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_grammar.py b/Lib/test/test_grammar.py
index 5235fa2..2f6716d 100644
--- a/Lib/test/test_grammar.py
+++ b/Lib/test/test_grammar.py
@@ -362,7 +362,7 @@
z = 2
def __init__(self, x):
self.x: int = x
- self.assertEqual(C.__annotations__, {'_C__foo': int, 's': str})
+ self.assertEqual(C.__annotations__, {'_C__foo': 'int', 's': 'str'})
with self.assertRaises(NameError):
class CBad:
no_such_name_defined.attr: int = 0
@@ -378,15 +378,15 @@
return {'__annotations__': CNS()}
class CC(metaclass=CMeta):
XX: 'ANNOT'
- self.assertEqual(CC.__annotations__['xx'], 'ANNOT')
+ self.assertEqual(CC.__annotations__['xx'], repr('ANNOT'))
def test_var_annot_module_semantics(self):
with self.assertRaises(AttributeError):
print(test.__annotations__)
self.assertEqual(ann_module.__annotations__,
- {1: 2, 'x': int, 'y': str, 'f': typing.Tuple[int, int]})
+ {1: 2, 'x': 'int', 'y': 'str', 'f': 'Tuple[int, int]'})
self.assertEqual(ann_module.M.__annotations__,
- {'123': 123, 'o': type})
+ {'123': 123, 'o': 'type'})
self.assertEqual(ann_module2.__annotations__, {})
def test_var_annot_in_module(self):
@@ -405,7 +405,7 @@
exec("'docstring'\n"
"__annotations__[1] = 2\n"
"x: int = 5\n", gns, lns)
- self.assertEqual(lns["__annotations__"], {1: 2, 'x': int})
+ self.assertEqual(lns["__annotations__"], {1: 2, 'x': 'int'})
with self.assertRaises(KeyError):
gns['__annotations__']
@@ -413,8 +413,8 @@
# tests with custom locals() and __annotations__
ns = {'__annotations__': CNS()}
exec('X: int; Z: str = "Z"; (w): complex = 1j', ns)
- self.assertEqual(ns['__annotations__']['x'], int)
- self.assertEqual(ns['__annotations__']['z'], str)
+ self.assertEqual(ns['__annotations__']['x'], 'int')
+ self.assertEqual(ns['__annotations__']['z'], 'str')
with self.assertRaises(KeyError):
ns['__annotations__']['w']
nonloc_ns = {}
@@ -428,7 +428,7 @@
def __getitem__(self, item):
return self._dct[item]
exec('x: int = 1', {}, CNS2())
- self.assertEqual(nonloc_ns['__annotations__']['x'], int)
+ self.assertEqual(nonloc_ns['__annotations__']['x'], 'int')
def test_var_annot_refleak(self):
# complex case: custom locals plus custom __annotations__
@@ -445,7 +445,7 @@
def __getitem__(self, item):
return self._dct[item]
exec('X: str', {}, CNS2())
- self.assertEqual(nonloc_ns['__annotations__']['x'], str)
+ self.assertEqual(nonloc_ns['__annotations__']['x'], 'str')
def test_var_annot_rhs(self):
ns = {}
@@ -625,50 +625,46 @@
# argument annotation tests
def f(x) -> list: pass
- self.assertEqual(f.__annotations__, {'return': list})
+ self.assertEqual(f.__annotations__, {'return': 'list'})
def f(x: int): pass
- self.assertEqual(f.__annotations__, {'x': int})
+ self.assertEqual(f.__annotations__, {'x': 'int'})
def f(x: int, /): pass
- self.assertEqual(f.__annotations__, {'x': int})
+ self.assertEqual(f.__annotations__, {'x': 'int'})
def f(x: int = 34, /): pass
- self.assertEqual(f.__annotations__, {'x': int})
+ self.assertEqual(f.__annotations__, {'x': 'int'})
def f(*x: str): pass
- self.assertEqual(f.__annotations__, {'x': str})
+ self.assertEqual(f.__annotations__, {'x': 'str'})
def f(**x: float): pass
- self.assertEqual(f.__annotations__, {'x': float})
- def f(x, y: 1+2): pass
- self.assertEqual(f.__annotations__, {'y': 3})
- def f(x, y: 1+2, /): pass
- self.assertEqual(f.__annotations__, {'y': 3})
+ self.assertEqual(f.__annotations__, {'x': 'float'})
def f(a, b: 1, c: 2, d): pass
- self.assertEqual(f.__annotations__, {'b': 1, 'c': 2})
+ self.assertEqual(f.__annotations__, {'b': '1', 'c': '2'})
def f(a, b: 1, /, c: 2, d): pass
- self.assertEqual(f.__annotations__, {'b': 1, 'c': 2})
+ self.assertEqual(f.__annotations__, {'b': '1', 'c': '2'})
def f(a, b: 1, c: 2, d, e: 3 = 4, f=5, *g: 6): pass
self.assertEqual(f.__annotations__,
- {'b': 1, 'c': 2, 'e': 3, 'g': 6})
+ {'b': '1', 'c': '2', 'e': '3', 'g': '6'})
def f(a, b: 1, c: 2, d, e: 3 = 4, f=5, *g: 6, h: 7, i=8, j: 9 = 10,
**k: 11) -> 12: pass
self.assertEqual(f.__annotations__,
- {'b': 1, 'c': 2, 'e': 3, 'g': 6, 'h': 7, 'j': 9,
- 'k': 11, 'return': 12})
+ {'b': '1', 'c': '2', 'e': '3', 'g': '6', 'h': '7', 'j': '9',
+ 'k': '11', 'return': '12'})
def f(a, b: 1, c: 2, d, e: 3 = 4, f: int = 5, /, *g: 6, h: 7, i=8, j: 9 = 10,
**k: 11) -> 12: pass
self.assertEqual(f.__annotations__,
- {'b': 1, 'c': 2, 'e': 3, 'f': int, 'g': 6, 'h': 7, 'j': 9,
- 'k': 11, 'return': 12})
+ {'b': '1', 'c': '2', 'e': '3', 'f': 'int', 'g': '6', 'h': '7', 'j': '9',
+ 'k': '11', 'return': '12'})
# Check for issue #20625 -- annotations mangling
class Spam:
def f(self, *, __kw: 1):
pass
class Ham(Spam): pass
- self.assertEqual(Spam.f.__annotations__, {'_Spam__kw': 1})
- self.assertEqual(Ham.f.__annotations__, {'_Spam__kw': 1})
+ self.assertEqual(Spam.f.__annotations__, {'_Spam__kw': '1'})
+ self.assertEqual(Ham.f.__annotations__, {'_Spam__kw': '1'})
# Check for SF Bug #1697248 - mixing decorators and a return annotation
def null(x): return x
@null
def f(x) -> list: pass
- self.assertEqual(f.__annotations__, {'return': list})
+ self.assertEqual(f.__annotations__, {'return': 'list'})
# Test expressions as decorators (PEP 614):
@False or null
@@ -1116,8 +1112,6 @@
# Not allowed at class scope
check_syntax_error(self, "class foo:yield 1")
check_syntax_error(self, "class foo:yield from ()")
- # Check annotation refleak on SyntaxError
- check_syntax_error(self, "def g(a:(yield)): pass")
def test_yield_in_comprehensions(self):
# Check yield in comprehensions