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Allow disabling cache_tag at build #144278
Description
This effectively disables automatic .pyc file generation and loading of __pycache__ files, which is stronger and more reliable than setting PYTHONDONTWRITEBYTECODE.
Historically, we have supported sys.implementation.cache_tag is None (it's throughout about half the relevant tests), but there's some work to do to get other tests to properly check.
The only build-time option I'm proposing is a preprocessor define that isn't set by default, and when set will set cache_tag to None rather than the default value. Patching in a preprocessor define is much easier to maintain than replacing the code, and I expect anyone who needs this (such as myself) is likely already patching other parts of the source and can easily add a define.
Activity
zooba commentedon Jan 27, 2026
It's actually documented that it may be None, so the fact that we don't handle it is the bug (mostly in tests). Adding the #ifdef with an internal name is hardly a feature.
pythongh-144278: Enable defining _PY_DISABLE_SYS_CACHE_TAG to disable…
Merge remote-tracking branch 'upstream/main' into pythongh-144278
Merge remote-tracking branch 'upstream/main' into pythongh-144278
Merge remote-tracking branch 'upstream/main' into pythongh-144278
pythongh-144278: Enable overriding TAG in sysmodule.c to change or di…
Merge branch 'main' into pythongh-144278
Merge branch 'main' into pythongh-144278
Merge remote-tracking branch 'upstream/main' into pythongh-144278
Merge remote-tracking branch 'upstream/main' into pythongh-144278
Merge branch 'pythongh-144278' of https://github.com/zooba/cpython into
gh-144278: Enable overriding sys.implementation's name and cache_tag …
pythongh-144278: Enable overriding sys.implementation's name and cach…
pythongh-144278: Enable overriding sys.implementation's name and cach…