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Generic typeddict may corrupt the cache #14638
Description
Bug Report
Using a generic TypedDict in another module may corrupt the cache. The cache doesn't recover and must be deleted.
To Reproduce
In module a, define a generic TypedDict,
# a.py
from typing import TypedDict, Generic, TypeVar
TValue = TypeVar("TValue")
class Dict(TypedDict, Generic[TValue]):
value: TValuein another module (say b) use this definition. The easiest way to trigger the bug is to have at least one typing error in the file (here g()).
# b.py
from a import Dict, TValue
def f(d: Dict[TValue]) -> TValue:
return d["value"]
def g(d: Dict[TValue]) -> TValue:
return d["x"] # errorNow, type check b
$ mypy b.py
b.py:8: error: TypedDict "a.Dict[TValue]" has no key "x" [typeddict-item]
Found 1 error in 1 file (checked 1 source file)
as expected.
However, running mypy b.py a second time reports an extra [type-arg] and a few more related errors as well,
$ mypy b.py
b.py:3: error: "Dict" expects no type arguments, but 1 given [type-arg]
b.py:3: error: A function returning TypeVar should receive at least one argument containing the same TypeVar [type-var]
b.py:4: error: Incompatible return value type (got "TValue", expected "TValue") [return-value]
b.py:7: error: "Dict" expects no type arguments, but 1 given [type-arg]
b.py:7: error: A function returning TypeVar should receive at least one argument containing the same TypeVar [type-var]
b.py:8: error: TypedDict "a.Dict[TValue]" has no key "x" [typeddict-item]
Found 6 errors in 1 file (checked 1 source file)
from then on, the only way to get rid of the [type-arg] error is to run with --no-increment or delete the cache. Here, I removed g(), leaving
# b.py [edited: deleted definition of g()]
from a import Dict, TValue
def f(d: Dict[TValue]) -> TValue:
return d["value"]and
$ mypy b.py
b.py:3: error: "Dict" expects no type arguments, but 1 given [type-arg]
b.py:3: error: A function returning TypeVar should receive at least one argument containing the same TypeVar [type-var]
b.py:4: error: Incompatible return value type (got "TValue", expected "TValue") [return-value]
Found 3 errors in 1 file (checked 1 source file)
but
$ mypy --no-increment b.py
Success: no issues found in 1 source file
Expected Behavior
No difference between mypy, mypy --no-increment and the generic TypedDict do not corrupt the cache.
Actual Behavior
mypy reports false positives
b.py:3: error: "Dict" expects no type arguments, but 1 given [type-arg]
b.py:3: error: A function returning TypeVar should receive at least one argument containing the same TypeVar [type-var]
b.py:4: error: Incompatible return value type (got "TValue", expected "TValue") [return-value]
Your Environment
- Mypy version used: 0.991, 1.0.0, master
- Mypy command-line flags:
mypyvs.mypy --no-increment - Mypy configuration options from
mypy.ini(and other config files): none - Python version used: 3.11 or importing
TypedDictfrommypy_extensionson Python 3.10.
I could also reproduce that under Linux (Ubuntu 22.04) and MacOS (M1---Python installed via MacPorts).
Activity
Fix generic TypedDict/NamedTuple fixup (#14675)
Fix generic TypedDict/NamedTuple fixup (python#14675)
Re-enable mypy cache