wp_login_form() ignoring login_form action hook

Question

I have created a custom login page that uses wp_login_form() to create the login form:

<div class="login-form">
  <?php
    wp_login_form( array(
        'remember' => false,
        'label_username' => '',
        'label_password' => ''
      )
    );
  ?>
</div>

I tried to add a simple message to the login form using the default example from the WordPress Codex page about the login form action hook, like this:

add_action( 'login_form', function(){

    //Adding the text

    ?>
    <p>You can type a little note to those logging in here.</p>

    <?php
});

I literally copy-pasted the last code snippet from the Codex into my custom themes functions.php, to test if it's working.

Now, when I open my custom login page, the text does not appear, but when I open the default login page, the text does appear.

So, does wp_login_form() simply not use the login_form action hook or am I missing something?

Answer 1

Yeah, it would appear, by taking a quick look at wp-login.php that it indeed does not tie to the actual form, but is run separately outside of the wp_login_form() function.

Lines 914-919 of wp-login.php

/**
 * Fires following the 'Password' field in the login form.
 *
 * @since 2.1.0
 */
do_action( 'login_form' )

Answer 2

In order for it to work the action function should be using the "echo" statement:

add_action('login_form', function () {
    echo "<p>You can type a little note to those logging in here.</p>";
});