Use TIterator as RegexIterator constructor param type to enable full generic inference

Change @param from Iterator<TKey, TValue> to TIterator in RegexIterator's
constructor stub, matching the pattern already used by IteratorIterator.
This allows PHPStan to infer TIterator from the actual argument type
(e.g. FilesystemIterator) rather than falling back to the bound
Traversable<TKey, TValue>.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: phpstan-bot

stubs/iterable.stub

@@ -440,7 +440,7 @@ class RegexIterator extends FilterIterator {
     const USE_KEY = 1 ;
 
     /**
-     * @param Iterator<TKey, TValue> $iterator
+     * @param TIterator $iterator
      * @param self::MATCH|self::GET_MATCH|self::ALL_MATCHES|self::SPLIT|self::REPLACE $mode
      */
     public function __construct(Iterator $iterator, string $regex, int $mode = self::MATCH, int $flags = 0, int $preg_flags = 0) {}

tests/PHPStan/Analyser/nsrt/bug-13325.php

@@ -0,0 +1,25 @@
+<?php
+
+namespace Bug13325Nsrt;
+
+use function PHPStan\Testing\assertType;
+
+class Foo
+{
+
+	/**
+	 * @param \Iterator<int, string> $iterator
+	 */
+	public function doFoo(\Iterator $iterator): void
+	{
+		$regexIterator = new \RegexIterator($iterator, '/pattern/');
+		assertType('RegexIterator<int, string, Iterator<int, string>>', $regexIterator);
+	}
+
+	public function doBar(): void
+	{
+		$regexIterator = new \RegexIterator(new \FilesystemIterator('foo'), '/pattern/');
+		assertType('RegexIterator<mixed, mixed, FilesystemIterator>', $regexIterator);
+	}
+
+}

tests/PHPStan/Rules/Methods/data/bug-13325.php

@@ -4,15 +4,24 @@
 
 namespace Bug13325;
 
+use FilesystemIterator;
 use Iterator;
 use RegexIterator;
-use Traversable;
 
 final class Foo
 {
-	/** @return RegexIterator<mixed, mixed, Traversable<mixed, mixed>> */
+	/** @return RegexIterator<mixed, mixed, Iterator> */
 	public function __invoke(Iterator $iterator): RegexIterator
 	{
 		return new RegexIterator($iterator, 'string');
 	}
+
+	/** @return RegexIterator<mixed, mixed, FilesystemIterator> */
+	public function createRegionIterator(): RegexIterator
+	{
+		return new RegexIterator(
+			new FilesystemIterator('foo'),
+			'/bar/',
+		);
+	}
 }