Support ZSTs in DispatchFromDyn #60369
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r? @eddyb (rust_highfive has picked a reviewer for you, use r? to override) |
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This possibly needs an FCP or some discussion so I've marked it as such tentatively. |
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Please ensure that the ZST has alignment ≤ a pointer, because we should not DispatchFromDyn those: #[repr(align(64))]
struct A;
struct P<'a, T: ?Sized + 'a> {
p: &'a T,
a: A,
}
fn main() {
use std::mem::size_of;
dbg!(size_of::<(P<'static, u8>, *const (/*vtable*/))>());
dbg!(size_of::<P<'static, dyn Sync>>());
} |
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@kennytm I'd prefer we check alignment to be |
eddyb
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Apr 30, 2019
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@bors r+ |
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📌 Commit 1b679e7 has been approved by |
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Support ZSTs in DispatchFromDyn Allows to use ZSTs with 1 byte alignment in `DispatchFromDyn` implementation. This is required for `Box<T, A: Alloc>` cc rust-lang#58457
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Support ZSTs in DispatchFromDyn Allows to use ZSTs with 1 byte alignment in `DispatchFromDyn` implementation. This is required for `Box<T, A: Alloc>` cc rust-lang#58457
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Support ZSTs in DispatchFromDyn Allows to use ZSTs with 1 byte alignment in `DispatchFromDyn` implementation. This is required for `Box<T, A: Alloc>` cc rust-lang#58457
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Rollup of 7 pull requests Successful merges: - #60327 (Search for incompatible universes in borrow errors) - #60330 (Suggest using an inclusive range instead of an exclusive range when the endpoint overflows by 1) - #60366 (build-gcc: Create missing cc symlink) - #60369 (Support ZSTs in DispatchFromDyn) - #60404 (Implement `BorrowMut<str>` for `String`) - #60417 (Rename hir::ExprKind::Use to ::DropTemps and improve docs.) - #60432 (Update clippy) Failed merges: r? @ghost
Centril
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Support ZSTs in DispatchFromDyn Allows to use ZSTs with 1 byte alignment in `DispatchFromDyn` implementation. This is required for `Box<T, A: Alloc>` cc rust-lang#58457
bors
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May 1, 2019
Rollup of 7 pull requests Successful merges: - #60287 (Use references for variances_of) - #60327 (Search for incompatible universes in borrow errors) - #60330 (Suggest using an inclusive range instead of an exclusive range when the endpoint overflows by 1) - #60366 (build-gcc: Create missing cc symlink) - #60369 (Support ZSTs in DispatchFromDyn) - #60404 (Implement `BorrowMut<str>` for `String`) - #60417 (Rename hir::ExprKind::Use to ::DropTemps and improve docs.) Failed merges: r? @ghost
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Allows to use ZSTs with 1 byte alignment in
DispatchFromDynimplementation. This is required forBox<T, A: Alloc>cc #58457