Refer here for information:
http://wiki.services.openoffice.org/wiki/Writing_warning-free_code
warnings01 was integrated in m173 but the functionality has not been implemented
for all platforms yet. By default m173 builds on GNU/Linux SPARC with warnings,
not errors. 

Some changes are required in solenv/inc/unxlngs.mk to implement the
functionality to make warnings be errors. Refer to the code in unxlngi6.mk for
the example. To see what is required, note the differences when warnings01 was
integrated:

http://tools.openoffice.org/source/browse/tools/solenv/inc/unxlngi6.mk?r1=1.19&r2=1.20
http://tools.openoffice.org/source/browse/tools/solenv/inc/unxlngs.mk?r1=1.17&r2=1.18

The method will be to complete a build of m173 first, then re-build with the new
code in unxlngs.mk and apply the patches from warningfixes01 and warningfixes02.