ICE: `None` in trait codegen

[matthiaskrgr]

auto-reduced (treereduce-rust):

mod foo {
    pub trait Callable {
        type Output;
        fn call() -> Self::Output;
    }

    impl<'a, V: ?Sized> Callable for &'a () {
        type Output = ();
    }
}
use foo::*;

fn test<'a>() -> impl Sized {
    <&'a () as Callable>::call()
}

fn main() {}

original:

#![feature(impl_trait_in_assoc_type, type_alias_impl_trait)]

mod foo {
    pub trait Callable {
        type Output;
        fn call() -> Self::Output;
    }

    pub type OutputHelper = impl Sized;
    impl<'a, V: ?Sized> Callable for &'a () {
        type Output = OutputHelper;
        fn call() -> Self::Output {}
    }
}
use foo::*;

fn test<'a>() -> impl Sized {
    <&'a () as Callable>::call()
}

fn want_static<T: 'static>(_: T) {}

fn test2<'a>() {
    want_static(<&'a () as Callable>::call());
}

fn main() {}

Version information

rustc 1.81.0-nightly (dd104ef16 2024-06-18)
binary: rustc
commit-hash: dd104ef16315e2387fe94e8c43eb5a66e3dbd660
commit-date: 2024-06-18
host: x86_64-unknown-linux-gnu
release: 1.81.0-nightly
LLVM version: 18.1.7

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc

Program output

thread 'rustc' panicked at compiler/rustc_traits/src/codegen.rs:81:38:
called `Option::unwrap()` on a `None` value
stack backtrace:
   0:     0x7200b847a935 - std::backtrace_rs::backtrace::libunwind::trace::h24001de405a19c29
                               at /rustc/dd104ef16315e2387fe94e8c43eb5a66e3dbd660/library/std/src/../../backtrace/src/backtrace/libunwind.rs:116:5
   1:     0x7200b847a935 - std::backtrace_rs::backtrace::trace_unsynchronized::h52cb31f58d87e795
                               at /rustc/dd104ef16315e2387fe94e8c43eb5a66e3dbd660/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7200b847a935 - std::sys::backtrace::_print_fmt::ha0a4a385e6305dc9
                               at /rustc/dd104ef16315e2387fe94e8c43eb5a66e3dbd660/library/std/src/sys/backtrace.rs:68:5
   3:     0x7200b847a935 - <std::sys::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hd2ac9d261fff2c5c
                               at /rustc/dd104ef16315e2387fe94e8c43eb5a66e3dbd660/library/std/src/sys/backtrace.rs:44:22
   4:     0x7200b84cb4db - core::fmt::rt::Argument::fmt::h5dd96858711c38a5
                               at /rustc/dd104ef16315e2387fe94e8c43eb5a66e3dbd660/library/core/src/fmt/rt.rs:165:63
   5:     0x7200b84cb4db - core::fmt::write::h9137aaeb0715e137
                               at /rustc/dd104ef16315e2387fe94e8c43eb5a66e3dbd660/library/core/src/fmt/mod.rs:1168:21
   6:     0x7200b846f51f - std::io::Write::write_fmt::h3d543f59fe71748a
                               at /rustc/dd104ef16315e2387fe94e8c43eb5a66e3dbd660/library/std/src/io/mod.rs:1835:15
   7:     0x7200b847a70e - std::sys::backtrace::_print::h4a7caef85c10fa0d
                               at /rustc/dd104ef16315e2387fe94e8c43eb5a66e3dbd660/library/std/src/sys/backtrace.rs:47:5
   8:     0x7200b847a70e - std::sys::backtrace::print::hf1ff8c4b50b84478
                               at /rustc/dd104ef16315e2387fe94e8c43eb5a66e3dbd660/library/std/src/sys/backtrace.rs:34:9
   9:     0x7200b847d149 - std::panicking::default_hook::{{closure}}::h76d1d90acd3a4473
  10:     0x7200b847ceec - std::panicking::default_hook::h2a49ac4243aa5140
                               at /rustc/dd104ef16315e2387fe94e8c43eb5a66e3dbd660/library/std/src/panicking.rs:292:9
  11:     0x7200b4cacd2f - std[49f1045a74567fa7]::panicking::update_hook::<alloc[5df14249ca9505f2]::boxed::Box<rustc_driver_impl[db4e8f03b5696bb3]::install_ice_hook::{closure#0}>>::{closure#0}
  12:     0x7200b847da6f - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h25f6191eb839a16b
                               at /rustc/dd104ef16315e2387fe94e8c43eb5a66e3dbd660/library/alloc/src/boxed.rs:2076:9
  13:     0x7200b847da6f - std::panicking::rust_panic_with_hook::hc9c5e69e405d5d6c
                               at /rustc/dd104ef16315e2387fe94e8c43eb5a66e3dbd660/library/std/src/panicking.rs:804:13
  14:     0x7200b847d663 - std::panicking::begin_panic_handler::{{closure}}::h1e191b09b1d4d3a1
                               at /rustc/dd104ef16315e2387fe94e8c43eb5a66e3dbd660/library/std/src/panicking.rs:663:13
  15:     0x7200b847adf9 - std::sys::backtrace::__rust_end_short_backtrace::hcf45e4c7144c2449
                               at /rustc/dd104ef16315e2387fe94e8c43eb5a66e3dbd660/library/std/src/sys/backtrace.rs:171:18
  16:     0x7200b847d324 - rust_begin_unwind
                               at /rustc/dd104ef16315e2387fe94e8c43eb5a66e3dbd660/library/std/src/panicking.rs:661:5
  17:     0x7200b84c7a93 - core::panicking::panic_fmt::h16e3e243fb3ae09b
                               at /rustc/dd104ef16315e2387fe94e8c43eb5a66e3dbd660/library/core/src/panicking.rs:74:14
  18:     0x7200b84c7b1c - core::panicking::panic::h602a9ee3e943791e
                               at /rustc/dd104ef16315e2387fe94e8c43eb5a66e3dbd660/library/core/src/panicking.rs:148:5
  19:     0x7200b84c7889 - core::option::unwrap_failed::h32ee57917be56d39
                               at /rustc/dd104ef16315e2387fe94e8c43eb5a66e3dbd660/library/core/src/option.rs:2011:5
  20:     0x7200b2adc83d - rustc_traits[85d1f1446d62d4f5]::codegen::codegen_select_candidate
  21:     0x7200b65d27b7 - rustc_query_impl[ed5fbfae2043678b]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[ed5fbfae2043678b]::query_impl::codegen_select_candidate::dynamic_query::{closure#2}::{closure#0}, rustc_middle[1b5811ec6d2edbd2]::query::erase::Erased<[u8; 16usize]>>
  22:     0x7200b65d2ae2 - rustc_query_system[f4d6069fb68f5c49]::query::plumbing::try_execute_query::<rustc_query_impl[ed5fbfae2043678b]::DynamicConfig<rustc_query_system[f4d6069fb68f5c49]::query::caches::DefaultCache<(rustc_middle[1b5811ec6d2edbd2]::ty::ParamEnv, rustc_type_ir[9d828e6be873c6e9]::predicate::TraitRef<rustc_middle[1b5811ec6d2edbd2]::ty::context::TyCtxt>), rustc_middle[1b5811ec6d2edbd2]::query::erase::Erased<[u8; 16usize]>>, false, false, false>, rustc_query_impl[ed5fbfae2043678b]::plumbing::QueryCtxt, false>
  23:     0x7200b65d275e - rustc_query_impl[ed5fbfae2043678b]::query_impl::codegen_select_candidate::get_query_non_incr::__rust_end_short_backtrace
  24:     0x7200b39e172a - rustc_ty_utils[cae5f04a34a68424]::instance::resolve_instance
  25:     0x7200b6539e69 - rustc_query_impl[ed5fbfae2043678b]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[ed5fbfae2043678b]::query_impl::resolve_instance::dynamic_query::{closure#2}::{closure#0}, rustc_middle[1b5811ec6d2edbd2]::query::erase::Erased<[u8; 32usize]>>
  26:     0x7200b653a1a5 - rustc_query_system[f4d6069fb68f5c49]::query::plumbing::try_execute_query::<rustc_query_impl[ed5fbfae2043678b]::DynamicConfig<rustc_query_system[f4d6069fb68f5c49]::query::caches::DefaultCache<rustc_middle[1b5811ec6d2edbd2]::ty::ParamEnvAnd<(rustc_span[b2dab8d5db9c06d4]::def_id::DefId, &rustc_middle[1b5811ec6d2edbd2]::ty::list::RawList<(), rustc_middle[1b5811ec6d2edbd2]::ty::generic_args::GenericArg>)>, rustc_middle[1b5811ec6d2edbd2]::query::erase::Erased<[u8; 32usize]>>, false, false, false>, rustc_query_impl[ed5fbfae2043678b]::plumbing::QueryCtxt, false>
  27:     0x7200b6539dfd - rustc_query_impl[ed5fbfae2043678b]::query_impl::resolve_instance::get_query_non_incr::__rust_end_short_backtrace
  28:     0x7200b653c7e8 - <rustc_middle[1b5811ec6d2edbd2]::ty::instance::Instance>::resolve
  29:     0x7200b640e003 - rustc_mir_build[10942160e2184657]::build::mir_build
  30:     0x7200b640b38e - rustc_query_impl[ed5fbfae2043678b]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[ed5fbfae2043678b]::query_impl::mir_built::dynamic_query::{closure#2}::{closure#0}, rustc_middle[1b5811ec6d2edbd2]::query::erase::Erased<[u8; 8usize]>>
  31:     0x7200b63be0ae - rustc_query_system[f4d6069fb68f5c49]::query::plumbing::try_execute_query::<rustc_query_impl[ed5fbfae2043678b]::DynamicConfig<rustc_query_system[f4d6069fb68f5c49]::query::caches::VecCache<rustc_span[b2dab8d5db9c06d4]::def_id::LocalDefId, rustc_middle[1b5811ec6d2edbd2]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[ed5fbfae2043678b]::plumbing::QueryCtxt, false>
  32:     0x7200b63bdbcd - rustc_query_impl[ed5fbfae2043678b]::query_impl::mir_built::get_query_non_incr::__rust_end_short_backtrace
  33:     0x7200b601e856 - rustc_mir_transform[9ac0af314c39e32b]::ffi_unwind_calls::has_ffi_unwind_calls
  34:     0x7200b601e2e9 - rustc_query_impl[ed5fbfae2043678b]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[ed5fbfae2043678b]::query_impl::has_ffi_unwind_calls::dynamic_query::{closure#2}::{closure#0}, rustc_middle[1b5811ec6d2edbd2]::query::erase::Erased<[u8; 1usize]>>
  35:     0x7200b63f3551 - rustc_query_system[f4d6069fb68f5c49]::query::plumbing::try_execute_query::<rustc_query_impl[ed5fbfae2043678b]::DynamicConfig<rustc_query_system[f4d6069fb68f5c49]::query::caches::VecCache<rustc_span[b2dab8d5db9c06d4]::def_id::LocalDefId, rustc_middle[1b5811ec6d2edbd2]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[ed5fbfae2043678b]::plumbing::QueryCtxt, false>
  36:     0x7200b63f3141 - rustc_query_impl[ed5fbfae2043678b]::query_impl::has_ffi_unwind_calls::get_query_non_incr::__rust_end_short_backtrace
  37:     0x7200b393f30b - rustc_mir_transform[9ac0af314c39e32b]::mir_promoted
  38:     0x7200b66cfb5a - rustc_query_impl[ed5fbfae2043678b]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[ed5fbfae2043678b]::query_impl::mir_promoted::dynamic_query::{closure#2}::{closure#0}, rustc_middle[1b5811ec6d2edbd2]::query::erase::Erased<[u8; 16usize]>>
  39:     0x7200b66cfe33 - rustc_query_system[f4d6069fb68f5c49]::query::plumbing::try_execute_query::<rustc_query_impl[ed5fbfae2043678b]::DynamicConfig<rustc_query_system[f4d6069fb68f5c49]::query::caches::VecCache<rustc_span[b2dab8d5db9c06d4]::def_id::LocalDefId, rustc_middle[1b5811ec6d2edbd2]::query::erase::Erased<[u8; 16usize]>>, false, false, false>, rustc_query_impl[ed5fbfae2043678b]::plumbing::QueryCtxt, false>
  40:     0x7200b6fb2c50 - rustc_query_impl[ed5fbfae2043678b]::query_impl::mir_promoted::get_query_non_incr::__rust_end_short_backtrace
  41:     0x7200b6fb2d43 - rustc_query_impl[ed5fbfae2043678b]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[ed5fbfae2043678b]::query_impl::mir_borrowck::dynamic_query::{closure#2}::{closure#0}, rustc_middle[1b5811ec6d2edbd2]::query::erase::Erased<[u8; 8usize]>>
  42:     0x7200b63be0ae - rustc_query_system[f4d6069fb68f5c49]::query::plumbing::try_execute_query::<rustc_query_impl[ed5fbfae2043678b]::DynamicConfig<rustc_query_system[f4d6069fb68f5c49]::query::caches::VecCache<rustc_span[b2dab8d5db9c06d4]::def_id::LocalDefId, rustc_middle[1b5811ec6d2edbd2]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[ed5fbfae2043678b]::plumbing::QueryCtxt, false>
  43:     0x7200b63bdb0d - rustc_query_impl[ed5fbfae2043678b]::query_impl::mir_borrowck::get_query_non_incr::__rust_end_short_backtrace
  44:     0x7200b6293a05 - rustc_middle[1b5811ec6d2edbd2]::query::plumbing::query_get_at::<rustc_query_system[f4d6069fb68f5c49]::query::caches::VecCache<rustc_span[b2dab8d5db9c06d4]::def_id::LocalDefId, rustc_middle[1b5811ec6d2edbd2]::query::erase::Erased<[u8; 8usize]>>>
  45:     0x7200b6dfdf4a - rustc_hir_analysis[afae3ead62935b7b]::collect::type_of::type_of_opaque
  46:     0x7200b6dfddab - rustc_query_impl[ed5fbfae2043678b]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[ed5fbfae2043678b]::query_impl::type_of_opaque::dynamic_query::{closure#2}::{closure#0}, rustc_middle[1b5811ec6d2edbd2]::query::erase::Erased<[u8; 8usize]>>
  47:     0x7200b609d75b - rustc_query_system[f4d6069fb68f5c49]::query::plumbing::try_execute_query::<rustc_query_impl[ed5fbfae2043678b]::DynamicConfig<rustc_query_system[f4d6069fb68f5c49]::query::caches::DefIdCache<rustc_middle[1b5811ec6d2edbd2]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[ed5fbfae2043678b]::plumbing::QueryCtxt, false>
  48:     0x7200b70f9876 - rustc_query_impl[ed5fbfae2043678b]::query_impl::type_of_opaque::get_query_non_incr::__rust_end_short_backtrace
  49:     0x7200b65f04d8 - rustc_middle[1b5811ec6d2edbd2]::query::plumbing::query_get_at::<rustc_query_system[f4d6069fb68f5c49]::query::caches::DefIdCache<rustc_middle[1b5811ec6d2edbd2]::query::erase::Erased<[u8; 8usize]>>>
  50:     0x7200b3b5b1c5 - rustc_hir_analysis[afae3ead62935b7b]::collect::type_of::type_of
  51:     0x7200b609eb6a - rustc_query_impl[ed5fbfae2043678b]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[ed5fbfae2043678b]::query_impl::type_of::dynamic_query::{closure#2}::{closure#0}, rustc_middle[1b5811ec6d2edbd2]::query::erase::Erased<[u8; 8usize]>>
  52:     0x7200b609d75b - rustc_query_system[f4d6069fb68f5c49]::query::plumbing::try_execute_query::<rustc_query_impl[ed5fbfae2043678b]::DynamicConfig<rustc_query_system[f4d6069fb68f5c49]::query::caches::DefIdCache<rustc_middle[1b5811ec6d2edbd2]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[ed5fbfae2043678b]::plumbing::QueryCtxt, false>
  53:     0x7200b609d2fb - rustc_query_impl[ed5fbfae2043678b]::query_impl::type_of::get_query_non_incr::__rust_end_short_backtrace
  54:     0x7200b65f04d8 - rustc_middle[1b5811ec6d2edbd2]::query::plumbing::query_get_at::<rustc_query_system[f4d6069fb68f5c49]::query::caches::DefIdCache<rustc_middle[1b5811ec6d2edbd2]::query::erase::Erased<[u8; 8usize]>>>
  55:     0x7200b2992133 - rustc_hir_analysis[afae3ead62935b7b]::check::check::check_item_type
  56:     0x7200b38a4407 - rustc_hir_analysis[afae3ead62935b7b]::check::wfcheck::check_well_formed
  57:     0x7200b63a843d - rustc_query_impl[ed5fbfae2043678b]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[ed5fbfae2043678b]::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle[1b5811ec6d2edbd2]::query::erase::Erased<[u8; 1usize]>>
  58:     0x7200b63a86aa - rustc_query_system[f4d6069fb68f5c49]::query::plumbing::try_execute_query::<rustc_query_impl[ed5fbfae2043678b]::DynamicConfig<rustc_query_system[f4d6069fb68f5c49]::query::caches::VecCache<rustc_hir[7b564558969ebbbd]::hir_id::OwnerId, rustc_middle[1b5811ec6d2edbd2]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[ed5fbfae2043678b]::plumbing::QueryCtxt, false>
  59:     0x7200b63a841a - rustc_query_impl[ed5fbfae2043678b]::query_impl::check_well_formed::get_query_non_incr::__rust_end_short_backtrace
  60:     0x7200b63a918f - rustc_hir_analysis[afae3ead62935b7b]::check::wfcheck::check_mod_type_wf
  61:     0x7200b63a8fd5 - rustc_query_impl[ed5fbfae2043678b]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[ed5fbfae2043678b]::query_impl::check_mod_type_wf::dynamic_query::{closure#2}::{closure#0}, rustc_middle[1b5811ec6d2edbd2]::query::erase::Erased<[u8; 1usize]>>
  62:     0x7200b6dd0bba - rustc_query_system[f4d6069fb68f5c49]::query::plumbing::try_execute_query::<rustc_query_impl[ed5fbfae2043678b]::DynamicConfig<rustc_query_system[f4d6069fb68f5c49]::query::caches::DefaultCache<rustc_span[b2dab8d5db9c06d4]::def_id::LocalModDefId, rustc_middle[1b5811ec6d2edbd2]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[ed5fbfae2043678b]::plumbing::QueryCtxt, false>
  63:     0x7200b6dd0975 - rustc_query_impl[ed5fbfae2043678b]::query_impl::check_mod_type_wf::get_query_non_incr::__rust_end_short_backtrace
  64:     0x7200b63bac8c - rustc_hir_analysis[afae3ead62935b7b]::check_crate
  65:     0x7200b6a032c7 - rustc_interface[c6ece38a3a908c28]::passes::analysis
  66:     0x7200b6a02e07 - rustc_query_impl[ed5fbfae2043678b]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[ed5fbfae2043678b]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[1b5811ec6d2edbd2]::query::erase::Erased<[u8; 1usize]>>
  67:     0x7200b6e360a5 - rustc_query_system[f4d6069fb68f5c49]::query::plumbing::try_execute_query::<rustc_query_impl[ed5fbfae2043678b]::DynamicConfig<rustc_query_system[f4d6069fb68f5c49]::query::caches::SingleCache<rustc_middle[1b5811ec6d2edbd2]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[ed5fbfae2043678b]::plumbing::QueryCtxt, false>
  68:     0x7200b6e35e0f - rustc_query_impl[ed5fbfae2043678b]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  69:     0x7200b6cdd3d2 - rustc_interface[c6ece38a3a908c28]::interface::run_compiler::<core[3c5d2e85893f84f8]::result::Result<(), rustc_span[b2dab8d5db9c06d4]::ErrorGuaranteed>, rustc_driver_impl[db4e8f03b5696bb3]::run_compiler::{closure#0}>::{closure#1}
  70:     0x7200b6cb54c9 - std[49f1045a74567fa7]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[c6ece38a3a908c28]::util::run_in_thread_with_globals<rustc_interface[c6ece38a3a908c28]::util::run_in_thread_pool_with_globals<rustc_interface[c6ece38a3a908c28]::interface::run_compiler<core[3c5d2e85893f84f8]::result::Result<(), rustc_span[b2dab8d5db9c06d4]::ErrorGuaranteed>, rustc_driver_impl[db4e8f03b5696bb3]::run_compiler::{closure#0}>::{closure#1}, core[3c5d2e85893f84f8]::result::Result<(), rustc_span[b2dab8d5db9c06d4]::ErrorGuaranteed>>::{closure#0}, core[3c5d2e85893f84f8]::result::Result<(), rustc_span[b2dab8d5db9c06d4]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[3c5d2e85893f84f8]::result::Result<(), rustc_span[b2dab8d5db9c06d4]::ErrorGuaranteed>>
  71:     0x7200b6cb527a - <<std[49f1045a74567fa7]::thread::Builder>::spawn_unchecked_<rustc_interface[c6ece38a3a908c28]::util::run_in_thread_with_globals<rustc_interface[c6ece38a3a908c28]::util::run_in_thread_pool_with_globals<rustc_interface[c6ece38a3a908c28]::interface::run_compiler<core[3c5d2e85893f84f8]::result::Result<(), rustc_span[b2dab8d5db9c06d4]::ErrorGuaranteed>, rustc_driver_impl[db4e8f03b5696bb3]::run_compiler::{closure#0}>::{closure#1}, core[3c5d2e85893f84f8]::result::Result<(), rustc_span[b2dab8d5db9c06d4]::ErrorGuaranteed>>::{closure#0}, core[3c5d2e85893f84f8]::result::Result<(), rustc_span[b2dab8d5db9c06d4]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[3c5d2e85893f84f8]::result::Result<(), rustc_span[b2dab8d5db9c06d4]::ErrorGuaranteed>>::{closure#2} as core[3c5d2e85893f84f8]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  72:     0x7200b84878eb - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::haf6c6ed15ef7c4b2
                               at /rustc/dd104ef16315e2387fe94e8c43eb5a66e3dbd660/library/alloc/src/boxed.rs:2062:9
  73:     0x7200b84878eb - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h3648257e1237816c
                               at /rustc/dd104ef16315e2387fe94e8c43eb5a66e3dbd660/library/alloc/src/boxed.rs:2062:9
  74:     0x7200b84878eb - std::sys::pal::unix::thread::Thread::new::thread_start::h379e689399d87cbf
                               at /rustc/dd104ef16315e2387fe94e8c43eb5a66e3dbd660/library/std/src/sys/pal/unix/thread.rs:108:17
  75:     0x7200b18a6ded - <unknown>
  76:     0x7200b192a0dc - <unknown>
  77:                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: please make sure that you have updated to the latest nightly

note: rustc 1.81.0-nightly (dd104ef16 2024-06-18) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [codegen_select_candidate] computing candidate for `<&() as foo::Callable>`
#1 [resolve_instance] resolving instance `<&() as foo::Callable>::call`
end of query stack
error[E0207]: the type parameter `V` is not constrained by the impl trait, self type, or predicates
 --> /tmp/icemaker_global_tempdir.cfm68XSIYmML/rustc_testrunner_tmpdir_reporting.iKwq5UVXig7Z/mvce.rs:7:14
  |
7 |     impl<'a, V: ?Sized> Callable for &'a () {
  |              ^ unconstrained type parameter

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0207`.

@rustbot label +F-impl_trait_in_assoc_type +F-type_alias_impl_trait

[matthiaskrgr]

#121154 cc @oli-obk