Change:
<!-- Thank you for filing a bug report! Please provide a short summary of the bug, along with any information you feel relevant to replicating the bug. --I tried this code: I expected to see this happen: program either compiled successful or compiler generate an error Instead, this happened: rustc eats 100% CPU for several minutes, but nothing generated. I compile this code using both and before I began to write this issue, but compiler do not compile even after this issue is submitted. <!-- 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<summaryBacktrace</summary<p</p</details
Slightly smaller:
Actually, I am very curious that, why rustc do not reach the recursion limit.
Oh sorry, you're right, it does hit the recursion limit if I let it run long enough (about 10 seconds).
Here's a proper minimization:
Partial backtrace of the hang: <details</details
So it actually hangs while trying to print the overflow error :laughing:
Bisected:
looks suspicious.
hang but generate a failed massage:
Assigning and removing .

Discussion:
use crate::ty::{self, ConstInt, DefIdTree, ParamConst, ScalarInt, Ty, TyCtxt, TypeFoldable}; use rustc_apfloat::ieee::{Double, Single}; use rustc_data_structures::fx::FxHashMap; <ins> use rustc_data_structures::sso::SsoHashSet; </ins> use rustc_hir as hir; use rustc_hir::def::{self, CtorKind, DefKind, Namespace}; use rustc_hir::def_id::{CrateNum, DefId, DefIdSet, CRATE_DEF_INDEX, LOCAL_CRATE};

} fn print_type(mut self, ty: Ty<'tcx>) -> Result<Self::Type, Self::Error> { <del> if self.tcx.sess.type_length_limit().value_within_limit(self.printed_type_count) { </del> <ins> let type_length_limit = self.tcx.sess.type_length_limit(); if type_length_limit.value_within_limit(self.printed_type_count) { </ins> self.printed_type_count += 1; self.pretty_print_type(ty) } else {

where T: TypeFoldable<'tcx>, { <del> struct LateBoundRegionNameCollector<'a>(&'a mut FxHashSet<Symbol>); impl<'tcx> ty::fold::TypeVisitor<'tcx> for LateBoundRegionNameCollector<'_> { </del> <ins> debug!("prepare_late_bound_region_info(value: {:?})", value); struct LateBoundRegionNameCollector<'a, 'tcx> { used_region_names: &'a mut FxHashSet<Symbol>, type_collector: SsoHashSet<Ty<'tcx>>, } impl<'tcx> ty::fold::TypeVisitor<'tcx> for LateBoundRegionNameCollector<'_, 'tcx> { type BreakTy = (); </ins> fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> { <ins> debug!("LateBoundRegionNameCollector::visit_region(r: {:?}, address: {:p})", r, &r); </ins> if let ty::ReLateBound(_, ty::BoundRegion { kind: ty::BrNamed(_, name), .. }) = *r { <del> self.0.insert(name); </del> <ins> self.used_region_names.insert(name); </ins> } r.super_visit_with(self) } <ins> // We collect types in order to prevent really large types from compiling for // a really long time. See issue #83150 for why this is necessary. fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<Self::BreakTy> { debug!("LateBoundRegionNameCollector::visit_ty(ty: {:?}", ty); let not_previously_inserted = self.type_collector.insert(ty); if not_previously_inserted { ty.super_visit_with(self) } else { ControlFlow::CONTINUE } } </ins> } self.used_region_names.clear(); <del> let mut collector = LateBoundRegionNameCollector(&mut self.used_region_names); </del> <ins> let mut collector = LateBoundRegionNameCollector { used_region_names: &mut self.used_region_names, type_collector: SsoHashSet::new(), }; </ins> value.visit_with(&mut collector); self.region_index = 0; }

<ins> // build-fail //~^ overflow evaluating fn main() { let mut iter = 0u8..1; func(&mut iter) } fn func<T: Iterator<Item = u8>>(iter: &mut T) { func(&mut iter.map(|x| x + 1)) } </ins>

<ins> error[E0275]: overflow evaluating the requirement `Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut std::ops::Range<u8>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>: Iterator` | = help: consider adding a `#![recursion_limit="256"]` attribute to your crate (`issue_83150`) = note: required because of the requirements on the impl of `Iterator` for `&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut std::ops::Range<u8>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>` error: aborting due to previous error For more information about this error, try `rustc --explain E0275`. </ins>