Add sys.builtin_module_names

Author: youknowone

tests/snippets/sysmod.py

@@ -4,3 +4,6 @@
 assert sys.argv[0].endswith('.py')
 
 assert sys.platform == "linux" or sys.platform == "darwin" or sys.platform == "win32" or sys.platform == "unknown"
+
+assert isinstance(sys.builtin_module_names, tuple)
+assert 'sys' in sys.builtin_module_names

vm/src/sysmodule.rs

@@ -4,7 +4,7 @@ use std::{env, mem};
 use crate::frame::FrameRef;
 use crate::function::{OptionalArg, PyFuncArgs};
 use crate::obj::objstr::PyStringRef;
-use crate::pyobject::{ItemProtocol, PyContext, PyObjectRef, PyResult};
+use crate::pyobject::{IntoPyObject, ItemProtocol, PyContext, PyObjectRef, PyResult};
 use crate::vm::VirtualMachine;
 
 /*
@@ -144,9 +144,14 @@ setprofile() -- set the global profiling function
 setrecursionlimit() -- set the max recursion depth for the interpreter
 settrace() -- set the global debug tracing function
 ";
+    let mut module_names: Vec<_> = vm.stdlib_inits.borrow().keys().cloned().collect();
+    module_names.push("sys".to_string());
+    module_names.push("builtins".to_string());
+    module_names.sort();
     let modules = ctx.new_dict();
     extend_module!(vm, module, {
       "argv" => argv(ctx),
+      "builtin_module_names" => ctx.new_tuple(module_names.iter().map(|v| v.into_pyobject(vm).unwrap()).collect()),
       "getrefcount" => ctx.new_rustfunc(sys_getrefcount),
       "getsizeof" => ctx.new_rustfunc(sys_getsizeof),
       "intern" => ctx.new_rustfunc(sys_intern),