panic: ` Not enough bound vars:`

trait I<'a, 'b, 'c> {
    type As;
}
trait H<'d, 'e>: for<'f> I<'d, 'f, 'e> + 'd {}

struct X<'x, 'y> {
    x: std::marker::PhantomData<&'x ()>,
    y: std::marker::PhantomData<&'y ()>,
}

fn foo5<T>()
where
    T: for<'l, 'i> H<'l, 'i, As: for<'j> H<'j, 'i, As: for<'k> H<'j, 'k, As = X<'j, 'k>> + 'j> + 'i>
{
}

fn main() {}

Database loaded:     350.16ms, 223minstr, 48mb (metadata 186.12ms, 972kinstr, 152kb; build 33.45ms, 171kinstr, 1392b)
  item trees: 1
  dependency lines of code: 1_478_357, item trees: 2_969
  dependency item stats: traits: 860, impl: 9_717, mods: 3_002, macro calls: 5_613, macro rules: 1_062
Item Tree Collection: 2.58s, 28ginstr, 431mb
  Total Statistics:
    crates: 1, mods: 1, decls: 5, bodies: 2, adts: 1, consts: 0, signatures: 5, variants: 1
  Workspace:
    traits: 2, macro_rules macros: 0, proc_macros: 0
    lines of code: 17, item trees: 1
    usages: traits: 2, impl: 0, mods: 0, macro calls: 0, macro rules: 0
  Dependencies:
    lines of code: 1_478_357, item trees: 2_969
    declarations: traits: 860, impl: 9_717, mods: 3_002, macro calls: 5_613, macro rules: 1_062
Item Collection:     1.48s, 13ginstr, 176mb
Crate lang items:    279.94ms, 2904minstr, 31mb
Expression Store Lowering: 213.53µs, 629kinstr, 12kb
0/2 0% processing: f::foo5
thread 'main' (17270) panicked at /home/matthias/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/ra-ap-rustc_type_ir-0.166.0/src/binder.rs:347:21:
Not enough bound vars: '^1.Named(FunctionId("foo5")) not found in [Region(BrNamed(FunctionId("foo5")))]
stack backtrace:
   0:     0x5623f3cfc1f1 - std[71a467343b18a2c1]::backtrace_rs::backtrace::libunwind::trace
                               at /rustc/0fc141305da7a8a222f65aef1f1acc739c46282b/library/std/src/../../backtrace/src/backtrace/libunwind.rs:117:9
   1:     0x5623f3cfc1f1 - std[71a467343b18a2c1]::backtrace_rs::backtrace::trace_unsynchronized::<std[71a467343b18a2c1]::sys::backtrace::_print_fmt::{closure#1}>
                               at /rustc/0fc141305da7a8a222f65aef1f1acc739c46282b/library/std/src/../../backtrace/src/backtrace/mod.rs:66:14
   2:     0x5623f3cfc1f1 - std[71a467343b18a2c1]::sys::backtrace::_print_fmt
                               at /rustc/0fc141305da7a8a222f65aef1f1acc739c46282b/library/std/src/sys/backtrace.rs:74:9
   3:     0x5623f3cfc1f1 - <<std[71a467343b18a2c1]::sys::backtrace::BacktraceLock>::print::DisplayBacktrace as core[11918ecc8322c3ee]::fmt::Display>::fmt
                               at /rustc/0fc141305da7a8a222f65aef1f1acc739c46282b/library/std/src/sys/backtrace.rs:44:26
   4:     0x5623f3d18e2a - <core[11918ecc8322c3ee]::fmt::rt::Argument>::fmt
                               at /rustc/0fc141305da7a8a222f65aef1f1acc739c46282b/library/core/src/fmt/rt.rs:152:76
   5:     0x5623f3d18e2a - core[11918ecc8322c3ee]::fmt::write
   6:     0x5623f3d05b6c - core[11918ecc8322c3ee]::io::write::default_write_fmt::<std[71a467343b18a2c1]::sys::stdio::unix::Stderr>
                               at /rustc/0fc141305da7a8a222f65aef1f1acc739c46282b/library/core/src/io/write.rs:402:11
   7:     0x5623f3d05b6c - <std[71a467343b18a2c1]::sys::stdio::unix::Stderr as core[11918ecc8322c3ee]::io::write::Write>::write_fmt
                               at /rustc/0fc141305da7a8a222f65aef1f1acc739c46282b/library/core/src/io/write.rs:335:13
   8:     0x5623f3cd2ee6 - <std[71a467343b18a2c1]::sys::backtrace::BacktraceLock>::print
                               at /rustc/0fc141305da7a8a222f65aef1f1acc739c46282b/library/std/src/sys/backtrace.rs:47:9
   9:     0x5623f3cd2ee6 - std[71a467343b18a2c1]::panicking::default_hook::{closure#0}
                               at /rustc/0fc141305da7a8a222f65aef1f1acc739c46282b/library/std/src/panicking.rs:289:27
  10:     0x5623f3cf1f81 - std[71a467343b18a2c1]::panicking::default_hook
                               at /rustc/0fc141305da7a8a222f65aef1f1acc739c46282b/library/std/src/panicking.rs:316:9
  11:     0x5623f3cf22ab - std[71a467343b18a2c1]::panicking::panic_with_hook
                               at /rustc/0fc141305da7a8a222f65aef1f1acc739c46282b/library/std/src/panicking.rs:811:13
  12:     0x5623f3cd2f92 - std[71a467343b18a2c1]::panicking::panic_handler::{closure#0}
                               at /rustc/0fc141305da7a8a222f65aef1f1acc739c46282b/library/std/src/panicking.rs:685:13
  13:     0x5623f3cca169 - std[71a467343b18a2c1]::sys::backtrace::__rust_end_short_backtrace::<std[71a467343b18a2c1]::panicking::panic_handler::{closure#0}, !>
                               at /rustc/0fc141305da7a8a222f65aef1f1acc739c46282b/library/std/src/sys/backtrace.rs:182:18
  14:     0x5623f3cd3dcd - __rustc[3b8ba45af69cfb7c]::rust_begin_unwind
                               at /rustc/0fc141305da7a8a222f65aef1f1acc739c46282b/library/std/src/panicking.rs:676:5
  15:     0x5623f3d196fc - core[11918ecc8322c3ee]::panicking::panic_fmt
                               at /rustc/0fc141305da7a8a222f65aef1f1acc739c46282b/library/core/src/panicking.rs:80:14
  16:     0x5623f36e8b1e - <ra_ap_rustc_type_ir[d972c936462dbb19]::binder::ValidateBoundVars<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner> as ra_ap_rustc_type_ir[d972c936462dbb19]::visit::TypeVisitor<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>::visit_region
                               at /home/matthias/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/ra-ap-rustc_type_ir-0.166.0/src/binder.rs:347:21
  17:     0x5623f3400fcb - <hir_ty[c6020b5b036d7a82]::next_solver::region::Region as ra_ap_rustc_type_ir[d972c936462dbb19]::visit::TypeVisitable<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>::visit_with::<ra_ap_rustc_type_ir[d972c936462dbb19]::binder::ValidateBoundVars<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>
                               at /home/matthias/vcs/github/rust-analyzer-debug-assertions/crates/hir-ty/src/next_solver/region.rs:217:17
  18:     0x5623f3400fcb - <hir_ty[c6020b5b036d7a82]::next_solver::generic_arg::GenericArg as ra_ap_rustc_type_ir[d972c936462dbb19]::visit::TypeVisitable<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>::visit_with::<ra_ap_rustc_type_ir[d972c936462dbb19]::binder::ValidateBoundVars<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>
                               at /home/matthias/vcs/github/rust-analyzer-debug-assertions/crates/hir-ty/src/next_solver/generic_arg.rs:366:48
  19:     0x5623f33a33b5 - <hir_ty[c6020b5b036d7a82]::next_solver::generic_arg::GenericArgs as ra_ap_rustc_type_ir[d972c936462dbb19]::visit::TypeVisitable<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>::visit_with::<ra_ap_rustc_type_ir[d972c936462dbb19]::binder::ValidateBoundVars<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>
                               at /home/matthias/vcs/github/rust-analyzer-debug-assertions/crates/hir-ty/src/next_solver/interner.rs:240:17
  20:     0x5623f33a33b5 - <ra_ap_rustc_type_ir[d972c936462dbb19]::ty_kind::AliasTy<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner> as ra_ap_rustc_type_ir[d972c936462dbb19]::visit::TypeVisitable<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>::visit_with::<ra_ap_rustc_type_ir[d972c936462dbb19]::binder::ValidateBoundVars<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>
                               at /home/matthias/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/ra-ap-rustc_type_ir-0.166.0/src/ty_kind.rs:440:10
  21:     0x5623f36e8f8d - <hir_ty[c6020b5b036d7a82]::next_solver::ty::Ty as ra_ap_rustc_type_ir[d972c936462dbb19]::visit::TypeSuperVisitable<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>::super_visit_with::<ra_ap_rustc_type_ir[d972c936462dbb19]::binder::ValidateBoundVars<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>
                               at /home/matthias/vcs/github/rust-analyzer-debug-assertions/crates/hir-ty/src/next_solver/ty.rs:928:45
  22:     0x5623f36e8f8d - <ra_ap_rustc_type_ir[d972c936462dbb19]::binder::ValidateBoundVars<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner> as ra_ap_rustc_type_ir[d972c936462dbb19]::visit::TypeVisitor<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>::visit_ty
                               at /home/matthias/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/ra-ap-rustc_type_ir-0.166.0/src/binder.rs:319:11
  23:     0x5623f33a33b5 - <hir_ty[c6020b5b036d7a82]::next_solver::generic_arg::GenericArgs as ra_ap_rustc_type_ir[d972c936462dbb19]::visit::TypeVisitable<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>::visit_with::<ra_ap_rustc_type_ir[d972c936462dbb19]::binder::ValidateBoundVars<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>
                               at /home/matthias/vcs/github/rust-analyzer-debug-assertions/crates/hir-ty/src/next_solver/interner.rs:240:17
  24:     0x5623f33a33b5 - <ra_ap_rustc_type_ir[d972c936462dbb19]::ty_kind::AliasTy<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner> as ra_ap_rustc_type_ir[d972c936462dbb19]::visit::TypeVisitable<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>::visit_with::<ra_ap_rustc_type_ir[d972c936462dbb19]::binder::ValidateBoundVars<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>
                               at /home/matthias/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/ra-ap-rustc_type_ir-0.166.0/src/ty_kind.rs:440:10
  25:     0x5623f36e8f8d - <hir_ty[c6020b5b036d7a82]::next_solver::ty::Ty as ra_ap_rustc_type_ir[d972c936462dbb19]::visit::TypeSuperVisitable<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>::super_visit_with::<ra_ap_rustc_type_ir[d972c936462dbb19]::binder::ValidateBoundVars<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>
                               at /home/matthias/vcs/github/rust-analyzer-debug-assertions/crates/hir-ty/src/next_solver/ty.rs:928:45
  26:     0x5623f36e8f8d - <ra_ap_rustc_type_ir[d972c936462dbb19]::binder::ValidateBoundVars<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner> as ra_ap_rustc_type_ir[d972c936462dbb19]::visit::TypeVisitor<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>::visit_ty
                               at /home/matthias/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/ra-ap-rustc_type_ir-0.166.0/src/binder.rs:319:11
  27:     0x5623f33cec75 - <hir_ty[c6020b5b036d7a82]::next_solver::ty::Ty as ra_ap_rustc_type_ir[d972c936462dbb19]::visit::TypeVisitable<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>::visit_with::<ra_ap_rustc_type_ir[d972c936462dbb19]::binder::ValidateBoundVars<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>
                               at /home/matthias/vcs/github/rust-analyzer-debug-assertions/crates/hir-ty/src/next_solver/ty.rs:895:17
  28:     0x5623f33cec75 - <hir_ty[c6020b5b036d7a82]::next_solver::generic_arg::GenericArg as ra_ap_rustc_type_ir[d972c936462dbb19]::visit::TypeVisitable<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>::visit_with::<ra_ap_rustc_type_ir[d972c936462dbb19]::binder::ValidateBoundVars<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>
                               at /home/matthias/vcs/github/rust-analyzer-debug-assertions/crates/hir-ty/src/next_solver/generic_arg.rs:367:44
  29:     0x5623f33cec75 - <hir_ty[c6020b5b036d7a82]::next_solver::generic_arg::GenericArgs as ra_ap_rustc_type_ir[d972c936462dbb19]::visit::TypeVisitable<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>::visit_with::<ra_ap_rustc_type_ir[d972c936462dbb19]::binder::ValidateBoundVars<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>
                               at /home/matthias/vcs/github/rust-analyzer-debug-assertions/crates/hir-ty/src/next_solver/interner.rs:240:17
  30:     0x5623f33a37f0 - <ra_ap_rustc_type_ir[d972c936462dbb19]::predicate::AliasTerm<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner> as ra_ap_rustc_type_ir[d972c936462dbb19]::visit::TypeVisitable<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>::visit_with::<ra_ap_rustc_type_ir[d972c936462dbb19]::binder::ValidateBoundVars<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>
                               at /home/matthias/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/ra-ap-rustc_type_ir-0.166.0/src/predicate.rs:666:10
  31:     0x5623f33a37f0 - <ra_ap_rustc_type_ir[d972c936462dbb19]::predicate::ProjectionPredicate<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner> as ra_ap_rustc_type_ir[d972c936462dbb19]::visit::TypeVisitable<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>::visit_with::<ra_ap_rustc_type_ir[d972c936462dbb19]::binder::ValidateBoundVars<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>
                               at /home/matthias/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/ra-ap-rustc_type_ir-0.166.0/src/predicate.rs:901:10
  32:     0x5623f34e7c31 - <ra_ap_rustc_type_ir[d972c936462dbb19]::binder::Binder<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner, ra_ap_rustc_type_ir[d972c936462dbb19]::predicate_kind::PredicateKind<hir_ty[c6020b5b036d7a82]::next_solver::interner::DbInterner>>>::bind_with_vars
                               at /home/matthias/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/ra-ap-rustc_type_ir-0.166.0/src/binder.rs:115:27
  33:     0x5623f3741c0b - <hir_ty[c6020b5b036d7a82]::lower::path::PathLoweringContext>::assoc_type_bindings_from_type_bound::{closure#0}::{closure#0}::{closure#2}
                               at /home/matthias/vcs/github/rust-analyzer-debug-assertions/crates/hir-ty/src/lower/path.rs:962:37
  34:     0x5623f3741c0b - <hir_ty[c6020b5b036d7a82]::lower::path::PathLoweringContext>::with_lifetime_elision::<(), <hir_ty[c6020b5b036d7a82]::lower::path::PathLoweringContext>::assoc_type_bindings_from_type_bound::{closure#0}::{closure#0}::{closure#2}>
                               at /home/matthias/vcs/github/rust-analyzer-debug-assertions/crates/hir-ty/src/lower/path.rs:146:22
  35:     0x5623f3741c0b - <hir_ty[c6020b5b036d7a82]::lower::path::PathLoweringContext>::assoc_type_bindings_from_type_bound::{closure#0}::{closure#0}
                               at /home/matthias/vcs/github/rust-analyzer-debug-assertions/crates/hir-ty/src/lower/path.rs:951:26
  36:     0x5623f3741c0b - <&mut <hir_ty[c6020b5b036d7a82]::lower::path::PathLoweringContext>::assoc_type_bindings_from_type_bound::{closure#0}::{closure#0} as core[11918ecc8322c3ee]::ops::function::FnOnce<((usize, &hir_def[b797b053043be09c]::expr_store::path::AssociatedTypeBinding),)>>::call_once
                               at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:310:21
  37:     0x5623f3741c0b - <core[11918ecc8322c3ee]::option::Option<(usize, &hir_def[b797b053043be09c]::expr_store::path::AssociatedTypeBinding)>>::map::<smallvec[30b7154c696f63a5]::SmallVec<[(hir_ty[c6020b5b036d7a82]::next_solver::predicate::Clause, hir_ty[c6020b5b036d7a82]::lower::GenericPredicateSource); 1usize]>, &mut <hir_ty[c6020b5b036d7a82]::lower::path::PathLoweringContext>::assoc_type_bindings_from_type_bound::{closure#0}::{closure#0}>
                               at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/option.rs:1165:29
  38:     0x5623f3741c0b - <core[11918ecc8322c3ee]::iter::adapters::map::Map<core[11918ecc8322c3ee]::iter::adapters::enumerate::Enumerate<core[11918ecc8322c3ee]::slice::iter::Iter<hir_def[b797b053043be09c]::expr_store::path::AssociatedTypeBinding>>, <hir_ty[c6020b5b036d7a82]::lower::path::PathLoweringContext>::assoc_type_bindings_from_type_bound::{closure#0}::{closure#0}> as core[11918ecc8322c3ee]::iter::traits::iterator::Iterator>::next
                               at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/iter/adapters/map.rs:107:26
  39:     0x5623f3741c0b - <core[11918ecc8322c3ee]::iter::adapters::fuse::Fuse<core[11918ecc8322c3ee]::iter::adapters::map::Map<core[11918ecc8322c3ee]::iter::adapters::enumerate::Enumerate<core[11918ecc8322c3ee]::slice::iter::Iter<hir_def[b797b053043be09c]::expr_store::path::AssociatedTypeBinding>>, <hir_ty[c6020b5b036d7a82]::lower::path::PathLoweringContext>::assoc_type_bindings_from_type_bound::{closure#0}::{closure#0}>> as core[11918ecc8322c3ee]::iter::adapters::fuse::FuseImpl<core[11918ecc8322c3ee]::iter::adapters::map::Map<core[11918ecc8322c3ee]::iter::adapters::enumerate::Enumerate<core[11918ecc8322c3ee]::slice::iter::Iter<hir_def[b797b053043be09c]::expr_store::path::AssociatedTypeBinding>>, <hir_ty[c6020b5b036d7a82]::lower::path::PathLoweringContext>::assoc_type_bindings_from_type_bound::{closure#0}::{closure#0}>>>::next
                               at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/iter/adapters/fuse.rs:403:29
  40:     0x5623f3741c0b - <core[11918ecc8322c3ee]::iter::adapters::fuse::Fuse<core[11918ecc8322c3ee]::iter::adapters::map::Map<core[11918ecc8322c3ee]::iter::adapters::enumerate::Enumerate<core[11918ecc8322c3ee]::slice::iter::Iter<hir_def[b797b053043be09c]::expr_store::path::AssociatedTypeBinding>>, <hir_ty[c6020b5b036d7a82]::lower::path::PathLoweringContext>::assoc_type_bindings_from_type_bound::{closure#0}::{closure#0}>> as core[11918ecc8322c3ee]::iter::traits::iterator::Iterator>::next
                               at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/iter/adapters/fuse.rs:51:9
  41:     0x5623f3741c0b - <core[11918ecc8322c3ee]::iter::adapters::flatten::FlattenCompat<core[11918ecc8322c3ee]::iter::adapters::map::Map<core[11918ecc8322c3ee]::iter::adapters::enumerate::Enumerate<core[11918ecc8322c3ee]::slice::iter::Iter<hir_def[b797b053043be09c]::expr_store::path::AssociatedTypeBinding>>, <hir_ty[c6020b5b036d7a82]::lower::path::PathLoweringContext>::assoc_type_bindings_from_type_bound::{closure#0}::{closure#0}>, smallvec[30b7154c696f63a5]::IntoIter<[(hir_ty[c6020b5b036d7a82]::next_solver::predicate::Clause, hir_ty[c6020b5b036d7a82]::lower::GenericPredicateSource); 1usize]>> as core[11918ecc8322c3ee]::iter::traits::iterator::Iterator>::next
                               at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/iter/adapters/flatten.rs:526:29
  42:     0x5623f3441225 - <core[11918ecc8322c3ee]::iter::adapters::flatten::FlatMap<core[11918ecc8322c3ee]::iter::adapters::enumerate::Enumerate<core[11918ecc8322c3ee]::slice::iter::Iter<hir_def[b797b053043be09c]::expr_store::path::AssociatedTypeBinding>>, smallvec[30b7154c696f63a5]::SmallVec<[(hir_ty[c6020b5b036d7a82]::next_solver::predicate::Clause, hir_ty[c6020b5b036d7a82]::lower::GenericPredicateSource); 1usize]>, <hir_ty[c6020b5b036d7a82]::lower::path::PathLoweringContext>::assoc_type_bindings_from_type_bound::{closure#0}::{closure#0}> as core[11918ecc8322c3ee]::iter::traits::iterator::Iterator>::next
                               at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/iter/adapters/flatten.rs:64:20
  43:     0x5623f3441225 - <alloc[b37a3ff7fa4d5f32]::vec::Vec<(hir_ty[c6020b5b036d7a82]::next_solver::predicate::Clause, hir_ty[c6020b5b036d7a82]::lower::GenericPredicateSource)> as alloc[b37a3ff7fa4d5f32]::vec::spec_from_iter_nested::SpecFromIterNested<(hir_ty[c6020b5b036d7a82]::next_solver::predicate::Clause, hir_ty[c6020b5b036d7a82]::lower::GenericPredicateSource), core[11918ecc8322c3ee]::iter::adapters::flatten::FlatMap<core[11918ecc8322c3ee]::iter::adapters::enumerate::Enumerate<core[11918ecc8322c3ee]::slice::