$(ISYSTEM) considered harmful (was: Re: Build broken)

On 31/03/13 14:52, Tor Lillqvist wrote:
> make clean helps. (if you have the patience, you can do "make
> foo.clean" for each module that depend on icu.)

if "make clean" helps, most likely something is clearly wrong.
in this case apparently the following commit broke incremental builds of
external libraries:

commit 151abb8b2b9d3a22229b98cec12e29484d12109b
Author: Luboš Luňák <l.lunak@suse.cz>
Date:   Tue Mar 19 16:39:49 2013 +0100

    use -isystem instead of -I for 3rd party headers

    This should avoid gcc warnings in external code we don't care about,
    so there'll be no need to fix them for WaE.

well it's true you don't get warnings when you use -isystem; you also
don't get makefile dependencies generated :(

reverted most of that on master.

unfortunately if you have built since that commit went in you likely do
need to "make clean" because there's no better way to get the
dependencies fixed...