Make nb_try_inc_ref and nb_enable_try_inc_ref public APIs

[hawkinsp]

I'm wondering if you would be open to exposing

nanobind/src/nb_ft.h

Line 28 in 62fc996

inline void nb_enable_try_inc_ref(PyObject *obj) noexcept {

as a nanobind API, perhaps with unstable in the name.

We found that we needed this exact feature in a user of nanobind but weren't thrilled to have to reimplement it, and it's probably good for the world that we don't end up with many copies of the fallback implementation (

nanobind/src/nb_ft.cpp

Line 23 in 62fc996

bool nb_try_inc_ref(PyObject *obj) noexcept {

)

[hawkinsp]

LLVM PR that needed this API: llvm/llvm-project#139721

[wjakob]

I am open to exposing this as one of the functions in nanobind/include/nanobind/nb_lib.h in the detail namespace, with the current function names. But please don't expect long term stability. Free-threaded python is still evolving, hence that whole part of nanobind is excluded from the usual SemVer guarantees. This caveat applies doubly to FT-related implementation details.