Including git-describe info as version strings for generic "-v" output

Hi all,

I hope the subject makes sense -- I'll explain what I'm trying to do.

I'm wondering what the best approaches are to being able to include output from git-describe [1] for generic version strings in projects managed by Git? This would have to work from within an autotools-managed project.

At the moment, I've managed to hook the output from git-describe in to a few .m4 files, which works only at ./configure time -- but of course, with this being Git, I'd ideally like the same mechanism to work in a situation where someone does:

$ git pull && make

It's knowing how to plumb this in to the Makefile.am part I'm hazy over.

Any help would be much appreciated.

Harry

[1] I know it's "git describe"; I'm using its hyphenated form for clarity of context.

Harry portobello <harryportobello@gmail.com> writes:

Perhaps take a look at GIT-VERSION-GEN that is part of the Git source?

Am 21.01.2012 23:03 schrieb Junio C Hamano:

At work, we have the same "problem". I solved it like so:

version.h: ---------------------------------------------- #ifndef __version_h__ #define __version_h__

#ifdef __cplusplus extern "C" { #endif

/*
 * Returns a version string as defined with the -D compiler switch.
 */
char const * software_version();

#ifdef __cplusplus } #endif

#endif ----------------------------------------------

version.c: ---------------------------------------------- #include "version.h"

char const * software_version()
{
    return SW_VERSION;
}
----------------------------------------------

And then make sure that ONLY version.c gets compiled like this:

gcc -DSW_VERSION=\"$(git describe --dirty)\" \
    [other options] \
    -c version.c -o version.o

Actually I use Scons to build my software (not Make). Scons automatically keeps track of dependencies and changed compiler switches between its runs. Thus it will re-compile version.c if the output of git-describe changes. That's why Scons users must make sure that the -D-switch is given only to version.c (else Scons would re-compile ALL files because of the different argument to -D).

If you are using Make then make sure that version.c gets compiled always. The drawback is that your app will be re-linked with every single Make run.

That's why I prefer Scons: it calculates the dependencies on a checksum basis. If the *contents* of version.c together with the compiler options didn't change, it won't re-compile it. Furtermore: if the *contents* of version.o didn't change, it won't re-link. Timestamps don't matter to Scons. But that's another topic :-)

HTH
    Dirk

On 21 January 2012 20:09, Harry portobello <harryportobello@gmail.com> wrote:

FWIW Perl does something like this. Have a look at the Perl makefiles for an example.

Yves