[NLL] A rejects-valid (a NLL regression) #48180
Description
This code compiles and runs correctly if I don't use the NLL feature:
#![feature(nll)]
use std::ops::{ShrAssign, BitOr, Shl, SubAssign};
use std::mem::swap;
trait HasTrailingZeros {
#[inline(always)]
fn trailing_zeros(self) -> u32;
}
impl HasTrailingZeros for u32 {
#[inline(always)]
fn trailing_zeros(self) -> u32 { self.trailing_zeros() }
}
fn gcd<T>(mut u: T, mut v: T) -> T
where T: PartialEq +
Copy +
From<u8> +
PartialOrd +
BitOr<Output=T> +
Shl<u32, Output=T> +
ShrAssign<u32> +
SubAssign +
HasTrailingZeros {
if u == 0.into() { return v; }
if v == 0.into() { return u; }
let shift = (u | v).trailing_zeros();
u >>= u.trailing_zeros();
loop {
v >>= v.trailing_zeros();
if u > v {
swap(&mut u, &mut v);
}
v -= u;
if v == 0.into() { break; }
}
u << shift
}
fn main() {
println!("{}", gcd(20u32, 10u32));
}
With the NLL feature it gives (it used to compile with NLL):
error[E0503]: cannot use `u` because it was mutably borrowed
--> ...\test.rs:28:11
|
28 | u >>= u.trailing_zeros();
| - ^ use of borrowed `u`
| |
| borrow of `u` occurs here
error[E0503]: cannot use `v` because it was mutably borrowed
--> ...\test.rs:30:15
|
30 | v >>= v.trailing_zeros();
| - ^ use of borrowed `v`
| |
| borrow of `v` occurs here
error: aborting due to 2 previous errors
...>rustc -vV
rustc 1.25.0-nightly (16362c737 2018-02-12)
binary: rustc
commit-hash: 16362c737fe740f630ada06349fa9004e2a51bb7
commit-date: 2018-02-12
host: x86_64-pc-windows-gnu
release: 1.25.0-nightly
LLVM version: 6.0