functions.php

<?php

/* ... */

function list_hooks( $hook = '' ) {
    global $wp_filter;
    if ( isset( $wp_filter[$hook]->callbacks ) ) {
        array_walk( $wp_filter[$hook]->callbacks, function( $callbacks, $priority ) use ( &$hooks ) {
            foreach ( $callbacks as $id => $callback )
                $hooks[] = array_merge( [ 'id' => $id, 'priority' => $priority ], $callback );
        });
    } else {
        return [];
    }
    foreach( $hooks as &$item ) {
        if ( !is_callable( $item['function'] ) ) continue;
        if ( is_string( $item['function'] ) ) {
            $ref = strpos( $item['function'], '::' ) ? new ReflectionClass( strstr( $item['function'], '::', true ) ) : new ReflectionFunction( $item['function'] );
            $item['file'] = $ref->getFileName();
            $item['line'] = get_class( $ref ) == 'ReflectionFunction'
                ? $ref->getStartLine()
                : $ref->getMethod( substr( $item['function'], strpos( $item['function'], '::' ) + 2 ) )->getStartLine();
        } elseif ( is_array( $item['function'] ) ) {
            $ref = new ReflectionClass( $item['function'][0] );
            $item['function'] = array(
                is_object( $item['function'][0] ) ? get_class( $item['function'][0] ) : $item['function'][0],
                $item['function'][1]
            );
            $item['file'] = $ref->getFileName();
            $item['line'] = strpos( $item['function'][1], '::' )
                ? $ref->getParentClass()->getMethod( substr( $item['function'][1], strpos( $item['function'][1], '::' ) + 2 ) )->getStartLine()
                : $ref->getMethod( $item['function'][1] )->getStartLine();
        } elseif ( is_callable( $item['function'] ) ) {
            $ref = new ReflectionFunction( $item['function'] );
            $item['function'] = get_class( $item['function'] );
            $item['file'] = $ref->getFileName();
            $item['line'] = $ref->getStartLine();
        }
    }
    return $hooks;
}

print_r( list_hooks( 'wp_login' ) );