bug#8493: autoconf fails if env var U set

[Tom Lane]

Eric Blake <address@hidden> writes:
> On 04/13/2011 11:31 AM, Tim Wallace wrote:
>> This is a bug discovered when trying to build postgresql 9.0.3 on Redhat
>> Enterprise Linux 5.  If env var U is set, it fails, as pointed out by
>> the Postgres maintainer.

> The issue still exists in autoconf 2.68 (and autoconf.git); but the
> rules are not using $U in the configure script (read those lines
> closely, and you'll note that what is really happening is that they are
> generating a literal '$U' for inclusion in the AC_SUBST of LIBOBJS and
> LTLIBOBJS).  So the real problem may be that automake is not prepared
> for the case when $U is defined at make time, rather than on autoconf
> for passing literal $U into the makefile in the first place during
> AC_LIBOBJ.

It may be relevant here that Postgres doesn't use automake, just bare
autoconf.  So the appearance of $U in the emitted value of LIBOBJS seems
completely useless for us.  It would be nice if there were a way to turn
that off.

If the intended use is only for ansi2knr, I'd even argue that it
should be off by default ... how many people care about ansi2knr
anymore?

                        regards, tom lane