num::NonZero::get can be 1 transmute instead of 2
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scottmcm
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Mar 27, 2024
| /// Types implementing this trait must be primitives that are valid when zeroed. | ||
| /// | ||
| /// The associated `Self::NonZeroInner` type must have the same size+align as `Self`, | ||
| /// but with a niche and bit validity making it so the following `transmutes` are sound: |
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I think these were already implied -- they certainly already hold for all the implementations that exist -- but figured I might as well write them out for anyone reading this stuff later.
(And it's a perma-unstable trait, so we can do whatever.)
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num::NonZero::get can be 1 transmute instead of 3num::NonZero::get can be 1 transmute instead of 2
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@bors r+ rollup |
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…pratt `num::NonZero::get` can be 1 transmute instead of 2 Just something I noticed in passing. No need for a `match` in here to call `unreachable_unchecked`, as `transmute_unchecked` will add the appropriate `llvm.assume` <https://rust.godbolt.org/z/W5hjeETnc>.
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…iaskrgr Rollup of 8 pull requests Successful merges: - rust-lang#121943 (Clarify atomic bit validity) - rust-lang#123089 (Add invariant to VecDeque::pop_* that len < cap if pop successful) - rust-lang#123101 (Delegation: fix ICE on wrong `Self` instantiation) - rust-lang#123130 (Load missing type of impl associated constant from trait definition) - rust-lang#123133 (chore: fix some comments) - rust-lang#123136 (Some wording improvement) - rust-lang#123139 (`num::NonZero::get` can be 1 transmute instead of 2) - rust-lang#123142 (Let nils know about changes to target docs) r? `@ghost` `@rustbot` modify labels: rollup
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…iaskrgr Rollup of 8 pull requests Successful merges: - rust-lang#121943 (Clarify atomic bit validity) - rust-lang#123075 (CFI: Fix drop and drop_in_place) - rust-lang#123101 (Delegation: fix ICE on wrong `Self` instantiation) - rust-lang#123130 (Load missing type of impl associated constant from trait definition) - rust-lang#123133 (chore: fix some comments) - rust-lang#123136 (Some wording improvement) - rust-lang#123139 (`num::NonZero::get` can be 1 transmute instead of 2) - rust-lang#123142 (Let nils know about changes to target docs) r? `@ghost` `@rustbot` modify labels: rollup
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Rollup merge of rust-lang#123139 - scottmcm:simpler-nonzero-get, r=jhpratt `num::NonZero::get` can be 1 transmute instead of 2 Just something I noticed in passing. No need for a `match` in here to call `unreachable_unchecked`, as `transmute_unchecked` will add the appropriate `llvm.assume` <https://rust.godbolt.org/z/W5hjeETnc>.
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Just something I noticed in passing. No need for a
matchin here to callunreachable_unchecked, astransmute_uncheckedwill add the appropriatellvm.assumehttps://rust.godbolt.org/z/W5hjeETnc.