Re: [OE-core] [PATCH] file: Remove unneccessary override of PACKAGECONFIG for native

["Andre McCurdy" <armccurdy@gmail.com>]

On Wed, May 13, 2020 at 2:31 PM Richard Purdie
<richard.purdie@linuxfoundation.org> wrote:
> On Wed, 2020-05-13 at 12:30 -0700, Andre McCurdy wrote:
> > Yes. Unfortunately making recipes robust for users who want to change
> > PACKAGECONFIG values doesn't seem to be a high priority for oe-core.
> > Why else would default PACKAGECONFIG values be assigned with ??=
> > instead of ?= other than as a trap for new users?
>
> I'm not sure I understand that, equally I'm tired so I'll assume I'm
> just missing something.
>
> I will say that there is no intention to make OE-Core hard to use or
> not robust, its only as good a the people contributing make it. In this
> case I'm not sure I understand/see the problem.
>
> If we should be using ?= instead of ??= then I'm open to an explanation
> why and patches to improve things.

If the default is assigned with ??= then trying to add to it with +=
results in the default value being lost. If the default is assigned
with ?= then adding to it with += works as expected.

To robustly enable a new PACKAGECONFIG option, users need to learn to
use PACKAGECONFIG_append (and obviously learn about the leading space
requirement there too) and not to try PACKAGECONFIG +=.

The reference manual does at least have an example which uses _append.
However it doesn't mention that += isn't safe or that _append will
affect native(sdk) and therefore _append_class-target is the safest
approach.

> Unfortunately we do have quite some legacy and ??= vs ?= has been
> troublesome in the many different contexts we have (recipe, class,
> conf, inc and so on).