Remove support for mixed format capabilities.

src/wp-includes/capabilities.php

@@ -1021,11 +1021,14 @@ function get_role( $role ) {
  * Adds a role, if it does not exist.
  *
  * @since 2.0.0
+ * @since x.y.z Support an array of strings for the capabilities array.
  *
  * @param string $role         Role name.
  * @param string $display_name Display name for role.
- * @param bool[] $capabilities List of capabilities keyed by the capability name,
+ * @param bool[]|string[] $capabilities List of capabilities keyed by the capability name,
  *                             e.g. array( 'edit_posts' => true, 'delete_posts' => false ).
+ *                             Also supports an array of capabilities assumed to be granted.
+ *
  * @return WP_Role|void WP_Role object, if the role is added.
  */
 function add_role( $role, $display_name, $capabilities = array() ) {

src/wp-includes/class-wp-roles.php

@@ -147,24 +147,24 @@ public function reinit() {
 	 * To explicitly deny the role a capability, set the value for that capability to false.
 	 *
 	 * @since 2.0.0
+	 * @since x.y.z Support an array of strings for the capabilities array.
 	 *
 	 * @param string $role         Role name.
 	 * @param string $display_name Role display name.
-	 * @param bool[] $capabilities Optional. List of capabilities keyed by the capability name,
-	 *                             e.g. `array( 'edit_posts' => true, 'delete_posts' => false )`.
+	 * @param bool[]|string[] $capabilities List of capabilities keyed by the capability name,
+	 *                             e.g. array( 'edit_posts' => true, 'delete_posts' => false ).
+	 *                             Also supports an array of capabilities assumed to be granted.
 	 *                             Default empty array.
+	 *
 	 * @return WP_Role|void WP_Role object, if the role is added.
 	 */
 	public function add_role( $role, $display_name, $capabilities = array() ) {
 		if ( empty( $role ) || isset( $this->roles[ $role ] ) ) {
 			return;
 		}
 
-		foreach ( $capabilities as $key => $value ) {
-			if ( ! is_bool( $value ) ) {
-				$capabilities[ $value ] = true;
-				unset( $capabilities[ $key ] );
-			}
+		if ( wp_is_numeric_array( $capabilities ) ) {
+			$capabilities = array_fill_keys( $capabilities, true );
 		}
 
 		$this->roles[ $role ] = array(

tests/phpunit/tests/user/capabilities.php

@@ -1001,7 +1001,6 @@ public function test_add_role_with_single_level_capabilities() {
 			'Janitor',
 			array(
 				'level_1',
-				'sweep_floors' => false,
 			)
 		);
 		$this->flush_roles();
@@ -1011,7 +1010,6 @@ public function test_add_role_with_single_level_capabilities() {
 		$user = new WP_User( $id );
 
 		$this->assertTrue( $user->has_cap( 'level_1' ) );
-		$this->assertFalse( $user->has_cap( 'sweep_floors' ) );
 	}
 
 	/**