GitLab

Adding smart_holder_type_caster_load::loaded_as_shared_ptr, currently bypassing smart_holder shared_ptr tracking completely, but the tests pass and are sanitizer clean.

Pure renaming of function and variable names, for better generalization when convoluting with inheritance. NO functional changes.

Pure renaming of function names in test_classh_inheritance, similar to the systematic approach used in test_class_wip. NO functional changes.

Removing stray isinstance<T>(src): it interferes with the py::module_local feature. Adding missing #includes.

First pass adjusting try_implicit_casts and try_load_foreign_module_local to capture loaded_v_h, but untested and guarded with pybind11_failure("Untested"). This was done mainly to determine general feasibility. Note the TODO in pybind11.h, where type_caster_generic::local_load is currently hard-coded. test_classh_wip and test_classh_inheritance still pass, as before.

Folding in modified_type_caster_generic_load_impl, just enough to pass test_class_wip. test_classh_inheritance is still failing, but with a different error: [RuntimeError: Incompatible type (as_raw_ptr_unowned).]

Copying classh type_casters from test_classh_wip.cpp UNMODIFIED, as a baseline for generalizing the code.

Moving factored-out make_constructor to test_classh_wip.cpp, restoring previous version of cast.h. This is currently the most practical approach. See PR #2798 for background.

Adding minor comment (change to internals needed to distinguish uninitialized/disowned in error message).

Using type_caster_base<mpty>::src_and_type directly, removing copy. Also renaming one cast to cast_const_raw_ptr, for clarity.

Open question, with respect to the original code:
https://github.com/pybind/pybind11/blob/76a160070b369f8d82b945c97924227e8b835c94/include/pybind11/pybind11.h#L1510
To me it looks like the exact situation marked as `std::shared_ptr<Good> gp1 = not_so_good.getptr();` here: https://en.cppreference.com/w/cpp/memory/enable_shared_from_this
The comment there is: `// undefined behavior (until C++17) and std::bad_weak_ptr thrown (since C++17)`
Does the existing code have UB pre C++17?

I'll leave handling of enable_shared_from_this for later, as the need arises.

See new bullet point in comment section near the top.

The variable was also renamed to reflect its function more accurately.

Copying type_caster_generic::cast into type_caster<mpty> as-is (preparation for handling smart pointers).

static cast handle for rtrn_valu works by simply dropping in code from type_caster_base (marked with comments). rtrn_rref raises a RuntimeError, to be investigated.

static cast handle for rtrn_cref works by simply dropping in code from type_caster_base (marked with comments). rtrn_mref and rtrn_mptr work via const_cast (to add const).