fix closure for static method array callables

src/functions.php

@@ -41,13 +41,14 @@ function closure($callable)
 
         case is_array($callable):
             list($object, $method) = $callable;
-            $reflection = new \ReflectionObject($object);
-            $method     = $reflection->getMethod($method);
+            // A static method ([Foo::class, 'method']) is given by its class name, not an object.
+            $class  = is_string($object) ? $object : get_class($object);
+            $method = new \ReflectionMethod($object, $method);
 
             if (!$method->isPublic()) {
                 $backtrace = debug_backtrace();
                 foreach ($backtrace as $trace) {
-                    if (isset($trace['class']) && $trace['class'] === $reflection->name) {
+                    if (isset($trace['class']) && $trace['class'] === $class) {
                         break;
                     }
 
@@ -58,7 +59,7 @@ function closure($callable)
                 }
             }
 
-            return $method->getClosure($object);
+            return $method->getClosure(is_string($object) ? null : $object);
 
         default:
             return \Closure::fromCallable($callable);

tests/Collections/TransformsTest.php

@@ -62,6 +62,11 @@ class TransformsTest extends \PHPUnit\Framework\TestCase
         $this->assertSeq(['x:1', 'y:2'], c\map(fn ($v, $k) => "$k:$v")(self::gen(['x' => 1, 'y' => 2])));
     }
 
+    public function testMapWithStaticMethodArrayCallable()
+    {
+        $this->assertSame(['a' => 2, 'b' => 4], c\map([TransformsTestHelper::class, 'double'])(['a' => 1, 'b' => 2]));
+    }
+
     public function testMapOnSetFollowsSetMap()
     {
         $result = c\map(fn ($v) => $v % 2)(new Set([1, 2, 3]));
@@ -418,3 +423,11 @@ class TransformsTest extends \PHPUnit\Framework\TestCase
         }
     }
 }
+
+class TransformsTestHelper
+{
+    public static function double(int $value): int
+    {
+        return $value * 2;
+    }
+}

tests/ReferencingTest.php

@@ -28,10 +28,20 @@ class TestObject
     {
         return ref([$this, 'priv']);
     }
+
+    public static function twice($x)
+    {
+        return $x * 2;
+    }
 }
 
 class ReferencingTest extends \PHPUnit\Framework\TestCase
 {
+    public function testReferenceStaticMethodArrayCallable()
+    {
+        $this->assertSame(4, ref([TestObject::class, 'twice'])(2));
+    }
+
     public function testReferenceClosure()
     {
         $f = function () { };