Re: PYTHONBIN for cross-compilation to different LOCALBASE

[Greg Troxel <gdt%lexort.com@localhost>]

Taylor R Campbell <campbell+netbsd-tech-pkg%mumble.net@localhost> writes:

> USE_TOOLS+=python isn't a thing (and the USE_TOOLS framework itself
> poses a difficulty with TOOLBASE/LOCALBASE split, with things like

Sure, but I think we're heading that way?

> USE_TOOLS+=sed vs USE_TOOLS+=sed:run, to be addressed separately).

I suspect we need to separate TOOLS into build (cross) and run (target),
and make people express both if that's how it is.  I think right now
:run sort of implies "at build and also at run".

> As you note, many Python packages use Python at build-time (e.g., to
> run setup.py) _and_ at run-time (e.g., in #! lines), via just
> pyversion.mk or application.mk.  These are the ones that need two
> variables to make the distinction.
>
> Question is, which use of the existing PYTHONBIN variable is more
> prevalent?

Part of this is what is more prevalent, but also about consistency
naming in the brave new world of full cross.

> Hoping to get a sense of this before committing to a new variable
> scheme that ends up requiring a mass-change later like my mistake with
> BUILD_DEPENDS and TOOL_DEPENDS.

Sure, but maybe we need to have a plan for whether TOOL means build
only, vs how we talk about runtime, and evaluate the whole plan, in
order to get a logically consistent naming scheme.  I see mass renames
as less harmful than confusing names in the long term.


I guess the first thing to detangle is the difference between
TOOL_DEPENDS and USE_TOOLS.   The basic issue is that we have blurred a
mechanism for naming and finding an adequate implementation of something
with the distinction of whether it needs to be present for the build or
at runtime.

If TOOL_DEPENDS is at build, then perhaps we should add

 TOOL_RUN_DEPENDS

to express that the tool must be available at runtime.  Which is sort
of like just DEPENDS, which can already end up resolving to a builtin.
It is striking me that USE_TOOLS and DEPENDS/builtin are different
mechanisms that are mostly doing the same thing.