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Fix None slice bounds with strict-optional #3445

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Merged
merged 4 commits into from
May 29, 2017
Merged

Fix None slice bounds with strict-optional #3445

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6135d6a
Fix None slice bounds with strict-optional
miedzinski May 24, 2017
a31b666
Add new strict-optional test
miedzinski May 24, 2017
ffe0c36
Use typeanal.make_optional_type
miedzinski May 25, 2017
2b1ad82
Merge branch 'master' into slice-none
miedzinski May 25, 2017
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3 changes: 2 additions & 1 deletion mypy/checkexpr.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1893,10 +1893,11 @@ def analyze_super(self, e: SuperExpr, is_lvalue: bool) -> Type:
return AnyType()

def visit_slice_expr(self, e: SliceExpr) -> Type:
expected = UnionType.make_union([NoneTyp(), self.named_type('builtins.int')])
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Should probably use typeanal.make_optional_type() instead.

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I was looking for such function/method, but couldn't find it. Thanks!

for index in [e.begin_index, e.end_index, e.stride]:
if index:
t = self.accept(index)
self.chk.check_subtype(t, self.named_type('builtins.int'),
self.chk.check_subtype(t, expected,
index, messages.INVALID_SLICE_INDEX)
return self.named_type('builtins.slice')

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1 change: 1 addition & 0 deletions test-data/unit/check-expressions.test
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Expand Up @@ -998,6 +998,7 @@ a[:o] # E: Slice index must be an integer or None
[builtins fixtures/slice.pyi]

[case testNoneSliceBounds]
# flags: --strict-optional
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We should probably test this both with and without strict-optional.

from typing import Any
a = None # type: Any
a[None:1]
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