fix: prevent panic when formatting complex generics #6630
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Handle cases where rewrite_generics fails due to long generic constraints by implementing a fallback to infinite width and preserving original formatting when necessary.
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Hi, I just came across your PR. Would it be alright if I try it out to see if #6396 fixes the unwrap error in that test case? (This seems orthogonal to the mentioned PR though, so just to verify whether the issue is duplicate or not) |
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@ding-young Sure, would be good to see. https://github.com/pulseengine/wrt is where my problem originate from. My patch makes this repository format again. Otherwise it actually stripped away code. |
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Fixes #6571
Problem
rustfmt panics with
Option::unwrap() on a None valuewhen formatting enums with very long generic type constraints. This occurs when the generic constraints exceed the available width budget (~80-100 characters), causingrewrite_genericsto fail andformat_genericsto returnNone, which is then unwrapped.Solution
This PR implements a three-tier fallback strategy in
format_generics:shape.infinite_width()Changes
format_genericsfunction insrc/items.rsto handle width budget exhaustion gracefullyissue-6571.rsto prevent future regressionsTesting
This fix ensures rustfmt can process files with complex generic constraints without crashing, while maintaining proper formatting where possible.