Make sure new arguments are pre-evaluated

The way we do this is quite fragile, and I've fallen into the
same trap in the past. This could use some refactoring.

Author: nikic

Zend/tests/constexpr/new_arg_eval.phpt

@@ -0,0 +1,31 @@
+--TEST--
+Check that const exprs are pre-evaluated in new arguments
+--FILE--
+<?php
+
+class C {
+    public function __construct(public $x) {}
+}
+function test(
+    $a = new C(__CLASS__),
+    $b = new C(__FUNCTION__),
+    $c = new C(x: __FILE__),
+) {
+    var_dump($a, $b, $c);
+}
+test();
+
+?>
+--EXPECTF--
+object(C)#1 (1) {
+  ["x"]=>
+  string(0) ""
+}
+object(C)#2 (1) {
+  ["x"]=>
+  string(4) "test"
+}
+object(C)#3 (1) {
+  ["x"]=>
+  string(%d) "%snew_arg_eval.php"
+}

Zend/zend_compile.c

@@ -10164,6 +10164,25 @@ void zend_eval_const_expr(zend_ast **ast_ptr) /* {{{ */
 			}
 			break;
 		}
+		// TODO: We should probably use zend_ast_apply to recursively walk nodes without
+		// special handling. It is required that all nodes that are part of a const expr
+		// are visited. Probably we should be distinguishing evaluation of const expr and
+		// normal exprs here.
+		case ZEND_AST_ARG_LIST:
+		{
+			zend_ast_list *list = zend_ast_get_list(ast);
+			for (uint32_t i = 0; i < list->children; i++) {
+				zend_eval_const_expr(&list->child[i]);
+			}
+			return;
+		}
+		case ZEND_AST_NEW:
+			zend_eval_const_expr(&ast->child[0]);
+			zend_eval_const_expr(&ast->child[1]);
+			return;
+		case ZEND_AST_NAMED_ARG:
+			zend_eval_const_expr(&ast->child[1]);
+			return;
 		default:
 			return;
 	}