Update dependencies #8006
Update dependencies #8006
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Mypy is still failing with this error: Which to me seems like a bug because I would be inclined to just downgrade it again or add a workaround since I don't have the time or energy to make a standalone reproduce for upstream. If someone else is interested through you are quite welcome to take a crack! |
Contrary to what I thought at the time when initially writing this,
typing.AnyStr isn't just an alias for IO[str] | IO[bytes], but is actually a
TypeVar. As per the Python docs, it should be used when there are *multiple*
places where the types need to match:
def concat(a: AnyStr, b: AnyStr) -> AnyStr:
return a + b
What we do instead is somewhat akin to "def fun() -> T:", which mypy already
comments on:
error: A function returning TypeVar should receive at least one argument
containing the same TypeVar [type-var]
def t() -> T:
Not quite sure why it doesn't in this case, or why it now raises an additional
error (possibly the new inferrence code or something?). Either way, with this
commit the annotations are now more correctly using Union[IO[str], IO[bytes]],
including typing.Literal overloads so that mypy actually knows what specific
type will be returned by a call.
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The error reporting in mypy is indeed a bit suboptimal. Here is a reproducer with some stuff I tried: import io
import contextlib
from typing import Iterator, IO, AnyStr, TypeVar
T = TypeVar("T", str, bytes)
def t() -> T:
return 42
def fun() -> IO[AnyStr]:
return io.StringIO()
def gen() -> Iterator[IO[AnyStr]]:
yield io.StringIO()
@contextlib.contextmanager
def ctx() -> Iterator[IO[AnyStr]]:
yield io.StringIO()Possibly related: However, I think I've been using |
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Oh, the mypy 1.7.0 changelog says this under "Improved Type Inference":
Which seems to pretty much be what we're seeing here. |
This was fixed up in #8006 after a mypy update caused us to examine the typing.AnyStr thing a bit more. But both overloads got set to have a `str` return type, so the possible bytes return type got lost. Mypy didn't pick that up because `binary=True` is only used in `qutebrowser/browser/webkit/cookies.py` which probably isn't being type checked. I had to remove the default from the binary arg of the bytes version (the ` = ...` bit) because if both overloads have the kwarg as optional mypy doesn't know which to match a call with just one positional argument against. Eg `savefile_open('some_file')` would match both. I checked with reveal_type: diff --git i/qutebrowser/utils/qtutils.py w/qutebrowser/utils/qtutils.py index 89175ca4ee60..5b86e441a1bc 100644 --- i/qutebrowser/utils/qtutils.py +++ w/qutebrowser/utils/qtutils.py @@ -290,6 +290,20 @@ def savefile_open( raise QtOSError(f, msg="Commit failed!") +def test_savefile_types() -> None: + from typing_extensions import reveal_type + + maybe_str_default = savefile_open("/tmp/string_file") + # note: Revealed type is "contextlib._GeneratorContextManager[typing.IO[builtins.str]]" + reveal_type(maybe_str_default) + maybe_str_explicit = savefile_open("/tmp/string_file", binary=False) + # note: Revealed type is "contextlib._GeneratorContextManager[typing.IO[builtins.str]]" + reveal_type(maybe_str_explicit) + maybe_bytes = savefile_open("/tmp/bytes_file", binary=True) + # note: Revealed type is "contextlib._GeneratorContextManager[typing.IO[builtins.bytes]]" + reveal_type(maybe_bytes) + + def qcolor_to_qsscolor(c: QColor) -> str: """Convert a QColor to a string that can be used in a QStyleSheet.""" ensure_valid(c)
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