wp-includes/l10n/class-wp-translation-controller.php:87Sets the current locale.
$localestring public function set_locale( string $locale ) { $this->current_locale = $locale; }Introduced in 6.5.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/l10n/class-wp-translation-controller.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.