query cycle: cycle detected when caching mir of `foo::{constant#1}` for CTFE

Code

fn foo<const N: usize, const K: usize>(_data: [u32; N]) -> [u8; { foo(N); 5 }] {
    [0; K]
}
fn main() {
}

Current output

error: generic parameters may not be used in const operations
 --> F2BA3E4A1C6EA7961BA8BFE1032468BB5A186D391F3B27D22A1638859E663E15.rs:3:71
  |
3 | ...> [u8; { foo(N); 5 }] {
  |                 ^ cannot perform const operation using `N`
  |
  = help: const parameters may only be used as standalone arguments, i.e. `N`
  = help: add `#![feature(generic_const_exprs)]` to allow generic const expressions

error[E0391]: cycle detected when caching mir of `foo::{constant#1}` for CTFE
 --> F2BA3E4A1C6EA7961BA8BFE1032468BB5A186D391F3B27D22A1638859E663E15.rs:3:65
  |
3 | ... -> [u8; { foo(N); 5 }] {
  |             ^^^^^^^^^^^^^
  |
note: ...which requires elaborating drops for `foo::{constant#1}`...
 --> F2BA3E4A1C6EA7961BA8BFE1032468BB5A186D391F3B27D22A1638859E663E15.rs:3:65
  |
3 | ... -> [u8; { foo(N); 5 }] {
  |             ^^^^^^^^^^^^^
note: ...which requires borrow-checking `foo::{constant#1}`...
 --> F2BA3E4A1C6EA7961BA8BFE1032468BB5A186D391F3B27D22A1638859E663E15.rs:3:65
  |
3 | ... -> [u8; { foo(N); 5 }] {
  |             ^^^^^^^^^^^^^
note: ...which requires promoting constants in MIR for `foo::{constant#1}`...
 --> F2BA3E4A1C6EA7961BA8BFE1032468BB5A186D391F3B27D22A1638859E663E15.rs:3:65
  |
3 | ... -> [u8; { foo(N); 5 }] {
  |             ^^^^^^^^^^^^^
note: ...which requires const checking `foo::{constant#1}`...
 --> F2BA3E4A1C6EA7961BA8BFE1032468BB5A186D391F3B27D22A1638859E663E15.rs:3:65
  |
3 | ... -> [u8; { foo(N); 5 }] {
  |             ^^^^^^^^^^^^^
note: ...which requires preparing `foo::{constant#1}` for borrow checking...
 --> F2BA3E4A1C6EA7961BA8BFE1032468BB5A186D391F3B27D22A1638859E663E15.rs:3:65
  |
3 | ... -> [u8; { foo(N); 5 }] {
  |             ^^^^^^^^^^^^^
note: ...which requires unsafety-checking `foo::{constant#1}`...
 --> F2BA3E4A1C6EA7961BA8BFE1032468BB5A186D391F3B27D22A1638859E663E15.rs:3:65
  |
3 | ... -> [u8; { foo(N); 5 }] {
  |             ^^^^^^^^^^^^^
note: ...which requires building MIR for `foo::{constant#1}`...
 --> F2BA3E4A1C6EA7961BA8BFE1032468BB5A186D391F3B27D22A1638859E663E15.rs:3:65
  |
3 | ... -> [u8; { foo(N); 5 }] {
  |             ^^^^^^^^^^^^^
note: ...which requires match-checking `foo::{constant#1}`...
 --> F2BA3E4A1C6EA7961BA8BFE1032468BB5A186D391F3B27D22A1638859E663E15.rs:3:65
  |
3 | ... -> [u8; { foo(N); 5 }] {
  |             ^^^^^^^^^^^^^
note: ...which requires type-checking `foo::{constant#1}`...
 --> F2BA3E4A1C6EA7961BA8BFE1032468BB5A186D391F3B27D22A1638859E663E15.rs:3:65
  |
3 | ... -> [u8; { foo(N); 5 }] {
  |             ^^^^^^^^^^^^^
note: ...which requires evaluating type-level constant...
 --> F2BA3E4A1C6EA7961BA8BFE1032468BB5A186D391F3B27D22A1638859E663E15.rs:3:65
  |
3 | ... -> [u8; { foo(N); 5 }] {
  |             ^^^^^^^^^^^^^
note: ...which requires const-evaluating + checking `foo::{constant#1}`...
 --> F2BA3E4A1C6EA7961BA8BFE1032468BB5A186D391F3B27D22A1638859E663E15.rs:3:65
  |
3 | ... -> [u8; { foo(N); 5 }] {
  |             ^^^^^^^^^^^^^
note: ...which requires const-evaluating + checking `foo::{constant#1}`...
 --> F2BA3E4A1C6EA7961BA8BFE1032468BB5A186D391F3B27D22A1638859E663E15.rs:3:65
  |
3 | ... -> [u8; { foo(N); 5 }] {
  |             ^^^^^^^^^^^^^
  = note: ...which again requires caching mir of `foo::{constant#1}` for CTFE, completing the cycle
note: cycle used when const-evaluating + checking `foo::{constant#1}`
 --> F2BA3E4A1C6EA7961BA8BFE1032468BB5A186D391F3B27D22A1638859E663E15.rs:3:65
  |
3 | ... -> [u8; { foo(N); 5 }] {
  |             ^^^^^^^^^^^^^
  = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information

error: aborting due to 2 previous errors

Desired output

We should have a proper diagnostic here and not talk about CTFE or mir

Rationale and extra context

cc https://github.com/rust-lang/rust/issues/119321

Other cases

No response

Anything else?

No response

Start by running the Rust reproducer in the issue and reading the referenced rustc-dev-guide query and CTFE material. Compare the behavior with issue #119321 and trace the diagnostic path that emits the MIR/CTFE cycle; done means this case produces a proper diagnostic without exposing the internal cycle details.