Stabilize `bind_by_move_pattern_guards` in Rust 1.39.0
Closes https://github.com/rust-lang/rust/issues/15287.
After stabilizing `#![feature(bind_by_move_pattern_guards)]`, you can now use bind-by-move bindings in patterns and take references to those bindings in `if` guards of `match` expressions. For example, the following now becomes legal:
```rust
fn main() {
let array: Box<[u8; 4]> = Box::new([1, 2, 3, 4]);
match array {
nums
// ---- `nums` is bound by move.
if nums.iter().sum::<u8>() == 10
// ^------ `.iter()` implicitly takes a reference to `nums`.
=> {
drop(nums);
// --------- Legal as `nums` was bound by move and so we have ownership.
}
_ => unreachable!(),
}
}
```
r? @matthewjasper
Remove `cfg(bootstrap)` code for array implementations
In https://github.com/rust-lang/rust/pull/62435 ("Use const generics for array impls [part 1]") the old macro-based implementations were not removed but still used with `cfg(bootstrap)` since the bootstrap compiler had some problems with const generics at the time. This does not seem to be the case anymore, so there is no reason to keep the old code.
Unfortunately, the diff is pretty ugly because much of the code was indented by one level before. The change is pretty trivial, though.
PS: I did not run the full test suite locally. There are 40°C outside and 31°C inside my room. I don't want my notebook to melt. I hope that CI is green.
r? @scottmcm
In PR #62435 ("Use const generics for array impls [part 1]") the old
macro-based implementations were not removed but still used with
`cfg(bootstrap)` since the bootstrap compiler had some problems with
const generics at the time. This does not seem to be the case anymore,
so there is no reason to keep the old code.
- uses a never-stable core::array::LengthAtMost32 to bound the impls
- includes a custom error message to avoid mentioning LengthAtMost32 too often
- doesn't use macros for the slice implementations to avoid #62433
Remove the default type of `Rem::Output`
Associated type defaults are not yet stable, and `Rem` is the only trait that specifies a default. Let's see what breaks when it's removed.
cc https://github.com/rust-lang/rust/pull/61812#issuecomment-502394566
cc @Centril
@bors try
