Invalid protocol definitions and usages

Reports invalid definitions and usages of protocols introduced in PEP-544.

Example:

from typing import Protocol


class MyProtocol(Protocol):
    def method(self, p: int) -> str:
        pass


class MyClass(MyProtocol):
    def method(self, p: str) -> int: # Type of 'method' is not compatible with 'MyProtocol'
        pass


class MyAnotherProtocol(MyClass, Protocol): # All bases of a protocol must be protocols
    pass

Locating this inspection

By ID

Can be used to locate inspection in e.g. Qodana configuration files, where you can quickly enable or disable it, or adjust its settings.

PyProtocol

Via Settings dialog

Path to the inspection settings via IntelliJ Platform IDE Settings dialog, when you need to adjust inspection settings directly from your IDE.

Settings or Preferences | Editor | Inspections | Python

Inspection ID: PyProtocolInspection

Suppressing Inspection

You can suppress this inspection by placing the following comment marker before the code fragment where you no longer want messages from this inspection to appear:

//noinspection PyProtocol

More detailed instructions as well as other ways and options that you have can be found in the product documentation:

Inspection Details
By default bundled with:	CLion 2025.2, DataSpell 2025.2, IntelliJ IDEA 2025.2, PyCharm 2025.2, Qodana for JVM 2025.2,

Last modified: 18 September 2025