In fedora, the installation fails

[danlopz]

Changed current directory to /home/dan/.config/composer
Using version ^0.4.2 for gbere/gb-cli
./composer.json has been created
Loading composer repositories with package information
Updating dependencies (including require-dev)
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - symfony/framework-bundle v4.0.9 requires ext-xml * -> the requested PHP extension xml is missing from your system.
    - symfony/framework-bundle v4.0.8 requires ext-xml * -> the requested PHP extension xml is missing from your system.
    - symfony/framework-bundle v4.0.7 requires ext-xml * -> the requested PHP extension xml is missing from your system.
    - symfony/framework-bundle v4.0.6 requires ext-xml * -> the requested PHP extension xml is missing from your system.
    - symfony/framework-bundle v4.0.5 requires ext-xml * -> the requested PHP extension xml is missing from your system.
    - symfony/framework-bundle v4.0.4 requires ext-xml * -> the requested PHP extension xml is missing from your system.
    - symfony/framework-bundle v4.0.3 requires ext-xml * -> the requested PHP extension xml is missing from your system.
    - symfony/framework-bundle v4.0.2 requires ext-xml * -> the requested PHP extension xml is missing from your system.
    - symfony/framework-bundle v4.0.10 requires ext-xml * -> the requested PHP extension xml is missing from your system.
    - symfony/framework-bundle v4.0.1 requires ext-xml * -> the requested PHP extension xml is missing from your system.
    - symfony/framework-bundle v4.0.0 requires ext-xml * -> the requested PHP extension xml is missing from your system.
    - gbere/gb-cli v0.4.2 requires symfony/framework-bundle ^4.0 -> satisfiable by symfony/framework-bundle[v4.0.0, v4.0.1, v4.0.10, v4.0.2, v4.0.3, v4.0.4, v4.0.5, v4.0.6, v4.0.7, v4.0.8, v4.0.9].
    - Installation request for gbere/gb-cli ^0.4.2 -> satisfiable by gbere/gb-cli[v0.4.2].

  To enable extensions, verify that they are enabled in your .ini files:
    - /etc/php.ini
    - /etc/php.d/20-bz2.ini
    - /etc/php.d/20-calendar.ini
    - /etc/php.d/20-ctype.ini
    - /etc/php.d/20-curl.ini
    - /etc/php.d/20-exif.ini
    - /etc/php.d/20-fileinfo.ini
    - /etc/php.d/20-ftp.ini
    - /etc/php.d/20-gettext.ini
    - /etc/php.d/20-iconv.ini
    - /etc/php.d/20-json.ini
    - /etc/php.d/20-phar.ini
    - /etc/php.d/20-sockets.ini
    - /etc/php.d/20-tokenizer.ini
  You can also run `php --ini` inside terminal to see which files are used by PHP in CLI mode.

Installation failed, deleting ./composer.json.