float::clamp: make treatment of signed zeros unspecified #149238
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I have the unfortunate pleasure of working on a project where the sign of 0.0 matters. Adding documentation for what Rust guarantees is a very positive step. For functions where the sign is ignored, it would be good to also point to alternative functions where -0.0 < +0.0, if they exist, or mention that the functionality can be implemented in some way |
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I don't think we should guarantee that these compare equal since that would rule out the ability to use the much more efficient |
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@Amanieu something like this? |
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@bors r+ rollup |
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Rollup of 8 pull requests Successful merges: - #149238 (float::clamp: make treatment of signed zeros unspecified) - #149270 (implement `Iterator::{exactly_one, collect_array}`) - #149295 (Suggest _bytes versions of endian-converting methods) - #149332 (fix rustdoc search says “Consider searching for "null" instead.” #149324) - #149349 (Fix typo in comment.) - #149353 (Tidying up UI tests [3/N]) - #149355 (Document that `build.description` affects symbol mangling and crate IDs) - #149360 (Enable CI download for windows-gnullvm) r? `@ghost` `@rustbot` modify labels: rollup
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Doesn't this require some sort of team decision, since it fixes a previously undescribed part of the API for |
Rollup merge of #149238 - RalfJung:clamp-signed-zeros, r=Amanieu float::clamp: make treatment of signed zeros unspecified Fixes #83984 by explicitly documenting that we do not specify the treatment of signed zeros in `clamp`. `@rust-lang/libs-api` Is this what you'd like to see? Cc `@tgross35` `@thomcc`
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Isn't non-deterministic return value pretty much a non-guarantee? |
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Yeah, so people might reasonably disagree and say we should guarantee something.
But I guess this PR does not commit us to anything we can't take back (other than "the return value will be one of the arguments").
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FWIW this was actually discussed in the libs-api meeting this week and it was a team decision to make this change to the docs. |
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Ah, thanks for clarifying. :) |
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Fixes #83984 by explicitly documenting that we do not specify the treatment of signed zeros in
clamp. @rust-lang/libs-api Is this what you'd like to see?Cc @tgross35 @thomcc