bpo-38605: Make 'from __future__ import annotations' the default (GH-20434)

The hard part was making all the tests pass; there are some subtle issues here, because apparently the future import wasn't tested very thoroughly in previous Python versions.

For example, `inspect.signature()` returned type objects normally (except for forward references), but strings with the future import. We changed it to try and return type objects by calling `typing.get_type_hints()`, but fall back on returning strings if that function fails (which it may do if there are future references in the annotations that require passing in a specific namespace to resolve).
This commit is contained in:
Batuhan Taskaya 2020-10-06 23:03:02 +03:00 committed by GitHub
parent bef7d299eb
commit 044a1048ca
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27 changed files with 403 additions and 299 deletions

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@ -302,14 +302,14 @@ class PositionalOnlyTestCase(unittest.TestCase):
def f(x: int, /): ...
return f
assert inner_has_pos_only().__annotations__ == {'x': int}
assert inner_has_pos_only().__annotations__ == {'x': 'int'}
class Something:
def method(self):
def f(x: int, /): ...
return f
assert Something().method().__annotations__ == {'x': int}
assert Something().method().__annotations__ == {'x': 'int'}
def multiple_levels():
def inner_has_pos_only():
@ -317,7 +317,7 @@ class PositionalOnlyTestCase(unittest.TestCase):
return f
return inner_has_pos_only()
assert multiple_levels().__annotations__ == {'x': int}
assert multiple_levels().__annotations__ == {'x': 'int'}
def test_same_keyword_as_positional_with_kwargs(self):
def f(something,/,**kwargs):
@ -429,17 +429,6 @@ class PositionalOnlyTestCase(unittest.TestCase):
self.assertEqual(C().method(), sentinel)
def test_annotations_constant_fold(self):
def g():
def f(x: not (int is int), /): ...
# without constant folding we end up with
# COMPARE_OP(is), IS_OP (0)
# with constant folding we should expect a IS_OP (1)
codes = [(i.opname, i.argval) for i in dis.get_instructions(g)]
self.assertNotIn(('UNARY_NOT', None), codes)
self.assertIn(('IS_OP', 1), codes)
if __name__ == "__main__":
unittest.main()