gh-101758: Clean Up Uses of Import State (gh-101919)

This change is almost entirely moving code around and hiding import state behind internal API.  We introduce no changes to behavior, nor to non-internal API.  (Since there was already going to be a lot of churn, I took this as an opportunity to re-organize import.c into topically-grouped sections of code.)  The motivation is to simplify a number of upcoming changes.

Specific changes:

* move existing import-related code to import.c, wherever possible
* add internal API for interacting with import state (both global and per-interpreter)
* use only API outside of import.c (to limit churn there when changing the location, etc.)
* consolidate the import-related state of PyInterpreterState into a single struct field (this changes layout slightly)
* add macros for import state in import.c (to simplify changing the location)
* group code in import.c into sections
*remove _PyState_AddModule()

https://github.com/python/cpython/issues/101758

1 files changed, 1 insertions, 1 deletions

diff --git a/Python/ceval.c b/Python/ceval.c
index 611d62b0eb..09fd2f2926 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -2688,7 +2688,7 @@ import_name(PyThreadState *tstate, _PyInterpreterFrame *frame,
     }
     PyObject *locals = frame->f_locals;
     /* Fast path for not overloaded __import__. */
-    if (import_func == tstate->interp->import_func) {
+    if (_PyImport_IsDefaultImportFunc(tstate->interp, import_func)) {
         int ilevel = _PyLong_AsInt(level);
         if (ilevel == -1 && _PyErr_Occurred(tstate)) {
             return NULL;