD), Qualifiers()); - ExprResult SubstConstr = - S.SubstConstraintExpr(const_cast<clang::Expr *>(ConstrExpr), MLTAL); + ExprResult SubstConstr = S.SubstConstraintExprWithoutSatisfaction( + const_cast<clang::Expr *>(ConstrExpr), MLTAL); if (SFINAE.hasErrorOccurred() || !SubstConstr.isUsable()) return nullptr; return SubstConstr.get(); @@ -814,12 +813,14 @@ bool Sema::AreConstraintExpressionsEqual(const NamedDecl *Old, if (Old && !New.isInvalid() && !New.ContainsDecl(Old) && Old->getLexicalDeclContext() != New.getLexicalDeclContext()) { if (const Expr *SubstConstr = - SubstituteConstraintExpression(*this, Old, OldConstr)) + SubstituteConstraintExpressionWithoutSatisfaction(*this, Old, + OldConstr)) OldConstr = SubstConstr; else return false; if (const Expr *SubstConstr = - SubstituteConstraintExpression(*this, New, NewConstr)) + SubstituteConstraintExpressionWithoutSatisfaction(*this, New, + NewConstr)) NewConstr = SubstConstr; else return false; diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp index df6b40999e645c..37e5b9cad08bc9 100644 --- a/clang/lib/Sema/SemaTemplateInstantiate.cpp +++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp @@ -1190,6 +1190,7 @@ namespace { const MultiLevelTemplateArgumentList &TemplateArgs; SourceLocation Loc; DeclarationName Entity; + // Whether to evaluate the C++20 constraints or simply substitute into them. bool EvaluateConstraints = true; public: @@ -2499,6 +2500,17 @@ TemplateInstantiator::TransformNestedRequirement( Req->getConstraintExpr()->getBeginLoc(), Req, Sema::InstantiatingTemplate::ConstraintsCheck{}, Req->getConstraintExpr()->getSourceRange()); + if (!getEvaluateConstraints()) { + ExprResult TransConstraint = TransformExpr(Req->getConstraintExpr()); + if (TransConstraint.isInvalid() || !TransConstraint.get()) + return nullptr; + if (TransConstraint.get()->isInstantiationDependent()) + return new (SemaRef.Context) + concepts::NestedRequirement(TransConstraint.get()); + ConstraintSatisfaction Satisfaction; + return new (SemaRef.Context) concepts::NestedRequirement( + SemaRef.Context, TransConstraint.get(), Satisfaction); + } ExprResult TransConstraint; ConstraintSatisfaction Satisfaction; @@ -4093,13 +4105,19 @@ Sema::SubstExpr(Expr *E, const MultiLevelTemplateArgumentList &TemplateArgs) { ExprResult Sema::SubstConstraintExpr(Expr *E, const MultiLevelTemplateArgumentList &TemplateArgs) { + // FIXME: should call SubstExpr directly if this function is equivalent or + // should it be diff erent? + return SubstExpr(E, TemplateArgs); +} + +ExprResult Sema::SubstConstraintExprWithoutSatisfaction( + Expr *E, const MultiLevelTemplateArgumentList &TemplateArgs) { if (!E) return E; - // This is where we need to make sure we 'know' constraint checking needs to - // happen. TemplateInstantiator Instantiator(*this, TemplateArgs, SourceLocation(), DeclarationName()); + Instantiator.setEvaluateConstraints(false); return Instantiator.TransformExpr(E); } diff --git a/clang/test/SemaTemplate/concepts-out-of-line-def.cpp b/clang/test/SemaTemplate/concepts-out-of-line-def.cpp index f134394615fb24..c4e8e6f720c492 100644 --- a/clang/test/SemaTemplate/concepts-out-of-line-def.cpp +++ b/clang/test/SemaTemplate/concepts-out-of-line-def.cpp @@ -504,3 +504,35 @@ struct bar { bar<int> x; } // namespace GH61763 + +namespace GH74314 { +template <class T, class U> constexpr bool is_same_v = __is_same(T, U); +template <class T, class U> constexpr bool is_not_same_v = !__is_same(T, U); + +template <class Result> +concept something_interesting = requires { + true; + requires is_same_v<int, Result>; +}; + +template <class T> +struct X { + void foo() requires requires { requires is_not_same_v<T, int>; }; + void bar(decltype(requires { requires is_not_same_v<T, int>; })); +}; + +template <class T> +void X<T>::foo() requires requires { requires something_interesting<T>; } {} +// expected-error@-1{{definition of 'foo' does not match any declaration}} +// expected-note@*{{}} + +template <class T> +void X<T>::foo() requires requires { requires is_not_same_v<T, int>; } {} // ok + +template <class T> +void X<T>::bar(decltype(requires { requires something_interesting<T>; })) {} +// expected-error@-1{{definition of 'bar' does not match any declaration}} + +template <class T> +void X<T>::bar(decltype(requires { requires is_not_same_v<T, int>; })) {} +} // namespace GH74314 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
