Merge branch '8.x'

Author: GrahamCampbell

LazyCollection.php

@@ -5,6 +5,7 @@
 use ArrayIterator;
 use Closure;
 use DateTimeInterface;
+use Generator;
 use Illuminate\Support\Traits\EnumeratesValues;
 use Illuminate\Support\Traits\Macroable;
 use IteratorAggregate;
@@ -29,7 +30,7 @@ class LazyCollection implements Enumerable
      */
     public function __construct($source = null)
     {
-        if ($source instanceof Closure || $source instanceof self) {
+        if ($source instanceof Closure || $source instanceof Generator || $source instanceof self) {
             $this->source = $source;
         } elseif (is_null($source)) {
             $this->source = static::empty();
@@ -1364,6 +1365,10 @@ public function count()
      */
     protected function makeIterator($source)
     {
+        if ($source instanceof Generator) {
+            return $source;
+        }
+
         if ($source instanceof IteratorAggregate) {
             return $source->getIterator();
         }