lua: we now watch require'd files in addition to the main config file

Finally got around to https://github.com/wez/wezterm/discussions/914#discussioncomment-960983

config/src/lua.rs

@@ -111,6 +111,28 @@ pub fn make_lua_context(config_file: &Path) -> anyhow::Result<Lua> {
             .to_str()
             .ok_or_else(|| anyhow!("config file path is not UTF-8"))?;
 
+        // Hook into loader and arrange to watch all require'd files.
+        // <https://www.lua.org/manual/5.3/manual.html#pdf-package.searchers>
+        // says that the second searcher function is the one that is responsible
+        // for loading lua files, so we shim around that and speculatively
+        // add the name of the file that it would find (as returned from
+        // package.searchpath) to the watch list, then we just call the
+        // original implementation.
+        lua.load(
+            r#"
+local orig = package.searchers[2]
+package.searchers[2] = function(module)
+  local name, err = package.searchpath(module, package.path)
+  if name then
+    package.loaded.wezterm.add_to_config_reload_watch_list(name)
+  end
+  return orig(module)
+end
+        "#,
+        )
+        .set_name("=searcher")?
+        .eval()?;
+
         wezterm_mod.set("config_file", config_file_str)?;
         wezterm_mod.set(
             "config_dir",

docs/changelog.md

@@ -18,6 +18,7 @@ As features stabilize some brief notes about them will accumulate here.
 * `colors.indexed` would error out with `Cannot convert String to u8`. [#2197](https://github.com/wez/wezterm/issues/2197)
 * X11: closing a window when multiple were open could result in an X protocol error that closed all windows [#2198](https://github.com/wez/wezterm/issues/2198)
 * Config will now automatically reload after error. Previously, you would need to manually reload the config using [ReloadConfiguration](config/lua/keyassignment/ReloadConfiguration.md). [#1174](https://github.com/wez/wezterm/issues/1174)
+* Config will now automatically reload for changes made to 'require'd lua files. Previously, only the main config file and any files that you explicitly passed to [add_to_config_reload_watch_list](config/lua/wezterm/add_to_config_reload_watch_list.md) would trigger a reload.
 
 ### 20220624-141144-bd1b7c5d
 

docs/config/lua/wezterm/add_to_config_reload_watch_list.md

@@ -7,5 +7,6 @@ If [automatically_reload_config](../config/automatically_reload_config.md)
 is enabled, then the config will be reloaded when any of the files
 that have been added to the watch list have changed.
 
-The intent of for this to be used together with a custom lua loader
-in a future iteration of wezterm.
+*Since: nightly builds only*
+
+This function is now called implicitly when you `require` a lua file.