Builtin modules can't depend on build-helper output because _freeze_module links every static module #160689

Feature or enhancement

On POSIX, Programs/_freeze_module and _bootstrap_python are linked with $(LIBRARY_OBJS_OMIT_FROZEN), which includes $(MODOBJS): every static module from every Setup file, including Modules/Setup.local and (with MODULE_BUILDTYPE=static) all of Setup.stdlib. The only objects left out vs. the final libpython are Python/frozen.o and, for _freeze_module, Modules/getpath.o.

So a builtin module can't depend on anything produced by the build helpers:

• If its source includes a header generated by $(FREEZE_MODULE), make reports a circular dependency and the module fails to compile because the header doesn't exist yet.
• If it references a symbol from Modules/getpath.o (e.g. _Py_Get_Getpath_CodeObject()), linking _freeze_module fails, since that binary gets getpath_noop.o instead.

We even have a workaround for the second case - getpath_noop.c stubs _Py_Get_Getpath_CodeObject() purely so that _testinternalcapi links into _freeze_module under MODULE_BUILDTYPE=static.

Windows doesn't have this problem: PCbuild/_freeze_module.vcxproj compiles a fixed list of sources with PC/config_minimal.c.

Proposed fix: link the helpers with the core objects plus the Modules/Setup.bootstrap modules only, i.e. the POSIX equivalent of config_minimal.c.

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

No response

Linked PRs

• gh-160689 : Link only the bootstrap modules into the build helper programs #160537