check/pylint sometimes doesn't check imports

[cduck]

An unused import (Optional) passed CI here: https://github.com/quantumlib/Cirq/blame/master/cirq/ops/pauli_gates.py#L15

Now I'm getting an error for that on Travis: https://travis-ci.com/quantumlib/Cirq/jobs/225990740#L253

When I run pylint locally, I don't catch this or other import errors. This has happened during my last few PRs: https://travis-ci.com/quantumlib/Cirq/jobs/225990740#L251

I updated my local pylint to pylint==2.3.1, astroid==2.1.0 and still don't get the errors that Travis shows.

Can anyone else reproduce this?

[vtomole]

Could it be that the errors have nothing to do with the unused import? What you linked has

cirq/optimizers/eject_phased_paulis_test.py:42:0: C0301: Line too long (83/80) (line-too-long)

cirq/optimizers/eject_phased_paulis_test.py:18:0: C0411: third party import "import numpy as np" should be placed before "import sympy" (wrong-import-order)

Alongside the unused import error.

[cduck]

The same thing happened in #1963 (last commit on Apr 15). I got an unused import error on Travis but no errors locally.

[vtomole]

I just ran your cduck:eject-pauli branch locally on my machine and i received lots of unused imports.

vtomole@vtomole:~/Cirq$ check/pylint
************* Module cirq.neutral_atoms.neutral_atom_devices
cirq/neutral_atoms/neutral_atom_devices.py:18:0: W0611: Unused DefaultDict imported from typing (unused-import)
************* Module cirq.optimizers.eject_z
cirq/optimizers/eject_z.py:17:0: W0611: Unused Dict imported from typing (unused-import)
cirq/optimizers/eject_z.py:17:0: W0611: Unused List imported from typing (unused-import)
cirq/optimizers/eject_z.py:17:0: W0611: Unused Tuple imported from typing (unused-import)
************* Module cirq.work.pauli_sum_collector
cirq/work/pauli_sum_collector.py:16:0: W0611: Unused MutableMapping imported from typing (unused-import)
************* Module cirq.value.linear_dict
cirq/value/linear_dict.py:17:0: W0611: Unused Dict imported from typing (unused-import)
************* Module cirq.sim.simulator
cirq/sim/simulator.py:30:0: W0611: Unused Hashable imported from typing (unused-import)
cirq/sim/simulator.py:30:0: W0611: Unused Tuple imported from typing (unused-import)
************* Module cirq.sim.wave_function_simulator
cirq/sim/wave_function_simulator.py:19:0: W0611: Unused Hashable imported from typing (unused-import)
************* Module cirq.ops.linear_combinations
cirq/ops/linear_combinations.py:15:0: W0611: Unused DefaultDict imported from typing (unused-import)
************* Module cirq.ops.op_tree
cirq/ops/op_tree.py:20:0: W0611: Unused Dict imported from typing (unused-import)
************* Module cirq.ops.pauli_gates
cirq/ops/pauli_gates.py:15:0: W0611: Unused Optional imported from typing (unused-import)
************* Module cirq.experiments.qubit_characterizations
cirq/experiments/qubit_characterizations.py:8:0: W0611: Unused Axes3D imported from mpl_toolkits.mplot3d (unused-import)
************* Module cirq.google.serializable_gate_set
cirq/google/serializable_gate_set.py:18:0: W0611: Unused List imported from typing (unused-import)
cirq/google/serializable_gate_set.py:18:0: W0611: Unused Type imported from typing (unused-import)
************* Module cirq.google.engine.engine
cirq/google/engine/engine.py:33:0: W0611: Unused Tuple imported from typing (unused-import)
************* Module cirq.protocols.has_unitary
cirq/protocols/has_unitary.py:15:0: W0611: Unused Dict imported from typing (unused-import)
************* Module cirq.contrib.acquaintance.optimizers
cirq/contrib/acquaintance/optimizers.py:15:0: W0611: Unused FrozenSet imported from typing (unused-import)
cirq/contrib/acquaintance/optimizers.py:15:0: W0611: Unused List imported from typing (unused-import)
cirq/contrib/acquaintance/optimizers.py:15:0: W0611: Unused Set imported from typing (unused-import)
************* Module cirq.contrib.acquaintance.executor
cirq/contrib/acquaintance/executor.py:15:0: W0611: Unused List imported from typing (unused-import)
************* Module cirq.contrib.qasm_import._parser
cirq/contrib/qasm_import/_parser.py:16:0: W0611: Unused Dict imported from typing (unused-import)
cirq/contrib/qasm_import/_parser.py:16:0: W0611: Unused Optional imported from typing (unused-import)
************* Module cirq.contrib.paulistring.convert_to_pauli_string_phasors
cirq/contrib/paulistring/convert_to_pauli_string_phasors.py:15:0: W0611: Unused List imported from typing (unused-import)
************* Module cirq.vis.heatmap
cirq/vis/heatmap.py:29:0: W0611: Unused List imported from typing (unused-import)

I also have pylint==2.3.1, astroid==2.1.0. I always get these but i ignore them and they pass on Travis.

[cduck]

At least some of those are imports only used in a type comment. The latest pylint version should handle that.

[vtomole]

We are on the latest version on pylint, what we are not on the latest version of is astroid because this bug has not been fixed https://github.com/PyCQA/astroid/issues/650.

[dabacon]

This is growing stale and we probably need someone to repo again to make progress.

[Strilanc]

I still notice pylint checks returning more results on my machine than in ci.

[balopat]

I noticed that the pylintrc has a weird configuration - it used [config] instead of [MASTER] section - not sure how it was working at all - I think we were running pylint with default settings everywhere.

https://github.com/quantumlib/Cirq/pull/3387 is fixing this + upgrades to the latest pylint.

I believe that #3387 should fix this issue.