Re: [BuildStream] Specifying default dependencies for element kinds

[Jürg Billeter <j bitron ch>]

On Thu, 2019-06-13 at 17:31 +0900, Tristan Van Berkom wrote:
> I think this can work very nicely, I tried to envision some chicken/egg
> cases with this... but as far as I can see it makes sense that you will
> anyway have to use a `manual` or `make` element to build the
> buildsystem element `components/buildsystem-autotools.bst`, so
> depending on the buildsystem that you require to build the buildsystem
> itself should not really be an issue.

Chicken/egg cases might still exist in some projects. E.g., you might
have bootstrap and final variants of self-hosted build tooling (such as
build system or compiler). A final variant of the build tooling might
be a default dependency, however, building that final variant of the
build tooling might use the same element plugin, yet needs to depend on
the bootstrap variant instead of the final variant.

Or maybe better to use a concrete example. You might have a stack that
provides a POSIX development environment, which includes a C compiler,
let's say gcc. It may make sense to add this stack as a default build
dependency for autotools elements. gcc.bst itself also wants to use the
autotools plugin but it obviously can't build-depend on itself.

Cheers,
Jürg