Re: pg_bsd_indent compiles bytecode

Hi,

On 2020-06-27 18:43:40 -0400, Tom Lane wrote:
> Andres Freund <andres(at)anarazel(dot)de> writes:
> > I can test that with another program, but for some reason pg_bsd_indent
> > fails to build against 13/HEAD, but builds fine against 12. Not sure yet
> > what's up:
>
> Huh. Works here on RHEL8 ... what platform are you using?

That was on Debian unstable, but I don't think it's really related. The
issue turns out to be that gcc 10 changed the default from -fno-common
to -fcommon, and I had 13/HEAD set up to use gcc 10, but 12 to use gcc
9.

The way that pg_bsd_indent defines its variables isn't standard C, as
far as I can tell, which explains the errors I was getting. All the
individual files include indent_globs.h, which declares/defines a bunch
of variables. Since it doesn't use extern, they'll all end up as full
definitions in each .o when -fno-common is used (the default now), hence
the multiple definition errors. The only reason it works with -fcommon
is that they'll end up processed as weak symbols and 'deduplicated' at
link time.

Ick.

Greetings,

Andres Freund