Re: pgxs and bison, flex

On ons, 2012-03-28 at 22:12 -0400, Tom Lane wrote:
> Peter Eisentraut <peter_e(at)gmx(dot)net> writes:
> > I propose that we apply the attached patch to make sure those variables
> > are set to a usable default value in any case.
>
> Won't this break usages such as in contrib/cube?
>
> cubeparse.c: cubeparse.y
> ifdef BISON
> $(BISON) $(BISONFLAGS) -o $@ $<
> else
> @$(missing) bison $< $@
> endif

No, the code in my patch is conditional on 'ifdef PGXS'. (Not visible
in the patch, unfortunately.)

I don't think we want to support external use of $(missing), since the
text it refers to is specific to PostgreSQL's distribution mechanisms.

> IMO, people building distribution packages in clean chroots are best
> advised to include bison and flex even if they're not strictly
> necessary. Otherwise the build could fall over unexpectedly and
> unnecessarily, depending on file timestamps and other phase-of-the-moon
> issues. If the package maker has adopted that elementary bit of
> self-defense, the whole thing is a non problem.

I don't agree with that. If this were a problem, dozens of packages
would be liable to break randomly, and this knowledge would have passed
into best practices and policies decades ago.

In any case, it won't really help because we can't enforce it, and we
can't tell the average person who installs from source to install
additional build dependencies that the installation instructions
explicitly say are not needed.