Implement Eq/Hash/Debug etc. for unsized tuples. #43011
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r? @sfackler |
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No RFC is needed, or a feature - trait implementations can't actually have feature gates applied to them. @rfcbot fcp merge |
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Team member @sfackler has proposed to merge this. The next step is review by the rest of the tagged teams: No concerns currently listed. Once these reviewers reach consensus, this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up! See this document for info about what commands tagged team members can give me. |
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ping @brson, you're the last checkbox needed here! |
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@bors: r+ rollup |
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📌 Commit 728d26c has been approved by |
Mark-Simulacrum
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Implement Eq/Hash/Debug etc. for unsized tuples. As I mentioned in [the comment in rust-lang#18469](rust-lang#18469 (comment)), the implementations of `PartialEq`, `Eq`, `PartialOrd`, `Ord`, `Debug`, `Hash` can be generalized to unsized tuples. This is consistent with the `derive` behavior for unsized structs. ```rust #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Debug, Default, Hash)] struct MyTuple<X, Y, Z: ?Sized>(X, Y, Z); fn f(x: &MyTuple<i32, i32, [i32]>) { x == x; x < x; println!("{:?}", x); } ``` Questions: - Need an RFC? - Need a feature gate? I don't think it does because the unsized tuple coercion rust-lang#42527 is feature-gated. - I changed `builder.field($name);` into `builder.field(&$name);` in the `Debug` implementation to pass compilation. This won't affect the behavior because `Debug for &'a T` is a mere redirection to `Debug for T`. However, I don't know if it affects code size / performance.
bors
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As I mentioned in the comment in #18469, the implementations of
PartialEq,Eq,PartialOrd,Ord,Debug,Hashcan be generalized to unsized tuples.This is consistent with the
derivebehavior for unsized structs.Questions:
builder.field($name);intobuilder.field(&$name);in theDebugimplementation to pass compilation. This won't affect the behavior becauseDebug for &'a Tis a mere redirection toDebug for T. However, I don't know if it affects code size / performance.