ICE: 'Ok([Binder {..}, ...) is not fully resolved'

[gpace1]

Code

trait Www {
    type W;
}

trait Xxx: Www<W = Self::X> {
    type X;
}

trait Yyy: Xxx {}

trait Zzz<'a>: Yyy + Xxx<X = Self::Z> {
    type Z;
}

trait Aaa {
    type Y: Yyy;
}

trait Bbb: Aaa<Y = Self::B> {
    type B: for<'a> Zzz<'a>;
}

impl<T> Bbb for T
where
    T: Aaa,
    T::Y: for<'a> Zzz<'a>,
{
    type B = T::Y;
}

The example will compile if the lifetime 'a of Zzz and all the associated HRTBs for Zzz are removed.

Meta

Error occurs for both stable, beta, and nightly. Code was tested in the playground.

Tested Versions:
stable: rustc 1.71.0 (8ede3aa 2023-07-12) running on x86_64-unknown-linux-gnu
nightly: rustc 1.73.0-nightly (0e8e857 2023-07-16) running on x86_64-unknown-linux-gnu

Error output

'`Ok([Binder(TraitPredicate(<<T as Aaa>::Y as Zzz<'a>>, polarity:Positive), [Region(BrNamed(DefId(0:18 ~ playground[90b5]::{impl#0}::'a), 'a))]), Binder(ProjectionPredicate(AliasTy { substs: [<T as Aaa>::Y], def_id: DefId(0:6 ~ playground[90b5]::Xxx::X) }, Term::Ty(<<T as Aaa>::Y as Zzz<'a>>::Z)), [Region(BrNamed(DefId(0:18 ~ playground[90b5]::{impl#0}::'a), 'a))]), Binder(TraitPredicate(<<T as Aaa>::Y as Xxx>, polarity:Positive), [Region(BrNamed(DefId(0:18 ~ playground[90b5]::{impl#0}::'a), 'a))]), Binder(ProjectionPredicate(AliasTy { substs: [<T as Aaa>::Y], def_id: DefId(0:4 ~ playground[90b5]::Www::W) }, Term::Ty(<<T as Aaa>::Y as Zzz<'_>>::Z)), [Region(BrNamed(DefId(0:18 ~ playground[90b5]::{impl#0}::'a), 'a))]), Binder(TraitPredicate(<<T as Aaa>::Y as Www>, polarity:Positive), [Region(BrNamed(DefId(0:18 ~ playground[90b5]::{impl#0}::'a), 'a))]), Binder(TraitPredicate(<<T as Aaa>::Y as Yyy>, polarity:Positive), [Region(BrNamed(DefId(0:18 ~ playground[90b5]::{impl#0}::'a), 'a))]), Binder(TraitPredicate(<T as Aaa>, polarity:Positive), []), Binder(TraitPredicate(<T as std::marker::Sized>, polarity:Positive), [])])` is not fully resolved', /rustc/8ede3aae28fe6e4d52b38157d7bfe0d3bceef225/compiler/rustc_infer/src/infer/mod.rs:1350:9

Backtrace

   Compiling playground v0.0.1 (/playground)
thread 'rustc' panicked at '`Ok([Binder { value: TraitPredicate(<<T as Aaa>::Y as Zzz<'a>>, polarity:Positive), bound_vars: [Region(BrNamed(DefId(0:18 ~ playground[4866]::{impl#0}::'a), 'a))] }, Binder { value: ProjectionPredicate(AliasTy { args: [<T as Aaa>::Y], def_id: DefId(0:6 ~ playground[4866]::Xxx::X) }, Term::Ty(<<T as Aaa>::Y as Zzz<'a>>::Z)), bound_vars: [Region(BrNamed(DefId(0:18 ~ playground[4866]::{impl#0}::'a), 'a))] }, Binder { value: TraitPredicate(<<T as Aaa>::Y as Xxx>, polarity:Positive), bound_vars: [Region(BrNamed(DefId(0:18 ~ playground[4866]::{impl#0}::'a), 'a))] }, Binder { value: ProjectionPredicate(AliasTy { args: [<T as Aaa>::Y], def_id: DefId(0:4 ~ playground[4866]::Www::W) }, Term::Ty(<<T as Aaa>::Y as Zzz<'_>>::Z)), bound_vars: [Region(BrNamed(DefId(0:18 ~ playground[4866]::{impl#0}::'a), 'a))] }, Binder { value: TraitPredicate(<<T as Aaa>::Y as Www>, polarity:Positive), bound_vars: [Region(BrNamed(DefId(0:18 ~ playground[4866]::{impl#0}::'a), 'a))] }, Binder { value: TraitPredicate(<<T as Aaa>::Y as Yyy>, polarity:Positive), bound_vars: [Region(BrNamed(DefId(0:18 ~ playground[4866]::{impl#0}::'a), 'a))] }, Binder { value: TraitPredicate(<T as Aaa>, polarity:Positive), bound_vars: [] }, Binder { value: TraitPredicate(<T as std::marker::Sized>, polarity:Positive), bound_vars: [] }])` is not fully resolved', /rustc/0e8e857b11f60a785aea24a84f280f6dad7a4d42/compiler/rustc_infer/src/infer/mod.rs:1379:9
stack backtrace:
   0:     0x7f6a8800b1e1 - std::backtrace_rs::backtrace::libunwind::trace::h5f856d2c12cc6674
                               at /rustc/0e8e857b11f60a785aea24a84f280f6dad7a4d42/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
   1:     0x7f6a8800b1e1 - std::backtrace_rs::backtrace::trace_unsynchronized::h8449257397d4b934
                               at /rustc/0e8e857b11f60a785aea24a84f280f6dad7a4d42/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f6a8800b1e1 - std::sys_common::backtrace::_print_fmt::hc0c3bab7873ac244
                               at /rustc/0e8e857b11f60a785aea24a84f280f6dad7a4d42/library/std/src/sys_common/backtrace.rs:65:5
   3:     0x7f6a8800b1e1 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h3787c35683fa4233
                               at /rustc/0e8e857b11f60a785aea24a84f280f6dad7a4d42/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7f6a8807119c - core::fmt::rt::Argument::fmt::hae0c3aa49888479e
                               at /rustc/0e8e857b11f60a785aea24a84f280f6dad7a4d42/library/core/src/fmt/rt.rs:138:9
   5:     0x7f6a8807119c - core::fmt::write::h0f833d45d904ecbb
                               at /rustc/0e8e857b11f60a785aea24a84f280f6dad7a4d42/library/core/src/fmt/mod.rs:1094:21
   6:     0x7f6a87ffdb8e - std::io::Write::write_fmt::h6fd13360259fea22
                               at /rustc/0e8e857b11f60a785aea24a84f280f6dad7a4d42/library/std/src/io/mod.rs:1714:15
   7:     0x7f6a8800aff5 - std::sys_common::backtrace::_print::h715af68f97f33bd8
                               at /rustc/0e8e857b11f60a785aea24a84f280f6dad7a4d42/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7f6a8800aff5 - std::sys_common::backtrace::print::h292b9e4a1d37eead
                               at /rustc/0e8e857b11f60a785aea24a84f280f6dad7a4d42/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7f6a8800dda3 - std::panicking::default_hook::{{closure}}::hab7084ecbd5f7152
                               at /rustc/0e8e857b11f60a785aea24a84f280f6dad7a4d42/library/std/src/panicking.rs:269:22
  10:     0x7f6a8800db34 - std::panicking::default_hook::hfbb8ba894af6577e
                               at /rustc/0e8e857b11f60a785aea24a84f280f6dad7a4d42/library/std/src/panicking.rs:288:9
  11:     0x7f6a8b2d143b - rustc_driver_impl[5bf76b44b01c010b]::install_ice_hook::{closure#0}
  12:     0x7f6a8800e5ce - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::hc6428110305b5cbe
                               at /rustc/0e8e857b11f60a785aea24a84f280f6dad7a4d42/library/alloc/src/boxed.rs:2021:9
  13:     0x7f6a8800e5ce - std::panicking::rust_panic_with_hook::h8a8f983a7c12e89b
                               at /rustc/0e8e857b11f60a785aea24a84f280f6dad7a4d42/library/std/src/panicking.rs:709:13
  14:     0x7f6a8800e357 - std::panicking::begin_panic_handler::{{closure}}::hcbc604b49027ff32
                               at /rustc/0e8e857b11f60a785aea24a84f280f6dad7a4d42/library/std/src/panicking.rs:597:13
  15:     0x7f6a8800b646 - std::sys_common::backtrace::__rust_end_short_backtrace::hb85256103978a5ea
                               at /rustc/0e8e857b11f60a785aea24a84f280f6dad7a4d42/library/std/src/sys_common/backtrace.rs:151:18
  16:     0x7f6a8800e0a2 - rust_begin_unwind
                               at /rustc/0e8e857b11f60a785aea24a84f280f6dad7a4d42/library/std/src/panicking.rs:593:5
  17:     0x7f6a8806d543 - core::panicking::panic_fmt::h3cc36a41bb894309
                               at /rustc/0e8e857b11f60a785aea24a84f280f6dad7a4d42/library/core/src/panicking.rs:67:14
  18:     0x7f6a89be7ee2 - rustc_trait_selection[4828e09977927b86]::traits::normalize_param_env_or_error
  19:     0x7f6a89be2e0c - rustc_ty_utils[ff0a06d2a6228635]::ty::param_env
  20:     0x7f6a892f2474 - rustc_query_impl[2a0ca4be8ec05b8b]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[2a0ca4be8ec05b8b]::query_impl::param_env::dynamic_query::{closure#2}::{closure#0}, rustc_middle[835d091ebc4d05d9]::query::erase::Erased<[u8; 8usize]>>
  21:     0x7f6a892f2440 - <rustc_query_impl[2a0ca4be8ec05b8b]::query_impl::param_env::dynamic_query::{closure#2} as core[ef917bd033b821fa]::ops::function::FnOnce<(rustc_middle[835d091ebc4d05d9]::ty::context::TyCtxt, rustc_span[a69db53e102135]::def_id::DefId)>>::call_once
  22:     0x7f6a893197f5 - rustc_query_system[95ed59712a59403e]::query::plumbing::try_execute_query::<rustc_query_impl[2a0ca4be8ec05b8b]::DynamicConfig<rustc_query_system[95ed59712a59403e]::query::caches::DefaultCache<rustc_span[a69db53e102135]::def_id::DefId, rustc_middle[835d091ebc4d05d9]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[2a0ca4be8ec05b8b]::plumbing::QueryCtxt, false>
  23:     0x7f6a8ac3e601 - rustc_query_impl[2a0ca4be8ec05b8b]::query_impl::param_env::get_query_non_incr::__rust_end_short_backtrace
  24:     0x7f6a89ece0d0 - rustc_middle[835d091ebc4d05d9]::query::plumbing::query_get_at::<rustc_query_system[95ed59712a59403e]::query::caches::DefaultCache<rustc_span[a69db53e102135]::def_id::DefId, rustc_middle[835d091ebc4d05d9]::query::erase::Erased<[u8; 8usize]>>>
  25:     0x7f6a89ecc312 - rustc_hir_analysis[dc7bd52400bbf8cf]::check::wfcheck::check_well_formed
  26:     0x7f6a892e065c - rustc_query_impl[2a0ca4be8ec05b8b]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[2a0ca4be8ec05b8b]::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle[835d091ebc4d05d9]::query::erase::Erased<[u8; 0usize]>>
  27:     0x7f6a89d0a7f6 - rustc_query_system[95ed59712a59403e]::query::plumbing::try_execute_query::<rustc_query_impl[2a0ca4be8ec05b8b]::DynamicConfig<rustc_query_system[95ed59712a59403e]::query::caches::VecCache<rustc_hir[9bd7153587c508c5]::hir_id::OwnerId, rustc_middle[835d091ebc4d05d9]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[2a0ca4be8ec05b8b]::plumbing::QueryCtxt, false>
  28:     0x7f6a89d0a562 - rustc_query_impl[2a0ca4be8ec05b8b]::query_impl::check_well_formed::get_query_non_incr::__rust_end_short_backtrace
  29:     0x7f6a8a6a0cdc - rustc_data_structures[d2b76f525e315882]::sync::par_for_each_in::<&[rustc_hir[9bd7153587c508c5]::hir::ImplItemId], <rustc_middle[835d091ebc4d05d9]::hir::ModuleItems>::par_impl_items<rustc_hir_analysis[dc7bd52400bbf8cf]::check::wfcheck::check_mod_type_wf::{closure#1}>::{closure#0}>
  30:     0x7f6a8a6a0b7a - rustc_hir_analysis[dc7bd52400bbf8cf]::check::wfcheck::check_mod_type_wf
  31:     0x7f6a89ff6bbc - rustc_query_impl[2a0ca4be8ec05b8b]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[2a0ca4be8ec05b8b]::query_impl::check_mod_type_wf::dynamic_query::{closure#2}::{closure#0}, rustc_middle[835d091ebc4d05d9]::query::erase::Erased<[u8; 0usize]>>
  32:     0x7f6a89ff6b9e - <rustc_query_impl[2a0ca4be8ec05b8b]::query_impl::check_mod_type_wf::dynamic_query::{closure#2} as core[ef917bd033b821fa]::ops::function::FnOnce<(rustc_middle[835d091ebc4d05d9]::ty::context::TyCtxt, rustc_span[a69db53e102135]::def_id::LocalDefId)>>::call_once
  33:     0x7f6a89c2b2ff - rustc_query_system[95ed59712a59403e]::query::plumbing::try_execute_query::<rustc_query_impl[2a0ca4be8ec05b8b]::DynamicConfig<rustc_query_system[95ed59712a59403e]::query::caches::VecCache<rustc_span[a69db53e102135]::def_id::LocalDefId, rustc_middle[835d091ebc4d05d9]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[2a0ca4be8ec05b8b]::plumbing::QueryCtxt, false>
  34:     0x7f6a8ac1a662 - rustc_query_impl[2a0ca4be8ec05b8b]::query_impl::check_mod_type_wf::get_query_non_incr::__rust_end_short_backtrace
  35:     0x7f6a8a6f1f27 - rustc_data_structures[d2b76f525e315882]::sync::par_for_each_in::<&[rustc_hir[9bd7153587c508c5]::hir_id::OwnerId], <rustc_middle[835d091ebc4d05d9]::hir::map::Map>::par_for_each_module<rustc_hir_analysis[dc7bd52400bbf8cf]::check_crate::{closure#5}::{closure#0}::{closure#0}>::{closure#0}>
  36:     0x7f6a8a6f1cf7 - <rustc_session[2927e3ab783c954a]::session::Session>::track_errors::<rustc_hir_analysis[dc7bd52400bbf8cf]::check_crate::{closure#5}, ()>
  37:     0x7f6a8a6f0aa8 - rustc_hir_analysis[dc7bd52400bbf8cf]::check_crate
  38:     0x7f6a8a6f026a - rustc_interface[950bb6185283f172]::passes::analysis
  39:     0x7f6a8a752f2a - rustc_query_impl[2a0ca4be8ec05b8b]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[2a0ca4be8ec05b8b]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[835d091ebc4d05d9]::query::erase::Erased<[u8; 1usize]>>
  40:     0x7f6a8a752f19 - <rustc_query_impl[2a0ca4be8ec05b8b]::query_impl::analysis::dynamic_query::{closure#2} as core[ef917bd033b821fa]::ops::function::FnOnce<(rustc_middle[835d091ebc4d05d9]::ty::context::TyCtxt, ())>>::call_once
  41:     0x7f6a8a91df48 - rustc_query_system[95ed59712a59403e]::query::plumbing::try_execute_query::<rustc_query_impl[2a0ca4be8ec05b8b]::DynamicConfig<rustc_query_system[95ed59712a59403e]::query::caches::SingleCache<rustc_middle[835d091ebc4d05d9]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[2a0ca4be8ec05b8b]::plumbing::QueryCtxt, false>
  42:     0x7f6a8a91dd27 - rustc_query_impl[2a0ca4be8ec05b8b]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  43:     0x7f6a8a5a2e85 - <rustc_middle[835d091ebc4d05d9]::ty::context::GlobalCtxt>::enter::<rustc_driver_impl[5bf76b44b01c010b]::run_compiler::{closure#1}::{closure#2}::{closure#4}, core[ef917bd033b821fa]::result::Result<(), rustc_span[a69db53e102135]::ErrorGuaranteed>>
  44:     0x7f6a8a5a24b2 - <rustc_interface[950bb6185283f172]::interface::Compiler>::enter::<rustc_driver_impl[5bf76b44b01c010b]::run_compiler::{closure#1}::{closure#2}, core[ef917bd033b821fa]::result::Result<core[ef917bd033b821fa]::option::Option<rustc_interface[950bb6185283f172]::queries::Linker>, rustc_span[a69db53e102135]::ErrorGuaranteed>>
  45:     0x7f6a8a59b825 - rustc_span[a69db53e102135]::set_source_map::<core[ef917bd033b821fa]::result::Result<(), rustc_span[a69db53e102135]::ErrorGuaranteed>, rustc_interface[950bb6185283f172]::interface::run_compiler<core[ef917bd033b821fa]::result::Result<(), rustc_span[a69db53e102135]::ErrorGuaranteed>, rustc_driver_impl[5bf76b44b01c010b]::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
  46:     0x7f6a8a59b296 - <scoped_tls[af683b2dcd27050]::ScopedKey<rustc_span[a69db53e102135]::SessionGlobals>>::set::<rustc_interface[950bb6185283f172]::interface::run_compiler<core[ef917bd033b821fa]::result::Result<(), rustc_span[a69db53e102135]::ErrorGuaranteed>, rustc_driver_impl[5bf76b44b01c010b]::run_compiler::{closure#1}>::{closure#0}, core[ef917bd033b821fa]::result::Result<(), rustc_span[a69db53e102135]::ErrorGuaranteed>>
  47:     0x7f6a8a59a85c - std[c0adc0b90f4efda2]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[950bb6185283f172]::util::run_in_thread_pool_with_globals<rustc_interface[950bb6185283f172]::interface::run_compiler<core[ef917bd033b821fa]::result::Result<(), rustc_span[a69db53e102135]::ErrorGuaranteed>, rustc_driver_impl[5bf76b44b01c010b]::run_compiler::{closure#1}>::{closure#0}, core[ef917bd033b821fa]::result::Result<(), rustc_span[a69db53e102135]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[ef917bd033b821fa]::result::Result<(), rustc_span[a69db53e102135]::ErrorGuaranteed>>
  48:     0x7f6a8a59a61e - <<std[c0adc0b90f4efda2]::thread::Builder>::spawn_unchecked_<rustc_interface[950bb6185283f172]::util::run_in_thread_pool_with_globals<rustc_interface[950bb6185283f172]::interface::run_compiler<core[ef917bd033b821fa]::result::Result<(), rustc_span[a69db53e102135]::ErrorGuaranteed>, rustc_driver_impl[5bf76b44b01c010b]::run_compiler::{closure#1}>::{closure#0}, core[ef917bd033b821fa]::result::Result<(), rustc_span[a69db53e102135]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[ef917bd033b821fa]::result::Result<(), rustc_span[a69db53e102135]::ErrorGuaranteed>>::{closure#1} as core[ef917bd033b821fa]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  49:     0x7f6a88018c55 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hee3992ac1361b768
                               at /rustc/0e8e857b11f60a785aea24a84f280f6dad7a4d42/library/alloc/src/boxed.rs:2007:9
  50:     0x7f6a88018c55 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h98eb33f4039b4e2e
                               at /rustc/0e8e857b11f60a785aea24a84f280f6dad7a4d42/library/alloc/src/boxed.rs:2007:9
  51:     0x7f6a88018c55 - std::sys::unix::thread::Thread::new::thread_start::h4a5bbbf722280c2f
                               at /rustc/0e8e857b11f60a785aea24a84f280f6dad7a4d42/library/std/src/sys/unix/thread.rs:108:17
  52:     0x7f6a87edf609 - start_thread
  53:     0x7f6a87e02133 - clone
  54:                0x0 - <unknown>

error: 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 1.73.0-nightly (0e8e857b1 2023-07-16) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type lib -C embed-bitcode=no -C codegen-units=1 -C debuginfo=2

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

query stack during panic:
#0 [param_env] computing normalized predicates of `<impl at src/lib.rs:23:1: 23:18>`
#1 [check_well_formed] checking that `<impl at src/lib.rs:23:1: 23:18>` is well-formed
#2 [check_mod_type_wf] checking that types are well-formed in top-level module
#3 [analysis] running analysis passes on this crate
end of query stack

[Jules-Bertholet]

Regressed from error in 1.65: https://rust.godbolt.org/z/ra4nMa31W

@rustbot label regression-from-stable-to-stable

[matthiaskrgr]

probably duplicate of #103708 in some way?

I have another 20-30 code snippets around thal all trigger the ice if anyone is interested

[lukas-code]

Regressed in #98559.

[apiraino]

@lukas-code cool! how did trace back to that PR? I was bisecting but ended in this bunch of commits for nightly-2022-12-18

commit[0] 2022-12-16: Auto merge of #105018 - zertosh:path_buf_deref_mut, r=dtolnay
  commit[1] 2022-12-16: Auto merge of #102318 - Amanieu:default_alloc_error_handler, r=oli-obk
  commit[2] 2022-12-17: Auto merge of #105804 - matthiaskrgr:rollup-iaqlbl3, r=matthiaskrgr
  commit[3] 2022-12-17: Auto merge of #105811 - ojeda:Dwarnings-no_fp_fmt_parse, r=Mark-Simulacrum
  commit[4] 2022-12-17: Auto merge of #105794 - ChrisDenton:internal-doc, r=jyn514
  commit[5] 2022-12-17: Auto merge of #105820 - matthiaskrgr:rollup-uzm1l8f, r=matthiaskrgr
  commit[6] 2022-12-17: Auto merge of #105421 - jacobbramley:jb/branch-prot-check, r=nagisa
  commit[7] 2022-12-17: Auto merge of #105800 - lqd:dylib-thinlto, r=bjorn3
  commit[8] 2022-12-17: Auto merge of #105827 - flip1995:clippyup, r=matthiaskrgr
  commit[9] 2022-12-17: Auto merge of #105145 - Ayush1325:sequential-remote-server, r=Mark-Simulacrum

Same result for #103708. But now I suspect my results are wrong (the ICE blurb changed the output, maybe that's the reason)

Tentatively closing in favor of #103708?

[lukas-code]

@apiraino I got the same results at first, but none of the changes looked related. Then I manually checked nightly-2022-12-17 and saw that it still ICEed. I continued bisecting with this script:

#!/bin/sh
E=$(cargo check 2>&1)
! grep "panicked" <<< "$E"

... and got these results:

found 10 bors merge commits in the specified range
  commit[0] 2022-09-09: Auto merge of #101611 - GuillaumeGomez:rollup-yw3qtug, r=GuillaumeGomez
  commit[1] 2022-09-09: Auto merge of #101617 - Dylan-DPC:rollup-iiy4ipc, r=Dylan-DPC
  commit[2] 2022-09-10: Auto merge of #101609 - flip1995:clippyup, r=Manishearth
  commit[3] 2022-09-10: Auto merge of #99916 - dpaoliello:stablizerawdylib, r=wesleywiser
  commit[4] 2022-09-10: Auto merge of #101639 - matthiaskrgr:rollup-sewkrgm, r=matthiaskrgr
  commit[5] 2022-09-10: Auto merge of #101483 - oli-obk:guaranteed_opt, r=fee1-dead
  commit[6] 2022-09-10: Auto merge of #100968 - cjgillot:mir-upvar-vec, r=wesleywiser
  commit[7] 2022-09-10: Auto merge of #101652 - Dylan-DPC:rollup-f4atky0, r=Dylan-DPC
  commit[8] 2022-09-10: Auto merge of #101647 - crlf0710:test_for_99551, r=bjorn3
  commit[9] 2022-09-10: Auto merge of #98559 - jackh726:remove-reempty, r=oli-obk

Given the error message from https://rust.godbolt.org/z/ra4nMa31W, the remove-reempty looked suspicious to me and so I manually built from the bors merge (2287107) and it's parent (4a6ac3c) to verify that it is indeed caused by that PR.

[apiraino]

WG-prioritization assigning priority (Zulip discussion).

@rustbot label -I-prioritize +P-medium

[cyrgani]

Reduced version copied from #132689:

trait Www {
    type W;
}
trait Xxx: Www<W = Self::X> {
    type X;
}
trait Zzz<'a>: Xxx<X = Self::Z> {
    type Z;
}
trait Bbb {}
impl<T> Bbb for T where T: for<'a> Zzz<'a> {}