wp-includes/deprecated.php:3522Private function to modify the current template when previewing a theme
stringfunction _preview_theme_template_filter() { _deprecated_function( __FUNCTION__, '4.3.0' ); return '';}Introduced in 2.9.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/deprecated.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.