Accept WTFPL as a GPL-compatible license

includes/Traits/License_Utils.php

@@ -56,6 +56,10 @@ protected function get_normalized_license( $license ) {
 		$license = preg_replace( '/GPL\s*[-|\.]*\s*[v]?([0-9])(\.[0])?/i', 'GPL$1', $license, 1 );
 		$license = preg_replace( '/Apache.*?([0-9])(\.[0])?/i', 'Apache$1', $license );
 		$license = preg_replace( '/(The\s+)?Unlicense/i', 'Unlicense', $license );
+		// Normalize WTFPL variations - must come before version removal to catch full text.
+		$license = preg_replace( '/Do\s+What\s+The\s+F[^\s]*\s+You\s+Want\s+To\s+Public\s+License/i', 'WTFPL', $license );
+		// Remove version numbers from WTFPL (e.g., "WTFPL v2" -> "WTFPL").
+		$license = preg_replace( '/WTFPL\s*[v]?([0-9])/i', 'WTFPL', $license );
 		$license = str_replace( '.', '', $license );
 
 		return $license;
@@ -84,7 +88,13 @@ protected function is_license_valid_identifier( $license ) {
 	 * @return bool true if the license is GPL compatible, otherwise false.
 	 */
 	protected function is_license_gpl_compatible( $license ) {
-		$match = preg_match( '/GPL|GNU|MIT|FreeBSD|New BSD|BSD-3-Clause|BSD 3 Clause|OpenLDAP|Expat|Apache2|MPL20|ISC|CC0|Unlicense/im', $license );
+		// Check for WTFPL in full text form before normalization.
+		$wtfpl_match = preg_match( '/Do\s+What\s+The\s+F[^\s]*\s+You\s+Want\s+To\s+Public\s+License/i', $license );
+		if ( $wtfpl_match ) {
+			return true;
+		}
+
+		$match = preg_match( '/GPL|GNU|MIT|FreeBSD|New BSD|BSD-3-Clause|BSD 3 Clause|OpenLDAP|Expat|Apache2|MPL20|ISC|CC0|Unlicense|WTFPL/im', $license );
 
 		return ( false === $match || 0 === $match ) ? false : true;
 	}

tests/phpunit/testdata/plugins/test-plugin-wtfpl-license/load.php

@@ -0,0 +1,12 @@
+<?php
+/**
+ * Plugin Name: Test Plugin with WTFPL License
+ * Plugin URI:  https://wordpress.org/plugins/test-plugin/
+ * Description: Test plugin for WTFPL license validation.
+ * Version:     1.0.0
+ * Author:      plugin-check
+ * Author URI:  https://wordpress.org/plugins/test-plugin/
+ * License:     WTFPL
+ * License URI: http://www.wtfpl.net/
+ * Text Domain: test-plugin
+ */

tests/phpunit/tests/Checker/Checks/Plugin_Header_Fields_Check_Tests.php

@@ -128,6 +128,25 @@ public function test_run_with_invalid_mpl1_license() {
 		$this->assertCount( 1, wp_list_filter( $errors['load.php'][0][0], array( 'code' => 'plugin_header_invalid_license' ) ) );
 	}
 
+	public function test_run_with_valid_wtfpl_license() {
+		$check         = new Plugin_Header_Fields_Check();
+		$check_context = new Check_Context( UNIT_TESTS_PLUGIN_DIR . 'test-plugin-wtfpl-license/load.php' );
+		$check_result  = new Check_Result( $check_context );
+
+		$check->run( $check_result );
+
+		$errors = $check_result->get_errors();
+
+		// Should not have invalid license error for WTFPL.
+		if ( isset( $errors['load.php'] ) && isset( $errors['load.php'][0][0] ) ) {
+			$invalid_license_errors = wp_list_filter( $errors['load.php'][0][0], array( 'code' => 'plugin_header_invalid_license' ) );
+			$this->assertEmpty( $invalid_license_errors, 'WTFPL license should be recognized as GPL-compatible' );
+		} else {
+			// If no errors at all, that's also fine - the license is valid.
+			$this->assertTrue( true );
+		}
+	}
+
 	public function test_run_with_invalid_header_fields() {
 		$check         = new Plugin_Header_Fields_Check();
 		$check_context = new Check_Context( UNIT_TESTS_PLUGIN_DIR . 'test-plugin-late-escaping-errors/load.php' );

tests/phpunit/tests/Traits/License_Utils_Tests.php

@@ -78,6 +78,11 @@ public function data_licenses_for_normalization() {
 
 			array( 'The Unlicense', 'Unlicense' ),
 			array( 'Unlicense', 'Unlicense' ),
+
+			array( 'WTFPL', 'WTFPL' ),
+			array( 'WTFPL v2', 'WTFPL' ),
+			array( 'Do What The F*ck You Want To Public License', 'WTFPL' ),
+			array( 'Do What The Fuck You Want To Public License', 'WTFPL' ),
 		);
 	}
 
@@ -120,6 +125,10 @@ public function data_license_gpl_compatibility() {
 			array( 'CC0 1.0 Universal', true ),
 			array( 'The Unlicense', true ),
 			array( 'Unlicense', true ),
+			array( 'WTFPL', true ),
+			array( 'WTFPL v2', true ),
+			array( 'Do What The F*ck You Want To Public License', true ),
+			array( 'Do What The Fuck You Want To Public License', true ),
 
 			array( 'EPL', false ),
 			array( 'EUPL', false ),