Add EmptyIterator stub

stubs/iterable.stub

@@ -436,3 +436,23 @@ class RegexIterator extends FilterIterator {
      */
     public function key() {}
 }
+
+/**
+ * @template-implements Iterator<never, never>
+ */
+class EmptyIterator implements Iterator {
+    /**
+     * @return never
+     */
+    public function current() {}
+
+    /**
+     * @return never
+     */
+    public function key() {}
+
+    /**
+     * @return false
+     */
+    public function valid() {}
+}

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -918,6 +918,7 @@ public function dataFileAsserts(): iterable
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-4117.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-7490.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/remember-possibly-impure-function-values.php');
+		yield from $this->gatherAssertTypes(__DIR__ . '/data/emptyiterator.php');
 	}
 
 	/**

tests/PHPStan/Analyser/data/emptyiterator.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace EmptyIteratorTest;
+
+use function PHPStan\Testing\assertType;
+
+class Foo
+{
+	public function doFoo(\EmptyIterator $it): void
+	{
+		assertType('EmptyIterator', $it);
+		assertType('*NEVER*', $it->key());
+		assertType('*NEVER*', $it->current());
+		assertType('void', $it->next());
+		assertType('false', $it->valid());
+	}
+
+}