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Documents that `BikeshedIntrinsicFrom` models transmute-via-union, which is slightly more expressive than the transmute-via-cast implemented by `transmute_copy`. Additionally, we provide an implementation of transmute-via-union as a method on the `BikeshedIntrinsicFrom` trait with additional documentation on the boundary between trait invariants and caller obligations. Whether or not transmute-via-union is the right kind of transmute to model remains up for discussion [1]. Regardless, it seems wise to document the present behavior. [1] https://rust-lang.zulipchat.com/#narrow/stream/216762-project-safe-transmute/topic/What.20'kind'.20of.20transmute.20to.20model.3F/near/426331967
23 lines
587 B
Diff
23 lines
587 B
Diff
- // MIR for `transmute_inhabited` before LowerIntrinsics
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+ // MIR for `transmute_inhabited` after LowerIntrinsics
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fn transmute_inhabited(_1: std::cmp::Ordering) -> i8 {
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debug c => _1;
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let mut _0: i8;
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let mut _2: std::cmp::Ordering;
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bb0: {
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StorageLive(_2);
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_2 = copy _1;
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- _0 = std::intrinsics::transmute::<std::cmp::Ordering, i8>(move _2) -> [return: bb1, unwind unreachable];
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+ _0 = move _2 as i8 (Transmute);
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+ goto -> bb1;
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}
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bb1: {
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StorageDead(_2);
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return;
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}
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}
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