Code change:
Found with the help of .
There's two slicing operations in . I'm trying to figure out how a non-boundary index could be appearing in there... maybe is calling with a span that begins at index 10? (where does this come from? ?) Building a debug compiler to check those log statements... Edit: Building the debug compiler was a bust. Embarassingly, things seem to have changed and I don't know how to get those debug macros to fire in the current compiler.
do you mean you were using and not seeing debug output? If so, that is because the environment variable name under was changed to . (I make this mistake pretty much every day due to muscle memory.) As an example, here is the tail of my log output:
triage: P-medium. Removing nomination.
This was broken between 1.15 and 1.16, but those are so old and the nature of the ICE itself has changed from 1.28 to 1.29, so I do not think bisection would be worthwhile.
<details<summaryOfftopic</summary : Thanks. Unfortunately, I did guess the name of after didn't work, and all it showed me was this: I set in my before building, and didn't see anything else in there. (I recall that and used to be but it is no longer, so I did not enable it.) </details
Okay, I did the following evil, evil thing: <details<summaryPure evil, do not open</summary</detailsAnd acquired the following backtrace of when the span was first constructed: It also gets constructed a second time: <details<summarySecond backtrace</summary(the region of the backtrace that differs between the two is items 22-29 in the first one, or 22-25 in the second) </detailsSome interesting spots from here: This is clearly where the value of 10 is created: calls this if there are no remaining tokens and it still hasn't seen the closing delimiter (it seems to have as an unstated precondition that the closing delimiter must exist). Here's the innermost bit that's specific to parsing. Doesn't look that odd...
I’m not familiar with I tend to list (comma separated) module paths in my own use of RUSTCLOG; did you try that? You can see an example in the transcript I gave in my comment above
Oh. (I'm so used to prompts I didn't notice you included the command!). Yeah, that was the issue.
Same ICE occurs with: Which returns:
could you post a base64-encoded version of your ? When I copy/paste what you've posted above, I don't see a compiler crash, presumably because some non-ascii characters are getting lost.
My bad
Hm, the example from hasn't been fixed?
Seems so, on the current nightly:
I guess my fix would help. I'll get some time to test it out.
Confirmed that my fix fixed this issue, I also add this unit test in this PR:

Related discussion:
text: <ins> error: this file contains an un-closed delimiter --> $DIR/issue-62524.rs:4:3 | LL | y![ |   - un-closed delimiter LL | Ϥ, |   ^ error: macros that expand to items must be delimited with braces or followed by a semicolon --> $DIR/issue-62524.rs:3:3 | LL |   y![ |  ___^ LL | | Ϥ, | |__^ | help: change the delimiters to curly braces | LL | y!{ LL | Ϥ} | help: add a semicolon | LL | Ϥ,; |   ^ error: cannot find macro `y` in this scope --> $DIR/issue-62524.rs:3:1 | LL | y![ | ^ error: aborting due to 3 previous errors </ins>