Add __main__.__cached__

Author: youknowone

crates/vm/src/vm/compile.rs

@@ -69,6 +69,7 @@ impl VirtualMachine {
                 self.ctx.new_str(path).into(),
                 self,
             )?;
+            module_dict.set_item(identifier!(self, __cached__), self.ctx.none(), self)?;
         }
 
         // Consider to use enum to distinguish `path`

crates/vm/src/vm/context.rs

@@ -98,6 +98,7 @@ declare_const_name! {
     __build_class__,
     __builtins__,
     __bytes__,
+    __cached__,
     __call__,
     __ceil__,
     __cformat__,

extra_tests/snippets/builtin___main__.py

@@ -0,0 +1,5 @@
+import sys
+
+main_module = sys.modules["__main__"]
+assert main_module.__file__.endswith("builtin___main__.py")
+assert main_module.__cached__ is None