Various enum fixes

Zend/tests/enum/empty-from.phpt

@@ -0,0 +1,12 @@
+--TEST--
+Empty enum with from/tryFrom doens't segfault
+--FILE--
+<?php
+
+enum A: string {}
+
+var_dump(A::tryFrom('B'));
+
+?>
+--EXPECT--
+NULL

Zend/tests/enum/magic-constants.phpt

@@ -0,0 +1,14 @@
+--TEST--
+Backed enums can contain magic constants
+--FILE--
+<?php
+
+enum Foo: string {
+    case Bar = __FILE__;
+}
+
+echo Foo::Bar->value, "\n";
+
+?>
+--EXPECTF--
+%smagic-constants.php

Zend/zend_compile.c

@@ -10473,6 +10473,9 @@ static void zend_eval_const_expr(zend_ast **ast_ptr) /* {{{ */
 		case ZEND_AST_NAMED_ARG:
 			zend_eval_const_expr(&ast->child[1]);
 			return;
+		case ZEND_AST_CONST_ENUM_INIT:
+			zend_eval_const_expr(&ast->child[2]);
+			return;
 		default:
 			return;
 	}

Zend/zend_enum.c

@@ -187,6 +187,7 @@ void zend_enum_add_interfaces(zend_class_entry *ce)
 zend_result zend_enum_build_backed_enum_table(zend_class_entry *ce)
 {
 	ZEND_ASSERT(ce->ce_flags & ZEND_ACC_ENUM);
+	ZEND_ASSERT(!(ce->ce_flags & ZEND_ACC_IMMUTABLE));
 	ZEND_ASSERT(ce->type == ZEND_USER_CLASS);
 
 	uint32_t backing_type = ce->enum_backing_type;
@@ -199,7 +200,7 @@ zend_result zend_enum_build_backed_enum_table(zend_class_entry *ce)
 
 	zend_string *name;
 	zval *val;
-	ZEND_HASH_MAP_FOREACH_STR_KEY_VAL(&ce->constants_table, name, val) {
+	ZEND_HASH_MAP_FOREACH_STR_KEY_VAL(CE_CONSTANTS_TABLE(ce), name, val) {
 		zend_class_constant *c = Z_PTR_P(val);
 		if ((ZEND_CLASS_CONST_FLAGS(c) & ZEND_CLASS_CONST_IS_CASE) == 0) {
 			continue;
@@ -281,6 +282,9 @@ ZEND_API zend_result zend_enum_get_case_by_value(zend_object **result, zend_clas
 			return FAILURE;
 		}
 	}
+	if (!ce->backed_enum_table) {
+		goto not_found;
+	}
 
 	zval *case_name_zv;
 	if (ce->enum_backing_type == IS_LONG) {
@@ -292,6 +296,7 @@ ZEND_API zend_result zend_enum_get_case_by_value(zend_object **result, zend_clas
 	}
 
 	if (case_name_zv == NULL) {
+not_found:
 		if (try) {
 			*result = NULL;
 			return SUCCESS;

Zend/zend_execute_API.c

@@ -346,6 +346,12 @@ ZEND_API void zend_shutdown_executor_values(bool fast_shutdown)
 				}
 			}
 
+			if (ce->type == ZEND_USER_CLASS && ce->backed_enum_table) {
+				ZEND_ASSERT(!(ce->ce_flags & ZEND_ACC_IMMUTABLE));
+				zend_hash_release(ce->backed_enum_table);
+				ce->backed_enum_table = NULL;
+			}
+
 			if (ce->ce_flags & ZEND_HAS_STATIC_IN_METHODS) {
 				zend_op_array *op_array;
 				ZEND_HASH_MAP_FOREACH_PTR(&ce->function_table, op_array) {