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 +3171,43 @@ 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 {
+			zend_array *arrval;
+			zend_long arrlen;
+			zval *entry;
+
+			arrval = Z_ARRVAL_P(obj);
+
+			arrlen = zend_hash_num_elements(arrval);
 
-	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_size(return_value, arrlen);
+			zend_hash_real_init_packed(Z_ARRVAL_P(return_value));
+
+			ZEND_HASH_FILL_PACKED(Z_ARRVAL_P(return_value)) {
+				ZEND_HASH_FOREACH_VAL(arrval, entry) {
+					if (UNEXPECTED(Z_ISREF_P(entry) && Z_REFCOUNT_P(entry) == 1)) {
+						entry = Z_REFVAL_P(entry);
+					}
+					Z_TRY_ADDREF_P(entry);
+					ZEND_HASH_FILL_ADD(entry);
+				} ZEND_HASH_FOREACH_END();
+			} ZEND_HASH_FILL_END();
+		}
+	}
+	else {
+		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 iterable, string given in %s:%d
 Stack trace:
 #0 %s(%d): iterator_to_array('test', 'test')
 #1 {main}