rust/tests/ui/explicit-tail-calls/ctfe-id-unlimited.rs
Esteban Küber 7d4d09eeeb Shorten span of panic failures in const context
Previously, we included a redundant prefix on the panic message and a postfix of the location of the panic. The prefix didn't carry any additional information beyond "something failed", and the location of the panic is redundant with the diagnostic's span, which gets printed out even if its code is not shown.

```
error[E0080]: evaluation of constant value failed
  --> $DIR/assert-type-intrinsics.rs:11:9
   |
LL |         MaybeUninit::<!>::uninit().assume_init();
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation panicked: aborted execution: attempted to instantiate uninhabited type `!`
```

```
error[E0080]: evaluation of `Fail::<i32>::C` failed
  --> $DIR/collect-in-dead-closure.rs:9:19
   |
LL |     const C: () = panic!();
   |                   ^^^^^^^^ evaluation panicked: explicit panic
   |
   = note: this error originates in the macro
`$crate::panic::panic_2015` which comes from the expansion of the macro
`panic` (in Nightly builds, run with -Z macro-backtrace for more info)
```

```
error[E0080]: evaluation of constant value failed
  --> $DIR/uninhabited.rs:41:9
   |
LL |         assert!(false);
   |         ^^^^^^^^^^^^^^ evaluation panicked: assertion failed: false
   |
   = note: this error originates in the macro `assert` (in Nightly builds, run with -Z macro-backtrace for more info)
```

---

When the primary span for a const error is the same as the first frame in the const error report, skip it.

```
error[E0080]: evaluation of constant value failed
  --> $DIR/issue-88434-removal-index-should-be-less.rs:3:24
   |
LL | const _CONST: &[u8] = &f(&[], |_| {});
   |                        ^^^^^^^^^^^^^^ evaluation panicked: explicit panic
   |
note: inside `f::<{closure@$DIR/issue-88434-removal-index-should-be-less.rs:3:31: 3:34}>`
  --> $DIR/issue-88434-removal-index-should-be-less.rs:10:5
   |
LL |     panic!()
   |     ^^^^^^^^ the failure occurred here
   = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
```
instead of
```
error[E0080]: evaluation of constant value failed
  --> $DIR/issue-88434-removal-index-should-be-less.rs:10:5
   |
LL |     panic!()
   |     ^^^^^^^^ explicit panic
   |
note: inside `f::<{closure@$DIR/issue-88434-removal-index-should-be-less.rs:3:31: 3:34}>`
  --> $DIR/issue-88434-removal-index-should-be-less.rs:10:5
   |
LL |     panic!()
   |     ^^^^^^^^
note: inside `_CONST`
  --> $DIR/issue-88434-removal-index-should-be-less.rs:3:24
   |
LL | const _CONST: &[u8] = &f(&[], |_| {});
   |                        ^^^^^^^^^^^^^^
   = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
```

---

Revert order of constant evaluation errors

Point at the code the user wrote first and std functions last.

```
error[E0080]: evaluation of constant value failed
  --> $DIR/const-errs-dont-conflict-103369.rs:5:25
   |
LL | impl ConstGenericTrait<{my_fn(1)}> for () {}
   |                         ^^^^^^^^ evaluation panicked: Some error occurred
   |
note: called from `my_fn`
  --> $DIR/const-errs-dont-conflict-103369.rs:10:5
   |
LL |     panic!("Some error occurred");
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
```
instead of
```
error[E0080]: evaluation of constant value failed
  --> $DIR/const-errs-dont-conflict-103369.rs:10:5
   |
LL |     panic!("Some error occurred");
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Some error occurred
   |
note: called from `<() as ConstGenericTrait<{my_fn(1)}>>::{constant#0}`
  --> $DIR/const-errs-dont-conflict-103369.rs:5:25
   |
LL | impl ConstGenericTrait<{my_fn(1)}> for () {}
   |                         ^^^^^^^^
   = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
```
2025-02-28 16:28:41 +00:00

35 lines
1.2 KiB
Rust

//@ revisions: become return
//@ [become] run-pass
#![expect(incomplete_features)]
#![feature(explicit_tail_calls)]
// This is an identity function (`|x| x`), but implemented using recursion.
// Each step we increment accumulator and decrement the number.
//
// With normal calls this fails compilation because of the recursion limit,
// but with tail calls/`become` we don't grow the stack/spend recursion limit
// so this should compile.
const fn rec_id(n: u32) -> u32 {
const fn inner(acc: u32, n: u32) -> u32 {
match n {
0 => acc,
#[cfg(r#become)] _ => become inner(acc + 1, n - 1),
#[cfg(r#return)] _ => return inner(acc + 1, n - 1),
}
}
inner(0, n)
}
// Some relatively big number that is higher than recursion limit
const ORIGINAL: u32 = 12345;
// Original number, but with identity function applied
// (this is the same, but requires execution of the recursion)
const ID_ED: u32 = rec_id(ORIGINAL); //[return]~ error: evaluation of constant value failed
// Assert to make absolutely sure the computation actually happens
const ASSERT: () = assert!(ORIGINAL == ID_ED);
fn main() {
let _ = ASSERT;
}