Allow to change error code on existing warnings with `--min-severity=warn`

[sobolevn]

Right now there's no way to fail the CI on warnings shown :(
The option to optionally fail the CI would be amazing.

[samwgoldman]

Yeah, maybe we should provide an option to treat warnings as errors, similar to -Werror in gcc/clang. I think this could be useful in CI while still allowing warnings during local development.

One thing you can do today is override the severity for unnecessary-type-conversion from warn to error in your pyrefly configuration. You can still run your program even if there are type errors, so using error severity always might be okay for your workflow.

In pyrefly.toml:

[errors]
unnecessary-type-conversion = "error"

Or pyproject.toml:

[tool.pyrefly.errors]
unnecessary-type-conversion = "error"

[sobolevn]

Thanks! While I can do this for a single known error code, I can't do that for any new potential warning. Projects that want to keep 0 known warnings policy has no options for it now.

[jbrunton96]

I'd like this feature as well. We're currently using Pyright with a few settings as warning severity to make them look distinct from actual type errors, but use pyright --warnings to fail CI if there's any warnings in the code. Would be really nice to be able to do that in Pyrefly so we don't need to set everything to error