Add check for alternative union syntax - PEP 604

[cdce8p]

Steps

• Add yourself to CONTRIBUTORS if you are a new contributor.
• Add a ChangeLog entry describing what your PR does.
• If it's a new feature or an important bug fix, add a What's New entry in doc/whatsnew/<current release.rst>.
• Write a good description on what the PR does.

Description

Add check for correct usage of alternative union syntax (PEP 604).

Example Python 3.7 - 3.9

from __future__ import annotations  # required

var: int | None
def func() -> str | int:
    ...

Alias = int | None  # [unsupported-binary-operation]

Example Python 3.10+

var: int | None
def func() -> str | int:
    ...

Alias = int | None

Links
https://www.python.org/dev/peps/pep-0604/
https://mypy.readthedocs.io/en/stable/runtime_troubles.html#using-x-y-syntax-for-unions
https://mypy.readthedocs.io/en/stable/runtime_troubles.html#future-annotations

Type of Changes

	Type
	🐛 Bug fix
✓	✨ New feature
	🔨 Refactoring
	📜 Docs

Related Issue

Closes #4065

[Pierre-Sassoulas]

Look like you're going to upgrade from "first time contributor" to "person who implemented all the checks for new typing syntax" as soon as the astroid master is fixed ;)

[cdce8p]

Look like you're going to upgrade from "first time contributor" to "person who implemented all the checks for new typing syntax" as soon as the astroid master is fixed ;)

I just would really like to use the new syntax in a project I frequently contribute to that just upgraded to min Python 3.8. Since we have a lot of beginners, it's just best to have checks in place to catch mistakes early. Especially if it's not exactly clear what works and what doesn't (#4059 😄).

[cdce8p]

@Pierre-Sassoulas Can you also tag it with 2.6.1? I would really like to see it be included in the next release.

[coveralls]

Coverage increased (+0.01%) to 90.569% when pulling 49ecbee on cdce8p:pep604-alternative_union_syntax into b6edb60 on PyCQA:master.

[coveralls]

Coverage increased (+0.01%) to 90.569% when pulling 49ecbee on cdce8p:pep604-alternative_union_syntax into b6edb60 on PyCQA:master.

[coveralls]

Coverage increased (+0.01%) to 90.576% when pulling 49ecbee on cdce8p:pep604-alternative_union_syntax into b6edb60 on PyCQA:master.