Change:
len: ty::Const<'tcx>, min_len: u64, ) -> (Option<Ty<'tcx>>, Ty<'tcx>) { <del> let guar = if let Some(len) = len.try_eval_target_usize(self.tcx, self.param_env) { </del> <ins> let len = match len.eval(self.tcx, self.param_env, None) { Ok(val) => val .try_to_scalar() .and_then(|scalar| scalar.try_to_int().ok()) .and_then(|int| int.try_to_target_usize(self.tcx).ok()), Err(ErrorHandled::Reported(..)) => { let guar = self.error_scrutinee_unfixed_length(span); return (Some(Ty::new_error(self.tcx, guar)), arr_ty); } Err(ErrorHandled::TooGeneric(..)) => None, }; let guar = if let Some(len) = len { </ins> // Now we know the length... if slice.is_none() { // ...and since there is no variable-length pattern,

Discussion:
<!-- Thank you for finding an Internal Compiler Error! If possible, try to provide a minimal verifiable example. You can read "Rust Bug Minimization Patterns" for how to create smaller examples. --<!-- If you're using the stable version of the compiler, you should also check if the bug also exists in the beta or nightly versions. --: <!-- Include a backtrace in the code block by setting in your environment. E.g. . --<details<summary<strongBacktrace</strong</summary<p</p</details
Regression in nightly-2021-09-01 found 9 bors merge commits in the specified range commit[0] 2021-08-30: Auto merge of - sexxi-goose:issue-, r=nikomatsakis commit[1] 2021-08-30: Auto merge of - lcnr:cec-rename, r=oli-obk commit[2] 2021-08-31: Auto merge of - HTG-YT:edition2021-compopt-stabilization, r=m-ou-se commit[3] 2021-08-31: Auto merge of - Aaron1011:guess-foreign-head-span, r=estebank commit[4] 2021-08-31: Auto merge of - sexxi-goose:issue-, r=nikomatsakis commit[5] 2021-08-31: Auto merge of - RalfJung:miri, r=RalfJung commit[6] 2021-08-31: Auto merge of - m-ou-se:rollup-az6xtc5, r=m-ou-se commit[7] 2021-08-31: Auto merge of - m-ou-se:rollup-jeusxbo, r=m-ou-se commit[8] 2021-08-31: Auto merge of - Mark-Simulacrum:fix-rlibs, r=ehuss

<!-- Thank you for finding an Internal Compiler Error! If possible, try to provide a minimal verifiable example. You can read "Rust Bug Minimization Patterns" for how to create smaller examples. --<!-- If you're using the stable version of the compiler, you should also check if the bug also exists in the beta or nightly versions. --: <!-- Include a backtrace in the code block by setting in your environment. E.g. . --<details<summary<strongBacktrace</strong</summary<p</p</details
cc
This also ICEs on stable with the same error, so I don't think this is related to any of my recent changes at a glance. Having a look at it though
Regression in nightly-2021-09-01 commit[0] 2021-08-30: Auto merge of - sexxi-goose:issue-, r=nikomatsakis commit[1] 2021-08-30: Auto merge of - lcnr:cec-rename, r=oli-obk commit[2] 2021-08-31: Auto merge of - HTG-YT:edition2021-compopt-stabilization, r=m-ou-se commit[3] 2021-08-31: Auto merge of - Aaron1011:guess-foreign-head-span, r=estebank commit[4] 2021-08-31: Auto merge of - sexxi-goose:issue-, r=nikomatsakis commit[5] 2021-08-31: Auto merge of - RalfJung:miri, r=RalfJung commit[6] 2021-08-31: Auto merge of - m-ou-se:rollup-az6xtc5, r=m-ou-se commit[7] 2021-08-31: Auto merge of - m-ou-se:rollup-jeusxbo, r=m-ou-se commit[8] 2021-08-31: Auto merge of - Mark-Simulacrum:fix-rlibs, r=ehuss
I suspect that might be a false positive bisect?

ah meh, probably, if the feature gate was renamed or something, the code with the "new" feature gate might no longer trigger the ice once needed the old feature gate -_-
Bisected to nightly-2022-11-27, probably caused by . <details<summary<codecargo-bisect-rustc</codeoutput </summary</details