ICE: Cycle with `#[const_continue]` on const blocks

[ShoyuVanilla]

Code

#![allow(incomplete_features)]
#![feature(loop_match)]
#![crate_type = "lib"]

fn test(mut state: u8) {
    const bar: u8 = 2_u8;
    #[loop_match]
    loop {
        state = 'blk: {
            match state {
                0 => {
                    #[const_continue]
                    break 'blk const { 4 + 5 };
                }

                _ => unreachable!(),
            }
        }
    }
}

Playground

Meta

rustc --version --verbose:

rustc 1.90.0-nightly (430d6eddf 2025-07-25)
binary: rustc
commit-hash: 430d6eddfc6a455ca4a0137c0822a982cccd3b2b
commit-date: 2025-07-25
host: x86_64-unknown-linux-gnu
release: 1.90.0-nightly
LLVM version: 20.1.8

Error output

error[E0391]: cycle detected when building MIR for `test`
  --> loop_match_cycle.rs:12:32
   |
12 |                     break 'blk const { 4 + 5 };
   |                                ^^^^^^^^^^^^^^^
   |
note: ...which requires evaluating type-level constant...
  --> loop_match_cycle.rs:12:38
   |
12 |                     break 'blk const { 4 + 5 };
   |                                      ^^^^^^^^^
note: ...which requires const-evaluating + checking `test::{constant#0}`...
  --> loop_match_cycle.rs:12:38
   |
12 |                     break 'blk const { 4 + 5 };
   |                                      ^^^^^^^^^
note: ...which requires caching mir of `test::{constant#0}` for CTFE...
  --> loop_match_cycle.rs:12:38
   |
12 |                     break 'blk const { 4 + 5 };
   |                                      ^^^^^^^^^
note: ...which requires elaborating drops for `test::{constant#0}`...
  --> loop_match_cycle.rs:12:38
   |
12 |                     break 'blk const { 4 + 5 };
   |                                      ^^^^^^^^^
note: ...which requires borrow-checking `test`...
  --> loop_match_cycle.rs:5:1
   |
5  | fn test(mut state: u8) {
   | ^^^^^^^^^^^^^^^^^^^^^^
note: ...which requires promoting constants in MIR for `test`...
  --> loop_match_cycle.rs:5:1
   |
5  | fn test(mut state: u8) {
   | ^^^^^^^^^^^^^^^^^^^^^^
note: ...which requires checking if `test` contains FFI-unwind calls...
  --> loop_match_cycle.rs:5:1
   |
5  | fn test(mut state: u8) {
   | ^^^^^^^^^^^^^^^^^^^^^^
   = note: ...which again requires building MIR for `test`, completing the cycle
note: cycle used when unsafety-checking `test`
  --> loop_match_cycle.rs:5:1
   |
5  | fn test(mut state: u8) {
   | ^^^^^^^^^^^^^^^^^^^^^^
   = 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 1 previous error

For more information about this error, try `rustc --explain E0391`.

[ShoyuVanilla]

Oh, this would be fixed by #143585