bpo-28411: Isolate PyInterpreterState.modules (#3575)

A bunch of code currently uses PyInterpreterState.modules directly instead of PyImport_GetModuleDict(). This complicates efforts to make changes relative to sys.modules. This patch switches to using PyImport_GetModuleDict() uniformly. Also, a number of related uses of sys.modules are updated for uniformity for the same reason.

Note that this code was already reviewed and merged as part of #1638. I reverted that and am now splitting it up into more focused parts.

2 files changed, 11 insertions, 5 deletions

diff --git a/Objects/moduleobject.c b/Objects/moduleobject.c
index 5fab06d31d..2be49fbda3 100644
--- a/Objects/moduleobject.c
+++ b/Objects/moduleobject.c
@@ -162,11 +162,17 @@ _add_methods_to_object(PyObject *module, PyObject *name, PyMethodDef *functions)
 PyObject *
 PyModule_Create2(struct PyModuleDef* module, int module_api_version)
 {
+    if (!_PyImport_IsInitialized(PyThreadState_GET()->interp))
+        Py_FatalError("Python import machinery not initialized");
+    return _PyModule_CreateInitialized(module, module_api_version);
+}
+
+PyObject *
+_PyModule_CreateInitialized(struct PyModuleDef* module, int module_api_version)
+{
     const char* name;
     PyModuleObject *m;
-    PyInterpreterState *interp = PyThreadState_Get()->interp;
-    if (interp->modules == NULL)
-        Py_FatalError("Python import machinery not initialized");
+
     if (!PyModuleDef_Init(module))
         return NULL;
     name = module->m_name;
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index dc4d2edc5c..9ebbb21ef8 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -3902,7 +3902,6 @@ import_copyreg(void)
 {
     PyObject *copyreg_str;
     PyObject *copyreg_module;
-    PyInterpreterState *interp = PyThreadState_GET()->interp;
     _Py_IDENTIFIER(copyreg);
 
     copyreg_str = _PyUnicode_FromId(&PyId_copyreg);
@@ -3914,7 +3913,8 @@ import_copyreg(void)
        by storing a reference to the cached module in a static variable, but
        this broke when multiple embedded interpreters were in use (see issue
        #17408 and #19088). */
-    copyreg_module = PyDict_GetItemWithError(interp->modules, copyreg_str);
+    PyObject *modules = PyImport_GetModuleDict();
+    copyreg_module = PyDict_GetItemWithError(modules, copyreg_str);
     if (copyreg_module != NULL) {
         Py_INCREF(copyreg_module);
         return copyreg_module;