Code change:
<details<summary<strongFull output including backtrace</strong</summary<p</p</detailsRegression from () <details<summaryBisection details</summarybisected with <a href=''cargo-bisect-rustc</av0.6.4 searched nightlies: from nightly-2022-10-06 to nightly-2022-10-28 regressed nightly: nightly-2022-10-09 searched commit range: regressed commit: Host triple: x8664-apple-darwin </details<!-- TRIAGEBOTSTART --<!-- TRIAGEBOTASSIGNSTART --<!-- TRIAGEBOTASSIGNDATASTARTTRIAGEBOTASSIGNDATAEND --<!-- TRIAGEBOTASSIGNEND --<!-- TRIAGEBOT_END --
this function call crash for the assertion fail, from the log, is with count = 1, and is also 1 when crashing. Do you have any clue? is implemented at here, I'm still not quite familar with the query part:
It looks like the parens are parsed as generic parameters for a type that doesn't have generic parameters? The simple fix is just check .
I think a reasonable fix is modifying the API for , It reasonable to add assertion for , but it's better to return false for outside of expected range?
Have a test on C++'s , which also has this assertion: emm, it's better to keep it for .
claim
I'd be curious to know if we can maintain an invariant in the HIR that it does not contain generics that do not align with . That was what I assumed when writing that code, but that may be too optimistic.
I considered removing the assert too, but I think it's better to have it since it exposes invalid assumptions as in this case.
We should (replacing the assertion) -- that's probably fine as long as it's understood why the does not line up here, and it's understood why we can't fix it somewhere upstream (e.g. in parsing or lowering instead)
I have a general question for , why we just exit when we find a fatal error in parsing (which can not recover by simply autofix). I have a real Dev experience when working on , I was editing an file with 3k+ lines of code, and I forgetted remove an extra '{', then the compiler give about 20+ errors, the first two are from parsing: But there are many many other errors from later phases... I need to scroll up several pages to the beginning of error to find the rootcause.
If we can not get valid AST in parsing, later phases such as analysising will report out extra (mostly unhelpful) errors?
The assertion is inside of the data structure. I generally expect data structures to simply assert on pre-conditions. We could put a delay-bug before the call, but that also seems like overkill since that is already on the error-reporting path. I agree there are cases where rustc should quit sooner. But in general I think we have to err on the side of recover-and-continue if there is some possibility that more helpful errors may be emitted.
This can happen. The parser should be more realistic on what it recovers and avoid errors from later passes that do not make sense. A few years back we would stop as soon as any error occurred in a given pass and avoid trying any further evaluation, and that was also a usability issue, because people would get a false sense of "how much work is left to fix". We shouldn't have a blanket evaluation stop, but maybe be more aggressive about pruning the AST when multiple parse errors have occurred.
do you want to take over this issue? I currently don't have any clue about the rootcause. Or we give it an simple fix now.
I can take a look.

Related discussion:
text: }); if check_params && let Some(args) = path.segments.last().unwrap().args { let params_in_repr = tcx.params_in_repr(def_id); <del> for (i, arg) in args.args.iter().enumerate() { </del> <ins> // the domain size check is needed because the HIR may not be well-formed at this point for (i, arg) in args.args.iter().enumerate().take(params_in_repr.domain_size()) { </ins> if let hir::GenericArg::Type(ty) = arg && params_in_repr.contains(i as u32) { find_item_ty_spans(tcx, ty, needle, spans, seen_representable); }