ICE: `failure to relate an opaque to itself should result in an error later on`

[kmicklas]

Code

pub trait BorrowComposite {
    type Ref<'a>
    where
        Self: 'a;
}

impl BorrowComposite for () {
    type Ref<'a> = ();
}

pub trait Component<Args: BorrowComposite> {
    type Output;
}

impl<Args: BorrowComposite> Component<Args> for () {
    type Output = ();
}

struct Delay<Make> {
    _make: Make,
}

impl<
        Args: BorrowComposite,
        Make: for<'a> FnMut(Args::Ref<'a>) -> C,
        C: Component<Args>,
    > Component<Args> for Delay<Make>
{
    type Output = C::Output;
}

pub fn delay<
    Args: BorrowComposite,
    Make: for<'a> FnMut(Args::Ref<'a>) -> C,
    C: Component<Args>,
>(
    make: Make,
) -> impl Component<Args, Output = C::Output> {
    Delay { _make: make }
}

pub fn crash() -> impl Component<(), Output = ()> {
    delay(|()| delay(|()| ()))
}

Meta

rustc --version --verbose:

rustc 1.73.0 (cc66ad468 2023-10-03)
binary: rustc
commit-hash: cc66ad468955717ab92600c770da8c1601a4ff33
commit-date: 2023-10-03
host: x86_64-unknown-linux-gnu
release: 1.73.0
LLVM version: 17.0.2

The same issue occurs with the latest nightly too.

Error output

error: internal compiler error: no errors encountered even though `delay_span_bug` issued

error: internal compiler error: failure to relate an opaque to itself should result in an error later on
  --> crash/src/lib.rs:43:16
   |
43 |     delay(|()| delay(|()| ()))
   |                ^
   |
note: delayed at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/compiler/rustc_infer/src/infer/nll_relate/mod.rs:500:37
         0: <rustc_errors::HandlerInner>::emit_diagnostic
         1: <rustc_errors::Handler>::delay_span_bug::<rustc_span::span_encoding::Span, &str>
         2: rustc_borrowck::type_check::type_check
         3: rustc_borrowck::nll::compute_regions
         4: rustc_borrowck::do_mir_borrowck
         5: rustc_borrowck::mir_borrowck
         6: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::mir_borrowck::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 8]>>
         7: <rustc_query_impl::query_impl::mir_borrowck::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_span::def_id::LocalDefId)>>::call_once
         8: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::Erased<[u8; 8]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
         9: rustc_query_impl::query_impl::mir_borrowck::get_query_incr::__rust_end_short_backtrace
        10: <rustc_borrowck::type_check::TypeChecker>::prove_closure_bounds
        11: <rustc_borrowck::type_check::TypeChecker>::typeck_mir
        12: rustc_borrowck::type_check::type_check
        13: rustc_borrowck::nll::compute_regions
        14: rustc_borrowck::do_mir_borrowck
        15: rustc_borrowck::mir_borrowck
        16: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::mir_borrowck::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 8]>>
        17: <rustc_query_impl::query_impl::mir_borrowck::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_span::def_id::LocalDefId)>>::call_once
        18: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::Erased<[u8; 8]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
        19: rustc_query_impl::query_impl::mir_borrowck::get_query_incr::__rust_end_short_backtrace
        20: rustc_hir_analysis::collect::type_of::opaque::find_opaque_ty_constraints_for_rpit
        21: rustc_hir_analysis::collect::type_of::type_of
        22: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::type_of::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 8]>>
        23: <rustc_query_impl::query_impl::type_of::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_span::def_id::DefId)>>::call_once
        24: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::DefaultCache<rustc_span::def_id::DefId, rustc_middle::query::erase::Erased<[u8; 8]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
        25: rustc_query_impl::query_impl::type_of::get_query_incr::__rust_end_short_backtrace
        26: rustc_middle::query::plumbing::query_get_at::<rustc_query_system::query::caches::DefaultCache<rustc_span::def_id::DefId, rustc_middle::query::erase::Erased<[u8; 8]>>>
        27: rustc_hir_analysis::check::check::check_mod_item_types
        28: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::check_mod_item_types::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 0]>>
        29: <rustc_query_impl::query_impl::check_mod_item_types::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_span::def_id::LocalModDefId)>>::call_once
        30: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::DefaultCache<rustc_span::def_id::LocalModDefId, rustc_middle::query::erase::Erased<[u8; 0]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
        31: rustc_query_impl::query_impl::check_mod_item_types::get_query_incr::__rust_end_short_backtrace
        32: <rustc_middle::hir::map::Map>::for_each_module::<rustc_hir_analysis::check_crate::{closure#6}::{closure#0}>
        33: rustc_hir_analysis::check_crate
        34: rustc_interface::passes::analysis
        35: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 1]>>
        36: <rustc_query_impl::query_impl::analysis::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, ())>>::call_once
        37: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 1]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
        38: rustc_query_impl::query_impl::analysis::get_query_incr::__rust_end_short_backtrace
        39: <rustc_interface::queries::QueryResult<&rustc_middle::ty::context::GlobalCtxt>>::enter::<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}::{closure#2}::{closure#6}>
        40: <rustc_interface::interface::Compiler>::enter::<rustc_driver_impl::run_compiler::{closure#1}::{closure#2}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>
        41: std::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>
        42: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
        43: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                   at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/alloc/src/boxed.rs:2007:9
        44: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                   at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/alloc/src/boxed.rs:2007:9
        45: std::sys::unix::thread::Thread::new::thread_start
                   at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/std/src/sys/unix/thread.rs:108:17
        46: start_thread
        47: __GI___clone3
  --> crash/src/lib.rs:43:16
   |
43 |     delay(|()| delay(|()| ()))
   |                ^

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 1.73.0 (cc66ad468 2023-10-03) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type lib -C embed-bitcode=no -C debuginfo=2 -C incremental=[REDACTED]

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

query stack during panic:
end of query stack

Backtrace

It doesn't look like I get any more info with RUST_BACKTRACE=1.

error: internal compiler error: no errors encountered even though `delay_span_bug` issued

error: internal compiler error: failure to relate an opaque to itself should result in an error later on
  --> crash/src/lib.rs:43:16
   |
43 |     delay(|()| delay(|()| ()))
   |                ^
   |
note: delayed at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/compiler/rustc_infer/src/infer/nll_relate/mod.rs:500:37
         0: <rustc_errors::HandlerInner>::emit_diagnostic
         1: <rustc_errors::Handler>::delay_span_bug::<rustc_span::span_encoding::Span, &str>
         2: rustc_borrowck::type_check::type_check
         3: rustc_borrowck::nll::compute_regions
         4: rustc_borrowck::do_mir_borrowck
         5: rustc_borrowck::mir_borrowck
         6: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::mir_borrowck::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 8]>>
         7: <rustc_query_impl::query_impl::mir_borrowck::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_span::def_id::LocalDefId)>>::call_once
         8: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::Erased<[u8; 8]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
         9: rustc_query_impl::query_impl::mir_borrowck::get_query_incr::__rust_end_short_backtrace
        10: <rustc_borrowck::type_check::TypeChecker>::prove_closure_bounds
        11: <rustc_borrowck::type_check::TypeChecker>::typeck_mir
        12: rustc_borrowck::type_check::type_check
        13: rustc_borrowck::nll::compute_regions
        14: rustc_borrowck::do_mir_borrowck
        15: rustc_borrowck::mir_borrowck
        16: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::mir_borrowck::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 8]>>
        17: <rustc_query_impl::query_impl::mir_borrowck::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_span::def_id::LocalDefId)>>::call_once
        18: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::Erased<[u8; 8]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
        19: rustc_query_impl::query_impl::mir_borrowck::get_query_incr::__rust_end_short_backtrace
        20: rustc_hir_analysis::collect::type_of::opaque::find_opaque_ty_constraints_for_rpit
        21: rustc_hir_analysis::collect::type_of::type_of
        22: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::type_of::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 8]>>
        23: <rustc_query_impl::query_impl::type_of::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_span::def_id::DefId)>>::call_once
        24: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::DefaultCache<rustc_span::def_id::DefId, rustc_middle::query::erase::Erased<[u8; 8]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
        25: rustc_query_impl::query_impl::type_of::get_query_incr::__rust_end_short_backtrace
        26: rustc_middle::query::plumbing::query_get_at::<rustc_query_system::query::caches::DefaultCache<rustc_span::def_id::DefId, rustc_middle::query::erase::Erased<[u8; 8]>>>
        27: rustc_hir_analysis::check::check::check_mod_item_types
        28: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::check_mod_item_types::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 0]>>
        29: <rustc_query_impl::query_impl::check_mod_item_types::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_span::def_id::LocalModDefId)>>::call_once
        30: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::DefaultCache<rustc_span::def_id::LocalModDefId, rustc_middle::query::erase::Erased<[u8; 0]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
        31: rustc_query_impl::query_impl::check_mod_item_types::get_query_incr::__rust_end_short_backtrace
        32: <rustc_middle::hir::map::Map>::for_each_module::<rustc_hir_analysis::check_crate::{closure#6}::{closure#0}>
        33: rustc_hir_analysis::check_crate
        34: rustc_interface::passes::analysis
        35: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 1]>>
        36: <rustc_query_impl::query_impl::analysis::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, ())>>::call_once
        37: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 1]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
        38: rustc_query_impl::query_impl::analysis::get_query_incr::__rust_end_short_backtrace
        39: <rustc_interface::queries::QueryResult<&rustc_middle::ty::context::GlobalCtxt>>::enter::<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}::{closure#2}::{closure#6}>
        40: <rustc_interface::interface::Compiler>::enter::<rustc_driver_impl::run_compiler::{closure#1}::{closure#2}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_span::ErrorGuaranteed>>
        41: std::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>
        42: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_span::ErrorGuaranteed>>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
        43: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                   at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/alloc/src/boxed.rs:2007:9
        44: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                   at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/alloc/src/boxed.rs:2007:9
        45: std::sys::unix::thread::Thread::new::thread_start
                   at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/std/src/sys/unix/thread.rs:108:17
        46: start_thread
        47: __GI___clone3
  --> crash/src/lib.rs:43:16
   |
43 |     delay(|()| delay(|()| ()))
   |                ^

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 1.73.0 (cc66ad468 2023-10-03) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type lib -C embed-bitcode=no -C debuginfo=2 -C incremental=[REDACTED]

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

query stack during panic:
end of query stack

[matthiaskrgr]

bit smaller:

pub trait BorrowComposite {
    type Ref<'a>: 'a;
}

impl BorrowComposite for () {
    type Ref<'a> = ();
}

pub trait Component<Args> {
    type Output;
}

impl<Args> Component<Args> for () {
    type Output = ();
}

pub fn delay<Args: BorrowComposite, Make: for<'a> FnMut(Args::Ref<'a>) -> C, C: Component<Args>>(
    make: Make,
) -> impl Component<Args> {
}

pub fn crash() -> impl Component<()> {
    delay(|()| delay(|()| ()))
}

pub fn main() {}

[matthiaskrgr]

Regression in nightly-2022-09-14

found 10 bors merge commits in the specified range
commit[0] 2022-09-12: Auto merge of #101729 - oli-obk:miriup, r=oli-obk
commit[1] 2022-09-12: Auto merge of #101736 - GuillaumeGomez:rollup-f71kjdb, r=GuillaumeGomez
commit[2] 2022-09-13: Auto merge of #99556 - davidtwco:collapse-debuginfo, r=wesleywiser
commit[3] 2022-09-13: Auto merge of #100101 - BelovDV:issue-99429, r=petrochenkov
commit[4] 2022-09-13: Auto merge of #100640 - reitermarkus:socket-display-buffer, r=thomcc
commit[5] 2022-09-13: Auto merge of #96709 - jackh726:gats-stabilization, r=compiler-errors
commit[6] 2022-09-13: Auto merge of #101757 - Dylan-DPC:rollup-wkt6oe9, r=Dylan-DPC
commit[7] 2022-09-13: Auto merge of #101615 - compiler-errors:rpitit-perf, r=oli-obk
commit[8] 2022-09-13: Auto merge of #101086 - cjgillot:thir-param, r=oli-obk
commit[9] 2022-09-13: Auto merge of #101777 - matthiaskrgr:rollup-x2dyaa2, r=matthiaskrgr

[Jules-Bertholet]

That "regression" would likely be due to #96709 which removed the GAT feature gate?

[compiler-errors]

Probably just need to test before 2022-09-14 with the GAT feature gate enabled.