PyAPI: use None for bpy.app.autoexec_override when it isn't set

Expose `bpy.app.autoexec_override` as as bool or None,
so the boolean can be used to indicate the command line
argument passed in.

Ref !164033

scripts/startup/bl_operators/wm.py

@@ -3749,7 +3749,7 @@ class WM_OT_drop_blend_file(Operator):
         # Excluded paths can't be trusted, unless the command line overrides the preference.
         is_untrusted = (
             context.preferences.filepaths.use_scripts_auto_execute and
-            not bpy.app.autoexec_override and
+            bpy.app.autoexec_override is None and
             not self._is_autoexec(filepath, skip_overrides=True)
         )
 

scripts/startup/bl_ui/space_userpref.py

@@ -1777,8 +1777,8 @@ class USERPREF_PT_saveload_autorun(FilePathsPanel, Panel):
 
         text = iface_("Auto Run Python Scripts")
 
-        if bpy.app.autoexec_override:
-            if bpy.app.autoexec:
+        if (autoexec_override := bpy.app.autoexec_override) is not None:
+            if autoexec_override:
                 text_warn = iface_("enabled on startup, overriding the preference")
             else:
                 text_warn = iface_("disabled on startup, overriding the preference")

source/blender/python/intern/bpy_app.cc

@@ -367,10 +367,10 @@ PyDoc_STRVAR(
 PyDoc_STRVAR(
     /* Wrap. */
     bpy_app_autoexec_override_doc,
-    "Boolean, True when the auto-execution preference is overridden by the command line "
+    "The auto-execution set by the command line, None when the preference isn't overridden "
     "(read-only).\n"
     "\n"
-    ":type: bool\n");
+    ":type: bool | None\n");
 PyDoc_STRVAR(
     /* Wrap. */
     bpy_app_autoexec_fail_doc,
@@ -391,6 +391,14 @@ static PyObject *bpy_app_global_flag_get(PyObject * /*self*/, void *closure)
   return PyBool_FromLong(G.f & flag);
 }
 
+static PyObject *bpy_app_autoexec_override_get(PyObject * /*self*/, void * /*closure*/)
+{
+  if ((G.f & G_FLAG_SCRIPT_OVERRIDE_PREF) == 0) {
+    Py_RETURN_NONE;
+  }
+  return PyBool_FromLong(G.f & G_FLAG_SCRIPT_AUTOEXEC);
+}
+
 static int bpy_app_global_flag_set(PyObject * /*self*/, PyObject *value, void *closure)
 {
   const int flag = POINTER_AS_INT(closure);
@@ -699,10 +707,10 @@ static PyGetSetDef bpy_app_getsets[] = {
      bpy_app_autoexec_doc,
      reinterpret_cast<void *>(G_FLAG_SCRIPT_AUTOEXEC)},
     {"autoexec_override",
-     bpy_app_global_flag_get,
+     bpy_app_autoexec_override_get,
      nullptr,
      bpy_app_autoexec_override_doc,
-     reinterpret_cast<void *>(G_FLAG_SCRIPT_OVERRIDE_PREF)},
+     nullptr},
     {"autoexec_fail",
      bpy_app_global_flag_get,
      nullptr,

tests/python/bl_blend_autoexec_cli.py

@@ -327,8 +327,13 @@ class TestAutoExecCLI(unittest.TestCase):
         self.assert_blend_file_state(states[0], filename, is_trusted=is_trusted, message=message)
         # Opening the same file interactively must default to the same trust.
         self.assertEqual(states[0]["trust_source"], is_trusted, message)
-        is_override = any(arg in {"--enable-autoexec", "--disable-autoexec"} for arg in args)
-        self.assertEqual(states[0]["autoexec_override"], is_override, message)
+        if "--enable-autoexec" in args:
+            autoexec_override = True
+        elif "--disable-autoexec" in args:
+            autoexec_override = False
+        else:
+            autoexec_override = None
+        self.assertEqual(states[0]["autoexec_override"], autoexec_override, message)
 
     # -------------------------------------------------------------------------
     # Tests with Auto-Execution Preference "Enabled"

tests/python/ui_simulate/test_blend_autoexec.py

@@ -175,7 +175,7 @@ def _setup(dirpath_temp, *, use_autoexec, autoexec_override=None):
     e = _events_after_load()
 
     t.assertEqual(bpy.data.filepath, "")
-    t.assertEqual(bpy.app.autoexec_override, autoexec_override is not None)
+    t.assertEqual(bpy.app.autoexec_override, autoexec_override)
     if autoexec_override is None:
         t.assertEqual(bpy.app.autoexec, use_autoexec, "Auto-execution follows the preference")
     else: