wp-includes/formatting.php:808Newline preservation help function for wpautop().
$matchesarraystringfunction _autop_newline_preservation_helper( $matches ) { return str_replace( "\n", '<WPPreserveNewline />', $matches[0] );}Introduced in 3.1.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/formatting.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.