Introduce phpstan and start fixing problems

composer.json

@@ -9,7 +9,8 @@
     "require-dev": {
         "phpunit/phpunit": "4.*",
         "squizlabs/php_codesniffer": "^2.6",
-        "phpdocumentor/reflection-docblock": "2.*"
+        "phpdocumentor/reflection-docblock": "2.*",
+        "szepeviktor/phpstan-wordpress": "^0.5.0"
     },
     "license": "GPL-2.0+",
     "authors": [

phpstan.neon.dist

@@ -0,0 +1,14 @@
+includes:
+    - phar://phpstan.phar/conf/bleedingEdge.neon
+    - vendor/szepeviktor/phpstan-wordpress/extension.neon
+parameters:
+#    level: max
+    level: 4
+    inferPrivatePropertyTypeFromConstructor: true
+    autoload_files:
+        - tests/phpstan/acf-stubs-5.8.0.php
+    paths:
+        - src/
+    ignoreErrors:
+        # Should be possible using Generics: https://medium.com/@ondrejmirtes/generics-in-php-using-phpdocs-14e7301953
+        - '#^Method StoutLogic\\AcfBuilder\\Transform\\\w+::getBuilder\(\) should return StoutLogic\\AcfBuilder\\\w+Builder but returns StoutLogic\\AcfBuilder\\Builder\.$#'

src/FieldsBuilder.php

@@ -196,8 +196,9 @@ public function addChoiceField($name, $type, array $args = [])
 
     /**
      * Initialize the FieldBuilder, add to FieldManager
-     * @param  FieldBuilder $field
-     * @return FieldBuilder
+     * @template FB of FieldBuilder
+     * @param  FB $field
+     * @return FB
      */
     protected function initializeField($field)
     {

src/ModifyFieldReturnTypeException.php

@@ -11,7 +11,7 @@ class ModifyFieldReturnTypeException extends \UnexpectedValueException
     /**
      * @param string $returnedType
      * @param int $code
-     * @param \Exception|null
+     * @param \Exception|null $previous
      */
     public function __construct($returnedType, $code = 0, $previous = null)
     {

src/Transform/RecursiveTransform.php

@@ -47,7 +47,7 @@ public function transform($config)
     /**
      * Based upon the value or key, determine if the transform function
      * should recurse.
-     * @param $value
+     * @param mixed $value
      * @param string $key
      * @return bool
      */

src/Transform/Transform.php

@@ -6,25 +6,26 @@
 
 /**
  * A Transform that is applied to configuration array of a Builder
+ * @template B of Builder
  */
 abstract class Transform
 {
     /**
      * Used to call funtions on the builder.
-     * @var \StoutLogic\AcfBuilder\Builder
+     * @var B
      */
     private $builder;
 
     /**
-     * @param Builder $builder
+     * @param B $builder
      */
     public function __construct(Builder $builder)
     {
         $this->builder = $builder;
     }
 
     /**
-     * @return Builder
+     * @return B
      */
     public function getBuilder()
     {