Обсуждение: Clean up build warnings of plperl with clang-12+

Hi all,

This is a follow-up of the discussion that happened here:
https://www.postgresql.org/message-id/YYoJYO475dsqYhta@paquier.xyz

Recently, we are getting warnings in the build of plperl when using at
least clang-12 because of their new flag -Wcompound-token-split-by-macro,
all the warnings coming from Perl itself.

Upstream has posted a fix about that but it will take time before this
propagates across the buildfarm (five~ animals are now impacted?):
https://www.nntp.perl.org/group/perl.perl5.changes/2021/07/msg57758.html

dangomushi is impacted by that, and I'd like to stick an -Werror in it
as it is proving to be good in detecting incorrect placeholders.

Tom has suggested that we could add -Wno-compound-token-split-by-macro
to take care of the issue on our side, and attached is a patch to do
so.

Any objections?  I'd like to get this back-patched.

Thanks,
--
Michael

On Wed, Nov 10, 2021 at 07:35:21AM +0900, Michael Paquier wrote:
> Tom has suggested that we could add -Wno-compound-token-split-by-macro
> to take care of the issue on our side, and attached is a patch to do
> so.
>
> Any objections?  I'd like to get this back-patched.

Backpatched this one as of 9ff47ea.  That should allow the addition of
-Werror on dangomushi.
--
Michael

Michael Paquier <michael@paquier.xyz> writes:
> Backpatched this one as of 9ff47ea.  That should allow the addition of
> -Werror on dangomushi.

Cool.  I have also enabled -Werror on florican.

            regards, tom lane

Michael Paquier <michael@paquier.xyz> writes:
> Backpatched this one as of 9ff47ea.  That should allow the addition of
> -Werror on dangomushi.

I see you tried to do that by adding -Werror to CPPFLAGS.  That doesn't
work because it breaks configure's tests.  (I wonder if meson is any
smarter than autoconf about that.)  The way I do it on my own
animals is like

if ($branch eq 'HEAD' or $branch ge 'REL9_3')
{
        # Add -Werror so we get errors for warning conditions.
        # Pre-9.3 PG doesn't compile cleanly with Sierra's cc.
        # Can't put this in CFLAGS because it breaks configure,
        # so use COPT instead.
        $conf{build_env}{COPT} = "-Werror";
}

Guess I could drop the branch check now.

            regards, tom lane

On 11/11/21 13:18, Tom Lane wrote:
> Michael Paquier <michael@paquier.xyz> writes:
>> Backpatched this one as of 9ff47ea.  That should allow the addition of
>> -Werror on dangomushi.
> I see you tried to do that by adding -Werror to CPPFLAGS.  That doesn't
> work because it breaks configure's tests.  (I wonder if meson is any
> smarter than autoconf about that.)  The way I do it on my own
> animals is like
>
> if ($branch eq 'HEAD' or $branch ge 'REL9_3')
> {
>         # Add -Werror so we get errors for warning conditions.
>         # Pre-9.3 PG doesn't compile cleanly with Sierra's cc.
>         # Can't put this in CFLAGS because it breaks configure,
>         # so use COPT instead.
>         $conf{build_env}{COPT} = "-Werror";
> }
>
> Guess I could drop the branch check now.
>
>     



Wouldn't it be better in any case just to add the clang fix for building
plperl rather than globally?


cheers


andrew


--
Andrew Dunstan
EDB: https://www.enterprisedb.com

Andrew Dunstan <andrew@dunslane.net> writes:
> Wouldn't it be better in any case just to add the clang fix for building
> plperl rather than globally?

That'd be considerably messier wouldn't it?  (And I wonder if the
meson system will be able to do it at all.)  If you feel motivated
to make that happen, go for it, but I don't.

            regards, tom lane

On Thu, Nov 11, 2021 at 01:18:32PM -0500, Tom Lane wrote:
> I see you tried to do that by adding -Werror to CPPFLAGS.  That doesn't
> work because it breaks configure's tests.  (I wonder if meson is any
> smarter than autoconf about that.)  The way I do it on my own
> animals is like

Nya.  (Japanized Meh)

> if ($branch eq 'HEAD' or $branch ge 'REL9_3')
> {
>         # Add -Werror so we get errors for warning conditions.
>         # Pre-9.3 PG doesn't compile cleanly with Sierra's cc.
>         # Can't put this in CFLAGS because it breaks configure,
>         # so use COPT instead.
>         $conf{build_env}{COPT} = "-Werror";
> }
>
> Guess I could drop the branch check now.

Thanks.  I'll switch to something like that.
--
Michael

On Thu, Nov 11, 2021 at 03:51:35PM -0500, Tom Lane wrote:
> That'd be considerably messier wouldn't it?

Yes, that would be a bit messier.  For example, we could do that with
something saved in Makefile.global.in by ./configure that plperl feeds
on to add this extra CFLAGS in its own local Makefile.

> (And I wonder if the
> meson system will be able to do it at all.)  If you feel motivated
> to make that happen, go for it, but I don't.

Neither am I.  9ff47ea is the least invasive solution, at least.
--
Michael