[OE-core] [PATCH] autotools.bbclass: Add functionality to force a distclean when reconfiguring

[Colin Walters]

On Fri, 2012-09-07 at 17:05 +0100, Richard Purdie wrote:
> Unfortunately whilst reruning configure and make against a project will mostly
> work there are situations where it does not correctly do the right thing.
> 
> In particular, eglibc and gcc will fail out with errors where settings
> do not match a previously built configuration. It could be argued they are
> broken but the situation is what it is. There is the possibility of more subtle
> errors too.
> 
> This patch adds a "make distclean" call to recipes where configure is
> rerunning and the sstate checksum for do_configure has changed. We could
> simply use a stamp but saving out the previous configuration checksum
> adds some data at no real overhead.

The major problem with distclean is that it completely falls over in the
scenario where the source code has changed; the new distclean won't know
about *old* object files it no longer builds, files renamed, etc.

In GNOME we just this cycle landed this patch to use "git clean -dfx"
instead of "make distclean" if possible:
https://bugzilla.gnome.org/show_bug.cgi?id=656081

It might be interesting to have an option to run:
"git init; git add .; git commit -a -m auto-import" on each tarball
build in OE.  I've been considering doing this for jhbuild.

(My latest build system *only* builds from git repositories, so
 it works there =) )