Add stub for DatePeriod

src/Psalm/Internal/Analyzer/FunctionLikeAnalyzer.php

@@ -65,8 +65,6 @@
 use function array_merge;
 use function array_search;
 use function array_values;
-use function assert;
-use function class_exists;
 use function count;
 use function end;
 use function in_array;

stubs/CoreImmutableClasses.phpstub

@@ -16,6 +16,24 @@ class DateTimeZone
     public function __construct(string $timezone) {}
 }
 
+/**
+ * @psalm-immutable
+ *
+ * @template-covariant Start of string|DateTimeInterface
+ * @implements Traversable<int, DateTimeInterface>
+ */
+class DatePeriod implements Traversable
+{
+    const EXCLUDE_START_DATE = 1;
+    /**
+     * @param Start $start
+     * @param (Start is string ? 0|self::EXCLUDE_START_DATE : DateInterval) $interval
+     * @param (Start is string ? never : DateTimeInterface|positive-int) $end
+     * @param (Start is string ? never : 0|self::EXCLUDE_START_DATE) $options
+     */
+    public function __construct($start, $interval = 0, $end = 1, $options = 0) {}
+}
+
 /**
  * @psalm-taint-specialize
  */

stubs/Php80.phpstub

@@ -82,3 +82,24 @@ class ReflectionUnionType extends ReflectionType {
 }
 
 class UnhandledMatchError extends Error {}
+
+/**
+ * @psalm-immutable
+ *
+ * @template-covariant Start of string|DateTimeInterface
+ * @implements IteratorAggregate<int, DateTimeInterface>
+ */
+class DatePeriod implements IteratorAggregate
+{
+    const EXCLUDE_START_DATE = 1;
+    /**
+     * @param Start $start
+     * @param (Start is string ? 0|self::EXCLUDE_START_DATE : DateInterval) $interval
+     * @param (Start is string ? never : DateTimeInterface|positive-int) $end
+     * @param (Start is string ? never : 0|self::EXCLUDE_START_DATE) $options
+     */
+    public function __construct($start, $interval = 0, $end = 1, $options = 0) {}
+
+    /** @psalm-return (Start is string ? (Traversable<int, DateTime>&Iterator) : (Traversable<int, Start>&Iterator)) */
+    public function getIterator(): Iterator {}
+}

tests/CoreStubsTest.php

@@ -33,5 +33,76 @@ public function providerValidCodeParse(): iterable
             'error_levels' => [],
             'php_version' => '8.0',
         ];
+        yield 'Iterating over \DatePeriod (#5954) PHP7 Traversable' => [
+            '<?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' => 'DateTimeInterface|null'
+            ],
+            'error_levels' => [],
+            'php_version' => '7.3',
+        ];
+        yield 'Iterating over \DatePeriod (#5954) PHP8 IteratorAggregate' => [
+            '<?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'
+            ],
+            'error_levels' => [],
+            'php_version' => '8.0',
+        ];
+        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'
+            ],
+            'error_levels' => [],
+            'php_version' => '8.0',
+        ];
+        yield 'DatePeriod implements only Traversable on PHP 7' => [
+            '<?php
+
+            $period = new DatePeriod("R4/2012-07-01T00:00:00Z/P7D");
+            if ($period instanceof IteratorAggregate) {}',
+            'assertions' => [],
+            'error_levels' => [],
+            'php_version' => '7.3',
+        ];
+        yield 'DatePeriod implements IteratorAggregate on PHP 8' => [
+            '<?php
+
+            $period = new DatePeriod("R4/2012-07-01T00:00:00Z/P7D");
+            if ($period instanceof IteratorAggregate) {}',
+            'assertions' => [],
+            'error_levels' => ['RedundantCondition'],
+            'php_version' => '8.0',
+        ];
     }
 }