Pyright showing errors

Vector Version

1.6.3

Python Version

3.12

OS / Environment

Almalinux9 with micromamba environment

Describe the bug

This is the same as:

https://github.com/scikit-hep/vector/issues/611

but I cannot reopen it. I was too busy to get back to it, but it keeps bugging me so I will open this.

The MRW is:

import vector
from vector import MomentumObject4D as v4d

a: v4d = vector.obj(pt=1.0, eta=0.1, phi=0.2, mass=0.5)
b: v4d = vector.obj(pt=2.0, eta=0.2, phi=0.3, mass=0.6)

x = 3
if x == 3:
    d = a
else:
    d = a - b

c = a + b
d = c + d

with pyright I see:

  /home/acampove/Tests/vector/type_error.py:14:5 - error: Operator "+" not supported for types "VectorProtocol" and "MomentumObject4D | VectorProtocol"
    Operator "+" not supported for types "VectorProtocol" and "VectorProtocol" (reportOperatorIssue)
1 error, 0 warnings, 0 informations

with mypy I see:

type_error.py:11: error: Incompatible types in assignment (expression has type "VectorProtocol", variable has type "MomentumObject4D")  [assignment]
type_error.py:14: error: Incompatible types in assignment (expression has type "VectorProtocol", variable has type "MomentumObject4D")  [assignment]
Found 2 errors in 1 file (checked 1 source file)

so, the problem is even worse with mypy.

Any additional but relevant log output

No response

Start with the minimal reproducer in type_error.py and compare its Pyright and mypy results for the Vector type annotations shown. Read the related issue 611 for prior context, then trace the annotations involved in vector.obj and vector arithmetic. Done means the reproducer no longer reports the incompatible operator and assignment errors under the relevant type checkers.