Today, there is a build target is added for each runner: flash, debug,
debugserver, attach.
And those runners will have a dependency to Zephyr logical target that
is built before invoking `west <runner>`.
This design has some flaws, mainly that additional dependencies directly
on the target will not be built when running `west <runner>` directly.
That generator expressions cannot be used for the DEPENDS argument.
Instead, the build target `<runner>` will not have any dependencies, and
will raise a build error if a dependency is added to the target.
Due to how `add_dependencies()` work, this must be done as a build time
check, and not configure time check.
`west <runner>` will invoke a build before executing the runner, and
this way ensure the build target is up-to-date, which again removes the
need for a dedicated `west_<runner>_target`.
It also minimizes the risk of developer errors, as developers no longer
need to consider the need for adding additional dependencies.
If a custom target is part of the default `all` build, then it's ensured
to be up-to-date.
Fixes: Issue reported on slack.
Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>
3dd65a7663