Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Friendlier errors for PEP 612 #12832

Merged
merged 3 commits into from May 23, 2022
Merged

Friendlier errors for PEP 612 #12832

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
793a9b9
Improve Callable error for PEP 612
May 21, 2022
5abcf0a
more errors
May 21, 2022
bd1cf23
fix test
May 21, 2022
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Jump to
Jump to file
Failed to load files.
Diff view
Diff view
14 changes: 11 additions & 3 deletions mypy/typeanal.py
View file
Open in desktop
Expand Up @@ -944,9 +944,13 @@ def analyze_callable_type(self, t: UnboundType) -> Type:
)
if maybe_ret is None:
# Callable[?, RET] (where ? is something invalid)
# TODO(PEP612): change error to mention paramspec, once we actually have some
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Or Concatenate?

Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Though that's getting a bit much for an error message.

Copy link
Collaborator

@ethanhs ethanhs May 21, 2022 •
edited

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I like the new language, maybe a note linking to some docs would be useful in addition however.

Copy link
Collaborator Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Yeah, Concatenate is why I went with the more generic "parameter specification" rather than "ParamSpec". This error is probably disproportionately encountered by new users, so don't want it to be too scary.

I could add a note for https://mypy.readthedocs.io/en/stable/kinds_of_types.html#callable-types-and-lambdas

# support for it
self.fail('The first argument to Callable must be a list of types or "..."', t)
self.fail(
'The first argument to Callable must be a '
'list of types, parameter specification, or "..."', t)
self.note(
'See https://mypy.readthedocs.io/en/stable/kinds_of_types.html#callable-types-and-lambdas', # noqa: E501
t
)
return AnyType(TypeOfAny.from_error)
ret = maybe_ret
else:
Expand Down Expand Up @@ -1180,6 +1184,10 @@ def anal_type(self, t: Type, nested: bool = True, *, allow_param_spec: bool = Fa
and analyzed.flavor == ParamSpecFlavor.BARE):
if analyzed.prefix.arg_types:
self.fail('Invalid location for Concatenate', t)
self.note(
'You can use Concatenate as the first argument to Callable',
t
)
else:
self.fail(f'Invalid location for ParamSpec "{analyzed.name}"', t)
self.note(
Expand Down
3 changes: 2 additions & 1 deletion test-data/unit/check-parameter-specification.test
View file
Open in desktop
Expand Up @@ -25,7 +25,8 @@ def foo1(x: Callable[P, int]) -> Callable[P, str]: ...
def foo2(x: P) -> P: ... # E: Invalid location for ParamSpec "P" \
# N: You can use ParamSpec as the first argument to Callable, e.g., 'Callable[P, int]'

def foo3(x: Concatenate[int, P]) -> int: ... # E: Invalid location for Concatenate
def foo3(x: Concatenate[int, P]) -> int: ... # E: Invalid location for Concatenate \
# N: You can use Concatenate as the first argument to Callable

def foo4(x: List[P]) -> None: ... # E: Invalid location for ParamSpec "P" \
# N: You can use ParamSpec as the first argument to Callable, e.g., 'Callable[P, int]'
Expand Down
3 changes: 2 additions & 1 deletion test-data/unit/semanal-errors.test
View file
Open in desktop
Expand Up @@ -867,7 +867,8 @@ x = None # type: Callable[int, str]
y = None # type: Callable[int]
z = None # type: Callable[int, int, int]
[out]
main:2: error: The first argument to Callable must be a list of types or "..."
main:2: error: The first argument to Callable must be a list of types, parameter specification, or "..."
main:2: note: See https://mypy.readthedocs.io/en/stable/kinds_of_types.html#callable-types-and-lambdas
main:3: error: Please use "Callable[[<parameters>], <return type>]" or "Callable"
main:4: error: Please use "Callable[[<parameters>], <return type>]" or "Callable"

Expand Down