[Bug c++/60512] would be useful if gcc implemented __has_feature similarly to clang

["cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60512

--- Comment #22 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Alex Coplan <acoplan@gcc.gnu.org>:

https://gcc.gnu.org/g:06280a906cb3dc80cf5e07cf3335b758848d488d

commit r14-5873-g06280a906cb3dc80cf5e07cf3335b758848d488d
Author: Alex Coplan <alex.coplan@arm.com>
Date:   Fri Mar 17 16:30:51 2023 +0000

    c-family: Implement __has_feature and __has_extension [PR60512]

    This patch implements clang's __has_feature and __has_extension in GCC.
    Currently the patch aims to implement all documented features (and some
    undocumented ones) following the documentation at
    https://clang.llvm.org/docs/LanguageExtensions.html with the exception
    of the legacy features for C++ type traits.  These are omitted, since as
    the clang documentation notes, __has_builtin is the correct "modern" way
    to query for these (which GCC already implements).

    gcc/c-family/ChangeLog:

            PR c++/60512
            * c-common.cc (struct hf_feature_info): New.
            (c_common_register_feature): New.
            (init_has_feature): New.
            (has_feature_p): New.
            * c-common.h (c_common_has_feature): New.
            (c_family_register_lang_features): New.
            (c_common_register_feature): New.
            (has_feature_p): New.
            * c-lex.cc (init_c_lex): Plumb through has_feature callback.
            (c_common_has_builtin): Generalize and move common part ...
            (c_common_lex_availability_macro): ... here.
            (c_common_has_feature): New.
            * c-ppoutput.cc (init_pp_output): Plumb through has_feature.

    gcc/c/ChangeLog:

            PR c++/60512
            * c-lang.cc (c_family_register_lang_features): New.
            * c-objc-common.cc (struct c_feature_info): New.
            (c_register_features): New.
            * c-objc-common.h (c_register_features): New.

    gcc/cp/ChangeLog:

            PR c++/60512
            * cp-lang.cc (c_family_register_lang_features): New.
            * cp-objcp-common.cc (struct cp_feature_selector): New.
            (cp_feature_selector::has_feature): New.
            (struct cp_feature_info): New.
            (cp_register_features): New.
            * cp-objcp-common.h (cp_register_features): New.

    gcc/ChangeLog:

            PR c++/60512
            * doc/cpp.texi: Document __has_{feature,extension}.

    gcc/objc/ChangeLog:

            PR c++/60512
            * objc-act.cc (struct objc_feature_info): New.
            (objc_nonfragile_abi_p): New.
            (objc_common_register_features): New.
            * objc-act.h (objc_common_register_features): New.
            * objc-lang.cc (c_family_register_lang_features): New.

    gcc/objcp/ChangeLog:

            PR c++/60512
            * objcp-lang.cc (c_family_register_lang_features): New.

    libcpp/ChangeLog:

            PR c++/60512
            * include/cpplib.h (struct cpp_callbacks): Add has_feature.
            (enum cpp_builtin_type): Add BT_HAS_{FEATURE,EXTENSION}.
            * init.cc: Add __has_{feature,extension}.
            * macro.cc (_cpp_builtin_macro_text): Handle
            BT_HAS_{FEATURE,EXTENSION}.

    gcc/testsuite/ChangeLog:

            PR c++/60512
            * c-c++-common/has-feature-common.c: New test.
            * c-c++-common/has-feature-pedantic.c: New test.
            * g++.dg/ext/has-feature.C: New test.
            * gcc.dg/asan/has-feature-asan.c: New test.
            * gcc.dg/has-feature.c: New test.
            * gcc.dg/ubsan/has-feature-ubsan.c: New test.
            * obj-c++.dg/has-feature.mm: New test.
            * objc.dg/has-feature.m: New test.

    Co-Authored-By: Iain Sandoe <iain@sandoe.co.uk>