[3.7] bpo-32873: Treat type variables and special typing forms as immutable by copy and pickle (GH-6216) #6264
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This also fixes python/typingGH-512
This also fixes python/typingGH-511
As was discussed in both issues, some typing forms deserve to be treated
as immutable by copy and pickle modules, so that:
This PR adds such behaviour to:
This not only resolves inconsistencies mentioned in the issues, but also
improves backwards compatibility with previous versions of Python
(including 3.6).
Note that this requires some dances with module for type variables
(similar to NamedTuple) because the class TypeVar itself is define in typing,
while type variables should get module where they were defined.
https://bugs.python.org/issue32873
(cherry picked from commit 8349403)
Co-authored-by: Ivan Levkivskyi [email protected]
https://bugs.python.org/issue32873