gh-117953: Track Extra Details in Global Extensions Cache (gh-118532)

We have only been tracking each module's PyModuleDef.  However, there are some problems with that.  For example, in some cases we load single-phase init extension modules from def->m_base.m_init or def->m_base.m_copy, but if multiple modules share a def then we can end up with unexpected behavior.

With this change, we track the following:

* PyModuleDef (same as before)
* for some modules, its init function or a copy of its __dict__, but specific to that module
* whether it is a builtin/core module or a "dynamic" extension
* the interpreter (ID) that owns the cached __dict__ (only if cached)

This also makes it easier to remember the module's kind (e.g. single-phase init) and if loading it previously failed, which I'm doing separately.

Include/internal/pycore_importdl.h

@@ -22,6 +22,11 @@ typedef enum ext_module_kind {
     _Py_ext_module_kind_INVALID = 3,
 } _Py_ext_module_kind;
 
+typedef enum ext_module_origin {
+    _Py_ext_module_origin_CORE = 1,
+    _Py_ext_module_origin_BUILTIN = 2,
+    _Py_ext_module_origin_DYNAMIC = 3,
+} _Py_ext_module_origin;
 
 /* Input for loading an extension module. */
 struct _Py_ext_module_loader_info {
@@ -34,6 +39,7 @@ struct _Py_ext_module_loader_info {
     /* path is always a borrowed ref of name or filename,
      * depending on if it's builtin or not. */
     PyObject *path;
+    _Py_ext_module_origin origin;
     const char *hook_prefix;
     const char *newcontext;
 };
@@ -42,7 +48,11 @@ extern void _Py_ext_module_loader_info_clear(
 extern int _Py_ext_module_loader_info_init(
     struct _Py_ext_module_loader_info *info,
     PyObject *name,
-    PyObject *filename);
+    PyObject *filename,
+    _Py_ext_module_origin origin);
+extern int _Py_ext_module_loader_info_init_for_core(
+    struct _Py_ext_module_loader_info *p_info,
+    PyObject *name);
 extern int _Py_ext_module_loader_info_init_for_builtin(
     struct _Py_ext_module_loader_info *p_info,
     PyObject *name);

Python/importdl.c

@@ -111,9 +111,12 @@ _Py_ext_module_loader_info_clear(struct _Py_ext_module_loader_info *info)
 
 int
 _Py_ext_module_loader_info_init(struct _Py_ext_module_loader_info *p_info,
-                                PyObject *name, PyObject *filename)
+                                PyObject *name, PyObject *filename,
+                                _Py_ext_module_origin origin)
 {
-    struct _Py_ext_module_loader_info info = {0};
+    struct _Py_ext_module_loader_info info = {
+        .origin=origin,
+    };
 
     assert(name != NULL);
     if (!PyUnicode_Check(name)) {
@@ -183,12 +186,25 @@ _Py_ext_module_loader_info_init_for_builtin(
         .name_encoded=name_encoded,
         /* We won't need filename. */
         .path=name,
+        .origin=_Py_ext_module_origin_BUILTIN,
         .hook_prefix=ascii_only_prefix,
         .newcontext=NULL,
     };
     return 0;
 }
 
+int
+_Py_ext_module_loader_info_init_for_core(
+                            struct _Py_ext_module_loader_info *info,
+                            PyObject *name)
+{
+    if (_Py_ext_module_loader_info_init_for_builtin(info, name) < 0) {
+        return -1;
+    }
+    info->origin = _Py_ext_module_origin_CORE;
+    return 0;
+}
+
 int
 _Py_ext_module_loader_info_init_from_spec(
                             struct _Py_ext_module_loader_info *p_info,
@@ -203,7 +219,9 @@ _Py_ext_module_loader_info_init_from_spec(
         Py_DECREF(name);
         return -1;
     }
-    int err = _Py_ext_module_loader_info_init(p_info, name, filename);
+    /* We could also accommodate builtin modules here without much trouble. */
+    _Py_ext_module_origin origin = _Py_ext_module_origin_DYNAMIC;
+    int err = _Py_ext_module_loader_info_init(p_info, name, filename, origin);
     Py_DECREF(name);
     Py_DECREF(filename);
     return err;