graphviz typing error

[barakatzir]

Information

graphviz_draw has wrong documentation of return type both in type annotation and docstring. It is marked as PIL.Image when in fact it should be PIL.Image.Image. This confused me for a good while, since the module is both camel cased and has the same name as the correct return type...

"Doctesting" with pyright, pyright --verifytypes rustworkx, reports the wrong documentation in the type annotation (mypy -p rustworkx misses it due to a # type: ignore on that line) .

• rustworkx version: 0.15.1
• Python version: 3.13

Steps to reproduce the problem

Use graphviz_draw anywhere and check your script and check with pyright or mypy, the return type is inferred incorrectly.

# script.py
from __future__ import annotations
from typing import reveal_type
import rustworkx

g: rustworkx.PyGraph[int, int] = rustworkx.PyGraph()
img = rustworkx.visualization.graphviz_draw(g)
reveal_type(img)

In runtime python script.py reports correctly Runtime type is 'PngImageFile' (PngImageFile is a subtype if Image.Image).

The two type checkers fail, one has missing inferred type and the other is wrong:

• If ran with pyright then output is script.py:8:13 - information: Type of "img" is "Unknown".
• If ran with mypy then output is script.py:8: note: Revealed type is "None".

[IvanIsCoding]

I need to check if this still applies to main with the latest commit after #1291. I believe the answer will be no.

None is a valid return type for that function though. If you specific a file it just writes to it. Maybe we should use @overload to split the file case with the in-memory case

[barakatzir]

Ah, sorry. I forgot to check main before opening the issue. It does look as though this is solved in main.

An @overload can be really nice here actually. If you're at it, you can also remove the uneeded # type: ignore if you want.

Thanks again for the quick response and a great package :)

[IvanIsCoding]

I have quite a few typing PRs open. Once Matthew has time to review them, I will work on the @overload and removing the # type: ignore.

I think the ignore was there initially because Pillow didn't have type stubs initially. And then we never updated it

[barakatzir]

Both mypy and pyright can be configured to emit an error if there is an unusued # type: ignore. For mypy --warn-unused-ignores or warn_unused_ignores. For pyright reportUnnecessaryTypeIgnoreComment.

[IvanIsCoding]

I have revisited this with pyright and overall the results do not seem very useful to me.

For graphviz specifically:

  /home/ivan/.venv/lib64/python3.13/site-packages/rustworkx/visualization/graphviz.pyi:17:23 - error: Type of parameter "graph" is partially unknown
    Parameter type is "PyDiGraph[_S@graphviz_draw, _T@graphviz_draw] | PyGraph[_S@graphviz_draw, _T@graphviz_draw]"

We annotated the argument with graph: PyDiGraph[_S, _T] | PyGraph[_S, _T], which for me seems to explicitly tell what the argument is. I found https://github.com/microsoft/pyright/issues/698 but that gave me more questions then doubts given we are using TypeVar

[barakatzir]

That's very surprising, @IvanIsCoding. How did you run pyright?

When I use rustworkx v0.16 with all the type-annotations improvements ️(♥️), pyright seems to be happy even in strict mode. In a fresh project I ran pip install rustworkx pyright pillow pydot and checked the script

# t.py
from __future__ import annotations
from typing import reveal_type
import rustworkx
import rustworkx.visualization

g1: rustworkx.PyGraph[int, int] = rustworkx.PyGraph()
img = rustworkx.visualization.graphviz_draw(g1)
reveal_type(img)

g2 = rustworkx.PyGraph[int, int]()
img = rustworkx.visualization.graphviz_draw(g2)
reveal_type(img)

g3 = rustworkx.PyGraph()
img = rustworkx.visualization.graphviz_draw(g3)
reveal_type(img)

Adding pyrightconfig.json to project root

{
    "typeCheckingMode": "strict",
}

I get no errors:

(.venv) $ pyright t.py
/home/barak-katzir/dev/rustworkx-check/t.py
  /home/barak-katzir/dev/rustworkx-check/t.py:9:13 - information: Type of "img" is "Image | None"
  /home/barak-katzir/dev/rustworkx-check/t.py:13:13 - information: Type of "img" is "Image | None"
  /home/barak-katzir/dev/rustworkx-check/t.py:17:13 - information: Type of "img" is "Image | None"
0 errors, 0 warnings, 3 informations 

Maybe pyright is confused by the rustworkx shim?

I did notice that the script I listed in the original post above still doesn't pass pyright, but for a different reason. pyright doesn't detect the rustworkx.visualization module without explicitly importing it, which is why I added the import rustworkx.visualization to the t.py test script.

[IvanIsCoding]

@barakatzir I just ran pyright --verifytypes rustworkx with the latest rustworkx distributed in PyPI and this is what I got: https://pastebin.com/TZjZDjYq

There are lots of errors ranging from errors propagating from the NumPy stubs to many other complaints about rustworkx. I will try to understand and possibly address them but overall for now I will say the output from mypy has been more useful for me

[barakatzir]

Wow! That is a very long list. I don't remember it being that long. I'll have a look at it after a good night's sleep.

[barakatzir]

Okay, so pyright indeed has an... opinionated default for whether to recurse through dependencies in --verifytypes, but this can be turned off with --ignoreexternal. If I do so I find a single error, a missing annotation of the aspect_ratio parameter in bipartite_layout function in rustworkx/__init__.pyi. I used the same strict setting as before:

(.venv) $ pyright --verifytypes rustworkx --ignoreexternal
Module name: "rustworkx"
Package directory: "/home/barak-katzir/dev/rustworkx-check/.venv/lib/python3.12/site-packages/rustworkx"
Module directory: "/home/barak-katzir/dev/rustworkx-check/.venv/lib/python3.12/site-packages/rustworkx"
Path of py.typed file: "/home/barak-katzir/dev/rustworkx-check/.venv/lib/python3.12/site-packages/rustworkx/py.typed"

Public modules: 7
   rustworkx
   rustworkx.generators
   rustworkx.rustworkx
   rustworkx.visit
   rustworkx.visualization
   rustworkx.visualization.graphviz
   rustworkx.visualization.matplotlib

Symbols used in public interface:
rustworkx.bipartite_layout
  /home/barak-katzir/dev/rustworkx-check/.venv/lib/python3.12/site-packages/rustworkx/__init__.pyi:461:5 - error: Type annotation for parameter "aspect_ratio" is missing

Symbols exported by "rustworkx": 707
  With known type: 706
  With ambiguous type: 0
  With unknown type: 1
    (Ignoring unknown types imported from other packages)

Other symbols referenced but not exported by "rustworkx": 59
  With known type: 59
  With ambiguous type: 0
  With unknown type: 0

Symbols without documentation:
  Functions without docstring: 586
  Functions without default param: 288
  Classes without docstring: 89

Type completeness score: 99.9%

Completed in 1.258sec

When I locally fix the annotation, pyright does not emit errors.

[barakatzir]

Note that if you want to add both mypy and pyright to do type checking they can clash in their pragma comment syntax.

If you do plan to add both I suggest you set "enableTypeIgnoreComments": false in pyright so that it is suppressed with # pyright: ignore[...] only.

This is only really problematic if you want them to emit an error for unnecessary ignores and their diagnosis differ (which does happen), but I think it is better to have separate ignores nonetheless (for pyright the setting is "reportUnnecessaryTypeIgnoreComment": "error", in the config and for mypy it is warn_unused_ignores = true).

I'm mentioning to hopefully save you time. I wasted a good hour on re-ignoring stuff in a private project.