Compiler crash with reference mismatch in 1.68 only

[AlaskanEmily]

Code

// Any copyright is dedicated to the Public Domain.
// https://creativecommons.org/publicdomain/zero/1.0/
use std::rc::Rc;
extern crate core;
use core::slice::Iter;
use core::ops::{Deref, Range};

pub struct RCSlice<T>{
    slice: Rc<[T]>,
    range: Range<u16>,
}

impl<T> RCSlice<T>{
    #[inline]
    pub fn new<U: Into<Rc<[T]>>>(that: U, range: Range<usize>) -> RCSlice<T>{   
        let range = (range.start as u16)..(range.end as u16);
        let slice = that.into();
        RCSlice{
            slice,
            range,
        }
    }    
    #[inline]
    pub fn as_slice(&self) -> &[T]{                                             
        let range = (self.range.start as usize)..(self.range.end as usize);     
        &(*self.slice)[range]
    }
    pub fn iter(&self) -> Iter<'_, T>{                                     
        self.as_slice().iter()                                                  
    } 
}

impl<T> Deref for RCSlice<T>{
    type Target = [T];
    #[inline]
    fn deref(&self) -> &[T]{
        self.as_slice()
    }
}

#[inline]
const fn lex_break(b: &u8) -> bool{
    *b == b' ' || *b == b'\t'
}

#[inline]
fn not_empty(that: (usize, &[u8])) -> bool{
    !that.1.is_empty()
}

fn parse<I>(
    iter: &mut I,
) -> Result<(), ()>
where
    I: Iterator<Item = RCSlice<u8>>
{
    for i in iter{
        let mut chunks = i.split(lex_break).enumerate().filter(not_empty);
        let mut i = 0;
        for (i, b) in chunks{

        }
    }
    Ok(())
}

Meta

rustc --version --verbose:

rustc 1.68.0 (2c8cc3432 2023-03-06) (built from a source tarball)
binary: rustc
commit-hash: 2c8cc343237b8f7d5a3c3703e3a87f2eb2c54a74
commit-date: 2023-03-06
host: x86_64-unknown-openbsd
release: 1.68.0
LLVM version: 15.0.6

Also tested with:

rustc 1.68.0 (2c8cc3432 2023-03-06)
binary: rustc
commit-hash: 2c8cc343237b8f7d5a3c3703e3a87f2eb2c54a74
commit-date: 2023-03-06
host: x86_64-unknown-linux-gnu
release: 1.68.0
LLVM version: 15.0.6

Error output

error: internal compiler error: compiler/rustc_infer/src/infer/region_constraints/mod.rs:568:17: cannot relate bound region: ReLateBound(DebruijnIndex(0), BoundRegion { var: 0, kind: BrNamed(DefId(0:31 ~ crash_1_68[721b]::not_empty::'_), '_) }) <= '_#23r

Backtrace

   0: std::panicking::begin_panic::<rustc_errors::ExplicitBug>
   1: std::panic::panic_any::<rustc_errors::ExplicitBug>
   2: <rustc_errors::HandlerInner>::span_bug::<rustc_span::span_encoding::Span, &alloc::string::String>
   3: <rustc_errors::Handler>::span_bug::<rustc_span::span_encoding::Span, &alloc::string::String>
   4: rustc_middle::util::bug::opt_span_bug_fmt::<rustc_span::span_encoding::Span>::{closure#0}
   5: rustc_middle::ty::context::tls::with_opt::<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>::{closure#0}
   6: rustc_middle::ty::context::tls::with_context_opt::<rustc_middle::ty::context::tls::with_opt<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
   7: rustc_middle::util::bug::opt_span_bug_fmt::<rustc_span::span_encoding::Span>
   8: rustc_middle::util::bug::span_bug_fmt::<rustc_span::span_encoding::Span>
   9: <rustc_infer::infer::region_constraints::RegionConstraintCollector>::make_subregion
  10: <rustc_infer::infer::region_constraints::RegionConstraintCollector>::make_eqregion
  11: <rustc_infer::infer::equate::Equate as rustc_middle::ty::relate::TypeRelation>::regions
  12: rustc_middle::ty::relate::super_relate_tys::<rustc_infer::infer::equate::Equate>
  13: <rustc_infer::infer::InferCtxt>::super_combine_tys::<rustc_infer::infer::equate::Equate>
  14: <rustc_infer::infer::equate::Equate as rustc_middle::ty::relate::TypeRelation>::tys
  15: <core::result::Result<rustc_middle::ty::Ty, rustc_middle::ty::error::TypeError> as rustc_type_ir::InternIteratorElement<rustc_middle::ty::Ty, rustc_middle::ty::Ty>>::intern_with::<core::iter::adapters::map::Map<core::iter::adapters::zip::Zip<core::iter::adapters::copied::Copied<core::slice::iter::Iter<rustc_middle::ty::Ty>>, core::iter::adapters::copied::Copied<core::slice::iter::Iter<rustc_middle::ty::Ty>>>, rustc_middle::ty::relate::super_relate_tys<rustc_infer::infer::equate::Equate>::{closure#2}>, <rustc_middle::ty::context::TyCtxt>::mk_tup<core::iter::adapters::map::Map<core::iter::adapters::zip::Zip<core::iter::adapters::copied::Copied<core::slice::iter::Iter<rustc_middle::ty::Ty>>, core::iter::adapters::copied::Copied<core::slice::iter::Iter<rustc_middle::ty::Ty>>>, rustc_middle::ty::relate::super_relate_tys<rustc_infer::infer::equate::Equate>::{closure#2}>>::{closure#0}>
  16: rustc_middle::ty::relate::super_relate_tys::<rustc_infer::infer::equate::Equate>
  17: <rustc_infer::infer::InferCtxt>::super_combine_tys::<rustc_infer::infer::equate::Equate>
  18: <rustc_infer::infer::equate::Equate as rustc_middle::ty::relate::TypeRelation>::tys
  19: <rustc_infer::infer::InferCtxt>::commit_if_ok::<rustc_infer::infer::InferOk<()>, rustc_middle::ty::error::TypeError, <rustc_infer::infer::at::Trace>::eq<rustc_middle::ty::Ty>::{closure#0}>
  20: <rustc_infer::infer::InferCtxt>::can_eq::<rustc_middle::ty::Ty>
  21: rustc_trait_selection::traits::error_reporting::suggestions::hint_missing_borrow
  22: <rustc_infer::infer::error_reporting::TypeErrCtxt as rustc_trait_selection::traits::error_reporting::suggestions::TypeErrCtxtExt>::report_closure_arg_mismatch
  23: <rustc_infer::infer::error_reporting::TypeErrCtxt as rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt>::report_selection_error
  24: <rustc_infer::infer::error_reporting::TypeErrCtxt as rustc_trait_selection::traits::error_reporting::InferCtxtPrivExt>::report_fulfillment_error
  25: <rustc_infer::infer::error_reporting::TypeErrCtxt as rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt>::report_fulfillment_errors
  26: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_argument_types
  27: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_method_argument_types
  28: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_kind
  29: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  30: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_decl
  31: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_stmt
  32: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_block_with_expected
  33: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_kind
  34: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  35: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_match::{closure#0}
  36: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_kind
  37: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  38: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_stmt
  39: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_block_with_expected
  40: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_kind
  41: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  42: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_match::{closure#0}
  43: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_kind
  44: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  45: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_kind
  46: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  47: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_stmt
  48: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_block_with_expected
  49: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_kind
  50: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  51: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_return_expr
  52: rustc_hir_typeck::check::check_fn
  53: rustc_hir_typeck::typeck
  54: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::typeck, rustc_query_impl::plumbing::QueryCtxt>
  55: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::typeck
  56: rustc_data_structures::sync::par_for_each_in::<&[rustc_span::def_id::LocalDefId], <rustc_middle::hir::map::Map>::par_body_owners<rustc_hir_typeck::typeck_item_bodies::{closure#0}>::{closure#0}>
  57: rustc_hir_typeck::typeck_item_bodies
  58: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::typeck_item_bodies, rustc_query_impl::plumbing::QueryCtxt>
  59: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::typeck_item_bodies
  60: <rustc_session::session::Session>::time::<(), rustc_hir_analysis::check_crate::{closure#7}>
  61: rustc_hir_analysis::check_crate
  62: rustc_interface::passes::analysis
  63: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::analysis, rustc_query_impl::plumbing::QueryCtxt>
  64: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::analysis
  65: <rustc_interface::passes::QueryContext>::enter::<rustc_driver::run_compiler::{closure#1}::{closure#2}::{closure#2}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
  66: <rustc_interface::queries::QueryResult<rustc_interface::passes::QueryContext>>::enter::<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}::{closure#2}::{closure#2}>
  67: rustc_span::with_source_map::<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
  68: <scoped_tls::ScopedKey<rustc_span::SessionGlobals>>::set::<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>

[AlaskanEmily]

This crash goes away if the code is fixed, by changing the signature of not_empty to be fn not_empty(that: &(usize, &[u8])) -> bool

This only seems to happen on 1.68, testing with 1.69 and 1.67 using godbolt shows it succeeds. For refernce, 1.68 is the version that ships with stable OpenBSD.

[ChrisDenton]

A fix is very unlikely to be backported to 1.68 by rust. You'd have to contact the OpenBSD package maintainers about that.

[est31]

This is a dupe of (closed) #109361 . The PR that OpenBSD maintainers would need to backport is #107306 .