Am 21.01.2012 23:03 schrieb Junio C Hamano:
> Harry portobello <harryportobello@xxxxxxxxx> writes:
>
>> I hope the subject makes sense -- I'll explain what I'm trying to do.
>
> Perhaps take a look at GIT-VERSION-GEN that is part of the Git source?
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
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