Re: [PATCH RESEND] gcc-plugins: avoid errors with -std=gnu++11 on old gcc

From: "Valdis Klētnieks" <valdis.kletnieks@vt.edu>
To: Masahiro Yamada <masahiroy@kernel.org>
Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
	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>
Subject: Re: [PATCH RESEND] gcc-plugins: avoid errors with -std=gnu++11 on old gcc
Date: Thu, 18 Mar 2021 07:47:06 -0400	[thread overview]
Message-ID: <299822.1616068026@turing-police> (raw)
In-Reply-To: <CAK7LNAT_hp0PmhWpb2=fScw6Q9DQsBztykis=xN0QCH==AVY6g@mail.gmail.com>

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On Thu, 18 Mar 2021 18:07:28 +0900, Masahiro Yamada said:

> We can require GCC 6+ for building GCC plugins.

> +       depends on CC_IS_GCC && GCC_VERSION >= 60000

I'd be OK with that personally, but the question is whether
any gcc 4.9 or 5.x users are using plugins.  That's a bit above
my pay grade.  Kees?  Do we have any data on that? (All I know
is that there is at least one, because they tripped over the GCC bug
that prompted the second patch)

> BTW, the commit message mentions that
> the issues only happen on GCC 4 and 5,
> but the added code was:
>
> GCC_FLAVOR = $(call cc-ifversion, -ge, 1100, 11, 98)
>
>   instead of
>
> GCC_FLAVOR = $(call cc-ifversion, -ge, 600, 11, 98)
>
> So, this patch is also requiring to cover two standards:
>
> GCC_VERSION >= 11  :  -std=gnu++11
> GCC_VERSION <  11  : -std=gnu++98

I chose 1100 so that everything from 4.9 to 10 would keep getting
handed gnu++98 the way they had been, and only change it for
gcc11.

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