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From:   Masahiro Yamada <masahiroy@kernel.org>
Date:   Thu, 18 Mar 2021 18:07:28 +0900
Message-ID: <CAK7LNAT_hp0PmhWpb2=fScw6Q9DQsBztykis=xN0QCH==AVY6g@mail.gmail.com>
Subject: Re: [PATCH RESEND] gcc-plugins: avoid errors with -std=gnu++11 on old gcc
To:     Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Cc:     =?UTF-8?Q?Valdis_Kl=C4=93tnieks?= <valdis.kletnieks@vt.edu>,
        Kees Cook <keescook@chromium.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        linux-hardening@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Joe Perches <joe@perches.com>
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On Thu, Mar 18, 2021 at 3:26 PM Miguel Ojeda
<miguel.ojeda.sandonis@gmail.com> wrote:
>
> On Thu, Mar 18, 2021 at 7:03 AM Valdis Kl=C4=93tnieks
> <valdis.kletnieks@vt.edu> wrote:
> >
> > Or declare that gcc6 is the minimum for building the kernel.
>
> Cc'ing some interested people in raising GCC's version for one reason
> or another, so that we put this as another one in the pile of reasons
> :-)
>
> https://lore.kernel.org/lkml/CAHk-=3Dwjgvt1Ei72BTrEH5fgfqykVH-AYt56-7yBT8=
Lcprj7bEg@mail.gmail.com/
>
> Cheers,
> Miguel


Previously we were discussing raising the min GCC
version 5.x,  but not further at this point of time.


We can require GCC 6+ for building GCC plugins.


--- a/scripts/gcc-plugins/Kconfig
+++ b/scripts/gcc-plugins/Kconfig
@@ -8,7 +8,7 @@ config HAVE_GCC_PLUGINS
 menuconfig GCC_PLUGINS
        bool "GCC plugins"
        depends on HAVE_GCC_PLUGINS
-       depends on CC_IS_GCC
+       depends on CC_IS_GCC && GCC_VERSION >=3D 60000
        depends on $(success,test -e $(shell,$(CC)
-print-file-name=3Dplugin)/include/plugin-version.h)
        default y
        help


BTW, the commit message mentions that
the issues only happen on GCC 4 and 5,
but the added code was:

GCC_FLAVOR =3D $(call cc-ifversion, -ge, 1100, 11, 98)

  instead of

GCC_FLAVOR =3D $(call cc-ifversion, -ge, 600, 11, 98)


So, this patch is also requiring to cover two standards:

GCC_VERSION >=3D 11  :  -std=3Dgnu++11
GCC_VERSION <  11  : -std=3Dgnu++98


--=20
Best Regards
Masahiro Yamada