Seal the types of sys.version_info and sys.flags

Author: steve-s

graalpython/com.oracle.graal.python.test/src/tests/unittest_tags/test_sys.txt

@@ -33,6 +33,8 @@
 *graalpython.lib-python.3.test.test_sys.SysModuleTest.test_c_locale_surrogateescape
 *graalpython.lib-python.3.test.test_sys.SysModuleTest.test_posix_locale_surrogateescape
 *graalpython.lib-python.3.test.test_sys.SysModuleTest.test_thread_info
+*graalpython.lib-python.3.test.test_sys.SysModuleTest.test_sys_version_info_no_instantiation
+*graalpython.lib-python.3.test.test_sys.SysModuleTest.test_sys_flags_no_instantiation
 *graalpython.lib-python.3.test.test_sys.UnraisableHookTest.test_custom_unraisablehook
 *graalpython.lib-python.3.test.test_sys.UnraisableHookTest.test_custom_unraisablehook_fail
 *graalpython.lib-python.3.test.test_sys.UnraisableHookTest.test_original_unraisablehook

graalpython/lib-graalpython/_descriptor.py

@@ -43,11 +43,23 @@ def _f(): pass
 
 
 def make_named_tuple_class(name, fields):
+    sealed = False
     class named_tuple(tuple):
         __name__ = name
+        __qualname__ = name
         n_sequence_fields = len(fields)
         fields = fields
 
+        @classmethod
+        def seal(cls):
+            nonlocal sealed
+            sealed = True
+
+        def __new__(cls, *args, **kwargs):
+            if sealed:
+                raise TypeError("cannot create '{}' instances".format(name))
+            return super(named_tuple, cls).__new__(cls, *args, **kwargs)
+
         def __str__(self):
             return self.__repr__()
 

graalpython/lib-graalpython/sys.py

@@ -44,12 +44,14 @@ def make_implementation_info():
     version_info_type = make_named_tuple_class(
         "version_info", ["major", "minor", "micro", "releaselevel", "serial"]
     )
-    return SimpleNamespace(
+    result = SimpleNamespace(
         name="graalpython",
         cache_tag="graalpython",
         version=version_info_type(version_info),
         _multiarch=__gmultiarch
     )
+    version_info_type.seal()
+    return result
 implementation = make_implementation_info()
 del make_implementation_info
 del __gmultiarch
@@ -69,6 +71,7 @@ def make_flags_class():
              "quiet", "verbose", "dev_mode", "utf8_mode"]
     return make_named_tuple_class("sys.flags", names)
 flags = make_flags_class()(__graalpython__.flags)
+type(flags).seal()
 del make_flags_class