build system issues

[Simon Marlow]

On 29/05/2009 17:34, Claus Reinke wrote:

>> I've just found some places we were depending on mk/config.mk where we
>> should have been depending on mk/project.mk. But this won't make any
>> difference in practice: configure always touches both of them anyway.
>> If we could prevent configure from touching files if they don't
>> change, that would help a lot.
>
> Why does configure need to rerun at all in that situation? config.mk is
> an output of configure, isn't it? So if configure had been rerun, my
> changes wouldn't have survived.

Right, if you have modified config.mk then you shouldn't run configure 
(obviously).

I was referring to a different problem - if you do re-run configure, 
perhaps because configure.ac has changed, or even if you just do 'sh 
config.status' because config.mk.in has changed, then config.mk ends up 
being touched even if it is the same as the previous version, and this 
can cause a lot of rebuilding.

Cheers,
	Simon