https://github.com/mizvekov updated https://github.com/llvm/llvm-project/pull/183614
>From 25c946cadc87fd74cfeb950c12202a3a6d75077a Mon Sep 17 00:00:00 2001 From: Matheus Izvekov <[email protected]> Date: Thu, 26 Feb 2026 16:33:36 -0300 Subject: [PATCH] [clang] stop error recovery in SFINAE for narrowing in converted constant expressions A narrowing conversion in a converted constant expression should produce an invalid expression so that [temp.deduct.general]p7 is satisfied, by stopping substitution at this point. Fixes #167709 --- clang/lib/Sema/SemaOverload.cpp | 8 ++++++++ clang/test/SemaTemplate/temp_arg_nontype_cxx11.cpp | 11 ++++++++++- 2 files changed, 18 insertions(+), 1 deletion(-) diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp index 41b0b64409fd5..1736bec3f1538 100644 --- a/clang/lib/Sema/SemaOverload.cpp +++ b/clang/lib/Sema/SemaOverload.cpp @@ -6470,6 +6470,12 @@ static ExprResult BuildConvertedConstantExpression(Sema &S, Expr *From, S.Diag(From->getBeginLoc(), diag::ext_cce_narrowing) << CCE << /*Constant*/ 1 << PreNarrowingValue.getAsString(S.Context, PreNarrowingType) << T; + // If this is an SFINAE Context, treat the result as invalid so it stops + // substitution at this point, respecting C++26 [temp.deduct.general]p7. + // FIXME: Should do this whenever the above diagnostic is an error, but + // without further changes this would degrade some other diagnostics. + if (S.isSFINAEContext()) + return ExprError(); break; case NK_Dependent_Narrowing: @@ -6485,6 +6491,8 @@ static ExprResult BuildConvertedConstantExpression(Sema &S, Expr *From, // constant expression. S.Diag(From->getBeginLoc(), diag::ext_cce_narrowing) << CCE << /*Constant*/ 0 << From->getType() << T; + if (S.isSFINAEContext()) + return ExprError(); break; } if (!ReturnPreNarrowingValue) diff --git a/clang/test/SemaTemplate/temp_arg_nontype_cxx11.cpp b/clang/test/SemaTemplate/temp_arg_nontype_cxx11.cpp index 45bdb4c623dfe..0b785700ee238 100644 --- a/clang/test/SemaTemplate/temp_arg_nontype_cxx11.cpp +++ b/clang/test/SemaTemplate/temp_arg_nontype_cxx11.cpp @@ -43,7 +43,7 @@ void TempFunc() {} void Useage() { //expected-error@+2 {{no matching function}} - //expected-note@-4 {{candidate template ignored: substitution failure [with a = 1, b = 4294967295, c = 1]: non-type template argument evaluates to -1, which cannot be narrowed to type 'unsigned int'}} + //expected-note@-4 {{candidate template ignored: invalid explicitly-specified argument for template parameter 'b'}} TempFunc<1, -1, 1>(); } } @@ -114,3 +114,12 @@ void lookup() { Kolumn<&container::a>().ls(); // expected-error {{<&container::a}} Kolumn<nullptr>().ls(); // expected-error {{<nullptr}} } + +namespace GH167709 { + template <unsigned I> struct A { + static_assert(false, "shouldn't instantiate this"); + }; + template <int> void f() {} + template <int I> typename A<I>::type f() = delete; + template void f<-1>(); +} // namespace GH167709 _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
