From 3f94cbf9eba7adef027cfc5d087b3660800df9d7 Mon Sep 17 00:00:00 2001
From: Nick Coghlan <ncoghlan@gmail.com>
Date: Sun, 15 Jul 2012 19:10:39 +1000
Subject: [PATCH] Actually initialize __main__.__loader__ with loader
 instances, not the corresponding type objects

---
 Lib/test/test_cmd_line_script.py | 3 ++-
 Python/pythonrun.c               | 8 ++++++--
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/Lib/test/test_cmd_line_script.py b/Lib/test/test_cmd_line_script.py
index 849abe24772..8b6083e84f9 100644
--- a/Lib/test/test_cmd_line_script.py
+++ b/Lib/test/test_cmd_line_script.py
@@ -37,7 +37,8 @@ f()
 assertEqual(result, ['Top level assignment', 'Lower level reference'])
 # Check population of magic variables
 assertEqual(__name__, '__main__')
-_loader = __loader__ if isinstance(__loader__, type) else type(__loader__)
+from importlib.machinery import BuiltinImporter
+_loader = __loader__ if __loader__ is BuiltinImporter else type(__loader__)
 print('__loader__==%a' % _loader)
 print('__file__==%a' % __file__)
 assertEqual(__cached__, None)
diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index 970834e0bbd..8130cc52893 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -1355,11 +1355,15 @@ set_main_loader(PyObject *d, const char *filename, const char *loader_name)
 {
     PyInterpreterState *interp;
     PyThreadState *tstate;
-    PyObject *loader;
+    PyObject *loader_type, *loader;
     /* Get current thread state and interpreter pointer */
     tstate = PyThreadState_GET();
     interp = tstate->interp;
-    loader = PyObject_GetAttrString(interp->importlib, loader_name);
+    loader_type = PyObject_GetAttrString(interp->importlib, loader_name);
+    if (loader_type == NULL) {
+        return -1;
+    }
+    loader = PyObject_CallFunction(loader_type, "ss", "__main__", filename);
     if (loader == NULL ||
         (PyDict_SetItemString(d, "__loader__", loader) < 0)) {
         return -1;