regression: let-else syntax restriction (right curly brace not allowed)

[Mark-Simulacrum]

https://crater-reports.s3.amazonaws.com/beta-1.77-3/beta-2024-02-18/gh/Rayzeq.UntimedExplosion/log.txt

I suspect this was an intentional change but we should track down the PR and make sure it's mentioned in relnotes.

[INFO] [stdout] error: right curly brace `}` before `else` in a `let...else` statement not allowed
[INFO] [stdout]    --> src/game.rs:349:13
[INFO] [stdout]     |
[INFO] [stdout] 349 |             } else { break; };
[INFO] [stdout]     |             ^
[INFO] [stdout]     |
[INFO] [stdout] help: use parentheses instead of braces for this macro
[INFO] [stdout]     |
[INFO] [stdout] 341 ~             let Some(msg) = select! ( else { break; };
[INFO] [stdout] 342 ~             let Some(msg) = select! ) else { break; };
[INFO] [stdout]     |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: right curly brace `}` before `else` in a `let...else` statement not allowed
[INFO] [stdout]    --> src/lobby.rs:282:13
[INFO] [stdout]     |
[INFO] [stdout] 282 |             } else { break; };
[INFO] [stdout]     |             ^
[INFO] [stdout]     |
[INFO] [stdout] help: use parentheses instead of braces for this macro
[INFO] [stdout]     |
[INFO] [stdout] 274 ~             let Some(msg) = select! ( else { break; };
[INFO] [stdout] 275 ~             let Some(msg) = select! ) else { break; };
[INFO] [stdout]     |

[ehuss]

I'm pretty sure this is from #119062.

[Mark-Simulacrum]

Thanks! It sounds like the FCP there was made with "no breakage found" (#119062 (comment)), so nominating for lang to see if we want to revisit the decision. (My sense is no, given the single GitHub repo that's affected based on beta crater).

[Mark-Simulacrum]

Dropping compiler while lang decides what to do.

[compiler-errors]

Looks like it was committed in the last month. Pretty hilarious and unfortunate timing, but I think that we should accept this breakage given it's a single crate -- however, let's double check with T-lang.

[dtolnay]

It was committed on December 18 (Rayzeq/UntimedExplosion@feed6fa), 25 hours after my analysis of crates.io in #118880 (comment). (The crate is not published to crates.io so I wouldn't have seen it anyway.)

Another unfortunate coincidence: the function it's in has the following comment, so the author is already having quite an experience with toolchains:

// WARNING: EventStream is broken with rust 1.74.X, stay on 1.73.X until this is fixed

https://github.com/Rayzeq/UntimedExplosion/blob/0296c09abc51d105080ecd6b817123d9522fb372/src/lobby.rs#L212