From b73fa20615105238d081f44660efd400f76af1cf Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Tue, 28 Nov 2023 18:25:14 +0100 Subject: [PATCH] c++: Fix up __has_extension (cxx_init_captures) On Mon, Nov 27, 2023 at 10:58:04AM +0000, Alex Coplan wrote: > Many thanks both for the reviews, this is now pushed (with Jason's > above changes implemented) as g:06280a906cb3dc80cf5e07cf3335b758848d488d. The new test FAILs everywhere with GXX_TESTSUITE_STDS=98,11,14,17,20,2b I'm normally using for testing. FAIL: g++.dg/ext/has-feature.C -std=gnu++11 (test for excess errors) Excess errors: /home/jakub/src/gcc/gcc/testsuite/g++.dg/ext/has-feature.C:185:2: error: #error This is on #if __has_extension (cxx_init_captures) != CXX11 #error #endif Comparing the values with clang++ on godbolt and with what is actually implemented: void foo () { auto a = [b = 3]() { return b; }; } both clang++ and GCC implement init captures as extension already in C++11 (and obviously not in C++98 because lambdas aren't implemented there), unless -pedantic-errors/-Werror=pedantic, so I think we should change the FE to match the test rather than the other way around. Making __has_extension return __has_feature for -pedantic-errors and not for -Werror=pedantic is just weird, but as that is what clang++ implements and this is for compatibility with it, I can live with it (but perhaps we should mention it in the documentation). Note, the warnings/errors can be changed using pragmas inside of the source, so whether one can use an extension or not depends on where in the code it is (__extension__ to the rescue if it can be specified around it). I wonder if the has-feature.C test shouldn't be #included in other 2 tests, one where -pedantic-errors would be in dg-options and through some macro tell the file that __has_extension will behave like __has_feature, and another with -Werror=pedantic to document that the option doesn't change it. 2023-11-28 Jakub Jelinek * cp-objcp-common.cc (cp_feature_table): Evaluate __has_extension (cxx_init_captures) to 1 even for -std=c++11. --- gcc/cp/cp-objcp-common.cc | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/gcc/cp/cp-objcp-common.cc b/gcc/cp/cp-objcp-common.cc index 70f9e4ab9e4..9439c4dc744 100644 --- a/gcc/cp/cp-objcp-common.cc +++ b/gcc/cp/cp-objcp-common.cc @@ -145,7 +145,7 @@ static constexpr cp_feature_info cp_feature_table[] = { "cxx_contextual_conversions", { cxx14, cxx98 } }, { "cxx_decltype_auto", cxx14 }, { "cxx_aggregate_nsdmi", cxx14 }, - { "cxx_init_captures", cxx14 }, + { "cxx_init_captures", { cxx14, cxx11 } }, { "cxx_generic_lambdas", cxx14 }, { "cxx_relaxed_constexpr", cxx14 }, { "cxx_return_type_deduction", cxx14 }, -- 2.11.4.GIT