Build system must regenerate file when template changes

[pspacek]

Proper fix for https://fedorahosted.org/freeipa/ticket/6498.

This PR obsoletes #251.

[MartinBasti]

works for me

[tiran]

I don't like the approach and prefer AC_CONFIG_FILE over manual sed for templating. You only have to add a couple of rules like

# Makefile.python.am
$(top_builddir)/ipasetup.py: $(top_builddir)/config.status $(top_builddir)/ipasetup.py.in
        $(MAKE) -C $(top_builddir) $(@F)

[pspacek]

I already described problems with AC_CONFIG_FILE in #251 (comment) a week ago, including envisioned move from AC_CONFIG_FILE to Makefile.am.

Please propose a solution which does not have problems mentioned in #251 (comment) so we can consider it.

For the record, this sed replacement is nothing unusual. The sed replacement is what Autoconf v2.69 manual chapter 4.8.2 Installation Directory Variables recommends and is already used all over the place in the build system (init directory, daemons/ipa-otpd, and elsewhere).

It is pitty that you did not comment on envisioned direction a week ago, nor a three days ago when first version of this PR was published.

[tiran]

You gave a good reason to not use CONFIG_STATUS_DEPEDENCIES and I agree with your reasoning. I don't see a case against AC_CONFIG_FILE, though. config.status substitution feature is more powerful than manual sed rules. I'm worried that we are going to run into problems in the future. It's surprising that some files can use all @VAR@ substitutions and some only a limited subset.

Your patch already introduces proper dependencies for ipasetup.py and version.py. Why not introduce a build rule for these files in Makefile.python.am?

[pspacek]

Oh, you are right, I was mixing CONFIG_STATUS_DEPEDENCIES and AC_CONFIG_FILES. Sorry!

So please let me explain the problem with AC_CONFIG_FILES:
AC_CONFIG_FILES properly substitutes variables only in Makefiles, as explained in Autoconf v2.69 manual chapter 4.8.2 Installation Directory Variables.

Yes, we can use AC_CONFIG_FILES so all variables can used for substitution, but in that case only subset of all usable variables will be substituted correctly. I do not think that it is right approach.

[MartinBasti]

Fixed upstream
master:
https://fedorahosted.org/freeipa/changeset/ba6ae666acaf8b930d18f45efc7c9c9faad3526b
https://fedorahosted.org/freeipa/changeset/6857de02f3a9c2d7e99e33863be3c65f71fa0d58
https://fedorahosted.org/freeipa/changeset/89739a6c910461a3cac3abc1bf2ff162c7c5bc82
https://fedorahosted.org/freeipa/changeset/6fcfe689f47a02df023de69f62c889d9b4dc26fe
https://fedorahosted.org/freeipa/changeset/6aa360775a781bee5a2fdd884cbfa33b545fcbb4
https://fedorahosted.org/freeipa/changeset/a89f63c5a62c4a02fc248a095f539a099a9c28c5