Description

The Python bindings use platform.system() for detecting Windows to run platform-specific code in many places. This works fine, but we run into issues with our type checker (mypy). It doesn't respect platform.system(), so we get type errors in some of our platform-specific code when the type checker runs on other platforms. see: comments on #16250

mypy does do the right thing if you use sys.platform for platform detection instead:

https://mypy.readthedocs.io/en/stable/common_issues.html#python-version-and-system-platform-checks

We should investigate where we are using platform.system() and switch to sys.platform if possible.

Reproducible Code

if platform.system() == "Windows"