Add Show and Clone trait to arrays
#18951
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Due to not being able to parametrize over array sizes, `Clone` is only implemented for element types that are `Copy`able.
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| // macro for implementing n-ary tuple functions and operations | ||
| macro_rules! array_impls { | ||
| ($($N:expr)+) => { | ||
| $( | ||
| #[unstable = "waiting for Clone to stabilize"] | ||
| impl<T:Copy> Clone for [T, ..$N] { | ||
| fn clone(&self) -> [T, ..$N] { |
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You should be able to implement for non-Copy Ts unsafely:
fn clone(&self) -> [T, ..$N] {
let mut cloned: [T, ..$N] = unsafe { mem::zeroed() };
for i in range(0, $N) {
cloned[i] = x[i].clone();
}
cloned
}I think this is safe with regards to destructors and clone() failing but someone else should confirm. :-)
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That's not safe because clone can throw, and calling a destructor on zeroed memory is not well-defined. Drop flags are an implementation detail and removing them is planned. It is possible to write this code correctly, but you need to handle the unwinding case manually.
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Exceptions are just plain awful.
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cc @aturon I'm assuming there'd be no objections, particularly as these impls are marked unstable. |
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Yep, LGTM |
lnicola
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Jan 20, 2025
Add missing `#[rust_analyzer::rust_fixture]` annotations
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Due to not being able to parametrize over array sizes,
Cloneis onlyimplemented for element types that are
Copyable.