[util/macros] factorize tests for xmlto

[Gaetan Nadon]

On Tue, 2010-01-05 at 09:08 +0100, Matthieu Herrb wrote:

> On Mon, Jan 04, 2010 at 10:26:58AM -0500, Gaetan Nadon wrote:
> > On Sun, 2010-01-03 at 18:16 +0100, Matthieu Herrb wrote:
> > 
> > > Hi and best wishes for 2010,
> > > 
> > > There are duplicated checks for xmlto in more and more X.Org packages.
> > > I've 2 problems with that:
> > > 
> > > - the 1st one is just code duplication
> > > - the 2nd one is that the code currently used doesn't allow to ignore
> > >   an installed xmlto package. 
> > >   I want this because the base OpenBSD system doen't have xmlto (and other
> > >   systems also don't have it) yet I want to have consistant X builds, wether
> > >   or not xmlto is installed as a 3rd party package.
> > > 
> > 
> > I have noticed the use of the logic: "if the tool exist, then build it,
> > otherwise ignore it". I had on my long-term todo list to review those
> > behaviours. There is an on-going effort to move the specs away from
> > xorg-docs into their respective modules. This will add the number of
> > modules building documentation.
> > 
> > Before reviewing th details of patches, I'd like to review the desired
> > behaviours. Adding a macro to util-macros is exposing it to 250 modules.
> > It must have the potential of being useful for many of those. Let' see
> > how this plays out.
> 
> Sure. I would like to see the way docs are handled standardized before
> more modules start to format their own docs, because otherwise it's going
> to become a nightmare for platforms which don't have the same tools 
> as Linux. 

Great. 

> 
> > The module, say xfs, decides if it wants to build doc or not. The
> > default (auto) is to build the doc if the tool is present. If xmlto is
> > not found a warning is issued and the makefile completes successfully.
> 
> Yes. That was the behaviour that's currently implemented.
> > 
> > If the builder specifies with-xmlto=no, a warning is issued and XMLTO is
> > unset. Is the warning necessary? The builder asked not to build. Is it
> > necessary (or even wise)  to unset the variable set by AC_PATH_PROG? The
> > makefile completes successfully.
> 
> My patch adds a warning if XMLTO is set in the environment and
> --with-xmlto=no is specified on the command line. If only --with-xmlto=no 
> is specified, there won't be any extra warning.

Ok, I missed that.

> 
> > If the builder specified -with=yes,  and the tool is not found, should
> > it not issue an error and stop? You specifically asked to build it. For
> > a developer, it is not important, but for an automated build machine, it
> > needs to stop when something goes wrong, however it happens.
> 
> Yes that should probably be done. 

I was speculating here, the more opinions the better.

> 
> > I wanted to spell out the functions the macro provide to see if they are
> > applicable to other modules as well. I agree with the problem you raised
> > and I am trying to apply your solution to more than a few modules.
> > 
> > One suggestion: would it be useful to factor out the check for xmlto in
> > a macro (XORG_CHECK_XMLTO)? This would allow other modules to make their
> > own decision about what to do when xmlto is not available. Look at
> > XORG_CHECK_DOCBOOK.
> 
> Yes. Again what's important for me here, is to be able to explicitely
> tell the build system to not use those tools, even if they are available. 
> We don't want those to become mandatory to build X modules (either 
> by providing pre-processed docs in the source tarballs, or by just
> don't formatting the docs if the tools are not there).
> 

Ok. That confirms what I understood. It's a tool issue. I naively
assumed all the tools invoked by Makefiles were available on all
platforms. In fact, I thought it was a hard requirement. The consequence
of not having the same tools on all platforms is some type of platform
dependant code in the Makefiles. I know little  about the tools that
build doc, but the first option would be to find/use common tools.

> > 
> > There are other tools used to build docs, so I can foresee other macros
> > based on this one. 
> 
> Agreed too. This is why it's important to adress the issue before
> it becomes a total mess.  I would hate to have to manage dozen of different
> hacks to handle the build of docs on BSD systems.
> 
> 
> > Some comments on the patch itself 
> > - The macro should be minimum version 1.5
> 
> Other have pointed at this too. Agreed.
> 
> > - The comment is confusing: XORG_CHECK_XMLTO or XORH_WITH_XMLTO?
> > - The comment should explain how to/why use the macro
> 
> Those are easy to fix in the next version of the patch.
> Of course.
> > 
> > Somewhat unrelated: 
> > I installed OpenBSD in a virtualBox. I haven't hunt down the toolchain
> > yet. It's be nice to list the tools that are or are not available in
> > this wiki: http://wiki.x.org/wiki/RequiredPackages. I did it for Ubuntu
> > and OpenSolaris.
> 
> I've added basic information. 

Thanks.


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