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).
diff --git a/Lib/test/test_functools.py b/Lib/test/test_functools.py
index edd5773..bee9f91 100644
--- a/Lib/test/test_functools.py
+++ b/Lib/test/test_functools.py
@@ -618,7 +618,7 @@
def _default_update(self):
- def f(a:'This is a new annotation'):
+ def f(a: int):
"""This is a test"""
pass
f.attr = 'This is also a test'
@@ -635,7 +635,7 @@
self.assertEqual(wrapper.__name__, 'f')
self.assertEqual(wrapper.__qualname__, f.__qualname__)
self.assertEqual(wrapper.attr, 'This is also a test')
- self.assertEqual(wrapper.__annotations__['a'], 'This is a new annotation')
+ self.assertEqual(wrapper.__annotations__['a'], 'int')
self.assertNotIn('b', wrapper.__annotations__)
@unittest.skipIf(sys.flags.optimize >= 2,