wp-includes/rewrite.php:278Removes rewrite rules and then recreate rewrite rules.
$hardbooloptionaltruefunction flush_rewrite_rules( $hard = true ) { global $wp_rewrite; if ( is_callable( array( $wp_rewrite, 'flush_rules' ) ) ) { $wp_rewrite->flush_rules( $hard ); }}Introduced in 3.0.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/rewrite.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.