Cannot create consistent method ordering when creating a class with multiple inheritance from the typing module #361

chrisnorman7 · 2020-09-11T14:44:17Z

Environment data

Language Server version: 2020.9.4
OS and version: Microsoft Windows [Version 10.0.19041.508]
Python version (& distribution if applicable, e.g. Anaconda): Python 3.8.5 (tags/v3.8.5:580fbb0, Jul 20 2020, 15:57:54) [MSC v.1924 64 bit (AMD64)] on win32

Expected behaviour

I should be able to create a class with multiple inheritance, and Pylance should be able to figure everything out.

Actual behaviour

I get the following error:

{
	"resource": "/c:/Users/chris/src/breaking/breaking.py",
	"owner": "_generated_diagnostic_collection_name_#0",
	"severity": 8,
	"message": "Cannot create consistent method ordering",
	"source": "Pylance",
	"startLineNumber": 6,
	"startColumn": 7,
	"endLineNumber": 6,
	"endColumn": 8
}

Logs

[Info  - 15:28:11] Pylance language server 2020.9.4 (pyright 9983747f) starting
[Info  - 15:28:11] Server root directory: c:\Users\chris\.vscode\extensions\ms-python.vscode-pylance-2020.9.4\dist
[Error - 15:28:11] stubPath typings is not a valid directory.
[Info  - 15:38:50] No configuration file found.
[Info  - 15:38:50] Setting pythonPath for service "breaking": "c:\Users\chris\src\breaking\env\Scripts\python.exe"
[Error - 15:38:50] stubPath typings is not a valid directory.
[Info  - 15:38:51] Assuming Python version 3.8
[Info  - 15:38:51] Assuming Python platform Windows
[Info  - 15:38:51] Searching for source files
[Info  - 15:38:51] Auto-excluding c:\Users\chris\src\breaking\env
[Info  - 15:38:51] Found 1 source file
Background analysis message: setConfigOptions
Background analysis message: setTrackedFiles
Background analysis message: markAllFilesDirty
Background analysis message: analyze
Background analysis message: setFileOpened
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange
[FG] parsing: c:\Users\chris\src\breaking\breaking.py (18ms)
[FG] parsing: c:\Users\chris\.vscode\extensions\ms-python.vscode-pylance-2020.9.4\dist\typeshed-fallback\stdlib\2and3\builtins.pyi (1239ms)
[FG] binding: c:\Users\chris\.vscode\extensions\ms-python.vscode-pylance-2020.9.4\dist\typeshed-fallback\stdlib\2and3\builtins.pyi (105ms)
[FG] binding: c:\Users\chris\src\breaking\breaking.py (5ms)
Background analysis message: analyze
[BG(1)] analyzing: c:\Users\chris\src\breaking\breaking.py ...
[BG(1)]   parsing: c:\Users\chris\src\breaking\breaking.py (16ms)
[BG(1)]   parsing: c:\Users\chris\.vscode\extensions\ms-python.vscode-pylance-2020.9.4\dist\typeshed-fallback\stdlib\2and3\builtins.pyi (96ms)
[BG(1)]   binding: c:\Users\chris\.vscode\extensions\ms-python.vscode-pylance-2020.9.4\dist\typeshed-fallback\stdlib\2and3\builtins.pyi (39ms)
[BG(1)]   binding: c:\Users\chris\src\breaking\breaking.py (0ms)
[BG(1)]   checking: c:\Users\chris\src\breaking\breaking.py ...
[BG(1)]     parsing: c:\Users\chris\.vscode\extensions\ms-python.vscode-pylance-2020.9.4\dist\typeshed-fallback\stdlib\3\typing.pyi (32ms)
[BG(1)]     binding: c:\Users\chris\.vscode\extensions\ms-python.vscode-pylance-2020.9.4\dist\typeshed-fallback\stdlib\3\typing.pyi (9ms)
[BG(1)]     parsing: c:\Users\chris\.vscode\extensions\ms-python.vscode-pylance-2020.9.4\dist\typeshed-fallback\stdlib\3\abc.pyi (5ms)
[BG(1)]     binding: c:\Users\chris\.vscode\extensions\ms-python.vscode-pylance-2020.9.4\dist\typeshed-fallback\stdlib\3\abc.pyi (0ms)
[BG(1)]   checking: c:\Users\chris\src\breaking\breaking.py (85ms)
[BG(1)] analyzing: c:\Users\chris\src\breaking\breaking.py (236ms)
Background analysis message: getSemanticTokens
Background analysis message: getSemanticTokens
Background analysis message: resumeAnalysis
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange
Background analysis message: setFileOpened
Background analysis message: markFilesDirty
Background analysis message: getSemanticTokens
[BG(1)] parsing: c:\Users\chris\src\breaking\breaking.py (1ms)
[BG(1)] binding: c:\Users\chris\src\breaking\breaking.py (1ms)
Background analysis message: analyze
[BG(1)] analyzing: c:\Users\chris\src\breaking\breaking.py ...
[BG(1)]   checking: c:\Users\chris\src\breaking\breaking.py (13ms)
[BG(1)] analyzing: c:\Users\chris\src\breaking\breaking.py (13ms)
Background analysis message: resumeAnalysis
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange
Background analysis message: markFilesDirty
Background analysis message: analyze
[FG] parsing: c:\Users\chris\src\breaking\breaking.py (3ms)
[FG] binding: c:\Users\chris\src\breaking\breaking.py (1ms)
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange
Background analysis message: setFileOpened
Background analysis message: markFilesDirty
Background analysis message: getSemanticTokens
[BG(1)] parsing: c:\Users\chris\src\breaking\breaking.py (0ms)
[BG(1)] binding: c:\Users\chris\src\breaking\breaking.py (1ms)
Background analysis message: analyze
[BG(1)] analyzing: c:\Users\chris\src\breaking\breaking.py ...
[BG(1)]   checking: c:\Users\chris\src\breaking\breaking.py (46ms)
[BG(1)] analyzing: c:\Users\chris\src\breaking\breaking.py (46ms)
Background analysis message: resumeAnalysis
Background analysis message: markFilesDirty
Background analysis message: analyze
[FG] parsing: c:\Users\chris\src\breaking\breaking.py (4ms)
[FG] binding: c:\Users\chris\src\breaking\breaking.py (0ms)
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange
Background analysis message: getDiagnosticsForRange

Code Snippet / Additional information

from typing import Generic, Iterator, Mapping, TypeVar

T = TypeVar('T')


class B(Generic[T], Mapping[str, T]):
    pass

    def __len__(self) -> int:
        return 0

    def __getitem__(self, k: str) -> T:
        return NotImplemented

    def __iter__(self) -> Iterator[str]:
        return iter([])

I created the above code in a clean virtualenv, with no extra packages installed.

The text was updated successfully, but these errors were encountered:

erictraut · 2020-09-11T15:29:59Z

Thanks for the report. The standard Python rules for constructing an MRO (method resolution ordering) would normally indicate that a proper MRO cannot be created in this case because Mapping derives from Generic. However, the Python interpreter isn't complaining in this case, so I presume that the Generic class is special-cased. There is nothing in the spec that indicates this, but empirical evidence would indicate as such. I can add this special-case handling to Pylance/Pyright to match the behavior of the interpreter.

As a workaround in the meantime, you can simply delete Generic[T] from your list of base classes. Generic[T] is unnecessary in this case because Mapping[str, T] already introduces the type variable T for your class B.

class B(Mapping[str, T]): ...

PEP 484 say:

The Generic[T] base class is redundant in simple cases where you subclass some other generic class and specify type variables for its parameters.

chrisnorman7 · 2020-09-11T15:40:15Z

Brilliant, thank you. I didn't know that.

erictraut · 2020-09-11T15:46:09Z

I'm going to keep this open for now because there's a bug that I'd still like to address.

erictraut · 2020-09-12T07:22:11Z

The incorrect error will be addressed in the next release of Pylance. Thanks again for reporting the problem.

CatNofishing · 2020-09-16T08:47:43Z

@erictraut Hello, can you solve this problem, no one responded😂，Two weeks have passed. #301

erictraut · 2020-09-16T12:28:32Z

I responded four days ago saying that the problem was fixed, and the fix will be included in the next release of Pylance. We typically release Pylance Wed or Thurs of each week.

chrisnorman7 · 2020-09-16T12:34:32Z

Magic, thank you so much for such a quick fix. Take care, Chris Norman

…

On Sat, 12 Sep 2020 at 08:22, Eric Traut ***@***.***> wrote: The incorrect error will be addressed in the next release of Pylance. Thanks again for reporting the problem. — You are receiving this because you modified the open/close state. Reply to this email directly, view it on GitHub <#361 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABBUZ2KWOUDFICBL6UXRYV3SFMOTBANCNFSM4RHUJ5OA> .

jakebailey · 2020-09-16T22:29:21Z

This issue has been fixed in version 2020.9.5, which we've just released. You can find the changelog here: https://github.com/microsoft/pylance-release/blob/master/CHANGELOG.md#202095-16-september-2020

levrik · 2020-10-13T12:39:23Z

@jakebailey I've just did a first-time install of Pylance (2020.10.0) and hitting exactly this issue.
Was there some regression?

jakebailey · 2020-10-13T17:23:54Z

This is a month old issue that should be fixed (and we typically add regression tests for these sorts of issues). If you see something again please file a new issue with a reproduction so we can track it. Thanks.

lonelygo · 2020-12-05T06:54:47Z

This is a month old issue that should be fixed (and we typically add regression tests for these sorts of issues). If you see something again please file a new issue with a reproduction so we can track it. Thanks.

pylance : 2020.12.0
mac vscode : 1.51.1
Still get this error

erictraut · 2020-12-05T08:14:19Z

@lonelygo, can you provide sample code for a repro?

github-actions bot added the triage label Sep 11, 2020

erictraut added the bug Something isn't working label Sep 11, 2020

github-actions bot removed the triage label Sep 11, 2020

chrisnorman7 closed this as completed Sep 11, 2020

erictraut reopened this Sep 11, 2020

heejaechang assigned heejaechang and unassigned heejaechang Sep 11, 2020

erictraut added the fixed in next version (main) A fix has been implemented and will appear in an upcoming version label Sep 12, 2020

jakebailey closed this as completed Sep 16, 2020

mandel mentioned this issue Feb 17, 2022

Change typing annotations to avoid pylance warnings IBM/lale#991

Merged

vbrodsky mentioned this issue Mar 14, 2023

Vb/document entity annotation al 5106 Labelbox/labelbox-python#987

Merged

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Cannot create consistent method ordering when creating a class with multiple inheritance from the typing module #361

Cannot create consistent method ordering when creating a class with multiple inheritance from the typing module #361

chrisnorman7 commented Sep 11, 2020

erictraut commented Sep 11, 2020

chrisnorman7 commented Sep 11, 2020

erictraut commented Sep 11, 2020

erictraut commented Sep 12, 2020

CatNofishing commented Sep 16, 2020

erictraut commented Sep 16, 2020

chrisnorman7 commented Sep 16, 2020 via email

jakebailey commented Sep 16, 2020

levrik commented Oct 13, 2020

jakebailey commented Oct 13, 2020

lonelygo commented Dec 5, 2020

erictraut commented Dec 5, 2020

Cannot create consistent method ordering when creating a class with multiple inheritance from the typing module #361

Cannot create consistent method ordering when creating a class with multiple inheritance from the typing module #361

Comments

chrisnorman7 commented Sep 11, 2020

Environment data

Expected behaviour

Actual behaviour

Logs

Code Snippet / Additional information

erictraut commented Sep 11, 2020

chrisnorman7 commented Sep 11, 2020

erictraut commented Sep 11, 2020

erictraut commented Sep 12, 2020

CatNofishing commented Sep 16, 2020

erictraut commented Sep 16, 2020

chrisnorman7 commented Sep 16, 2020 via email

jakebailey commented Sep 16, 2020

levrik commented Oct 13, 2020

jakebailey commented Oct 13, 2020

lonelygo commented Dec 5, 2020

erictraut commented Dec 5, 2020