Re: Git 2.18: RUNTIME_PREFIX... is it working?

[Daniel Jacques <dnj@google.com>]

Apologies for the delayed response - I've been out of town - and It
looks like Paul is already on the right track.

Johannes: I believe the GIT_EXEC_PATH snipped that you listed is not
incorrect. It's defined to "gitexecdir_SQ", and RUNTIME_PREFIX expects
(and enforces, as you snipped) that this is a relative path in
Makefile.

On non-RUNTIME_PREFIX builds, it should still be the absolute path, as
this is how Git self-locates, so using "gitexecdir_SQ" there makes
sense to me.

So:
RUNTIME_PREFIX=No, gitexecdir_SQ is absolute, GIT_EXEC_PATH is
absolute, used to find Git:
https://github.com/git/git/blob/ccdcbd54c4475c2238b310f7113ab3075b5abc9c/exec-cmd.c#L281
RUNTIME_PREFIX=YesPlease, gitexecdir_SQ is relative, GIT_EXEC_PATH is
relative and used to identify the search root of the Git installation:
https://github.com/git/git/blob/ccdcbd54c4475c2238b310f7113ab3075b5abc9c/exec-cmd.c#L40

The dual-use is confusing, and it took me a few to walk back through
how it is employed in each scenario. For clarity's sake, it may be
worth defining two variables and making one explicitly relative, but I
think it is functional as-is.

Paul: I used "config.mak" to configure RUNTIME_PREFIX when I used it
to the same effect:
https://chromium.googlesource.com/infra/infra/+/ca729b99c1f82665b634ef2ff69d93c97dfcda99/recipes/recipe_modules/third_party_packages/git.py#78

I forewent autoconf because I was concerned that the option was too
obscure and the configuration too nuanced to be worth adding via flag,
as RUNTIME_PREFIX requires some degree of path alignment and is fairly
special-case. If you prefer autoconf, though, it sounds like a good
thing to add, and I'm happy that you are finding the feature useful!

Cheers,
-Dan

On Fri, Jul 6, 2018 at 5:00 AM Johannes Schindelin
<Johannes.Schindelin@gmx.de> wrote:
>
> Hi Paul,
>
> On Thu, 5 Jul 2018, Paul Smith wrote:
>
> > On Wed, 2018-07-04 at 13:22 +0200, Johannes Schindelin wrote:
> > > > Basically what happens is that I run configure with
> > > > --prefix=/my/install/path --with-gitconfig=etc/gitconfig
> > > > --with-gitattributes=etc/gitattributes.
> > > >
> > > > Then I run make with RUNTIME_PREFIX=YesPlease.
> > >
> > > Ah. In Git for Windows, we do not use configure. I *think* this
> > > points to an incompatibility of the RUNTIME_PREFIX feature with our
> > > autoconf support, and this is a grand opportunity for you to step in
> > > and help.
> > >
> > > Essentially, what you will want to do is to implement a new configure
> > > option --with-runtime-prefix that then prevents the autoconf script
> > > from munging the relative paths in the way it does.
> >
> > FYI I was able to get this to work by overriding variables on the make
> > command line, like this:
> >
> >   make ... RUNTIME_PREFIX=YesPlease \
> >       gitexecdir=libexec/git-core \
> >       template_dir=share/git-core/templates \
> >       sysconfdir=etc
> >
> > I agree a new autoconf option would be much simpler to use.  I'll think
> > about it as I happen to have some some experience in these areas ;) ...
>
> I look forward to reviewing this...
>
> > but time is limited of course :).
>
> Yep. Same here ;-)
>
> Ciao,
> Johannes