Type hinting a return type as nullable renders None

[ViRuSTriNiTy]

Bug description

Hi there,

the following code

class Foo:
    def bar() -> int | None:
        pass

produces

meaning None is not considered as part of the type hint. My current workaround is to revert back to Optional[T] like

class Foo:
    def bar() -> Optional[int]:
        pass

which correctly produces

I think the handling for the new syntax for nullable is missing, which would explain why Optional[T] is working but T | None is not.

Configuration

`pyreverse --version`


pyreverse is included in pylint:
pylint 2.17.2
astroid 2.15.3
Python 3.11.2 (tags/v3.11.2:878ead1, Feb  7 2023, 16:38:35) [MSC v.1934 64 bit (AMD64)]

### Command used

```shell
`pyreverse -o png -m y src/mt5_proxies`

Pylint output

See bug description

Expected behavior

Type hint T | None is correctly handled like Option[T]

Pylint version

Python 3.11.2

OS / Environment

No response

Additional dependencies

No response

[ViRuSTriNiTy]

It seems that there is a general issue with the X | Y syntax as using int | str produces the same result.

[ViRuSTriNiTy]

Hmm, seems like the output type is involved here too. Using the built-in mermaidjs printer produces the diagram correctly:

[Pierre-Sassoulas]

Thank you for the analysis @ViRuSTriNiTy, we probably need to change the rendering to handle the | operator for renderer that do not support it natively. The code to change would be here for plantuml and here for dot. So probably replace the generic pylint.pyreverse.utils.get_annotation_label to something specific to each printer.

[ViRuSTriNiTy]

@Pierre-Sassoulas Thanks for pointing me into the right direction.

I think I found the line that produces the wrong output, already added some commits in my fork. It is caused by missing escape handling. The docs of the DOT language mention this requirement in section Record-based Nodes with

Braces, vertical bars and angle brackets must be escaped with a backslash character if you wish them to appear as a literal character.

I will provide a PR to fix this.