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9d6d5d4894
Lint overlapping ranges as a separate pass This reworks the [`overlapping_range_endpoints`](https://doc.rust-lang.org/beta/nightly-rustc/rustc_lint_defs/builtin/static.OVERLAPPING_RANGE_ENDPOINTS.html) lint. My motivations are: - It was annoying to have this lint entangled with the exhaustiveness algorithm, especially wrt librarification; - This makes the lint behave consistently. Here's the consistency story. Take the following matches: ```rust match (0u8, true) { (0..=10, true) => {} (10..20, true) => {} (10..20, false) => {} _ => {} } match (true, 0u8) { (true, 0..=10) => {} (true, 10..20) => {} (false, 10..20) => {} _ => {} } ``` There are two semantically consistent options: option 1 we lint all overlaps between the ranges, option 2 we only lint the overlaps that could actually occur (i.e. the ones with `true`). Option 1 is what this PR does. Option 2 is possible but would require the exhaustiveness algorithm to track more things for the sake of the lint. The status quo is that we're inconsistent between the two. Option 1 generates more false postives, but I prefer it from a maintainer's perspective. I do think the difference is minimal; cases where the difference is observable seem rare. This PR adds a separate pass, so this will have a perf impact. Let's see how bad, it looked ok locally. |
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