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Rollup merge of #114800 - RalfJung:transparent, r=cuviper

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std: add some missing repr(transparent)

For some types we don't want to stably guarantee this, so hide the `repr` from rustdoc. This nice approach was suggested by `@thomcc.`
This commit is contained in:
Guillaume Gomez
2023-08-15 14:29:46 +02:00
committed by GitHub
parent f0987ab45b fe1a034f16
commit f527d56c08
5 changed files with 26 additions and 18 deletions
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10
library/std/src/sys/wasi/fd.rs
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@@ -16,14 +16,20 @@ pub struct WasiFd {
fn iovec<'a>(a: &'a mut [IoSliceMut<'_>]) -> &'a [wasi::Iovec] {
assert_eq!(mem::size_of::<IoSliceMut<'_>>(), mem::size_of::<wasi::Iovec>());
assert_eq!(mem::align_of::<IoSliceMut<'_>>(), mem::align_of::<wasi::Iovec>());
// SAFETY: `IoSliceMut` and `IoVec` have exactly the same memory layout
// SAFETY: `IoSliceMut` and `IoVec` have exactly the same memory layout.
// We decorate our `IoSliceMut` with `repr(transparent)` (see `io.rs`), and
// `crate::io::IoSliceMut` is a `repr(transparent)` wrapper around our type, so this is
// guaranteed.
unsafe { mem::transmute(a) }
}
fn ciovec<'a>(a: &'a [IoSlice<'_>]) -> &'a [wasi::Ciovec] {
assert_eq!(mem::size_of::<IoSlice<'_>>(), mem::size_of::<wasi::Ciovec>());
assert_eq!(mem::align_of::<IoSlice<'_>>(), mem::align_of::<wasi::Ciovec>());
// SAFETY: `IoSlice` and `CIoVec` have exactly the same memory layout
// SAFETY: `IoSlice` and `CIoVec` have exactly the same memory layout.
// We decorate our `IoSlice` with `repr(transparent)` (see `io.rs`), and
// `crate::io::IoSlice` is a `repr(transparent)` wrapper around our type, so this is
// guaranteed.
unsafe { mem::transmute(a) }
}