"E1130: bad operand type for unary -: ArrayImpl (invalid-unary-operand-type)" pylint errors in latest release (0.4.24)

[fabianp]

Description

Running pylint (pylint test.py) on this simple file

"""Test file for 'E1130: bad operand type for unary -:'."""
from jax import numpy as jnp

a = -jnp.ones([])

fails with the latest release of jax (0.4.24) :

❯ pylint test.py
************* Module test
test.py:4:4: E1130: bad operand type for unary -: ArrayImpl (invalid-unary-operand-type)

-------------------------------------

The same code doesn't raise any error with jax 0.4.23.

This has led to some tests failures in other packages such as optax

What jax/jaxlib version are you using?

0.4.24 0.4.24

Which accelerator(s) are you using?

CPU

Additional system info?

Tried on both linux and mac

NVIDIA GPU info

No response

[jakevdp]

Hi - thanks for the report. Do you understand where pytype is inferring that ones returns ArrayImpl? The pyi file has not changed, and declares that ones returns Array unconditionally: https://github.com/google/jax/blob/4c505f8bac45517970149b13343988090fdaa920/jax/numpy/__init__.pyi#L610-L611

I just double-checked that the pyi file is included in the v0.4.24 distribution, so I'm not sure why pytype would be ignoring it. Do you have any ideas?

[fabianp]

Thanks Jake for the prompt reply.

No, I don't understand why pylint is doing that inference. A couple of more observations:

• changing -jnp.ones([]) to jnp.negative(jnp.ones([])) works fine (does not raise the error)
• I don't think the error is specific to jnp.ones. In particular, -jnp.full([], 2.) has the same issue

[jakevdp]

Chatting with @superbobry, it seems this is coming from pylint, not pytype. pylint has some level of type checking built-in, but it seems that it ignores pyi files and thus will not work correctly with dynamically-defined attributes. Here's a repro:

$ ls
mymodule.py  mymodule.pyi  test.py

$ cat mymodule.py
class Foo:
  pass
setattr(Foo, "__neg__", lambda self: self)

$ cat mymodule.pyi
class Foo:
  def __neg__(self) -> Foo: ...

$ cat test.py
"""Test file for incorrect E1130"""
from mymodule import Foo
result = -Foo()

$ mypy test.py
Success: no issues found in 1 source file

$ pylint test.py
************* Module test
test.py:3:9: E1130: bad operand type for unary -: Foo (invalid-unary-operand-type)

------------------------------------------------------------------
Your code has been rated at 0.00/10 (previous run: 0.00/10, +0.00)

So in summary, this looks like a bug in pylint – it's trying to do type checking without taking into account the interface files that we've defined for the sake of type checking.

What do you think?

[fabianp]

Thanks @jakevdp for reporting this upstream! I'll close the issue here since it does seem more of an issue in pylint