[PATCH] libcpp: Use [[likely]] conditionally

[Jeff Law]

On 11/23/2021 1:34 PM, Christophe Lyon wrote:
>
>
> On Tue, Nov 23, 2021 at 4:41 PM Jeff Law via Gcc-patches 
> <gcc-patches@gcc.gnu.org> wrote:
>
>
>
>     On 11/23/2021 8:26 AM, Christophe LYON via Gcc-patches wrote:
>     > Hi!
>     >
>     > On 23/11/2021 01:26, Jeff Law via Gcc-patches wrote:
>     >>
>     >>
>     >> On 11/22/2021 10:22 AM, Marek Polacek via Gcc-patches wrote:
>     >>> Let's hide [[likely]] behind a macro, to suppress warnings if the
>     >>> compiler doesn't support it.
>     >>>
>     >>> Co-authored-by: Jonathan Wakely <jwakely@redhat.com>
>     >>>
>     >>> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
>     >>>
>     >>>     PR preprocessor/103355
>     >>>
>     >>> libcpp/ChangeLog:
>     >>>
>     >>>     * lex.c: Use ATTR_LIKELY instead of [[likely]].
>     >>>     * system.h (ATTR_LIKELY): Define.
>     >> OK
>     >> jeff
>     >
>     >
>     > This patch breaks the build when the host compiler is gcc-4.8.5,
>     > because __has_cpp_attribute is not defined.
>     Sigh.  I'd like to move to a more recent prereq if we could.
>
>
> I don't know why we have such an old dependency indeed.
> I am not requesting it, I just happen to have an old enough host
> compiler so that I can check/complain when we accidentally
> break the dependency :-)
Probably the enterprise distros.  I suspect we'll be able to roll 
forward in 2-3 years...

Jeff