Added support for passing new class as parameter defaults.

Added exception handling for passing `default` to required parameters.
Fixed default_value leak in ZEND_FETCH_DEFAULT_ARG handler.

Author: Bilge

Zend/tests/default_expression/default to required parameter of internal class.phpt

@@ -0,0 +1,10 @@
+--TEST--
+Tests passing default to a required parameter of an internal class
+--FILE--
+<?php
+
+DateTime::createFromInterface(default);
+?>
+--EXPECTF--
+Fatal error: Uncaught ValueError: Cannot pass default to required parameter 1 of DateTime::createFromInterface() in %s:%d
+Stack trace:%a

Zend/tests/default_expression/default to required parameter of internal function.phpt

@@ -0,0 +1,10 @@
+--TEST--
+Tests passing default to a required parameter of an internal function
+--FILE--
+<?php
+
+json_encode(default);
+?>
+--EXPECTF--
+Fatal error: Uncaught ValueError: Cannot pass default to required parameter 1 of json_encode() in %s:%d
+Stack trace:%a

Zend/tests/default_expression/internal function.phpt

@@ -3,7 +3,7 @@ Tests passing default to an internal function parameter
 --FILE--
 <?php
 
-json_encode([], depth: $D = default);
+json_encode([], 0, $D = default);
 var_dump($D);
 ?>
 --EXPECT--

Zend/tests/default_expression/named arguments.phpt

@@ -0,0 +1,16 @@
+--TEST--
+Tests passing default as a named argument
+--FILE--
+<?php
+
+json_encode([], depth: $D = default);
+var_dump($D);
+
+function F($V = 'Alfa', $V2 = 1) {
+    var_dump($V2);
+}
+F(V2: default + 1);
+?>
+--EXPECT--
+int(512)
+int(2)

Zend/tests/default_expression/new class parameter.phpt

@@ -0,0 +1,12 @@
+--TEST--
+Test passing default to a parameter with a new class as the default
+--FILE--
+<?php
+
+function F($V = new stdClass) {}
+F($D = default);
+var_dump($D);
+?>
+--EXPECT--
+object(stdClass)#1 (0) {
+}

Zend/zend_vm_def.h

@@ -9821,10 +9821,29 @@ ZEND_VM_HANDLER(210, ZEND_FETCH_DEFAULT_ARG, UNUSED|NUM, UNUSED)
 	pr.arg_info = &called_func->common.arg_info[pr.offset];
 	pr.fptr = called_func;
 
+	if (pr.required) {
+		zend_value_error("Cannot pass default to required parameter %u of %s%s%s()",
+			opline->op1.num,
+			called_func->common.scope ? ZSTR_VAL(called_func->common.scope->name) : "",
+			called_func->common.scope ? "::" : "",
+			ZSTR_VAL(called_func->common.function_name)
+		);
+		HANDLE_EXCEPTION();
+	}
+
 	zval default_value;
 	get_parameter_default(&default_value, &pr);
 
+	// Evaluate AST value, e.g. new class.
+	if (Z_TYPE(default_value) == IS_CONSTANT_AST) {
+		if (UNEXPECTED(zval_update_constant_ex(&default_value, called_func->common.scope) != SUCCESS)) {
+			HANDLE_EXCEPTION();
+		}
+	}
+
 	ZVAL_COPY(EX_VAR(opline->result.var), &default_value);
+	zval_ptr_dtor(&default_value);
+
 	ZEND_VM_NEXT_OPCODE_CHECK_EXCEPTION();
 }