ACF acf_the_content Filter Causes Fatal Error When convert_smilies is Disabled in Theme

[invocation97]

Describe the bug

The convert_smilies filter in ACF’s acf_the_content hook causes a fatal error when a count() function is called on a non-countable variable. This happens because convert_smilies attempts to count an array or object that sometimes returns as false. This issue occurs even if convert_smilies is disabled at the theme level.

To Reproduce

Steps to reproduce the behavior:

Add ACF fields with content processed by the acf_the_content filter.
Disable the convert_smilies filter in the theme by adding remove_filter( 'the_content', 'convert_smilies' ); to functions.php.
View any post or page where acf_the_content is called, and observe the PHP fatal error related to count() in convert_smilies.
Expected behavior
ACF should respect the filter removal applied by the theme, or the add_filters function should verify if filters like convert_smilies are already disabled before adding them to acf_the_content. This would prevent fatal errors when filters are already removed or unnecessary.

Error caused:

PHP Fatal error:  Uncaught TypeError: count(): Argument #1 ($value) must be of type Countable|array, bool given in /var/www/html/wp-includes/formatting.php:3495
Stack trace:
#0 /var/www/html/wp-includes/class-wp-hook.php(324): convert_smilies()
#1 /var/www/html/wp-includes/plugin.php(205): WP_Hook->apply_filters()
#2 /var/www/html/wp-includes/post-template.php(256): apply_filters()
#3 /var/www/html/wp-content/themes/healingWaves/single.php(116): the_content()
#4 /var/www/html/wp-includes/template-loader.php(106): include('...')
#5 /var/www/html/wp-blog-header.php(19): require_once('...')
#6 /var/www/html/index.php(17): require('...')
#7 {main}
  thrown in /var/www/html/wp-includes/formatting.php on line 3495

Screenshots or Video

Not applicable, as the issue results in a fatal error.

Code

function add_filters() {
    add_filter( 'acf_the_content', 'capital_P_dangit', 11 );
    add_filter( 'acf_the_content', 'wptexturize' );
    add_filter( 'acf_the_content', 'convert_smilies', 20 );
    add_filter( 'acf_the_content', 'wpautop' );
    add_filter( 'acf_the_content', 'shortcode_unautop' );
    add_filter( 'acf_the_content', 'do_shortcode', 11 );

    if ( isset( $GLOBALS['wp_embed'] ) ) {
        add_filter( 'acf_the_content', array( $GLOBALS['wp_embed'], 'run_shortcode' ), 8 );
        add_filter( 'acf_the_content', array( $GLOBALS['wp_embed'], 'autoembed' ), 8 );
    }
}

Proposed solution

function add_filters() {
    // Determine the correct image tag filter for compatibility
    $wp_filter_content_tags = function_exists('wp_filter_content_tags') ? 'wp_filter_content_tags' : 'wp_make_content_images_responsive';

    // Mimic filters added to "the_content" in "wp-includes/default-filters.php"
    add_filter('acf_the_content', 'capital_P_dangit', 11);

    // Apply wptexturize if it’s available and not disabled in theme settings
    if (function_exists('wptexturize') && !has_filter('acf_the_content', 'wptexturize')) {
        add_filter('acf_the_content', 'wptexturize');
    }

    // Conditionally add convert_smilies only if it’s not disabled in theme settings
    if (function_exists('convert_smilies') && !has_filter('acf_the_content', 'convert_smilies')) {
        add_filter('acf_the_content', 'convert_smilies', 20);
    }

    // Add wpautop, shortcode_unautop, and other filters with similar checks
    if (function_exists('wpautop') && !has_filter('acf_the_content', 'wpautop')) {
        add_filter('acf_the_content', 'wpautop');
    }
    
    if (function_exists('shortcode_unautop') && !has_filter('acf_the_content', 'shortcode_unautop')) {
        add_filter('acf_the_content', 'shortcode_unautop');
    }

    // Apply the image tag filter if defined
    if (!has_filter('acf_the_content', $wp_filter_content_tags)) {
        add_filter('acf_the_content', $wp_filter_content_tags);
    }

    // Add do_shortcode for executing shortcodes in ACF content
    if (function_exists('do_shortcode') && !has_filter('acf_the_content', 'do_shortcode')) {
        add_filter('acf_the_content', 'do_shortcode', 11);
    }

    // Embed support checks
    if (isset($GLOBALS['wp_embed'])) {
        add_filter('acf_the_content', array($GLOBALS['wp_embed'], 'run_shortcode'), 8);
        add_filter('acf_the_content', array($GLOBALS['wp_embed'], 'autoembed'), 8);
    }
}

Version Information:

• WordPress Version: 6.6.2
• PHP Version: 8.1.23
• ACF Version: ACF PRO 6.3.9
• Browser: N/A (server-side error)

Additional context

The convert_smilies filter can cause fatal errors if it’s enabled by ACF but explicitly disabled by the theme, as it attempts to count() a non-countable value. A suggested fix is to add conditional checks in add_filters to respect removed filters and check their availability before adding them to acf_the_content.