[oe] additional bitbake test

[Chris Larson]

On Thu, May 27, 2010 at 11:36 PM, Frans Meulenbroeks <
fransmeulenbroeks at gmail.com> wrote:

> Hi,
>
> I'd like to propose to add a test in bitbake to see if an overlay dir
> exists when specifying overlays.
>
> In the past I bumped into a problem where BBFILE_PATTERN_local =
> "^${OE_TOPDIR}/myoverlay/recipes" was not processed properly because
> OE_TOPDIR was not passed using BB_ENV_EXTRAWHITE, resulting in the
> regexp match with the dir always returning false due to OE_TOPDIR not
> being expanded.
> A simple test could warn users against errors like this one.
>

Hmm, I'm not sure how best to implement the warning.  I'd rather not grep,
and we don't currently have a way to determine what variables a given value
references.  I guess we could notice if a given pattern didn't match any
files in BBFILES, and warn on that.  Does that sound reasonable?

Aside: the fact that a nonexistant var is left as is, to be expanded in
shell, is horrible, imo.  They should expand to the empty string when unset,
or error, or something.
-- 
Christopher Larson
clarson at kergoth dot com
Founder - BitBake, OpenEmbedded, OpenZaurus
Maintainer - Tslib
Senior Software Engineer, Mentor Graphics