ICE: `bound types encountered in super_relate_tys`

[matthiaskrgr]

Code

#![feature(non_lifetime_binders)]
#![crate_type = "lib"]

pub trait Lifetime<'a> {}

struct Foo2<Drop>
where
    for<'a> L: Lifetime<'a>,
{
    l: L,
}

impl<T: > Drop for Foo2<T>
where
    for<T: > T: Lifetime<'x>,
{
    fn drop(&mut self) {}
}

Meta

rustc --version --verbose:

rustc 1.71.0-nightly (c609da59d 2023-04-18)
binary: rustc
commit-hash: c609da59d9fc05b1c7dc879d79700ccd8140b5fc
commit-date: 2023-04-18
host: x86_64-unknown-linux-gnu
release: 1.71.0-nightly
LLVM version: 16.0.2

Error output

error[E0261]: use of undeclared lifetime name `'x`
  --> treereduce.out:15:26
   |
15 |     for<T: > T: Lifetime<'x>,
   |                          ^^ undeclared lifetime
   |
   = note: for more information on higher-ranked polymorphism, visit https://doc.rust-lang.org/nomicon/hrtb.html
help: consider making the bound lifetime-generic with a new `'x` lifetime
   |
15 |     for<T: > T: for<'x> Lifetime<'x>,
   |                 +++++++
help: consider making the bound lifetime-generic with a new `'x` lifetime
   |
15 |     for<'x, T: > T: Lifetime<'x>,
   |         +++
help: consider introducing lifetime `'x` here
   |
13 | impl<'x, T: > Drop for Foo2<T>
   |      +++

error[E0412]: cannot find type `L` in this scope
 --> treereduce.out:8:13
  |
8 |     for<'a> L: Lifetime<'a>,
  |             ^ not found in this scope
  |
help: you might be missing a type parameter
  |
6 | struct Foo2<Drop, L>
  |                 +++

error[E0412]: cannot find type `L` in this scope
  --> treereduce.out:10:8
   |
10 |     l: L,
   |        ^ not found in this scope
   |
help: you might be missing a type parameter
   |
6  | struct Foo2<Drop, L>
   |                 +++

warning: the feature `non_lifetime_binders` is incomplete and may not be safe to use and/or cause compiler crashes
 --> treereduce.out:1:12
  |
1 | #![feature(non_lifetime_binders)]
  |            ^^^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #108185 <https://github.com/rust-lang/rust/issues/108185> for more information
  = note: `#[warn(incomplete_features)]` on by default

Backtrace

error: internal compiler error: /rustc/c609da59d9fc05b1c7dc879d79700ccd8140b5fc/compiler/rustc_middle/src/ty/relate.rs:408:13: bound types encountered in super_relate_tys

thread 'rustc' panicked at 'Box<dyn Any>', /rustc/c609da59d9fc05b1c7dc879d79700ccd8140b5fc/compiler/rustc_errors/src/lib.rs:1643:9
stack backtrace:
   0:     0x7ff3e75653c2 - std::backtrace_rs::backtrace::libunwind::trace::h4acdb82da48c9833
                               at /rustc/c609da59d9fc05b1c7dc879d79700ccd8140b5fc/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
   1:     0x7ff3e75653c2 - std::backtrace_rs::backtrace::trace_unsynchronized::hf2cc6a3a410a5594
                               at /rustc/c609da59d9fc05b1c7dc879d79700ccd8140b5fc/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7ff3e75653c2 - std::sys_common::backtrace::_print_fmt::hbbc6914b749d0ada
                               at /rustc/c609da59d9fc05b1c7dc879d79700ccd8140b5fc/library/std/src/sys_common/backtrace.rs:65:5
   3:     0x7ff3e75653c2 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h3d5a35293018c1e6
                               at /rustc/c609da59d9fc05b1c7dc879d79700ccd8140b5fc/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7ff3e75c95df - core::fmt::write::hcd8095c096d51cb1
                               at /rustc/c609da59d9fc05b1c7dc879d79700ccd8140b5fc/library/core/src/fmt/mod.rs:1254:17
   5:     0x7ff3e7558401 - std::io::Write::write_fmt::hfb074efb44accf99
                               at /rustc/c609da59d9fc05b1c7dc879d79700ccd8140b5fc/library/std/src/io/mod.rs:1698:15
   6:     0x7ff3e75651c5 - std::sys_common::backtrace::_print::hf3de088e34eea71b
                               at /rustc/c609da59d9fc05b1c7dc879d79700ccd8140b5fc/library/std/src/sys_common/backtrace.rs:47:5
   7:     0x7ff3e75651c5 - std::sys_common::backtrace::print::h8c1956d8c9acf6e3
                               at /rustc/c609da59d9fc05b1c7dc879d79700ccd8140b5fc/library/std/src/sys_common/backtrace.rs:34:9
   8:     0x7ff3e7567e87 - std::panicking::default_hook::{{closure}}::h0f8c867eadb4985a
   9:     0x7ff3e7567c75 - std::panicking::default_hook::h749ec9b15ecb3c39
                               at /rustc/c609da59d9fc05b1c7dc879d79700ccd8140b5fc/library/std/src/panicking.rs:288:9
  10:     0x7ff3ea830cf5 - rustc_driver_impl[7fdb2e8792375136]::DEFAULT_HOOK::{closure#0}::{closure#0}
  11:     0x7ff3e75685c5 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::ha6bcd52ce2118341
                               at /rustc/c609da59d9fc05b1c7dc879d79700ccd8140b5fc/library/alloc/src/boxed.rs:1987:9
  12:     0x7ff3e75685c5 - std::panicking::rust_panic_with_hook::h553363ec26086b73
                               at /rustc/c609da59d9fc05b1c7dc879d79700ccd8140b5fc/library/std/src/panicking.rs:695:13
  13:     0x7ff3ead18461 - std[aef50eda90d64d90]::panicking::begin_panic::<rustc_errors[934a790ce3691480]::ExplicitBug>::{closure#0}
  14:     0x7ff3ead17456 - std[aef50eda90d64d90]::sys_common::backtrace::__rust_end_short_backtrace::<std[aef50eda90d64d90]::panicking::begin_panic<rustc_errors[934a790ce3691480]::ExplicitBug>::{closure#0}, !>
  15:     0x7ff3ead5a9b6 - std[aef50eda90d64d90]::panicking::begin_panic::<rustc_errors[934a790ce3691480]::ExplicitBug>
  16:     0x7ff3ead83c26 - <rustc_errors[934a790ce3691480]::HandlerInner>::bug::<&alloc[3ca5cc4d7c388e]::string::String>
  17:     0x7ff3ead838f0 - <rustc_errors[934a790ce3691480]::Handler>::bug::<&alloc[3ca5cc4d7c388e]::string::String>
  18:     0x7ff3ead4463b - rustc_middle[8054a8be7b277c97]::util::bug::opt_span_bug_fmt::<rustc_span[8c04062e23e0b099]::span_encoding::Span>::{closure#0}
  19:     0x7ff3ead43f1a - rustc_middle[8054a8be7b277c97]::ty::context::tls::with_opt::<rustc_middle[8054a8be7b277c97]::util::bug::opt_span_bug_fmt<rustc_span[8c04062e23e0b099]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  20:     0x7ff3ead43ee6 - rustc_middle[8054a8be7b277c97]::ty::context::tls::with_context_opt::<rustc_middle[8054a8be7b277c97]::ty::context::tls::with_opt<rustc_middle[8054a8be7b277c97]::util::bug::opt_span_bug_fmt<rustc_span[8c04062e23e0b099]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  21:     0x7ff3e89e6a7d - rustc_middle[8054a8be7b277c97]::util::bug::bug_fmt
  22:     0x7ff3ea03040a - rustc_middle[8054a8be7b277c97]::ty::relate::super_relate_tys::<rustc_hir_analysis[42144caad347631]::check::dropck::SimpleEqRelation>
  23:     0x7ff3e9e2f48f - <rustc_middle[8054a8be7b277c97]::ty::subst::GenericArg as rustc_middle[8054a8be7b277c97]::ty::relate::Relate>::relate::<rustc_hir_analysis[42144caad347631]::check::dropck::SimpleEqRelation>
  24:     0x7ff3e9e2f0b0 - <core[7c99772fdcabedb3]::result::Result<rustc_middle[8054a8be7b277c97]::ty::subst::GenericArg, rustc_middle[8054a8be7b277c97]::ty::error::TypeError> as rustc_type_ir[e1ddc2cff5d0a20e]::CollectAndApply<rustc_middle[8054a8be7b277c97]::ty::subst::GenericArg, &rustc_middle[8054a8be7b277c97]::ty::list::List<rustc_middle[8054a8be7b277c97]::ty::subst::GenericArg>>>::collect_and_apply::<core[7c99772fdcabedb3]::iter::adapters::map::Map<core[7c99772fdcabedb3]::iter::adapters::zip::Zip<core[7c99772fdcabedb3]::iter::adapters::copied::Copied<core[7c99772fdcabedb3]::slice::iter::Iter<rustc_middle[8054a8be7b277c97]::ty::subst::GenericArg>>, core[7c99772fdcabedb3]::iter::adapters::copied::Copied<core[7c99772fdcabedb3]::slice::iter::Iter<rustc_middle[8054a8be7b277c97]::ty::subst::GenericArg>>>, rustc_middle[8054a8be7b277c97]::ty::relate::relate_substs<rustc_hir_analysis[42144caad347631]::check::dropck::SimpleEqRelation>::{closure#0}>, <rustc_middle[8054a8be7b277c97]::ty::context::TyCtxt>::mk_substs_from_iter<core[7c99772fdcabedb3]::iter::adapters::map::Map<core[7c99772fdcabedb3]::iter::adapters::zip::Zip<core[7c99772fdcabedb3]::iter::adapters::copied::Copied<core[7c99772fdcabedb3]::slice::iter::Iter<rustc_middle[8054a8be7b277c97]::ty::subst::GenericArg>>, core[7c99772fdcabedb3]::iter::adapters::copied::Copied<core[7c99772fdcabedb3]::slice::iter::Iter<rustc_middle[8054a8be7b277c97]::ty::subst::GenericArg>>>, rustc_middle[8054a8be7b277c97]::ty::relate::relate_substs<rustc_hir_analysis[42144caad347631]::check::dropck::SimpleEqRelation>::{closure#0}>, core[7c99772fdcabedb3]::result::Result<rustc_middle[8054a8be7b277c97]::ty::subst::GenericArg, rustc_middle[8054a8be7b277c97]::ty::error::TypeError>>::{closure#0}>
  25:     0x7ff3e9e2ebd8 - <rustc_middle[8054a8be7b277c97]::ty::sty::TraitRef as rustc_middle[8054a8be7b277c97]::ty::relate::Relate>::relate::<rustc_hir_analysis[42144caad347631]::check::dropck::SimpleEqRelation>
  26:     0x7ff3e9e2e8a7 - <rustc_middle[8054a8be7b277c97]::ty::TraitPredicate as rustc_middle[8054a8be7b277c97]::ty::relate::Relate>::relate::<rustc_hir_analysis[42144caad347631]::check::dropck::SimpleEqRelation>
  27:     0x7ff3e9e2e57d - <core[7c99772fdcabedb3]::iter::adapters::copied::Copied<core[7c99772fdcabedb3]::slice::iter::Iter<rustc_middle[8054a8be7b277c97]::ty::Predicate>> as core[7c99772fdcabedb3]::iter::traits::iterator::Iterator>::try_fold::<(), core[7c99772fdcabedb3]::iter::traits::iterator::Iterator::any::check<rustc_middle[8054a8be7b277c97]::ty::Predicate, rustc_hir_analysis[42144caad347631]::check::dropck::ensure_drop_predicates_are_implied_by_item_defn::{closure#0}>::{closure#0}, core[7c99772fdcabedb3]::ops::control_flow::ControlFlow<()>>
  28:     0x7ff3e9e2d947 - rustc_hir_analysis[42144caad347631]::check::dropck::check_drop_impl
  29:     0x7ff3e9e2d2f7 - <rustc_middle[8054a8be7b277c97]::ty::context::TyCtxt>::calculate_dtor::<rustc_hir_analysis[42144caad347631]::check::dropck::check_drop_impl>::{closure#0}
  30:     0x7ff3e9e2ce21 - <rustc_middle[8054a8be7b277c97]::ty::context::TyCtxt>::calculate_dtor::<rustc_hir_analysis[42144caad347631]::check::dropck::check_drop_impl>
  31:     0x7ff3e9e2cb5b - rustc_hir_analysis[42144caad347631]::check::adt_destructor
  32:     0x7ff3e9cf5c1f - rustc_query_system[354c60129646c01e]::query::plumbing::try_execute_query::<rustc_query_impl[4ebfc2cbb59026c7]::queries::adt_destructor, rustc_query_impl[4ebfc2cbb59026c7]::plumbing::QueryCtxt>
  33:     0x7ff3e9cf5618 - <rustc_query_impl[4ebfc2cbb59026c7]::Queries as rustc_middle[8054a8be7b277c97]::ty::query::QueryEngine>::adt_destructor
  34:     0x7ff3e934594a - <rustc_middle[8054a8be7b277c97]::ty::adt::AdtDef>::destructor
  35:     0x7ff3e933e8f2 - rustc_hir_analysis[42144caad347631]::check::check::check_mod_item_types
  36:     0x7ff3e9e6fea1 - rustc_query_system[354c60129646c01e]::query::plumbing::try_execute_query::<rustc_query_impl[4ebfc2cbb59026c7]::queries::check_mod_item_types, rustc_query_impl[4ebfc2cbb59026c7]::plumbing::QueryCtxt>
  37:     0x7ff3e9e6fac9 - <rustc_query_impl[4ebfc2cbb59026c7]::Queries as rustc_middle[8054a8be7b277c97]::ty::query::QueryEngine>::check_mod_item_types
  38:     0x7ff3e9c0fbac - <rustc_middle[8054a8be7b277c97]::hir::map::Map>::for_each_module::<rustc_hir_analysis[42144caad347631]::check_crate::{closure#6}::{closure#0}>
  39:     0x7ff3e9c0bfab - rustc_hir_analysis[42144caad347631]::check_crate
  40:     0x7ff3e9c05e3d - rustc_interface[7925d28b3b6d3805]::passes::analysis
  41:     0x7ff3e9fa3712 - rustc_query_system[354c60129646c01e]::query::plumbing::try_execute_query::<rustc_query_impl[4ebfc2cbb59026c7]::queries::analysis, rustc_query_impl[4ebfc2cbb59026c7]::plumbing::QueryCtxt>
  42:     0x7ff3e9fa3420 - <rustc_query_impl[4ebfc2cbb59026c7]::Queries as rustc_middle[8054a8be7b277c97]::ty::query::QueryEngine>::analysis
  43:     0x7ff3e9e64ca6 - <std[aef50eda90d64d90]::thread::local::LocalKey<core[7c99772fdcabedb3]::cell::Cell<*const ()>>>::with::<rustc_middle[8054a8be7b277c97]::ty::context::tls::enter_context<<rustc_middle[8054a8be7b277c97]::ty::context::GlobalCtxt>::enter<rustc_driver_impl[7fdb2e8792375136]::run_compiler::{closure#1}::{closure#2}::{closure#4}, core[7c99772fdcabedb3]::result::Result<(), rustc_span[8c04062e23e0b099]::ErrorGuaranteed>>::{closure#0}, core[7c99772fdcabedb3]::result::Result<(), rustc_span[8c04062e23e0b099]::ErrorGuaranteed>>::{closure#0}, core[7c99772fdcabedb3]::result::Result<(), rustc_span[8c04062e23e0b099]::ErrorGuaranteed>>
  44:     0x7ff3e9a529a7 - <rustc_interface[7925d28b3b6d3805]::interface::Compiler>::enter::<rustc_driver_impl[7fdb2e8792375136]::run_compiler::{closure#1}::{closure#2}, core[7c99772fdcabedb3]::result::Result<core[7c99772fdcabedb3]::option::Option<rustc_interface[7925d28b3b6d3805]::queries::Linker>, rustc_span[8c04062e23e0b099]::ErrorGuaranteed>>
  45:     0x7ff3e9a4ca8f - rustc_span[8c04062e23e0b099]::set_source_map::<core[7c99772fdcabedb3]::result::Result<(), rustc_span[8c04062e23e0b099]::ErrorGuaranteed>, rustc_interface[7925d28b3b6d3805]::interface::run_compiler<core[7c99772fdcabedb3]::result::Result<(), rustc_span[8c04062e23e0b099]::ErrorGuaranteed>, rustc_driver_impl[7fdb2e8792375136]::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
  46:     0x7ff3e9a4c6a8 - <scoped_tls[6d453f3239404e]::ScopedKey<rustc_span[8c04062e23e0b099]::SessionGlobals>>::set::<rustc_interface[7925d28b3b6d3805]::interface::run_compiler<core[7c99772fdcabedb3]::result::Result<(), rustc_span[8c04062e23e0b099]::ErrorGuaranteed>, rustc_driver_impl[7fdb2e8792375136]::run_compiler::{closure#1}>::{closure#0}, core[7c99772fdcabedb3]::result::Result<(), rustc_span[8c04062e23e0b099]::ErrorGuaranteed>>
  47:     0x7ff3e9a4bcbb - std[aef50eda90d64d90]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[7925d28b3b6d3805]::util::run_in_thread_pool_with_globals<rustc_interface[7925d28b3b6d3805]::interface::run_compiler<core[7c99772fdcabedb3]::result::Result<(), rustc_span[8c04062e23e0b099]::ErrorGuaranteed>, rustc_driver_impl[7fdb2e8792375136]::run_compiler::{closure#1}>::{closure#0}, core[7c99772fdcabedb3]::result::Result<(), rustc_span[8c04062e23e0b099]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[7c99772fdcabedb3]::result::Result<(), rustc_span[8c04062e23e0b099]::ErrorGuaranteed>>
  48:     0x7ff3ea101861 - <<std[aef50eda90d64d90]::thread::Builder>::spawn_unchecked_<rustc_interface[7925d28b3b6d3805]::util::run_in_thread_pool_with_globals<rustc_interface[7925d28b3b6d3805]::interface::run_compiler<core[7c99772fdcabedb3]::result::Result<(), rustc_span[8c04062e23e0b099]::ErrorGuaranteed>, rustc_driver_impl[7fdb2e8792375136]::run_compiler::{closure#1}>::{closure#0}, core[7c99772fdcabedb3]::result::Result<(), rustc_span[8c04062e23e0b099]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[7c99772fdcabedb3]::result::Result<(), rustc_span[8c04062e23e0b099]::ErrorGuaranteed>>::{closure#1} as core[7c99772fdcabedb3]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  49:     0x7ff3e7572a85 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::he0dee4d73e6ebe6e
                               at /rustc/c609da59d9fc05b1c7dc879d79700ccd8140b5fc/library/alloc/src/boxed.rs:1973:9
  50:     0x7ff3e7572a85 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hdfd4a296008e148d
                               at /rustc/c609da59d9fc05b1c7dc879d79700ccd8140b5fc/library/alloc/src/boxed.rs:1973:9
  51:     0x7ff3e7572a85 - std::sys::unix::thread::Thread::new::thread_start::h8f06ac6e30e47e34
                               at /rustc/c609da59d9fc05b1c7dc879d79700ccd8140b5fc/library/std/src/sys/unix/thread.rs:108:17
  52:     0x7ff3e730dbb5 - <unknown>
  53:     0x7ff3e738fd90 - <unknown>
  54:                0x0 - <unknown>

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 1.71.0-nightly (c609da59d 2023-04-18) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [adt_destructor] computing `Drop` impl for `Foo2`
#1 [check_mod_item_types] checking item types in top-level module
#2 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 4 previous errors; 1 warning emitted

Some errors have detailed explanations: E0261, E0412.
For more information about an error, try `rustc --explain E0261`.