Subject: Re: [PATCH] Documentation/Makefile: don't re-build on 'git version' changes

From: Junio C Hamano <[email-masked]>
Date: Fri, 02 Jul 2021 08:53:20 -0700

Ævar Arnfjörð Bjarmason  <[email-masked]> writes:

> Since 9a71722b4df (Doc: auto-detect changed build flags, 2019-03-17)
> we've been eagerly re-building the documentation whenever the output
> of "git version" (via the GIT-VERSION file) changed. This was never
> the intention, and was a regression on what we intended in
> 7b8a74f39cb (Documentation: Replace @@GIT_VERSION@@ in documentation,
> 2007-03-25).

I am not sure.  Even if there were no changes in say
'Documentation/git-cat-file.txt' and the sources it depends on
between 'master' and 'next', after doing this:

    $ git checkout next
    $ make prefix=$HOME/git-next/ install install-doc
    $ git checkout master
    $ make prefix=$HOME/git-master/ install install-doc
    $ $HOME/git-master/bin/git help cat-file | tail -n 1

I should see that the documentation should say it is from the
'master' branch in its footer, no?

In other words, I think 7b8a74f39cb's reasoning (not the
implementation), especially the last sentence of its log message, is
flawed, where it said:

    Documentation: Replace @@GIT_VERSION@@ in documentation
    
    Include GIT-VERSION-FILE and replace @@GIT_VERSION@@ in
    the HTML and XML asciidoc output. The documentation
    doesn't depend on GIT-VERSION-FILE so it will not be
    automatically rebuild if nothing else changed.

Thanks.