Added array_key_first and array_key_last stubs (#2381)

src/Psalm/Internal/Stubs/CoreGenericFunctions.php

@@ -114,6 +114,32 @@ function key($arr)
 {
 }
 
+/**
+ * @psalm-template TKey as array-key
+ *
+ * @param array<TKey, mixed> $arr
+ *
+ * @return TKey|null
+ * @psalm-ignore-nullable-return
+ * @psalm-pure
+ */
+function array_key_first($arr)
+{
+}
+
+/**
+ * @psalm-template TKey as array-key
+ *
+ * @param array<TKey, mixed> $arr
+ *
+ * @return TKey|null
+ * @psalm-ignore-nullable-return
+ * @psalm-pure
+ */
+function array_key_last($arr)
+{
+}
+
 /**
  * @psalm-template T
  *

tests/FunctionCallTest.php

@@ -1022,6 +1022,26 @@ class FunctionCallTest extends TestCase
                     '$c' => 'int',
                 ],
             ],
+            'array_key_first' => [
+                '<?php
+                    $a = ["one" => 1, "two" => 3];
+                    $b = array_key_first($a);
+                    $c = $a[$b];',
+                'assertions' => [
+                    '$b' => 'null|string',
+                    '$c' => 'int',
+                ],
+            ],
+            'array_key_last' => [
+                '<?php
+                    $a = ["one" => 1, "two" => 3];
+                    $b = array_key_last($a);
+                    $c = $a[$b];',
+                'assertions' => [
+                    '$b' => 'null|string',
+                    '$c' => 'int',
+                ],
+            ],
             'explode' => [
                 '<?php
                     /** @var string $string */