Rust 1.74 #16416
Rust 1.74 #16416
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!ci-nightly-me |
| // simultaneously, and | ||
| // * the underlying pointer is in the correct state to be | ||
| // mutable, since we can call [`get_mut_unchecked`] in | ||
| // nightly, or can call [`get_mut`] and unwrap if this is | ||
| // the only live reference. | ||
| &mut *(((&*self.0) as *const Self::Target) as *mut Self::Target) |
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1.74 throws a compiler error here. There might be some other way to get it to stop complaining, but I think this is equivalent without the illegal cast
| @@ -1,7 +1,7 @@ | |||
| macro_rules! impl_caml_pointer { | |||
| ($name: ident => $typ: ty) => { | |||
| #[derive(std::fmt::Debug, Clone, ::ocaml_gen::CustomType)] | |||
| pub struct $name(pub ::std::rc::Rc<$typ>); | |||
| pub struct $name(pub ::std::rc::Rc<std::cell::UnsafeCell<$typ>>); | |||
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Note as it is important for the Caml binding: UnsafeCell is implemented as:
#[lang = "unsafe_cell"]
#[stable(feature = "rust1", since = "1.0.0")]
#[repr(transparent)]
#[rustc_pub_transparent]
pub struct UnsafeCell<T: ?Sized> {
value: T,
}
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I guess we're adding a new indirection? We might lose some performances?
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Note as it is important for the Caml binding: UnsafeCell is implemented as:
The nightly tests were passing with this change, does this mean that that the ocaml bindings lib was able to resolve this on its own or is it just coincidence because maybe the runtime rep is the same
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I guess we're adding a new indirection? We might lose some performances?
My intuition is that this UnsafeCell should be optimized away. We can discuss
| // simultaneously, and | ||
| // * the underlying pointer is in the correct state to be | ||
| // mutable, since we can call [`get_mut_unchecked`] in | ||
| // nightly, or can call [`get_mut`] and unwrap if this is | ||
| // the only live reference. | ||
| &mut *(((&*self.0) as *const Self::Target) as *mut Self::Target) | ||
| &mut *self.0.get() |
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Note: implementation of get.
#[inline(always)]
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_stable(feature = "const_unsafecell_get", since = "1.32.0")]
#[rustc_never_returns_null_ptr]
pub const fn get(&self) -> *mut T {
// We can just cast the pointer from `UnsafeCell<T>` to `T` because of
// #[repr(transparent)]. This exploits std's special status, there is
// no guarantee for user code that this will work in future versions of the compiler!
self as *const UnsafeCell<T> as *const T as *mut T
}
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Nit: cargo fmt reformats this line. It seems we do not run in the Mina CI clippy nor fmt.
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Note: implementation of get.
This makes me think someone was trying to get around using UnsafeCell when they wrote this the first time. I would hope that this would be optimized away
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LGTM so far, modulo comments. |
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Feel free to cherry-picked some changes from #16411 |
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Depends on #16405 and proof-systems-2868 and proof-systems-2875
This PR updates the rust compiler to
1.74. It is a stepping stone in updating thewasm-packandwasm-bindgen-clidependencies, but it is also good housekeeping to not fall too far behind.