ctutils: add CtNeg trait
#1286
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ctutils: add CtNeg trait
#1286
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For full feature parity with `subtle`, this adds a conditional negation trait called `CtNeg`. It uses a slightly different design from `subtle`, supporting both in-place operation ala `subtle` with `ct_neg_assign`, while also supporting `core::ops::Neg`-like usage with `ct_neg`. Using one trait with two methods permits a default implementation of `ct_neg_assign` while still letting it be overridden, which is useful for e.g. heap-allocated types. It could arguably be split into `CtNeg` and `CtNegAssign` but we would lose that default impl (and the same argument could be made for splitting up e.g. `CtSelect`, with the same drawbacks) By default impls are written for the signed integer (`i*`) types: `i8`, `i16`, `i32`, `i64, `i128`.
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tarcieri
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Dec 27, 2025
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For full feature parity with
subtle, this adds a conditional negation trait calledCtNeg.It uses a slightly different design from
subtle, supporting both in-place operation alasubtlewithct_neg_assign, while also supportingcore::ops::Neg-like usage withct_neg.Using one trait with two methods permits a default implementation of
ct_neg_assignwhile still letting it be overridden, which is useful for e.g. heap-allocated types. It could arguably be split intoCtNegandCtNegAssignbut we would lose that default impl (and the same argument could be made for splitting up e.g.CtSelect, with the same drawbacks)By default impls are written for the signed integer (
i*) types:i8,i16,i32,i64,i128.