Add unused-type-ignore rule#3784
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* Projects using multiple type checkers put `# type: ignore` for mypy without wanting pyrefly to flag them, so this rule is a separate opt-in (off by default) distinct from the existing `unused-ignore` rule which covers `# pyrefly: ignore` comments * Added `UnusedTypeIgnore` error kind with `Severity::Ignore` default; extended `collect_unused_ignore_errors` to detect `Tool::Type` suppressions that cover no pyrefly errors on their line, treating any mypy-style codes as blanket since they are not pyrefly codes * Fixed `collect_unused_ignore_errors_for_display` to look up severity by each error's own kind rather than hardcoding `UnusedIgnore`, so the two rules can be configured independently * Added three unit tests and documented the new rule in error-kinds.mdx
* Mirrors the existing unused-ignore LSP test pattern with two tests: one verifying the diagnostic appears when the rule is enabled in config, and one verifying it is silent by default (off-by-default behavior)
yangdanny97
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Jun 12, 2026
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| // For Tool::Type (`# type: ignore`), codes are mypy codes (not pyrefly |
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codes are mypy codes
I'm not sure this is true, I don't think type: ignore as written in the typing spec has official codes
that said, if someone does use it with a code we proabbly can't shouldn't assume we understand it
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I see, sure, I will remove these unnecessary comments.
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I would have thought we could use simpler tests for this, but I checked and the other unused-ignore is tested the same way. I think this is fine for now. This can probably be merged after some editing of the comments @NathanTempest |
* Replace inaccurate "mypy codes" description with a simpler statement of the actual behavior
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Summary
Adds a new
unused-type-ignorerule that reports# type: ignorecomments that are not suppressing any error.Fixes #3766
This rule is off by default to avoid breaking projects using multiple type checkers (e.g. mypy + pyrefly). Enable it in
pyrefly.toml:Test Plan