Make iterator_to_array() accept all iterables

While calling this function on an array either is a no-op or is equivalent to
`\array_values()` if the `$preserve_keys` flag is `false`, it is also
unnecessarily limiting for it to reject proper arrays.

By allowing it to take the full `iterable` family, it is more easily possible
to write a function that operates on an arbitrary `iterable` and internally
uses array-specific functionality, such as `array_filter` or `array_map`:

    function test(iterable $foo) {
        $foo = iterator_to_array($foo);

        return array_map(strlen(...), $foo);
    }

With this change it behaves similarly to `Array.from()` in JavaScript.

Author: TimWolla

ext/spl/php_spl.stub.php

@@ -51,4 +51,4 @@ function iterator_apply(Traversable $iterator, callable $callback, ?array $args
 function iterator_count(Traversable $iterator): int {}
 
 /** @refcount 1 */
-function iterator_to_array(Traversable $iterator, bool $preserve_keys = true): array {}
+function iterator_to_array(iterable $iterator, bool $preserve_keys = true): array {}

ext/spl/php_spl_arginfo.h

@@ -3171,12 +3171,22 @@ PHP_FUNCTION(iterator_to_array)
 	zval  *obj;
 	bool use_keys = 1;
 
-	if (zend_parse_parameters(ZEND_NUM_ARGS(), "O|b", &obj, zend_ce_traversable, &use_keys) == FAILURE) {
-		RETURN_THROWS();
+	ZEND_PARSE_PARAMETERS_START(1, 2)
+		Z_PARAM_ITERABLE(obj)
+		Z_PARAM_OPTIONAL
+		Z_PARAM_BOOL(use_keys)
+	ZEND_PARSE_PARAMETERS_END();
+
+	if (Z_TYPE_P(obj) == IS_ARRAY) {
+		if (use_keys) {
+			RETURN_COPY(obj);
+		} else {
+			RETVAL_ARR(zend_array_to_list(Z_ARRVAL_P(obj)));
+		}
+	} else {
+		array_init(return_value);
+		spl_iterator_apply(obj, use_keys ? spl_iterator_to_array_apply : spl_iterator_to_values_apply, (void*)return_value);
 	}
-
-	array_init(return_value);
-	spl_iterator_apply(obj, use_keys ? spl_iterator_to_array_apply : spl_iterator_to_values_apply, (void*)return_value);
 } /* }}} */
 
 static int spl_iterator_count_apply(zend_object_iterator *iter, void *puser) /* {{{ */

ext/spl/spl_iterators.c

@@ -13,7 +13,7 @@ iterator_to_array('test','test');
 
 ?>
 --EXPECTF--
-Fatal error: Uncaught TypeError: iterator_to_array(): Argument #1 ($iterator) must be of type Traversable, string given in %s:%d
+Fatal error: Uncaught TypeError: iterator_to_array(): Argument #1 ($iterator) must be of type Traversable|array, string given in %s:%d
 Stack trace:
 #0 %s(%d): iterator_to_array('test', 'test')
 #1 {main}

ext/spl/tests/iterator_to_array.phpt

@@ -0,0 +1,42 @@
+--TEST--
+SPL: iterator_to_array() supports arrays.
+--FILE--
+<?php
+
+var_dump(iterator_to_array([]));
+var_dump(iterator_to_array([1]));
+var_dump(iterator_to_array(['a' => 1, 'b' => 2, 5 => 3]));
+var_dump(iterator_to_array([], false));
+var_dump(iterator_to_array([1], false));
+var_dump(iterator_to_array(['a' => 1, 'b' => 2, 5 => 3], false));
+
+?>
+--EXPECT--
+array(0) {
+}
+array(1) {
+  [0]=>
+  int(1)
+}
+array(3) {
+  ["a"]=>
+  int(1)
+  ["b"]=>
+  int(2)
+  [5]=>
+  int(3)
+}
+array(0) {
+}
+array(1) {
+  [0]=>
+  int(1)
+}
+array(3) {
+  [0]=>
+  int(1)
+  [1]=>
+  int(2)
+  [2]=>
+  int(3)
+}