cannot relate region: LUB(ReErased, ReEmpty(U22))

[LeCyberDucky]

Hi, it appears that I've stumbled upon an internal compiler error.

Code

I'm sorry that I can't provide a minimal example, but I'm not on a level to understand what is going on (at least for now, heh :P). I'm just here, because the compiler told me to go here. I have, however, pushed a commit of my project in the state that yields the error: https://github.com/LeCyberDucky/bitgeon/tree/Error-handling

The error occurs when running cargo check --bin main or cargo +nightly check --bin main, for that matter.

Meta

rustc --version --verbose:

rustc 1.45.2 (d3fb005a3 2020-07-31)
binary: rustc
commit-hash: d3fb005a39e62501b8b0b356166e515ae24e2e54
commit-date: 2020-07-31
host: x86_64-pc-windows-msvc
release: 1.45.2
LLVM version: 10.0

Also happens on nightly:

rustc 1.47.0-nightly (5180f3da5 2020-08-23)
binary: rustc
commit-hash: 5180f3da5fd72627a8d38558ad1297df38793acd
commit-date: 2020-08-23
host: x86_64-pc-windows-msvc
release: 1.47.0-nightly
LLVM version: 11.0

Error output

error: internal compiler error: src\librustc_infer\infer\lexical_region_resolve\mod.rs:501:17: cannot relate region: LUB(ReErased, ReEmpty(U0))

thread 'rustc' panicked at 'Box<Any>', src\librustc_errors\lib.rs:918:9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: rustc 1.47.0-nightly (5180f3da5 2020-08-23) running on x86_64-pc-windows-msvc

note: compiler flags: -C embed-bitcode=no -C debuginfo=2 -C incremental --crate-type bin

note: some of the compiler flags provided by cargo are hidden

Backtrace

thread 'rustc' panicked at 'Box<Any>', src\librustc_errors\lib.rs:918:9
stack backtrace:
   0:     0x7ffa741d9f69 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hfae6a97726d8b736
   1:     0x7ffa74206f7b - core::fmt::write::hce2ddfec834877b8
   2:     0x7ffa741cbae4 - <std::io::IoSlice as core::fmt::Debug>::fmt::h57a15d9f0ff2a3bc
   3:     0x7ffa741df5cb - std::panicking::take_hook::h1925373a96008b93
   4:     0x7ffa741df209 - std::panicking::take_hook::h1925373a96008b93
   5:     0x7ffa4057e2da - rustc_driver::report_ice::h691a614479cbf5f9
   6:     0x7ffa741dff60 - std::panicking::rust_panic_with_hook::h7f7de81d557f54d3
   7:     0x7ffa44ad9420 - rustc_errors::annotate_snippet_emitter_writer::AnnotateSnippetEmitterWriter::ui_testing::h342a15b3ea83deed
   8:     0x7ffa44ad9299 - rustc_errors::annotate_snippet_emitter_writer::AnnotateSnippetEmitterWriter::ui_testing::h342a15b3ea83deed
   9:     0x7ffa44ad93c1 - rustc_errors::annotate_snippet_emitter_writer::AnnotateSnippetEmitterWriter::ui_testing::h342a15b3ea83deed
  10:     0x7ffa44aa741f - rustc_errors::HandlerInner::err_count::hde95b83d37d5673c
  11:     0x7ffa44aa58e2 - rustc_errors::Handler::bug::h8dde62b9b1066bb6
  12:     0x7ffa447b16f8 - rustc_middle::util::bug::bug_fmt::h582d9a3024b38eb2
  13:     0x7ffa447a74c0 - rustc_middle::ty::context::tls::ImplicitCtxt::new::hee3ec7f9c2036613
  14:     0x7ffa447a73f6 - rustc_middle::ty::context::tls::ImplicitCtxt::new::hee3ec7f9c2036613
  15:     0x7ffa447b162c - rustc_middle::util::bug::bug_fmt::h582d9a3024b38eb2
  16:     0x7ffa447b1590 - rustc_middle::util::bug::bug_fmt::h582d9a3024b38eb2
  17:     0x7ffa4441f9d5 - rustc_infer::infer::at::At::eq_impl_headers::h0438c0123706fd52
  18:     0x7ffa4441f60b - rustc_infer::infer::at::At::eq_impl_headers::h0438c0123706fd52
  19:     0x7ffa4441c618 - rustc_infer::infer::at::At::eq_impl_headers::h0438c0123706fd52
  20:     0x7ffa4441ae3e - rustc_infer::infer::at::At::eq_impl_headers::h0438c0123706fd52
  21:     0x7ffa444477a5 - rustc_infer::infer::InferCtxt::resolve_regions_and_report_errors::hdc4ef9538c1690b0
  22:     0x7ffa42c9faa5 - rustc_typeck::check::regionck::<impl rustc_typeck::check::FnCtxt>::regionck_fn::h2c0844d774a487aa
  23:     0x7ffa42ea395e - <rustc_typeck::astconv::PathSeg as core::fmt::Debug>::fmt::hd47536854a836cae
  24:     0x7ffa42ca427f - <rustc_typeck::check::fixup_opaque_types::FixupFolder as rustc_middle::ty::fold::TypeFolder>::fold_ty::h867fe2289cbd19a6
  25:     0x7ffa42e25e7e - <rustc_typeck::check::method::CandidateSource as core::fmt::Debug>::fmt::h9df5f6aadf76f4c6
  26:     0x7ffa42da9b76 - <rustc_typeck::outlives::explicit::ExplicitPredicatesMap as core::fmt::Debug>::fmt::h23984b0fc0edb9dc
  27:     0x7ffa42df3697 - <rustc_typeck::check::wfcheck::CheckTypeWellFormedVisitor as rustc_hir::intravisit::Visitor>::visit_generic_param::hd6c2af7cc4c28074
  28:     0x7ffa42e022d2 - <rustc_typeck::check::wfcheck::CheckTypeWellFormedVisitor as rustc_hir::intravisit::Visitor>::visit_generic_param::hd6c2af7cc4c28074
  29:     0x7ffa42d1133e - rustc_typeck::check::intrinsic::check_platform_intrinsic_type::h10efa74617b992ec
  30:     0x7ffa42e45e8a - <rustc_typeck::collect::AnonConstInParamListDetector as rustc_hir::intravisit::Visitor>::visit_anon_const::h7a95589413018206
  31:     0x7ffa42decfa1 - <rustc_typeck::check::wfcheck::CheckTypeWellFormedVisitor as rustc_hir::intravisit::Visitor>::visit_generic_param::hd6c2af7cc4c28074
  32:     0x7ffa42da9200 - <rustc_typeck::outlives::explicit::ExplicitPredicatesMap as core::fmt::Debug>::fmt::h23984b0fc0edb9dc
  33:     0x7ffa42df444b - <rustc_typeck::check::wfcheck::CheckTypeWellFormedVisitor as rustc_hir::intravisit::Visitor>::visit_generic_param::hd6c2af7cc4c28074
  34:     0x7ffa42e045dc - <rustc_typeck::check::wfcheck::CheckTypeWellFormedVisitor as rustc_hir::intravisit::Visitor>::visit_generic_param::hd6c2af7cc4c28074
  35:     0x7ffa42d28c5b - rustc_typeck::check::intrinsic::check_platform_intrinsic_type::h10efa74617b992ec
  36:     0x7ffa42e1cd41 - rustc_typeck::check::method::probe::provide::h9dacf3c90b52281a
  37:     0x7ffa42e17486 - rustc_typeck::check::method::probe::provide::h9dacf3c90b52281a
  38:     0x7ffa42e16022 - rustc_typeck::check::method::probe::provide::h9dacf3c90b52281a
  39:     0x7ffa42eb2697 - <rustc_typeck::astconv::PathSeg as core::fmt::Debug>::fmt::hd47536854a836cae
  40:     0x7ffa42c79f96 - rustc_typeck::check::method::probe::<impl rustc_typeck::check::FnCtxt>::probe_for_name::hfd99b115a5e97702
  41:     0x7ffa42c87c16 - rustc_typeck::check::method::<impl rustc_typeck::check::FnCtxt>::lookup_method::h605ea8d44c69baf9
  42:     0x7ffa42c65cf0 - rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation::h31fe46ad61575e66
  43:     0x7ffa42c65346 - rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation::h31fe46ad61575e66
  44:     0x7ffa42cc6137 - rustc_typeck::check::FnCtxt::check_stmt::he9fdfdadf00ae15c
  45:     0x7ffa42cc6b16 - rustc_typeck::check::FnCtxt::check_block_no_value::h587532fce6d42b9a
  46:     0x7ffa42c658a8 - rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation::h31fe46ad61575e66
  47:     0x7ffa42c65346 - rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation::h31fe46ad61575e66
  48:     0x7ffa42c4b9df - rustc_typeck::check::_match::<impl rustc_typeck::check::FnCtxt>::check_match::ha2741c781afdaf34
  49:     0x7ffa42c65a2f - rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation::h31fe46ad61575e66
  50:     0x7ffa42c65346 - rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation::h31fe46ad61575e66
  51:     0x7ffa42cc6b4d - rustc_typeck::check::FnCtxt::check_block_no_value::h587532fce6d42b9a
  52:     0x7ffa42cc647a - rustc_typeck::check::FnCtxt::check_block_no_value::h587532fce6d42b9a
  53:     0x7ffa42c6efbf - rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation::h31fe46ad61575e66
  54:     0x7ffa42c65346 - rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation::h31fe46ad61575e66
  55:     0x7ffa42cc5f2c - rustc_typeck::check::FnCtxt::check_stmt::he9fdfdadf00ae15c
  56:     0x7ffa42cc6b16 - rustc_typeck::check::FnCtxt::check_block_no_value::h587532fce6d42b9a
  57:     0x7ffa42c658a8 - rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation::h31fe46ad61575e66
  58:     0x7ffa42c65346 - rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation::h31fe46ad61575e66
  59:     0x7ffa42c77718 - rustc_typeck::check::expr::<impl rustc_typeck::check::FnCtxt>::check_expr_with_expectation::h31fe46ad61575e66
  60:     0x7ffa42ca5bf0 - <rustc_typeck::check::GatherLocalsVisitor as rustc_hir::intravisit::Visitor>::visit_pat::h91ac2640bc869925
  61:     0x7ffa42ea33f1 - <rustc_typeck::astconv::PathSeg as core::fmt::Debug>::fmt::hd47536854a836cae
  62:     0x7ffa42ca427f - <rustc_typeck::check::fixup_opaque_types::FixupFolder as rustc_middle::ty::fold::TypeFolder>::fold_ty::h867fe2289cbd19a6
  63:     0x7ffa42e25e7e - <rustc_typeck::check::method::CandidateSource as core::fmt::Debug>::fmt::h9df5f6aadf76f4c6
  64:     0x7ffa42da9b76 - <rustc_typeck::outlives::explicit::ExplicitPredicatesMap as core::fmt::Debug>::fmt::h23984b0fc0edb9dc
  65:     0x7ffa42df3697 - <rustc_typeck::check::wfcheck::CheckTypeWellFormedVisitor as rustc_hir::intravisit::Visitor>::visit_generic_param::hd6c2af7cc4c28074
  66:     0x7ffa42e022d2 - <rustc_typeck::check::wfcheck::CheckTypeWellFormedVisitor as rustc_hir::intravisit::Visitor>::visit_generic_param::hd6c2af7cc4c28074
  67:     0x7ffa42d1133e - rustc_typeck::check::intrinsic::check_platform_intrinsic_type::h10efa74617b992ec
  68:     0x7ffa42e45e8a - <rustc_typeck::collect::AnonConstInParamListDetector as rustc_hir::intravisit::Visitor>::visit_anon_const::h7a95589413018206
  69:     0x7ffa42e25db1 - <rustc_typeck::check::method::CandidateSource as core::fmt::Debug>::fmt::h9df5f6aadf76f4c6
  70:     0x7ffa42da9200 - <rustc_typeck::outlives::explicit::ExplicitPredicatesMap as core::fmt::Debug>::fmt::h23984b0fc0edb9dc
  71:     0x7ffa42df444b - <rustc_typeck::check::wfcheck::CheckTypeWellFormedVisitor as rustc_hir::intravisit::Visitor>::visit_generic_param::hd6c2af7cc4c28074
  72:     0x7ffa42e045dc - <rustc_typeck::check::wfcheck::CheckTypeWellFormedVisitor as rustc_hir::intravisit::Visitor>::visit_generic_param::hd6c2af7cc4c28074
  73:     0x7ffa42d28c5b - rustc_typeck::check::intrinsic::check_platform_intrinsic_type::h10efa74617b992ec
  74:     0x7ffa42d64791 - rustc_typeck::check::intrinsic::check_platform_intrinsic_type::h10efa74617b992ec
  75:     0x7ffa42e40b1e - <rustc_typeck::collect::CollectItemTypesVisitor as rustc_hir::intravisit::Visitor>::visit_impl_item::h36434602c51150aa
  76:     0x7ffa42e3cabb - <rustc_typeck::coherence::unsafety::UnsafetyChecker as rustc_hir::itemlikevisit::ItemLikeVisitor>::visit_item::hce7e1143b3799b82
  77:     0x7ffa42d6f65d - rustc_typeck::check::intrinsic::check_platform_intrinsic_type::h10efa74617b992ec
  78:     0x7ffa42dab9e6 - <rustc_typeck::outlives::explicit::ExplicitPredicatesMap as core::fmt::Debug>::fmt::h23984b0fc0edb9dc
  79:     0x7ffa42df68af - <rustc_typeck::check::wfcheck::CheckTypeWellFormedVisitor as rustc_hir::intravisit::Visitor>::visit_generic_param::hd6c2af7cc4c28074
  80:     0x7ffa42e03092 - <rustc_typeck::check::wfcheck::CheckTypeWellFormedVisitor as rustc_hir::intravisit::Visitor>::visit_generic_param::hd6c2af7cc4c28074
  81:     0x7ffa42d17908 - rustc_typeck::check::intrinsic::check_platform_intrinsic_type::h10efa74617b992ec
  82:     0x7ffa42d641c5 - rustc_typeck::check::intrinsic::check_platform_intrinsic_type::h10efa74617b992ec
  83:     0x7ffa42d710c3 - rustc_typeck::check::intrinsic::check_platform_intrinsic_type::h10efa74617b992ec
  84:     0x7ffa42e54717 - rustc_typeck::check_crate::hfa34d01a976dedf2
  85:     0x7ffa4087b65a - rustc_interface::passes::QueryContext::print_stats::h20b8fe0532b52929
  86:     0x7ffa4059c00b - <rustc_driver::DEFAULT_HOOK as core::ops::deref::Deref>::deref::hadcd711a94621615
  87:     0x7ffa4050ca26 - <rustc_lint::BuiltinCombinedEarlyLintPass as rustc_lint::passes::EarlyLintPass>::check_mac_def::hb3829129d340a05d
  88:     0x7ffa40585222 - <rustc_driver::DEFAULT_HOOK as core::ops::deref::Deref>::deref::hadcd711a94621615
  89:     0x7ffa40592032 - <rustc_driver::DEFAULT_HOOK as core::ops::deref::Deref>::deref::hadcd711a94621615
  90:     0x7ffa40540ca3 - <rustc_middle::traits::chalk::RustInterner as chalk_ir::interner::Interner>::generic_arg_data::h71f2dc6ba8dcf3ae
  91:     0x7ffa4059cd7b - <rustc_driver::DEFAULT_HOOK as core::ops::deref::Deref>::deref::hadcd711a94621615
  92:     0x7ffa405332cc - <rustc_driver::args::Error as core::fmt::Debug>::fmt::h02e1be4607868908
  93:     0x7ffa4059f1ab - <rustc_driver::DEFAULT_HOOK as core::ops::deref::Deref>::deref::hadcd711a94621615
  94:     0x7ffa4058bce0 - <rustc_driver::DEFAULT_HOOK as core::ops::deref::Deref>::deref::hadcd711a94621615
  95:     0x7ffa40592d89 - <rustc_driver::DEFAULT_HOOK as core::ops::deref::Deref>::deref::hadcd711a94621615
  96:     0x7ffa4052b7b3 - <rustc_middle::ty::SymbolName as core::fmt::Display>::fmt::h6ff509d3525ea80f
  97:     0x7ffa741efcca - std::sys::windows::thread::Thread::new::h84550e08827b3a3a
  98:     0x7ffab0816fd4 - BaseThreadInitThunk
  99:     0x7ffab18fcec1 - RtlUserThreadStart

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: rustc 1.47.0-nightly (5180f3da5 2020-08-23) running on x86_64-pc-windows-msvc

note: compiler flags: -C embed-bitcode=no -C debuginfo=2 -C incremental --crate-type bin

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
#0 [typeck] type-checking `ui::UI::interact`
#1 [fn_sig] computing function signature of `ui::UI::interact`
#2 [typeck] type-checking `ui::UI::run`
#3 [fn_sig] computing function signature of `ui::UI::run`
#4 [collect_mod_item_types] collecting item types in module `ui`
#5 [analysis] running analysis passes on this crate
end of query stack

I hope this helps. Please tell me, if there's more you need me to do. 🦀

[matthiaskrgr]

reduced:

pub struct UI {}

impl UI {
    pub fn run() -> Result<_> {
        let mut ui = UI {};
        ui.interact();

        unimplemented!();
    }

    pub fn interact(&mut self) -> Result<_> {
        unimplemented!();
    }
}

[tesuji]

@rustbot modify labels: -E-needs-mcve

[spastorino]

Assigning P-medium as discussed as part of the Prioritization Working Group procedure and removing I-prioritize.

[matthiaskrgr]

This ICEs since 1.44
@rustbot modify labels: +regression-from-stable-to-stable