I close the issue, it seems like all subtasks have been completed.

Summary of the issue:

* The following macros have been converted to static inline functions:

  - Py_INCREF(), Py_DECREF()
  - Py_XINCREF(), Py_XDECREF()
  - PyObject_INIT(), PyObject_INIT_VAR()
  - _Py_NewReference(), _Py_ForgetReference()
  - _Py_Dealloc()
  - _PyObject_GC_TRACK(), _PyObject_GC_UNTRACK()

* There is no significant impact on performance:

  * I ran performance benchmark on Python compiled in release mode
  * I ran the Python test suite on Python compiled in debug mode
  * I measured the compilation time in release an debug mode

* It has been decided to use "static inline" to declare inline function (write directly "static inline", no macro).
* It has been decided to no use __attribute__((always_inline)) nor __forceinline (ask the compiler to always inline).


--

Benjamin Peterson would "like to see Py_LOCAL_INLINE removed, too, fwiw", but it's part of the public C API. It would require a deprecation period. I'm not interested to touch the public C API.

Benjamin: please open a new issue if you still want to remove it :-)