[OE-core] [PATCH v2] classes/waf: Fix builds when B != S

[Andreas Müller]

On Mon, Dec 3, 2018 at 11:22 PM Joshua Watt <jpewhacker at gmail.com> wrote:
> > Hmm - the a2jmidid shows what's going to happen: All packets shipping
> > older waf need workaround hacks. This should not be the way to go
> > because then we can remove waf.bbclass entirely.
>
> Yes, that might actually be the most "waf" answer to that problem...
> for better or worse waf is designed to be fully self contained, so
> having a "standard" class that builds it is somewhat problematic. Waf
> itself could change at any time and render the canned configuration
> useless. This doesn't really affect any of the projects using waf
> because they usually just download (or build) the latest when they
> start development and don't upgrade (or do so infrequently).
>
> The other option that I've though about (not that I really like it) is
> to have some sort of WAF_VERSION variable that waf.bbclass keys off of
> to detect what support is available. However, even this isn't fool
> proof because of add-in modules that you can choose to build into your
> project's version of waf... these can basically do whatever you want
> including adding new command line arguments, and adding or modifying
> existing behaviors. I'm not in favor of going down the road of making
> variables like WAF_HAS_GNU_DIRS_PLUGIN that each project has to
> configure.
>
> OTOH, as long as the projects we are building with waf currently use a
> new enough version (I know 1.7 works and 1.4 is broken), our current
> bbclass works and maybe that's "good enough" for now?
>
> I'm open to suggestions.
Have meta-qt5-extra with many recipes on old sources which potentially
fail for this change. Will build with your's and Khem's patch and fix
affected recipes. Think version magic is not necessary.

Andreas