rustc does not clear temporary files after `unconditional_panic` error

[buyukakyuz]

This is a simple code to check Rust's bound checking:

fn main() {
    let a = [1, 2, 3, 4, 5];
    let _x = a[9];
}

If we try to compile it with rustc (not cargo), rustc produces a bunch of object files

If we fix the code and recompile it, rust clears the produced files.

[aDotInTheVoid]

Interestingly, this seems specific to the unconditional panic (Or at least doesn't occour on all errors)

nixon@Ashtabula:/tmp/rust-107001$ cat code.rs
fn main() {
    let a = [1, 2, 3, 4, 5];
    let _x = a[a];

}
nixon@Ashtabula:/tmp/rust-107001$ rustc code.rs
error[E0277]: the type `[{integer}]` cannot be indexed by `[{integer}; 5]`
 --> code.rs:3:16
  |
3 |     let _x = a[a];
  |                ^ slice indices are of type `usize` or ranges of `usize`
  |
  = help: the trait `SliceIndex<[{integer}]>` is not implemented for `[{integer}; 5]`
  = note: required for `[{integer}]` to implement `Index<[{integer}; 5]>`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0277`.
nixon@Ashtabula:/tmp/rust-107001$ ls
code  code.rs
nixon@Ashtabula:/tmp/rust-107001$ vim code.rs
nixon@Ashtabula:/tmp/rust-107001$ cat code.rs
fn main() {
    let a = [1, 2, 3, 4, 5];
    let _x = a[9];

}
nixon@Ashtabula:/tmp/rust-107001$ rustc code.rs
error: this operation will panic at runtime
 --> code.rs:3:14
  |
3 |     let _x = a[9];
  |              ^^^^ index out of bounds: the length is 5 but the index is 9
  |
  = note: `#[deny(unconditional_panic)]` on by default

error: aborting due to previous error

nixon@Ashtabula:/tmp/rust-107001$ ls
code                          code.code.3969b7e3-cgu.0.rcgu.o  code.code.3969b7e3-cgu.2.rcgu.o  code.code.3969b7e3-cgu.4.rcgu.o
code.2w63xc29o8jhg8wq.rcgu.o  code.code.3969b7e3-cgu.1.rcgu.o  code.code.3969b7e3-cgu.3.rcgu.o  code.rs

[buyukakyuz]

That's correct, this is not generally true. I couldn't reproduce the problem except for this specific panic.

[jyn514]

I think unconditional_panic is one of the few lints that's emitted post monomorphization.

rust/compiler/rustc_mir_transform/src/const_prop_lint.rs

Line 671 in 11d96b5

lint::builtin::UNCONDITIONAL_PANIC,