[Buildroot] [PATCH 2/2] support/scripts/size-stats: properly assign pre-compiled .pyc files

[yann.morin at orange.com]

Vincent, All,

On 2026-09-14 11:27 +0200, MORIN Yann INNOV/IT-S spake thusly:
> On 2026-08-19 13:44 +0000, Vincent Fazio spake thusly:
[--SNIP--]
> > Maybe we can leverage `source_from_cache` [2] and compare the file names?
> Ah, good idea if it can work out-of-tree as we install for the target.
> I'll look into that.

Oh, wait, wait... That's the other way around: we do have the path of
the original .py file, and we are looking for the path of the
pre-compiled file!

So I gave it a try with cache_from_source() [0] instead, and it kinda
of works...

"Kinda", because it only works when we do have both the source and the
pre-compiled files together (BR2_PACKAGE_PYTHON3_PY_PYC), but fails
when we only have the precompiled files (BR2_PACKAGE_PYTHON3_PYC_ONLY).
That's because cache_from_source() only work on the path string, and
does not check files.

But that is not an issue in practice:

1. BR2_PACKAGE_PYTHON3_PY_ONLY: we only have .py files, so when we try
   to look at the cprfe-copmpiled files, it will not be found, and thus
   ignored (as it is today already)

2. BR2_PACKAGE_PYTHON3_PYC_ONLY: we'll only have the .pyc file in the
   pycache directory, and the .py file will be ignored (as it is today
   already).

3. BR2_PACKAGE_PYTHON3_PY_PYC: both will be found, and we'll properly
   account for both (unlike today)

So, that's what I'm going to go with, using cache_from_source(), rather
than with my open-coding the split. Thanks for the hint! 👍

However, I have not seen a way to convert from a source file path to an
*optimised* precompiled pyc file. So I still believe this should be
addressed when (if!) we eventually add squpport for optimised
precompiled pyc files. If we forget about size-stat then, that's not a
problem: the interested parties will have to fixup afterward (like I'm
currently doing anyway ;-) ).

[0] https://github.com/python/cpython/blob/20e6c2fc7c174342214d561845419c4030f8638f/Lib/importlib/_bootstrap_external.py#L239

Regards,
Yann E. MORIN.

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