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Auto merge of #83406 - b-naber:issue-83510, r=lcnr
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Prevent very long compilation runtimes in LateBoundRegionNameCollector

Fixes #83150

On recursive types such as in the example given in #83150, the current implementation of `LateBoundRegionNameCollector` has very long compilation runtimes. To prevent those we store the types visited in the `middle::ty::Visitor` implementation of `LateBoundRegionNameCollector` in a `SsoHashSet`.
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bors committed Apr 5, 2021
2 parents 5a7a0ac + 3194b26 commit d203fce
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Showing 3 changed files with 50 additions and 5 deletions.
36 changes: 31 additions & 5 deletions compiler/rustc_middle/src/ty/print/pretty.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@ use crate::ty::subst::{GenericArg, GenericArgKind, Subst};
use crate::ty::{self, ConstInt, DefIdTree, ParamConst, ScalarInt, Ty, TyCtxt, TypeFoldable};
use rustc_apfloat::ieee::{Double, Single};
use rustc_data_structures::fx::FxHashMap;
use rustc_data_structures::sso::SsoHashSet;
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};
Expand Down Expand Up @@ -1421,7 +1422,8 @@ impl<F: fmt::Write> Printer<'tcx> for FmtPrinter<'_, 'tcx, F> {
}

fn print_type(mut self, ty: Ty<'tcx>) -> Result<Self::Type, Self::Error> {
if self.tcx.sess.type_length_limit().value_within_limit(self.printed_type_count) {
let type_length_limit = self.tcx.sess.type_length_limit();
if type_length_limit.value_within_limit(self.printed_type_count) {
self.printed_type_count += 1;
self.pretty_print_type(ty)
} else {
Expand Down Expand Up @@ -1863,18 +1865,42 @@ impl<F: fmt::Write> FmtPrinter<'_, 'tcx, F> {
where
T: TypeFoldable<'tcx>,
{
struct LateBoundRegionNameCollector<'a>(&'a mut FxHashSet<Symbol>);
impl<'tcx> ty::fold::TypeVisitor<'tcx> for LateBoundRegionNameCollector<'_> {
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 = ();

fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
debug!("LateBoundRegionNameCollector::visit_region(r: {:?}, address: {:p})", r, &r);
if let ty::ReLateBound(_, ty::BoundRegion { kind: ty::BrNamed(_, name), .. }) = *r {
self.0.insert(name);
self.used_region_names.insert(name);
}
r.super_visit_with(self)
}

// 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
}
}
}

self.used_region_names.clear();
let mut collector = LateBoundRegionNameCollector(&mut self.used_region_names);
let mut collector = LateBoundRegionNameCollector {
used_region_names: &mut self.used_region_names,
type_collector: SsoHashSet::new(),
};
value.visit_with(&mut collector);
self.region_index = 0;
}
Expand Down
11 changes: 11 additions & 0 deletions src/test/ui/recursion/issue-83150.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,11 @@
// 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))
}
8 changes: 8 additions & 0 deletions src/test/ui/recursion/issue-83150.stderr
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Original file line number Diff line number Diff line change
@@ -0,0 +1,8 @@
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`.

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