diff --git a/.github/workflows/test-requirements-check.yml b/.github/workflows/test-requirements-check.yml
new file mode 100644
index 0000000000..db58a4e52d
--- /dev/null
+++ b/.github/workflows/test-requirements-check.yml
@@ -0,0 +1,210 @@
+name: Test requirements check
+
+on:
+  # Run on pushes to the main branches and on pull requests which touch files related to the requirements check.
+  # No need to run this workflow when there are only irrelevant changes.
+  push:
+    branches:
+      - 4.x
+    tags:
+      - '**'
+    paths:
+      - '.github/workflows/test-requirements-check.yml'
+      - '.github/workflows/reusable-build-phar.yml'
+      - 'bin/phpcs'
+      - 'bin/phpcbf'
+      - 'phpcs.xml.dist'
+      - 'requirements.php'
+      - 'scripts/**'
+  pull_request:
+    paths:
+      - '.github/workflows/test-requirements-check.yml'
+      - '.github/workflows/reusable-build-phar.yml'
+      - 'bin/phpcs'
+      - 'bin/phpcbf'
+      - 'phpcs.xml.dist'
+      - 'requirements.php'
+      - 'scripts/**'
+
+  # Allow manually triggering the workflow.
+  workflow_dispatch:
+
+# Cancels all previous workflow runs for the same branch that have not yet completed.
+concurrency:
+  # The concurrency group contains the workflow name and the branch name.
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  # Make sure that the files involved in the requirements check don't contain parse errors
+  # for the PHP versions supported by the requirements check to prevent the tests being run
+  # failing on the parse errors instead of on the requirements check
+  # (which would easily go unnoticed).
+  lint:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        php: ['5.3', '5.4', '5.5', '5.6', '7.0', '7.1']
+
+    name: "Lint: PHP ${{ matrix.php }}"
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Install PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php }}
+          coverage: none
+
+      - name: "Lint bin/phpcs"
+        run: php -l ./bin/phpcs
+
+      - name: "Lint bin/phpcbf"
+        run: php -l ./bin/phpcbf
+
+      - name: "Lint requirements.php"
+        run: php -l ./requirements.php
+
+  # The matrix for these tests should be the same for the "plain" file test as for the PHAR test.
+  # This matrix, however, is quite complex, making maintaining it manually pretty error prone.
+  # So this job uses a PHP script to generate the matrix based on a fixed set of variables.
+  #
+  # The resulting matrix contains builds which combine the following variables:
+  # - os: ubuntu / windows
+  # - cmd: phpcs / phpcbf
+  # - php: 7.2 (minimum PHP version for 4.x), latest and nightly with the required extensions (should pass the check).
+  # - php: 5.3 (minimum for the requirements check) and 7.1 with the required extension (should fail the PHP version check).
+  # - php: 7.2 (minimum PHP version for 4.x), latest and nightly WITHOUT required extensions (should fail the check for extensions).
+  #
+  # Each combination also contains a "expect" key to set the expectations for success / failure.
+  #
+  # The scripts involved in generating the matrix can be found in the `/scripts/` directory.
+  prepare-matrix:
+    needs: lint
+
+    name: Get test matrix
+    runs-on: ubuntu-latest
+
+    outputs:
+      matrix: ${{ steps.set-matrix.outputs.MATRIX }}
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Install PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: 'latest'
+          ini-values: 'error_reporting=-1, display_errors=On'
+          coverage: none
+
+      - name: Set matrix
+        id: set-matrix
+        run: echo "MATRIX=$(php scripts/get-requirements-check-matrix.php)" >> "$GITHUB_OUTPUT"
+
+      - name: "DEBUG: show generated matrix"
+        run: echo ${{ steps.set-matrix.outputs.MATRIX }}
+
+  # Test that the requirements check works correctly when using a Composer install or git clone of PHPCS.
+  test-plain:
+    needs: prepare-matrix
+
+    strategy:
+      fail-fast: false
+      matrix: ${{ fromJson(needs.prepare-matrix.outputs.MATRIX) }}
+
+    # yamllint disable-line rule:line-length
+    name: "Plain: ${{ matrix.cmd == 'phpcs' && 'cs' || 'cbf' }} / ${{ matrix.php }} / ${{ matrix.name }} (${{ matrix.os == 'ubuntu-latest' && 'nix' || 'Win' }})"
+
+    continue-on-error: ${{ matrix.php == 'nightly' }}
+
+    runs-on: ${{ matrix.os }}
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Install PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php }}
+          ini-values: 'error_reporting=-1, display_errors=On'
+          extensions: ${{ matrix.extensions }}
+          coverage: none
+        env:
+          fail-fast: true
+
+      # We're only testing the requirements check here, so we just need to verify that PHPCS/PHPCBF starts. Nothing more.
+      - name: Run the test
+        id: check
+        continue-on-error: true
+        run: php "bin/${{ matrix.cmd }}" --version
+
+      - name: Check the result of a successful test against expectation
+        if: ${{ steps.check.outcome == 'success' && matrix.expect == 'fail' }}
+        run: exit 1
+
+      - name: Check the result of a failed test against expectation
+        if: ${{ steps.check.outcome != 'success' && matrix.expect == 'success' }}
+        run: exit 1
+
+  build-phars:
+    needs: lint
+
+    name: "Build Phar on PHP 8.0"
+
+    uses: ./.github/workflows/reusable-build-phar.yml
+    with:
+      uploadArtifacts: true
+
+  # Test that the requirements check works correctly when using a PHPCS/PHPCBF PHAR file.
+  test-phar:
+    needs: [prepare-matrix, build-phars]
+
+    strategy:
+      fail-fast: false
+      matrix: ${{ fromJson(needs.prepare-matrix.outputs.MATRIX) }}
+
+    # yamllint disable-line rule:line-length
+    name: "PHAR: ${{ matrix.cmd == 'phpcs' && 'cs' || 'cbf' }} / ${{ matrix.php }} / ${{ matrix.name }} (${{ matrix.os == 'ubuntu-latest' && 'nix' || 'Win' }})"
+
+    continue-on-error: ${{ matrix.php == 'nightly' }}
+
+    runs-on: ${{ matrix.os }}
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Install PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php }}
+          ini-values: 'error_reporting=-1, display_errors=On'
+          extensions: ${{ matrix.extensions }}
+          coverage: none
+        env:
+          fail-fast: true
+
+      - name: Download the phar
+        uses: actions/download-artifact@v4
+        with:
+          name: ${{ matrix.cmd }}-phar
+
+      # We're only testing the requirements check here, so we just need to verify that PHPCS/PHPCBF starts. Nothing more.
+      - name: Run the test
+        id: check
+        continue-on-error: true
+        run: php ${{ matrix.cmd }}.phar --version
+
+      - name: Check the result of a successful test against expectation
+        if: ${{ steps.check.outcome == 'success' && matrix.expect == 'fail' }}
+        run: exit 1
+
+      - name: Check the result of a failed test against expectation
+        if: ${{ steps.check.outcome != 'success' && matrix.expect == 'success' }}
+        run: exit 1
diff --git a/bin/phpcbf b/bin/phpcbf
index c804bdf10e..95a872cd9c 100755
--- a/bin/phpcbf
+++ b/bin/phpcbf
@@ -3,12 +3,28 @@
 /**
  * PHP Code Beautifier and Fixer fixes violations of a defined coding standard.
  *
+ * :WARNING:
+ *   This file MUST stay cross-version compatible with older PHP versions (min: PHP 5.3) to allow
+ *   for the requirements check to work correctly.
+ *
+ *   The PHP 5.3 minimum is set as the previous PHPCS major (3.x) already had a PHP 5.4 minimum
+ *   requirement and didn't take parse errors caused due to the use of namespaces into account
+ *   in its requirements check, so running PHPCS 3.x on PHP < 5.3 would have failed with a parse
+ *   error already anyway, so PHP 5.3 seems reasonable to keep as the minimum for this.
+ * :WARNING:
+ *
  * @author    Greg Sherwood <gsherwood@squiz.net>
+ * @author    Juliette Reinders Folmer <phpcs_nospam@adviesenzo.nl>
  * @copyright 2006-2015 Squiz Pty Ltd (ABN 77 084 670 600)
+ * @copyright 2024 PHPCSStandards and contributors
  * @license   https://github.com/PHPCSStandards/PHP_CodeSniffer/blob/master/licence.txt BSD Licence
  */
 
-require_once __DIR__.'/../autoload.php';
+// Check if the PHP version and extensions comply with the minimum requirements before anything else.
+require_once dirname(__DIR__).'/requirements.php';
+PHP_CodeSniffer\checkRequirements();
+
+require_once dirname(__DIR__).'/autoload.php';
 
 $runner   = new PHP_CodeSniffer\Runner();
 $exitCode = $runner->runPHPCBF();
diff --git a/bin/phpcs b/bin/phpcs
index d098bf8783..fe3adaf58a 100755
--- a/bin/phpcs
+++ b/bin/phpcs
@@ -3,12 +3,28 @@
 /**
  * PHP_CodeSniffer detects violations of a defined coding standard.
  *
+ * :WARNING:
+ *   This file MUST stay cross-version compatible with older PHP versions (min: PHP 5.3) to allow
+ *   for the requirements check to work correctly.
+ *
+ *   The PHP 5.3 minimum is set as the previous PHPCS major (3.x) already had a PHP 5.4 minimum
+ *   requirement and didn't take parse errors caused due to the use of namespaces into account
+ *   in its requirements check, so running PHPCS 3.x on PHP < 5.3 would have failed with a parse
+ *   error already anyway, so PHP 5.3 seems reasonable to keep as the minimum for this.
+ * :WARNING:
+ *
  * @author    Greg Sherwood <gsherwood@squiz.net>
+ * @author    Juliette Reinders Folmer <phpcs_nospam@adviesenzo.nl>
  * @copyright 2006-2015 Squiz Pty Ltd (ABN 77 084 670 600)
+ * @copyright 2024 PHPCSStandards and contributors
  * @license   https://github.com/PHPCSStandards/PHP_CodeSniffer/blob/master/licence.txt BSD Licence
  */
 
-require_once __DIR__.'/../autoload.php';
+// Check if the PHP version and extensions comply with the minimum requirements before anything else.
+require_once dirname(__DIR__).'/requirements.php';
+PHP_CodeSniffer\checkRequirements();
+
+require_once dirname(__DIR__).'/autoload.php';
 
 $runner   = new PHP_CodeSniffer\Runner();
 $exitCode = $runner->runPHPCS();
diff --git a/phpcs.xml.dist b/phpcs.xml.dist
index 0fd2f38d0f..d7f885554c 100644
--- a/phpcs.xml.dist
+++ b/phpcs.xml.dist
@@ -3,6 +3,7 @@
     <description>The coding standard for PHP_CodeSniffer itself.</description>
 
     <file>autoload.php</file>
+    <file>requirements.php</file>
     <file>bin</file>
     <file>scripts</file>
     <file>src</file>
@@ -58,7 +59,11 @@
     <rule ref="Squiz.WhiteSpace.MemberVarSpacing"/>
     <rule ref="Squiz.WhiteSpace.OperatorSpacing"/>
     <rule ref="Squiz.WhiteSpace.SuperfluousWhitespace"/>
-    <rule ref="Generic.Arrays.DisallowLongArraySyntax"/>
+    <rule ref="Generic.Arrays.DisallowLongArraySyntax">
+        <!-- Files involved in the requirements check should stay compatible with PHP 5.3. -->
+        <exclude-pattern>bin/phpc(s|bf)$</exclude-pattern>
+        <exclude-pattern>requirements\.php$</exclude-pattern>
+    </rule>
     <rule ref="Generic.Commenting.Todo"/>
     <rule ref="Generic.ControlStructures.DisallowYodaConditions"/>
     <rule ref="Generic.ControlStructures.InlineControlStructure"/>
diff --git a/phpstan.neon.dist b/phpstan.neon.dist
index bdc3e983d3..4060a3800c 100644
--- a/phpstan.neon.dist
+++ b/phpstan.neon.dist
@@ -4,6 +4,7 @@ parameters:
         max: 80499
     level: 0
     paths:
+        - requirements.php
         - src
     bootstrapFiles:
         - tests/bootstrap.php
diff --git a/requirements.php b/requirements.php
new file mode 100644
index 0000000000..c15cd6524b
--- /dev/null
+++ b/requirements.php
@@ -0,0 +1,71 @@
+<?php
+/**
+ * Requirements check for PHP_CodeSniffer.
+ *
+ * :WARNING:
+ *   This file MUST stay cross-version compatible with older PHP versions (min: PHP 5.3) to allow
+ *   for the requirements check to work correctly.
+ *
+ *   The PHP 5.3 minimum is set as the previous PHPCS major (3.x) already had a PHP 5.4 minimum
+ *   requirement and didn't take parse errors caused due to the use of namespaces into account
+ *   in its requirements check, so running PHPCS 3.x on PHP < 5.3 would have failed with a parse
+ *   error already anyway, so PHP 5.3 seems reasonable to keep as the minimum for this.
+ * :WARNING:
+ *
+ * @author    Greg Sherwood <gsherwood@squiz.net>
+ * @author    Juliette Reinders Folmer <phpcs_nospam@adviesenzo.nl>
+ * @copyright 2006-2015 Squiz Pty Ltd (ABN 77 084 670 600)
+ * @copyright 2024 PHPCSStandards and contributors
+ * @license   https://github.com/PHPCSStandards/PHP_CodeSniffer/blob/master/licence.txt BSD Licence
+ */
+
+namespace PHP_CodeSniffer;
+
+
+/**
+ * Exits if the minimum requirements of PHP_CodeSniffer are not met.
+ *
+ * @return void
+ */
+function checkRequirements()
+{
+    $exitCode = 3;
+
+    // Check the PHP version.
+    if (PHP_VERSION_ID < 70200) {
+        echo 'ERROR: PHP_CodeSniffer requires PHP version 7.2.0 or greater.'.PHP_EOL;
+        exit($exitCode);
+    }
+
+    $requiredExtensions = array(
+        'tokenizer',
+        'xmlwriter',
+        'SimpleXML',
+    );
+    $missingExtensions  = array();
+
+    foreach ($requiredExtensions as $extension) {
+        if (extension_loaded($extension) === false) {
+            $missingExtensions[] = $extension;
+        }
+    }
+
+    if (empty($missingExtensions) === false) {
+        $last      = array_pop($requiredExtensions);
+        $required  = implode(', ', $requiredExtensions);
+        $required .= ' and '.$last;
+
+        if (count($missingExtensions) === 1) {
+            $missing = $missingExtensions[0];
+        } else {
+            $last     = array_pop($missingExtensions);
+            $missing  = implode(', ', $missingExtensions);
+            $missing .= ' and '.$last;
+        }
+
+        $error = 'ERROR: PHP_CodeSniffer requires the %s extensions to be enabled. Please enable %s.'.PHP_EOL;
+        printf($error, $required, $missing);
+        exit($exitCode);
+    }
+
+}//end checkRequirements()
diff --git a/scripts/BuildRequirementsCheckMatrix.php b/scripts/BuildRequirementsCheckMatrix.php
new file mode 100644
index 0000000000..f7b395a7f5
--- /dev/null
+++ b/scripts/BuildRequirementsCheckMatrix.php
@@ -0,0 +1,188 @@
+<?php
+/**
+ * Build a dynamic matrix for the requirements check workflow.
+ *
+ * This matrix is used in two different GH Actions jobs and would be excruciating
+ * (and pretty error-prone) to manually maintain, so better to generate it dynamically.
+ *
+ * @author    Juliette Reinders Folmer <phpcs_nospam@adviesenzo.nl>
+ * @copyright 2024 PHPCSStandards and contributors
+ * @license   https://github.com/PHPCSStandards/PHP_CodeSniffer/blob/master/licence.txt BSD Licence
+ */
+
+namespace PHP_CodeSniffer;
+
+class BuildRequirementsCheckMatrix
+{
+
+    /**
+     * Range of valid PHP versions against which select tests should run.
+     *
+     * @var array<string>
+     */
+    private $validPhp = [
+        '7.2',
+        'latest',
+        'nightly',
+    ];
+
+    /**
+     * Range of *in*valid PHP versions against which select tests should run.
+     *
+     * @var array<string>
+     */
+    private $invalidPhp = [
+        '5.3',
+        '7.1',
+    ];
+
+    /**
+     * The PHPCS commands with which the tests should run.
+     *
+     * @var array<string>
+     */
+    private $cmd = [
+        'phpcs',
+        'phpcbf',
+    ];
+
+    /**
+     * The operating systems against which the tests should run.
+     *
+     * @var array<string>
+     */
+    private $os = [
+        'ubuntu-latest',
+        'windows-latest',
+    ];
+
+
+    /**
+     * Get all the builds.
+     *
+     * @return array<array<string, string>>
+     */
+    public function getBuilds()
+    {
+        $builds = array_merge(
+            self::getValidBuilds(),
+            self::getInvalidPHPBuilds(),
+            self::getMissingExtensionsBuilds()
+        );
+
+        return $builds;
+
+    }//end getBuilds()
+
+
+    /**
+     * Get the builds for tests which should succeed.
+     *
+     * I.e. these build comply with the minimum requirements for PHPCS.
+     *
+     * @return array<array<string, string>>
+     */
+    private function getValidBuilds()
+    {
+        $extensions = ['minimal' => 'none, tokenizer, xmlwriter, SimpleXML'];
+
+        $builds = [];
+        foreach ($this->validPhp as $php) {
+            foreach ($this->cmd as $cmd) {
+                foreach ($extensions as $name => $exts) {
+                    foreach ($this->os as $os) {
+                        $builds[] = [
+                            'name'       => "✔ exts: $name",
+                            'os'         => $os,
+                            'cmd'        => $cmd,
+                            'php'        => $php,
+                            'extensions' => $exts,
+                            'expect'     => 'success',
+                        ];
+                    }
+                }
+            }
+        }
+
+        return $builds;
+
+    }//end getValidBuilds()
+
+
+    /**
+     * Get the builds for tests which should fail because the PHP version does not comply with the minimum PHP requirement.
+     *
+     * @return array<array<string, string>>
+     */
+    private function getInvalidPHPBuilds()
+    {
+        $extensions = ['default' => ''];
+
+        $builds = [];
+        foreach ($this->invalidPhp as $php) {
+            foreach ($this->cmd as $cmd) {
+                foreach ($extensions as $exts) {
+                    foreach ($this->os as $os) {
+                        $builds[] = [
+                            'name'       => '❌ PHP too low',
+                            'os'         => $os,
+                            'cmd'        => $cmd,
+                            'php'        => $php,
+                            'extensions' => $exts,
+                            'expect'     => 'fail',
+                        ];
+                    }
+                }
+            }
+        }
+
+        return $builds;
+
+    }//end getInvalidPHPBuilds()
+
+
+    /**
+     * Get the builds for tests which should fail because the PHP extensions do not comply with the requirements of PHPCS.
+     *
+     * @return array<array<string, string>>
+     */
+    private function getMissingExtensionsBuilds()
+    {
+        $extensions = [
+            'missing tokenizer'     => 'none, xmlwriter, SimpleXML',
+            'missing xmlwriter'     => ':xmlwriter',
+            'missing SimpleXML'     => ':SimpleXML',
+            'missing both XML exts' => 'none, tokenizer',
+        ];
+
+        $builds = [];
+        foreach ($this->validPhp as $php) {
+            foreach ($this->cmd as $cmd) {
+                foreach ($extensions as $name => $exts) {
+                    foreach ($this->os as $os) {
+                        // Skip the extension requirements check on Windows as the required extensions cannot be
+                        // disabled on Windows. They are compiled statically into the PHP binary.
+                        // {@link https://github.com/shivammathur/setup-php/issues/887}.
+                        if ($os === 'windows-latest') {
+                            continue;
+                        }
+
+                        $builds[] = [
+                            'name'       => "❌ $name",
+                            'os'         => $os,
+                            'cmd'        => $cmd,
+                            'php'        => $php,
+                            'extensions' => $exts,
+                            'expect'     => 'fail',
+                        ];
+                    }
+                }
+            }//end foreach
+        }//end foreach
+
+        return $builds;
+
+    }//end getMissingExtensionsBuilds()
+
+
+}//end class
diff --git a/scripts/build-phar.php b/scripts/build-phar.php
index 57bf3fd2d3..3d4aeeb251 100644
--- a/scripts/build-phar.php
+++ b/scripts/build-phar.php
@@ -138,6 +138,9 @@ function stripWhitespaceAndComments($fullpath, $config)
         ++$fileCount;
     }//end foreach
 
+    // Add requirements check.
+    $phar->addFromString('requirements.php', stripWhitespaceAndComments(realpath(__DIR__.'/../requirements.php'), $config));
+
     // Add autoloader.
     $phar->addFromString('autoload.php', stripWhitespaceAndComments(realpath(__DIR__.'/../autoload.php'), $config));
 
@@ -155,6 +158,8 @@ function stripWhitespaceAndComments($fullpath, $config)
     $stub  = '#!/usr/bin/env php'."\n";
     $stub .= '<?php'."\n";
     $stub .= 'Phar::mapPhar(\''.$pharName.'\');'."\n";
+    $stub .= 'require_once "phar://'.$pharName.'/requirements.php";'."\n";
+    $stub .= 'PHP_CodeSniffer\checkRequirements();'."\n";
     $stub .= 'require_once "phar://'.$pharName.'/autoload.php";'."\n";
     $stub .= '$runner = new PHP_CodeSniffer\Runner();'."\n";
     $stub .= '$exitCode = $runner->run'.$script.'();'."\n";
diff --git a/scripts/get-requirements-check-matrix.php b/scripts/get-requirements-check-matrix.php
new file mode 100644
index 0000000000..ea50ed5e47
--- /dev/null
+++ b/scripts/get-requirements-check-matrix.php
@@ -0,0 +1,18 @@
+#!/usr/bin/env php
+<?php
+/**
+ * Build a dynamic matrix for the requirements check workflow.
+ *
+ * This matrix is used in two different GH Actions jobs and would be excruciating
+ * (and pretty error-prone) to manually maintain, so better to generate it dynamically.
+ *
+ * @author    Juliette Reinders Folmer <phpcs_nospam@adviesenzo.nl>
+ * @copyright 2024 PHPCSStandards and contributors
+ * @license   https://github.com/PHPCSStandards/PHP_CodeSniffer/blob/master/licence.txt BSD Licence
+ */
+
+error_reporting(E_ALL);
+
+require_once __DIR__.'/BuildRequirementsCheckMatrix.php';
+
+echo json_encode(['include' => (new PHP_CodeSniffer\BuildRequirementsCheckMatrix())->getBuilds()]);
diff --git a/src/Runner.php b/src/Runner.php
index d527ea575e..88f0740a7e 100644
--- a/src/Runner.php
+++ b/src/Runner.php
@@ -61,7 +61,6 @@ public function runPHPCS()
 
         try {
             Timing::startTiming();
-            Runner::checkRequirements();
 
             if (defined('PHP_CODESNIFFER_CBF') === false) {
                 define('PHP_CODESNIFFER_CBF', false);
@@ -167,7 +166,6 @@ public function runPHPCBF()
 
         try {
             Timing::startTiming();
-            Runner::checkRequirements();
 
             // Creating the Config object populates it with all required settings
             // based on the CLI arguments provided to the script and any config
@@ -245,54 +243,6 @@ public function runPHPCBF()
     }//end runPHPCBF()
 
 
-    /**
-     * Exits if the minimum requirements of PHP_CodeSniffer are not met.
-     *
-     * @return void
-     * @throws \PHP_CodeSniffer\Exceptions\DeepExitException If the requirements are not met.
-     */
-    public function checkRequirements()
-    {
-        // Check the PHP version.
-        if (PHP_VERSION_ID < 50400) {
-            $error = 'ERROR: PHP_CodeSniffer requires PHP version 5.4.0 or greater.'.PHP_EOL;
-            throw new DeepExitException($error, 3);
-        }
-
-        $requiredExtensions = [
-            'tokenizer',
-            'xmlwriter',
-            'SimpleXML',
-        ];
-        $missingExtensions  = [];
-
-        foreach ($requiredExtensions as $extension) {
-            if (extension_loaded($extension) === false) {
-                $missingExtensions[] = $extension;
-            }
-        }
-
-        if (empty($missingExtensions) === false) {
-            $last      = array_pop($requiredExtensions);
-            $required  = implode(', ', $requiredExtensions);
-            $required .= ' and '.$last;
-
-            if (count($missingExtensions) === 1) {
-                $missing = $missingExtensions[0];
-            } else {
-                $last     = array_pop($missingExtensions);
-                $missing  = implode(', ', $missingExtensions);
-                $missing .= ' and '.$last;
-            }
-
-            $error = 'ERROR: PHP_CodeSniffer requires the %s extensions to be enabled. Please enable %s.'.PHP_EOL;
-            $error = sprintf($error, $required, $missing);
-            throw new DeepExitException($error, 3);
-        }
-
-    }//end checkRequirements()
-
-
     /**
      * Init the rulesets and other high-level settings.
      *