Add MissingClosureParameterTypehintRule (#18)

* Add MissingClosureParameterTypehintRule

* Fix 7.1 compatibility

README.md

@@ -36,6 +36,8 @@ but don't use the result; likely an error of the transition from mutable DateTim
 1. `SlamPhpStan\SymfonyProcessRule`: forbid calls to raw system functions well wrapped by
 [`symfony/process`](https://github.com/symfony/process) component
 1. `SlamPhpStan\UnusedVariableRule`: check for variable inside functions never used after initial assignment
+1. `SlamPhpStan\MissingClosureParameterTypehintRule`: requires parameter typehints for closures; WARNING: no PhpDoc
+allowed, see [`phpstan/phpstan-strict-rules#87`](https://github.com/phpstan/phpstan-strict-rules/issues/87)
 1. `SlamPhpStan\StringToClassRule`: requires strings that refer to classes to be expressed with `::class` notation
 1. `SlamPhpStan\GotoRule`: no goto allowed
 1. `SlamPhpStan\ClassNotationRule`:

conf/slam-rules.neon

@@ -31,3 +31,7 @@ services:
         class: SlamPhpStan\SymfonyProcessRule
         tags:
             - phpstan.rules.rule
+    -
+        class: SlamPhpStan\MissingClosureParameterTypehintRule
+        tags:
+            - phpstan.rules.rule

lib/MissingClosureParameterTypehintRule.php

@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SlamPhpStan;
+
+use PhpParser\Node;
+use PHPStan\Analyser\Scope;
+use PHPStan\Rules\Rule;
+
+final class MissingClosureParameterTypehintRule implements Rule
+{
+    public function getNodeType(): string
+    {
+        return \PhpParser\Node\Expr\Closure::class;
+    }
+
+    /**
+     * @param \PhpParser\Node\Expr\Closure $node
+     *
+     * @return string[] errors
+     */
+    public function processNode(Node $node, Scope $scope): array
+    {
+        $messages = [];
+
+        foreach ($node->params as $index => $param) {
+            if (null !== $param->type || ! $param->var instanceof Node\Expr\Variable || ! \is_string($param->var->name)) {
+                continue;
+            }
+
+            $messages[] = \sprintf('Parameter #%d $%s of anonymous function has no typehint.', 1 + $index, $param->var->name);
+        }
+
+        return $messages;
+    }
+}

tests/MissingClosureParameterTypehintRuleTest.php

@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SlamPhpStan\Tests;
+
+use PHPStan\Rules\Rule;
+use PHPStan\Testing\RuleTestCase;
+use SlamPhpStan\MissingClosureParameterTypehintRule;
+
+/**
+ * @covers \SlamPhpStan\MissingClosureParameterTypehintRule
+ */
+final class MissingClosureParameterTypehintRuleTest extends RuleTestCase
+{
+    protected function getRule(): Rule
+    {
+        return new MissingClosureParameterTypehintRule();
+    }
+
+    public function testClassConstant()
+    {
+        $this->analyse(
+            [
+                __DIR__ . '/TestAsset/MissingClosureParameterTypehintRule/fixture.php',
+            ],
+            [
+                [
+                    'Parameter #1 $class of anonymous function has no typehint.',
+                    7,
+                ],
+                [
+                    'Parameter #2 $int of anonymous function has no typehint.',
+                    8,
+                ],
+            ]
+        );
+    }
+}

tests/TestAsset/MissingClosureParameterTypehintRule/fixture.php

@@ -0,0 +1,10 @@
+<?php
+
+namespace SlamPhpStan\Tests\TestAsset\MissingClosureParameterTypehintRule;
+
+function foo($ref) {}
+
+$foo1 = function ($class) {};
+$foo2 = function (array $array, $int = null) {};
+$foo3 = function (\stdClass $class) {};
+$foo4 = function (?int $int) {};