Add test + improve error message for static properties of readonly classes

Author: kocsismate

Zend/tests/readonly_classes/readonly_class_property3.phpt

@@ -0,0 +1,13 @@
+--TEST--
+Declaring static property for a readonly class is forbidden
+--FILE--
+<?php
+
+readonly class Foo
+{
+    public static int $bar;
+}
+
+?>
+--EXPECTF--
+Fatal error: Readonly class Foo cannot declare static properties in %s on line %d

Zend/zend_compile.c

@@ -7223,6 +7223,12 @@ static void zend_compile_prop_decl(zend_ast *ast, zend_ast *type_ast, uint32_t f
 		zend_error_noreturn(E_COMPILE_ERROR, "Properties cannot be declared abstract");
 	}
 
+	if ((ce->ce_flags & ZEND_ACC_READONLY_CLASS) && (flags & ZEND_ACC_STATIC)) {
+		zend_error_noreturn(E_COMPILE_ERROR, "Readonly class %s cannot declare static properties",
+			ZSTR_VAL(ce->name)
+		);
+	}
+
 	for (i = 0; i < children; ++i) {
 		zend_property_info *info;
 		zend_ast *prop_ast = list->child[i];