Add stub for DatePeriod

stubs/CoreImmutableClasses.phpstub

@@ -16,6 +16,27 @@ class DateTimeZone
     public function __construct(string $timezone) {}
 }
 
+/**
+ * @psalm-immutable
+ *
+ * @template-covariant From of string|DateTimeInterface
+ * @implements IteratorAggregate<int, DateTimeInterface>
+ */
+class DatePeriod implements IteratorAggregate
+{
+    const EXCLUDE_START_DATE = 1;
+    /**
+     * @param From $from
+     * @param (From is string ? 0|self::EXCLUDE_START_DATE : DateInterval) $interval_or_options
+     * @param (From is string ? never : DateTimeInterface|positive-int) $end_or_recurrences
+     * @param (From is string ? never : 0|self::EXCLUDE_START_DATE) $options
+     */
+    public function __construct($from, $interval_or_options = 0, $end_or_recurrences = 1, $options = 0) {}
+
+    /** @psalm-return (From is string ? (Traversable<int, DateTime>&Iterator) : (Traversable<int, From>&Iterator)) */
+    public function getIterator(): Iterator {}
+}
+
 /**
  * @psalm-taint-specialize
  */

tests/CoreStubsTest.php

@@ -33,5 +33,35 @@ public function providerValidCodeParse(): iterable
             'error_levels' => [],
             'php_version' => '8.0',
         ];
+        yield 'Iterating over \DatePeriod (#5954)' => [
+            '<?php
+
+            $period = new DatePeriod(
+                new DateTimeImmutable("now"),
+                DateInterval::createFromDateString("1 day"),
+                new DateTime("+1 week")
+            );
+            $dt = null;
+            foreach ($period as $dt) {
+                echo $dt->format("Y-m-d");
+            }',
+            'assertions' => [
+                '$period' => 'DatePeriod<DateTimeImmutable>',
+                '$dt' => 'DateTimeImmutable|null'
+            ],
+        ];
+        yield 'Iterating over \DatePeriod (#5954), ISO string' => [
+            '<?php
+
+            $period = new DatePeriod("R4/2012-07-01T00:00:00Z/P7D");
+            $dt = null;
+            foreach ($period as $dt) {
+                echo $dt->format("Y-m-d");
+            }',
+            'assertions' => [
+                '$period' => 'DatePeriod<string>',
+                '$dt' => 'DateTime|null'
+            ],
+        ];
     }
 }