PyAPI: postpone loading add-ons until after key-maps have been defined

Loading add-ons after key-maps resolves a problem where add-ons would
setup shortcuts before Blender had created the key-maps.
Making add-ons have to declare the key-maps using region & window types
matching Blender's internal values.

This PR a pitfall pointed out in #110030.

Ref !110092

scripts/modules/bpy/__init__.py

@@ -57,7 +57,9 @@ def main():
 
     # Initializes Python classes.
     # (good place to run a profiler or trace).
-    utils.load_scripts()
+    # Postpone loading `extensions` scripts (add-ons & app-templates),
+    # until after the key-maps have been initialized.
+    utils.load_scripts(extensions=False)
 
 
 main()

scripts/modules/bpy/utils/__init__.py

@@ -189,7 +189,7 @@ _global_loaded_modules = []  # store loaded module names for reloading.
 import bpy_types as _bpy_types  # keep for comparisons, never ever reload this.
 
 
-def load_scripts(*, reload_scripts=False, refresh_scripts=False):
+def load_scripts(*, reload_scripts=False, refresh_scripts=False, extensions=True):
     """
     Load scripts and run each modules register function.
 
@@ -199,6 +199,8 @@ def load_scripts(*, reload_scripts=False, refresh_scripts=False):
     :arg refresh_scripts: only load scripts which are not already loaded
        as modules.
     :type refresh_scripts: bool
+    :arg: extensions: Loads additional scripts (add-ons & app-templates).
+    :type: extensions: bool
     """
     use_time = use_class_register_check = _bpy.app.debug_python
     use_user = not _is_factory_startup
@@ -306,21 +308,8 @@ def load_scripts(*, reload_scripts=False, refresh_scripts=False):
                         for mod in modules_from_path(path, loaded_modules):
                             test_register(mod)
 
-    # load template (if set)
+    if extensions:
-    if any(_bpy.utils.app_template_paths()):
+        load_scripts_extensions(reload_scripts=reload_scripts)
-        import bl_app_template_utils
-        bl_app_template_utils.reset(reload_scripts=reload_scripts)
-        del bl_app_template_utils
-
-    # Deal with add-ons separately.
-    _initialize_once = getattr(_addon_utils, "_initialize_once", None)
-    if _initialize_once is not None:
-        # First time, use fast-path.
-        _initialize_once()
-        del _addon_utils._initialize_once
-    else:
-        _addon_utils.reset_all(reload_scripts=reload_scripts)
-    del _initialize_once
 
     if reload_scripts:
         _bpy.context.window_manager.tag_script_reload()
@@ -342,6 +331,31 @@ def load_scripts(*, reload_scripts=False, refresh_scripts=False):
                         )
 
 
+def load_scripts_extensions(*, reload_scripts=False):
+    """
+    Load extensions scripts (add-ons and app-templates)
+
+    :arg reload_scripts: Causes all scripts to have their unregister method
+       called before loading.
+    :type reload_scripts: bool
+    """
+    # load template (if set)
+    if any(_bpy.utils.app_template_paths()):
+        import bl_app_template_utils
+        bl_app_template_utils.reset(reload_scripts=reload_scripts)
+        del bl_app_template_utils
+
+    # deal with addons separately
+    _initialize = getattr(_addon_utils, "_initialize", None)
+    if _initialize is not None:
+        # first time, use fast-path
+        _initialize()
+        del _addon_utils._initialize
+    else:
+        _addon_utils.reset_all(reload_scripts=reload_scripts)
+    del _initialize
+
+
 def script_path_user():
     """returns the env var and falls back to home dir or None"""
     path = _user_resource('SCRIPTS')

source/blender/windowmanager/intern/wm_init_exit.cc

@@ -133,6 +133,8 @@ CLG_LOGREF_DECLARE_GLOBAL(WM_LOG_TOOLS, "wm.tool");
 CLG_LOGREF_DECLARE_GLOBAL(WM_LOG_MSGBUS_PUB, "wm.msgbus.pub");
 CLG_LOGREF_DECLARE_GLOBAL(WM_LOG_MSGBUS_SUB, "wm.msgbus.sub");
 
+static void wm_init_scripts_extensions_once(bContext *C);
+
 static void wm_init_reports(bContext *C)
 {
   ReportList *reports = CTX_wm_reports(C);
@@ -358,6 +360,13 @@ void WM_init(bContext *C, int argc, const char **argv)
 
   STRNCPY(G.lib, BKE_main_blendfile_path_from_global());
 
+  CTX_py_init_set(C, true);
+  WM_keyconfig_init(C);
+
+  /* Load add-ons after key-maps have been initialized (but before the blend file has been read),
+   * important to guarantee default key-maps have been declared & before post-read handlers run. */
+  wm_init_scripts_extensions_once(C);
+
   wm_homefile_read_post(C, params_file_read_post);
 }
 
@@ -416,6 +425,13 @@ void WM_init_splash(bContext *C)
   CTX_wm_window_set(C, prevwin);
 }
 
+/** Load add-ons & app-templates once on startup. */
+static void wm_init_scripts_extensions_once(bContext *C)
+{
+  const char *imports[] = {"bpy", nullptr};
+  BPY_run_string_eval(C, imports, "bpy.utils.load_scripts_extensions()");
+}
+
 /* free strings of open recent files */
 static void free_openrecent()
 {

source/creator/creator.cc

@@ -545,9 +545,6 @@ int main(int argc,
       "this is not intended for typical usage\n\n");
 #endif
 
-  CTX_py_init_set(C, true);
-  WM_keyconfig_init(C);
-
 #ifdef WITH_FREESTYLE
   /* Initialize Freestyle. */
   FRS_init();