make test_atexit pass in MODE=

_testcapi.run_in_subinterp makes a questionable PyImport_Cleanup(),
which we work around by having a separate cleanup function for the
lookup tables.

also added a separate initialization function for the lookup tables
for symmetry.

some commented out code in the previous commit messed with GC, it was
made visible again.

third_party/python/Include/import.h

@@ -73,6 +73,8 @@ PyObject * PyImport_GetImporter(PyObject *path);
 PyObject * PyImport_Import(PyObject *name);
 PyObject * PyImport_ReloadModule(PyObject *m);
 void PyImport_Cleanup(void);
+void _PyImportLookupTables_Init(void);
+void _PyImportLookupTables_Cleanup(void);
 #if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03030000
 int PyImport_ImportFrozenModuleObject(
     PyObject *name

third_party/python/Python/finalize.c

@@ -96,6 +96,7 @@ Py_FinalizeEx(void)
 #endif
     /* Destroy all modules */
     PyImport_Cleanup();
+    _PyImportLookupTables_Cleanup();
 
     /* Flush sys.stdout and sys.stderr (again, in case more was printed) */
     if (_Py_FlushStdFiles() < 0) {

third_party/python/Python/import.c

@@ -154,8 +154,6 @@ static int cmp_initentry(const void *_x, const void *_y) {
 void
 _PyImport_Init(void)
 {
-    size_t i, n;
-
     PyInterpreterState *interp = PyThreadState_Get()->interp;
     initstr = PyUnicode_InternFromString("__init__");
     if (initstr == NULL)
@@ -163,27 +161,44 @@ _PyImport_Init(void)
     interp->builtins_copy = PyDict_Copy(interp->builtins);
     if (interp->builtins_copy == NULL)
         Py_FatalError("Can't backup builtins dict");
+}
 
-    for(n=0; PyImport_Inittab[n].name; n++);
-    Builtins_Lookup.n = n;
-    Builtins_Lookup.entries = malloc(sizeof(initentry) * n);
-    for(i=0; i < n; i++) {
-        Builtins_Lookup.entries[i].name = PyImport_Inittab[i].name;
-        Builtins_Lookup.entries[i].tab = &(PyImport_Inittab[i]);
+void _PyImportLookupTables_Init(void) {
+    size_t i, n;
+    if (Builtins_Lookup.entries == NULL) {
+        for(n=0; PyImport_Inittab[n].name; n++);
+        Builtins_Lookup.n = n;
+        Builtins_Lookup.entries = malloc(sizeof(initentry) * n);
+        for(i=0; i < n; i++) {
+            Builtins_Lookup.entries[i].name = PyImport_Inittab[i].name;
+            Builtins_Lookup.entries[i].tab = &(PyImport_Inittab[i]);
+        }
+        qsort(Builtins_Lookup.entries, Builtins_Lookup.n, sizeof(initentry), cmp_initentry);
     }
-    qsort(Builtins_Lookup.entries, Builtins_Lookup.n, sizeof(initentry), cmp_initentry);
-
-    for(n=0; PyImport_FrozenModules[n].name; n++);
-    Frozens_Lookup.n = n;
-    Frozens_Lookup.entries = malloc(sizeof(initentry) * n);
-    for(i=0; i<n; i++) {
-        Frozens_Lookup.entries[i].name = PyImport_FrozenModules[i].name;
-        Frozens_Lookup.entries[i].frz = &(PyImport_FrozenModules[i]);
+    if (Frozens_Lookup.entries == NULL) {
+        for(n=0; PyImport_FrozenModules[n].name; n++);
+        Frozens_Lookup.n = n;
+        Frozens_Lookup.entries = malloc(sizeof(initentry) * n);
+        for(i=0; i<n; i++) {
+            Frozens_Lookup.entries[i].name = PyImport_FrozenModules[i].name;
+            Frozens_Lookup.entries[i].frz = &(PyImport_FrozenModules[i]);
+        }
+        qsort(Frozens_Lookup.entries, Frozens_Lookup.n, sizeof(initentry), cmp_initentry);
     }
-    qsort(Frozens_Lookup.entries, Frozens_Lookup.n, sizeof(initentry), cmp_initentry);
     qsort(ZipCdir_Lookup.entries, ZipCdir_Lookup.n, sizeof(initentry), cmp_initentry);
 }
 
+void _PyImportLookupTables_Cleanup(void) {
+    if (Builtins_Lookup.entries != NULL) {
+        free(Builtins_Lookup.entries);
+        Builtins_Lookup.entries = NULL;
+    }
+    if (Frozens_Lookup.entries != NULL) {
+        free(Frozens_Lookup.entries);
+        Frozens_Lookup.entries = NULL;
+    }
+}
+
 void
 _PyImportHooks_Init(void)
 {
@@ -473,15 +488,6 @@ PyImport_Cleanup(void)
     PyObject *weaklist = NULL;
     const char * const *p;
 
-    if (Builtins_Lookup.entries != NULL) {
-        free(Builtins_Lookup.entries);
-        Builtins_Lookup.entries = NULL;
-    }
-    if (Frozens_Lookup.entries != NULL) {
-        free(Frozens_Lookup.entries);
-        Frozens_Lookup.entries = NULL;
-    }
-
     if (modules == NULL)
         return; /* Already done */
 
@@ -623,7 +629,6 @@ PyImport_Cleanup(void)
 
     /* Once more */
     _PyGC_CollectNoFail();
-
 #undef CLEAR_MODULE
 #undef STORE_MODULE_WEAKREF
 }
@@ -1085,11 +1090,11 @@ static const struct _frozen * find_frozen(PyObject *);
 static int
 is_builtin(PyObject *name)
 {
-    static initentry key;
+    initentry key;
     initentry *res;
     key.name = PyUnicode_AsUTF8(name);
     key.tab = NULL;
-    if(!key.name)
+    if(!name || !key.name)
         return 0;
     res = bsearch(&key, Builtins_Lookup.entries, Builtins_Lookup.n, sizeof(initentry), cmp_initentry);
     if (res) {
@@ -1196,14 +1201,12 @@ _imp_create_builtin(PyObject *module, PyObject *spec)
         return NULL;
     }
 
-    /* all builtins are static */
-    /*
     mod = _PyImport_FindExtensionObject(name, name);
     if (mod || PyErr_Occurred()) {
         Py_DECREF(name);
         Py_XINCREF(mod);
         return mod;
-    } */
+    }
 
     namestr = PyUnicode_AsUTF8(name);
     if (namestr == NULL) {

third_party/python/Python/pylifecycle.c

@@ -248,6 +248,7 @@ _Py_InitializeEx_Private(int install_sigs, int install_importlib)
     PySys_SetObject("__stderr__", pstderr);
     Py_DECREF(pstderr);
 
+    _PyImportLookupTables_Init();
     _PyImport_Init();
 
     _PyImportHooks_Init();