Source

File: wp-admin/includes/comment.php

function edit_comment() {
	if ( ! current_user_can( 'edit_comment', (int) $_POST['comment_ID'] ) ) {
		wp_die( __( 'Sorry, you are not allowed to edit comments on this post.' ) );
	}

	if ( isset( $_POST['newcomment_author'] ) ) {
		$_POST['comment_author'] = $_POST['newcomment_author'];
	}
	if ( isset( $_POST['newcomment_author_email'] ) ) {
		$_POST['comment_author_email'] = $_POST['newcomment_author_email'];
	}
	if ( isset( $_POST['newcomment_author_url'] ) ) {
		$_POST['comment_author_url'] = $_POST['newcomment_author_url'];
	}
	if ( isset( $_POST['comment_status'] ) ) {
		$_POST['comment_approved'] = $_POST['comment_status'];
	}
	if ( isset( $_POST['content'] ) ) {
		$_POST['comment_content'] = $_POST['content'];
	}
	if ( isset( $_POST['comment_ID'] ) ) {
		$_POST['comment_ID'] = (int) $_POST['comment_ID'];
	}

	foreach ( array( 'aa', 'mm', 'jj', 'hh', 'mn' ) as $timeunit ) {
		if ( ! empty( $_POST[ 'hidden_' . $timeunit ] ) && $_POST[ 'hidden_' . $timeunit ] != $_POST[ $timeunit ] ) {
			$_POST['edit_date'] = '1';
			break;
		}
	}

	if ( ! empty( $_POST['edit_date'] ) ) {
		$aa = $_POST['aa'];
		$mm = $_POST['mm'];
		$jj = $_POST['jj'];
		$hh = $_POST['hh'];
		$mn = $_POST['mn'];
		$ss = $_POST['ss'];
		$jj = ( $jj > 31 ) ? 31 : $jj;
		$hh = ( $hh > 23 ) ? $hh - 24 : $hh;
		$mn = ( $mn > 59 ) ? $mn - 60 : $mn;
		$ss = ( $ss > 59 ) ? $ss - 60 : $ss;

		$_POST['comment_date'] = "$aa-$mm-$jj $hh:$mn:$ss";
	}

	return wp_update_comment( $_POST, true );
}