[PATCH util-macros] XORG_GIT_MODULE_VERSION: writes module version in xorg-git-version.h

[Dan Nicholson]

On Tue, Apr 20, 2010 at 11:10 AM, Gaetan Nadon <memsize at videotron.ca> wrote:
> On Mon, 2010-04-19 at 21:34 -0700, Dan Nicholson wrote:
>
> On Mon, Apr 19, 2010 at 5:54 PM, Peter Hutterer
> <peter.hutterer at who-t.net> wrote:
>> On Mon, Apr 19, 2010 at 11:00:08PM +0200, Julien Cristau wrote:
>>> On Mon, Apr 19, 2010 at 14:52:55 -0400, Gaetan Nadon wrote:
>>>
>>> > Generates the git module version according to the "git describe HEAD"
>>> > If the git module has pending changes, it appends "-dirty" to the
>>> > version tag
>>> >
>>> > Signed-off-by: Gaetan Nadon <memsize at videotron.ca>
>>> > ---
>>> >  xorg-macros.m4.in |   18 ++++++++++++++++++
>>> >  1 files changed, 18 insertions(+), 0 deletions(-)
>>> >
>>> > diff --git a/xorg-macros.m4.in b/xorg-macros.m4.in
>>> > index 916b472..efb2e53 100644
>>> > --- a/xorg-macros.m4.in
>>> > +++ b/xorg-macros.m4.in
>>> > @@ -1009,3 +1009,21 @@ mv \$(top_srcdir)/.INSTALL.tmp
>>> > \$(top_srcdir)/INSTALL) \
>>> >  echo 'util-macros \"pkgdatadir\" from xorg-macros.pc not found:
>>> > installing possibly empty INSTALL.' >&2)"
>>> >  AC_SUBST([INSTALL_CMD])
>>> >  ]) # XORG_INSTALL
>>> > +
>>> > +# XORG_GIT_MODULE_VERSION()
>>> > +# -------------------------
>>> > +# Minimum version: 1.8.0
>>> > +#
>>> > +# Generates the git module version according to the "git describe
>>> > HEAD"
>>> > +# If the git module has pending changes, it appends "-dirty" to the
>>> > version tag
>>> > +#
>>> > +AC_DEFUN([XORG_GIT_MODULE_VERSION], [
>>> > +GIT_MODULE_VERSION_CMD="VER=\`GIT_DIR=\$(top_srcdir)/.git git describe
>>> > HEAD 2>/dev/null\`; \
>>> > +DVER=\`GIT_DIR=\$(top_srcdir)/.git git diff-index HEAD 2>/dev/null\`;
>>> > \
>>> > +OUTSTR=\"\#undef XORG_GIT_VERSION\" ; \
>>> > +OUTFILE=\"xorg-git-version.h\"; \
>>> > +test -n \"\$\$VER\" && OUTSTR=\"\#define XORG_GIT_VERSION \$\$VER\" &&
>>> > test -n \"\$\$DVER\" && OUTSTR=\"\#define XORG_GIT_VERSION \$\$VER-dirty\";
>>> > \
>>> > +test -e \"\$\$OUTFILE\" || echo \"\$\$OUTSTR\" > \"\$\$OUTFILE\"; \
>>> > +CONTENT=\`cat \$\$OUTFILE\` && test \"\$\$CONTENT\" = \"\$\$OUTSTR\"
>>> > || echo \$\$OUTSTR > \$\$OUTFILE;"
>>> > +AC_SUBST([GIT_MODULE_VERSION_CMD])
>>> > +]) # XORG_GIT_MODULE_VERSION
>>
>> my eyes!
>>
>>> As I said in reply to the initial patch by Peter I'd like a way to
>>> disable this, because packages might be built from a git tree, which
>>> might be unrelated to the xorg one, or outside of any git tree.  What's
>>> the output like if not building from git?  Does 'make
>>> GIT_MODULE_VERSION_CMD=:' work to disable it (I guess not, because
>>> anything trying to include xorg-git-version.h will be unhappy)?
>>
>> it simply sets the #undef and nothing will be printed to the log file. Is
>> there any specific argument against _running_ the macro as long if it
>> doesn't add anything to the logfile?
>>
>> Gaetan:
>> I'm not a big fan of the -dirty either but I guess if others want it we
>> can
>> leave it in.  Two questions though:
>> - If modules start using this macro, do they stillhave to add to
>>   DISTCLEANFILES and friends?
>
> I think it would be run all the time depending on .git/HEAD (or
> .git/`git symbolic-ref HEAD` like krh suggested), but it entirely
> depends what you do in the Makefile.am.
>
>> - This macro only gets invoked on automake runs, right? So if I pull and
>>  just rebuild, would it update the git version?
>
> It depends how fancy you want to be with the Makefile.am. To me, the
> following is "the right way to do it", but it requires touching more
> files.
>
> configure.ac:
> AM_CONDITIONAL([USING_GIT], [test -f "$srcdir/.git/HEAD"])
>
> Makefile.am:
> if USING_GIT
> GIT_HEAD = $(top_srcdir)/.git/HEAD
> endif
> noinst_HEADERS = git-xorg-version.h
> git-xorg-version.h: $(GIT_HEAD)
>     $(AM_V_GEN)$(GIT_MODULE_VERSION_CMD) $@
>
> If you have a checkout, the header depends on .git/HEAD, so it will
> get rebuilt any time HEAD gets updated. Actually, that doesn't seem
> like it would work that well since HEAD seems to take the modification
> time of the ref it's following, so the header wouldn't get updated if
> you checked out an older branch. Probably best would be:
>
> noinst_HEADERS = git-xorg-version.h
> git-xorg-version.h:
>     $(AM_V_GEN)$(GIT_MODULE_VERSION_CMD) $@
> .PHONY: git-xorg-version.h
>
> Sounds the best to me. I would put the generated file in DISTCLEANFILES.
> It will cause less rebuilds than if it is in CLEANFILES, in the case the
> generated
> .h file is included by millions of other .h files and you just clean one
> subtree.

Yeah, I think you'll need to, anyway, to pass distcheck.

> And then you'd just have to depend on GIT_MODULE_VERSION_CMD not
> updating the file unnecessarily to prevent spurious rebuilds. Gaeton's
> version seems to do that.
>
> It does.
>
>
> I posted the patch v2 yesterday. Is the usage of $@ is correct?
>
>
> VER=`GIT_DIR=$(top_srcdir)/.git git describe HEAD 2>/dev/null`;
> DVER=`GIT_DIR=$(top_srcdir)/.
> git git diff-index HEAD 2>/dev/null`;
> OUTSTR="\#undef XORG_GIT_VERSION" ;
> OUTFILE=$(@);
> test -n "$$VER" && OUTSTR="\#define XORG_GIT_VERSION $$VER";
> test -n "$$DVER" && OUTSTR="$$OUTSTR-with-uncommitted-changes";
> test -e "$$OUTFILE" || echo "$$OUTSTR" > "$$OUTFILE";
> CONTENT=`cat $$OUTFILE` && test "$$CONTENT" = "$$OUTSTR" || echo $$OUTSTR >
> $$OUTFILE;

I would personally replace all occurrences of $$OUTFILE with $@. I
don't think the () are necessary, either.

> It's no so bad when you look at it in the Makefile, with a different hair
> do. Just a couple of backslashes.
>
> Last call if reviewers want to remove with-uncommitted-changes.

I'd rather not have it since it doesn't tell me anything useful, but
if other people do want it, that's OK.

--
Dan