[Libreoffice] clean rebuilds needed

[Stephan Bergmann]

On 09/26/2011 10:01 PM, Bjoern Michaelsen wrote:
> On Mon, 26 Sep 2011 21:33:03 +0200
> Stephan Bergmann<sbergman at redhat.com>
> wrote:
>
>> I think its *file based* dependencies that's the problem here -- they
>> are simply not at the right level of granularity.  (Then again, I'm
>> not sure there's at all a working theory of making arbitrary changes
>> to your source tree and then rebuilding everything that needs to be
>> rebuilt while only rebuilding as little as possible what would not
>> necessarily need to be rebuilt.)
>
> No need for such theory, as for all practical proposes, there is ccache
> doing exactly that (although with a bit of addition IO). As for finer
> granularity: With the practical reality of C/C++ with preprocessing,
> context sensitive syntax and commandline switches to influence the
> compile result there is little hope for such a thing existing _and_ be
> reasonably fast (read: orders of magnitude faster than just frigging
> compiling it).

"there is ccache doing exactly that": but not everything is being built 
by the C/C++ compilers...

"finer granularity": I did not mean finer granularity within C/C++ files 
(so that a changed header does not necessarily cause rebuild of every 
file including it), but rather within the makefiles themselves (so that 
a change to one recipe in one makefile would not cause everything to be 
rebuilt if we had targets depend on the makefiles their recipes come from):

-Stephan