ext/standard: Add get_declared_enums function

Adds a `get_declared_enums()` function that returns a list of declared Enums.
This function is similar to the existing `get_declared_(classes|interfaces|traits)` functions.

Author: Ayesh

NEWS

@@ -13,6 +13,7 @@ PHP                                                                        NEWS
     casting any non-integer value to a string.
     As such, passing invalid types to exit/die may now result in a TypeError
     being thrown. (Girgias)
+  . Added get_declared_enums() function. (Ayesh Karunaratne)
 
 - Hash:
   . Fix GH-15384 (Build fails on Alpine / Musl for amd64). (timwolla)

UPGRADING

@@ -391,6 +391,7 @@ PHP 8.4 UPGRADE NOTES
   . Added a new RoundingMode enum with clearer naming and improved discoverability
     compared to the PHP_ROUND_* constants.
     RFC: https://wiki.php.net/rfc/correctly_name_the_rounding_mode_and_make_it_an_enum
+  . Added get_declared_enums() function that returns a list of declared enums.
 
 - SOAP:
   . Added support for clark notation for namespaces in class map.

Zend/Optimizer/zend_func_infos.h

@@ -11,6 +11,7 @@ static const func_info_t func_infos[] = {
 	F1("get_declared_classes", MAY_BE_ARRAY|MAY_BE_ARRAY_KEY_LONG|MAY_BE_ARRAY_OF_STRING),
 	F1("get_declared_traits", MAY_BE_ARRAY|MAY_BE_ARRAY_KEY_LONG|MAY_BE_ARRAY_OF_STRING),
 	F1("get_declared_interfaces", MAY_BE_ARRAY|MAY_BE_ARRAY_KEY_LONG|MAY_BE_ARRAY_OF_STRING),
+	F1("get_declared_enums", MAY_BE_ARRAY|MAY_BE_ARRAY_KEY_LONG|MAY_BE_ARRAY_OF_STRING),
 	F1("get_defined_functions", MAY_BE_ARRAY|MAY_BE_ARRAY_KEY_STRING|MAY_BE_ARRAY_OF_ARRAY),
 	F1("get_defined_vars", MAY_BE_ARRAY|MAY_BE_ARRAY_KEY_STRING|MAY_BE_ARRAY_OF_ANY|MAY_BE_ARRAY_OF_REF),
 	F1("get_resource_type", MAY_BE_STRING),

Zend/zend_builtin_functions.c

@@ -1381,7 +1381,7 @@ static inline void get_declared_class_impl(INTERNAL_FUNCTION_PARAMETERS, int fla
 	ZEND_HASH_FILL_PACKED(Z_ARRVAL_P(return_value)) {
 		ZEND_HASH_MAP_FOREACH_STR_KEY_VAL(EG(class_table), key, zv) {
 			ce = Z_PTR_P(zv);
-			if ((ce->ce_flags & (ZEND_ACC_LINKED|ZEND_ACC_INTERFACE|ZEND_ACC_TRAIT)) == flags
+			if ((ce->ce_flags & (ZEND_ACC_LINKED|ZEND_ACC_INTERFACE|ZEND_ACC_TRAIT|ZEND_ACC_ENUM)) == flags
 			 && key
 			 && ZSTR_VAL(key)[0] != 0) {
 				ZEND_HASH_FILL_GROW();
@@ -1419,6 +1419,13 @@ ZEND_FUNCTION(get_declared_interfaces)
 }
 /* }}} */
 
+/* {{{ Returns an array of all declared enums. */
+ZEND_FUNCTION(get_declared_enums)
+{
+	get_declared_class_impl(INTERNAL_FUNCTION_PARAM_PASSTHRU, ZEND_ACC_LINKED | ZEND_ACC_ENUM);
+}
+/* }}} */
+
 /* {{{ Returns an array of all defined functions */
 ZEND_FUNCTION(get_defined_functions)
 {

Zend/zend_builtin_functions.stub.php

@@ -140,6 +140,12 @@ function get_declared_traits(): array {}
  */
 function get_declared_interfaces(): array {}
 
+/**
+ * @return array<int, string>
+ * @refcount 1
+ */
+function get_declared_enums(): array {}
+
 /**
  * @return array<string, array>
  * @refcount 1

Zend/zend_builtin_functions_arginfo.h

@@ -0,0 +1,56 @@
+--TEST--
+Test get_declared_enums() function
+--FILE--
+<?php
+
+enum MyUnitEnum {}
+enum MyStringBackedEnum: string {
+    case FOO = 'test';
+}
+enum MyIntBackedEnum: string {
+    case FOO = 'test';
+}
+enum MyEnumImplementation implements Countable {
+    public function count(): int {
+        return 0;
+    }
+}
+
+var_dump(get_declared_enums());
+
+foreach (get_declared_enums() as $enum) {
+    if (!enum_exists($enum)) {
+        echo "Error: $enum is not a valid enum.\n";
+    }
+}
+
+echo "Ensure all enums are included.\n";
+
+var_dump(in_array('MyUnitEnum', get_declared_enums()));
+var_dump(in_array('MyStringBackedEnum', get_declared_enums()));
+var_dump(in_array('MyIntBackedEnum', get_declared_enums()));
+var_dump(in_array('MyEnumImplementation', get_declared_enums()));
+
+echo "Ensure interfaces are not included.\n";
+var_dump(in_array('Throwable', get_declared_enums()));
+var_dump(in_array('IntBackedEnum', get_declared_enums()));
+
+echo "Ensure classes are not included.\n";
+var_dump(in_array('stdClass', get_declared_enums()));
+echo "Done";
+?>
+--EXPECTF--
+array(%d) {
+%a
+}
+Ensure all enums are included.
+bool(true)
+bool(true)
+bool(true)
+bool(true)
+Ensure interfaces are not included.
+bool(false)
+bool(false)
+Ensure classes are not included.
+bool(false)
+Done