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get_unwrap changes mutability #9909
Description
Summary
.
Lint Name
get_unwrap
Reproducer
I tried this code:
fn linidx(row: usize, col: usize) -> usize {
row * 1 + col * 3
}
fn main() {
let mut mat = [1.0f32, 5.0, 9.0, 2.0, 6.0, 10.0, 3.0, 7.0, 11.0, 4.0, 8.0, 12.0];
for i in 0..2 {
for j in i+1..3 {
if mat[linidx(j, 3)] > mat[linidx(i, 3)] {
for k in 0..4 {
let (x, rest) = mat.split_at_mut(linidx(i, k) + 1);
let a = x.last_mut().unwrap();
let b = rest.get_mut(linidx(j, k) - linidx(i, k) - 1).unwrap();
::std::mem::swap(a, b);
}
}
}
}
assert_eq!([9.0, 5.0, 1.0, 10.0, 6.0, 2.0, 11.0, 7.0, 3.0, 12.0, 8.0, 4.0], mat);
}I saw this happen:
cargo clippy --fix -- -Aclippy::all -Wclippy::get_unwrap
Checking clpy v0.1.0 (/tmp/clpy)
warning: failed to automatically apply fixes suggested by rustc to crate `clpy`
after fixes were automatically applied the compiler reported errors within these files:
* src/main.rs
This likely indicates a bug in either rustc or cargo itself,
and we would appreciate a bug report! You're likely to see
a number of compiler warnings after this message which cargo
attempted to fix but failed. If you could open an issue at
https://github.com/rust-lang/rust/issues
quoting the full output of this command we'd be very appreciative!
Note that you may be able to make some more progress in the near-term
fixing code with the `--broken-code` flag
The following errors were reported:
error[E0308]: mismatched types
--> src/main.rs:16:49
|
16 | ... ::std::mem::swap(a, b);
| ---------------- ^
| | |
| | expected `&mut f32`, found `f32`
| | help: consider mutably borrowing here: `&mut b`
| arguments to this function are incorrect
|
note: function defined here
--> /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/mem/mod.rs:719:14
|
719 | pub const fn swap<T>(x: &mut T, y: &mut T) {
| ^^^^
error: aborting due to previous error
For more information about this error, try `rustc --explain E0308`.
Original diagnostics will follow.
warning: called `.get_mut().unwrap()` on a slice. Using `[]` is more clear and more concise
--> src/main.rs:15:37
|
15 | ... let b = rest.get_mut(linidx(j, k) - linidx(i, k) - 1).unwrap();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `rest[linidx(j, k) - linidx(i, k) - 1]`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#get_unwrap
= note: requested on the command line with `-W clippy::get-unwrap`
Version
rustc 1.67.0-nightly (c5d82ed7a 2022-11-19)
binary: rustc
commit-hash: c5d82ed7a4ad94a538bb87e5016e7d5ce0bd434b
commit-date: 2022-11-19
host: x86_64-unknown-linux-gnu
release: 1.67.0-nightly
LLVM version: 15.0.4
Additional Labels
No response
Activity
Auto merge of #10979 - y21:issue9909, r=giraffate