False positive on numpy.mgrid

[Brow71189]

Bug Report

The following code triggers a mypy type checking failure:

import numpy

numpy.mgrid[0:10:1j]

Mypy reports "Slice index must be an integer or None" on this code snippet.

Admittedly this is a special case, because numpy.mgrid does not get "called" with parenthesis but square brackets. But a complex number as the third argument to mgrid is valid code and has a special meaning (it makes mgrid create an array with this many entries). See also: https://numpy.org/doc/stable/reference/generated/numpy.mgrid.html

EDIT:

numpy.mgrid also allows floats for the first two "slices", which also triggers a mypy error:

import numpy

numpy.mgrid[-1.5: 1.5]

To Reproduce

Type check the above code snippet with mypy.

Expected Behavior

The above code should pass type checking.

Actual Behavior

Mypy reports "Slice index must be an integer or None".

Your Environment

• Mypy version used: 0.910
• Mypy command-line flags: None
• Mypy configuration options from mypy.ini (and other config files): None
• Python version used: 3.9.7
• Operating system and version: Windows 10
• numpy version: 1.20.3

[ethanhs]

Duplicate of #2410