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joey-laminar opened this issue Jan 6, 2022 · 1 comment · Fixed by #11962
Closed

Make enum values final #11919

joey-laminar opened this issue Jan 6, 2022 · 1 comment · Fixed by #11962
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bug mypy got something wrong topic-enum

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@joey-laminar
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#10852 made it so that boolean values are correctly identified as Literals in an enum. Other values seem to not be:

from enum import Enum

class Truth(Enum):
    true = True
    false = False

class MyInt(Enum):
    a = 0
    b = 1

class MyStr(Enum):
    a = "a"
    b = "b"

reveal_type(Truth.false.value)
reveal_type(MyInt.a.value)
reveal_type(MyStr.a.value)

Results in:

a.py:15: note: Revealed type is "Literal[False]?"
a.py:16: note: Revealed type is "builtins.int"
a.py:17: note: Revealed type is "builtins.str"

Expected result:

a.py:15: note: Revealed type is "Literal[False]?"
a.py:16: note: Revealed type is "Literal[0]"
a.py:17: note: Revealed type is "Literal['a']"

The enum members themselves (MyInt.a) are correctly identified as final, but their values should be as well
@joey-laminar joey-laminar added the bug mypy got something wrong label Jan 6, 2022
@joey-laminar
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Some experimentation shows that commenting out lvalue.is_inferred_def = False inside of store_declared_types in semanal.py fixes this issue, although I'm sure it breaks a bunch of other things. I don't yet understand enough to know why this is called for all types except bool

joey-laminar added a commit to joey-laminar/mypy that referenced this issue Jan 10, 2022
@joey-laminar
Make enum values final - fixes python#11919
10ccceb 
This fix allows using enum values in place of literals.

For example:

```
def is_a(a: Literal["a"]): return None
class MyStr(Enum):
    a = "a"
    b = "b"

is_a(MyStr.a.value)
```

Currently this fails with

```
error: Argument 1 to "is_a" has incompatible type "str"; expected "Literal['a']"
```

The fix itself is simple - the special casing of  final status for enums was being
called too late to have an effect. Moving the function call up solves
the problem.
@joey-laminar joey-laminar mentioned this issue Jan 10, 2022
Merged
JelleZijlstra pushed a commit that referenced this issue Jan 10, 2022
@joey-laminar
Make enum values final - fixes #11919 (#11962)
48d810d 
This fix allows using enum values in place of literals.

For example:

```
def is_a(a: Literal["a"]): return None
class MyStr(Enum):
    a = "a"
    b = "b"

is_a(MyStr.a.value)
```

Currently this fails with

```
error: Argument 1 to "is_a" has incompatible type "str"; expected "Literal['a']"
```

The fix itself is simple - the special casing of  final status for enums was being
called too late to have an effect. Moving the function call up solves
the problem.

Fixes #11919
tushar-deepsource pushed a commit to DeepSourceCorp/mypy that referenced this issue Jan 20, 2022
@joey-laminar @tushar-deepsource
Make enum values final - fixes python#11919 (python#11962)
c0ba36a 
This fix allows using enum values in place of literals.

For example:

```
def is_a(a: Literal["a"]): return None
class MyStr(Enum):
    a = "a"
    b = "b"

is_a(MyStr.a.value)
```

Currently this fails with

```
error: Argument 1 to "is_a" has incompatible type "str"; expected "Literal['a']"
```

The fix itself is simple - the special casing of  final status for enums was being
called too late to have an effect. Moving the function call up solves
the problem.

Fixes python#11919
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Make enum values final - fixes #11919 joey-laminar/mypy
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@97littleleaf11 @joey-laminar