ICE: asked to assemble auto trait candidates of unexpected type: FreshTy(0)

auto-reduced (treereduce-rust):

trait Project {
    const SELF: Self;
}

fn take1(_: Project<SELF = {}>) {}

original:

trait Project {
    const SELF: Self;
}

fn take1(_: Project<SELF = {
    let mut res = Vec::new();
    loop {
        match decode_packet(itr) {
            Some(p) => { res.push(p); },
            None    => break
        }
    }

    return res;
}>) {}

Version information

rustc 1.83.0-nightly (8c2c9a9ef 2024-09-15)
binary: rustc
commit-hash: 8c2c9a9ef527edb453bcee638d34beb0e7b4616b
commit-date: 2024-09-15
host: x86_64-unknown-linux-gnu
release: 1.83.0-nightly
LLVM version: 19.1.0

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

Program output

error[E0658]: associated const equality is incomplete
 --> /tmp/icemaker_global_tempdir.gI8qCq1Vuhv8/rustc_testrunner_tmpdir_reporting.wExSU1hbC7Cc/mvce.rs:5:21
  |
5 | fn take1(_: Project<SELF = {}>) {}
  |                     ^^^^^^^^^
  |
  = note: see issue #92827 <https://github.com/rust-lang/rust/issues/92827> for more information
  = help: add `#![feature(associated_const_equality)]` to the crate attributes to enable
  = note: this compiler was built on 2024-09-15; consider upgrading it if it is out of date

error[E0601]: `main` function not found in crate `mvce`
 --> /tmp/icemaker_global_tempdir.gI8qCq1Vuhv8/rustc_testrunner_tmpdir_reporting.wExSU1hbC7Cc/mvce.rs:5:35
  |
5 | fn take1(_: Project<SELF = {}>) {}
  |                                   ^ consider adding a `main` function to `/tmp/icemaker_global_tempdir.gI8qCq1Vuhv8/rustc_testrunner_tmpdir_reporting.wExSU1hbC7Cc/mvce.rs`

warning: trait objects without an explicit `dyn` are deprecated
 --> /tmp/icemaker_global_tempdir.gI8qCq1Vuhv8/rustc_testrunner_tmpdir_reporting.wExSU1hbC7Cc/mvce.rs:5:13
  |
5 | fn take1(_: Project<SELF = {}>) {}
  |             ^^^^^^^^^^^^^^^^^^
  |
  = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
  = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
  = note: `#[warn(bare_trait_objects)]` on by default
help: if this is an object-safe trait, use `dyn`
  |
5 | fn take1(_: dyn Project<SELF = {}>) {}
  |             +++

error[E0308]: mismatched types
 --> /tmp/icemaker_global_tempdir.gI8qCq1Vuhv8/rustc_testrunner_tmpdir_reporting.wExSU1hbC7Cc/mvce.rs:5:28
  |
5 | fn take1(_: Project<SELF = {}>) {}
  |                            ^^ expected fresh type, found `()`
  |
  = note:   expected type `FreshTy(0)`
          found unit type `()`

error: internal compiler error: compiler/rustc_infer/src/infer/relate/generalize.rs:464:17: unexpected infer type: FreshTy(0)

thread 'rustc' panicked at compiler/rustc_infer/src/infer/relate/generalize.rs:464:17:
Box<dyn Any>
stack backtrace:
   0:     0x7f8b8806c1da - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::hf576e3db34dcd4c0
   1:     0x7f8b88803297 - core::fmt::write::h6031a1fcd647db63
   2:     0x7f8b89710373 - std::io::Write::write_fmt::h9c4d18eebfa610c9
   3:     0x7f8b8806c032 - std::sys::backtrace::BacktraceLock::print::hd5d6f94195a58c57
   4:     0x7f8b8806e7b1 - std::panicking::default_hook::{{closure}}::he12b6c1c70a494ea
   5:     0x7f8b8806e5e4 - std::panicking::default_hook::h79139f377ef49e73
   6:     0x7f8b8717090f - std[1fc20c4bf4345a88]::panicking::update_hook::<alloc[31ea272c46cb0a00]::boxed::Box<rustc_driver_impl[bd499d3fdd772cd8]::install_ice_hook::{closure#0}>>::{closure#0}
   7:     0x7f8b8806eed8 - std::panicking::rust_panic_with_hook::hb2e822dcfa6f992d
   8:     0x7f8b871aa631 - std[1fc20c4bf4345a88]::panicking::begin_panic::<rustc_errors[22b46ce98bbdbfbc]::ExplicitBug>::{closure#0}
   9:     0x7f8b8719de46 - std[1fc20c4bf4345a88]::sys::backtrace::__rust_end_short_backtrace::<std[1fc20c4bf4345a88]::panicking::begin_panic<rustc_errors[22b46ce98bbdbfbc]::ExplicitBug>::{closure#0}, !>
  10:     0x7f8b87199389 - std[1fc20c4bf4345a88]::panicking::begin_panic::<rustc_errors[22b46ce98bbdbfbc]::ExplicitBug>
  11:     0x7f8b871b3951 - <rustc_errors[22b46ce98bbdbfbc]::diagnostic::BugAbort as rustc_errors[22b46ce98bbdbfbc]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
  12:     0x7f8b877d10e4 - rustc_middle[75f727fe079a4f22]::util::bug::opt_span_bug_fmt::<rustc_span[a0fd5433b72e73f5]::span_encoding::Span>::{closure#0}
  13:     0x7f8b877b6bda - rustc_middle[75f727fe079a4f22]::ty::context::tls::with_opt::<rustc_middle[75f727fe079a4f22]::util::bug::opt_span_bug_fmt<rustc_span[a0fd5433b72e73f5]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  14:     0x7f8b877b6a8b - rustc_middle[75f727fe079a4f22]::ty::context::tls::with_context_opt::<rustc_middle[75f727fe079a4f22]::ty::context::tls::with_opt<rustc_middle[75f727fe079a4f22]::util::bug::opt_span_bug_fmt<rustc_span[a0fd5433b72e73f5]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  15:     0x7f8b84d715c0 - rustc_middle[75f727fe079a4f22]::util::bug::bug_fmt
  16:     0x7f8b888e7f52 - <rustc_infer[6668340c28d2c56d]::infer::relate::generalize::Generalizer as rustc_type_ir[c12c9ed35f9c7001]::relate::TypeRelation<rustc_middle[75f727fe079a4f22]::ty::context::TyCtxt>>::tys::{closure#0}
  17:     0x7f8b888d7bdf - <rustc_infer[6668340c28d2c56d]::infer::relate::type_relating::TypeRelating as rustc_type_ir[c12c9ed35f9c7001]::relate::TypeRelation<rustc_middle[75f727fe079a4f22]::ty::context::TyCtxt>>::tys
  18:     0x7f8b888c7c92 - <rustc_hir_typeck[4fd6adf6e1b8df80]::fn_ctxt::FnCtxt>::coerce
  19:     0x7f8b88a30655 - rustc_hir_typeck[4fd6adf6e1b8df80]::typeck
  20:     0x7f8b88a2dd25 - rustc_query_impl[85a0e4e3d1ea5e51]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::typeck::dynamic_query::{closure#2}::{closure#0}, rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 8usize]>>
  21:     0x7f8b88c776bd - rustc_query_system[5ff4688cf420f9ff]::query::plumbing::try_execute_query::<rustc_query_impl[85a0e4e3d1ea5e51]::DynamicConfig<rustc_query_system[5ff4688cf420f9ff]::query::caches::VecCache<rustc_span[a0fd5433b72e73f5]::def_id::LocalDefId, rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[85a0e4e3d1ea5e51]::plumbing::QueryCtxt, false>
  22:     0x7f8b88c7628d - rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::typeck::get_query_non_incr::__rust_end_short_backtrace
  23:     0x7f8b890a433d - rustc_mir_build[a4d1425a7ec00b3f]::thir::pattern::check_match::check_match
  24:     0x7f8b890a3a63 - rustc_query_impl[85a0e4e3d1ea5e51]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::check_match::dynamic_query::{closure#2}::{closure#0}, rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 1usize]>>
  25:     0x7f8b890a31d8 - rustc_query_system[5ff4688cf420f9ff]::query::plumbing::try_execute_query::<rustc_query_impl[85a0e4e3d1ea5e51]::DynamicConfig<rustc_query_system[5ff4688cf420f9ff]::query::caches::VecCache<rustc_span[a0fd5433b72e73f5]::def_id::LocalDefId, rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[85a0e4e3d1ea5e51]::plumbing::QueryCtxt, false>
  26:     0x7f8b890a2e5d - rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::check_match::get_query_non_incr::__rust_end_short_backtrace
  27:     0x7f8b890b15d2 - rustc_mir_build[a4d1425a7ec00b3f]::build::mir_build
  28:     0x7f8b88806dd4 - rustc_mir_transform[24b7b05644591e31]::mir_built
  29:     0x7f8b88806d97 - rustc_query_impl[85a0e4e3d1ea5e51]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::mir_built::dynamic_query::{closure#2}::{closure#0}, rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 8usize]>>
  30:     0x7f8b88c776bd - rustc_query_system[5ff4688cf420f9ff]::query::plumbing::try_execute_query::<rustc_query_impl[85a0e4e3d1ea5e51]::DynamicConfig<rustc_query_system[5ff4688cf420f9ff]::query::caches::VecCache<rustc_span[a0fd5433b72e73f5]::def_id::LocalDefId, rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[85a0e4e3d1ea5e51]::plumbing::QueryCtxt, false>
  31:     0x7f8b88c771cd - rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::mir_built::get_query_non_incr::__rust_end_short_backtrace
  32:     0x7f8b89132f27 - rustc_mir_transform[24b7b05644591e31]::mir_const_qualif
  33:     0x7f8b89132e1b - rustc_query_impl[85a0e4e3d1ea5e51]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::mir_const_qualif::dynamic_query::{closure#2}::{closure#0}, rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 4usize]>>
  34:     0x7f8b8913220b - rustc_query_system[5ff4688cf420f9ff]::query::plumbing::try_execute_query::<rustc_query_impl[85a0e4e3d1ea5e51]::DynamicConfig<rustc_query_system[5ff4688cf420f9ff]::query::caches::DefIdCache<rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 4usize]>>, false, false, false>, rustc_query_impl[85a0e4e3d1ea5e51]::plumbing::QueryCtxt, false>
  35:     0x7f8b89131fa3 - rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::mir_const_qualif::get_query_non_incr::__rust_end_short_backtrace
  36:     0x7f8b85ccdc73 - rustc_mir_transform[24b7b05644591e31]::mir_promoted
  37:     0x7f8b88d30f92 - rustc_query_impl[85a0e4e3d1ea5e51]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::mir_promoted::dynamic_query::{closure#2}::{closure#0}, rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 16usize]>>
  38:     0x7f8b88d3125a - rustc_query_system[5ff4688cf420f9ff]::query::plumbing::try_execute_query::<rustc_query_impl[85a0e4e3d1ea5e51]::DynamicConfig<rustc_query_system[5ff4688cf420f9ff]::query::caches::VecCache<rustc_span[a0fd5433b72e73f5]::def_id::LocalDefId, rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 16usize]>>, false, false, false>, rustc_query_impl[85a0e4e3d1ea5e51]::plumbing::QueryCtxt, false>
  39:     0x7f8b89857190 - rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::mir_promoted::get_query_non_incr::__rust_end_short_backtrace
  40:     0x7f8b89857283 - rustc_query_impl[85a0e4e3d1ea5e51]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::mir_borrowck::dynamic_query::{closure#2}::{closure#0}, rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 8usize]>>
  41:     0x7f8b88c776bd - rustc_query_system[5ff4688cf420f9ff]::query::plumbing::try_execute_query::<rustc_query_impl[85a0e4e3d1ea5e51]::DynamicConfig<rustc_query_system[5ff4688cf420f9ff]::query::caches::VecCache<rustc_span[a0fd5433b72e73f5]::def_id::LocalDefId, rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[85a0e4e3d1ea5e51]::plumbing::QueryCtxt, false>
  42:     0x7f8b88c77113 - rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::mir_borrowck::get_query_non_incr::__rust_end_short_backtrace
  43:     0x7f8b88c7ff2d - rustc_mir_transform[24b7b05644591e31]::mir_drops_elaborated_and_const_checked
  44:     0x7f8b88c7f555 - rustc_query_impl[85a0e4e3d1ea5e51]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::mir_drops_elaborated_and_const_checked::dynamic_query::{closure#2}::{closure#0}, rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 8usize]>>
  45:     0x7f8b88c776bd - rustc_query_system[5ff4688cf420f9ff]::query::plumbing::try_execute_query::<rustc_query_impl[85a0e4e3d1ea5e51]::DynamicConfig<rustc_query_system[5ff4688cf420f9ff]::query::caches::VecCache<rustc_span[a0fd5433b72e73f5]::def_id::LocalDefId, rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[85a0e4e3d1ea5e51]::plumbing::QueryCtxt, false>
  46:     0x7f8b88c77065 - rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::mir_drops_elaborated_and_const_checked::get_query_non_incr::__rust_end_short_backtrace
  47:     0x7f8b891477b9 - rustc_mir_transform[24b7b05644591e31]::mir_for_ctfe
  48:     0x7f8b89147679 - rustc_query_impl[85a0e4e3d1ea5e51]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::mir_for_ctfe::dynamic_query::{closure#2}::{closure#0}, rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 8usize]>>
  49:     0x7f8b8882f8ae - rustc_query_system[5ff4688cf420f9ff]::query::plumbing::try_execute_query::<rustc_query_impl[85a0e4e3d1ea5e51]::DynamicConfig<rustc_query_system[5ff4688cf420f9ff]::query::caches::DefIdCache<rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[85a0e4e3d1ea5e51]::plumbing::QueryCtxt, false>
  50:     0x7f8b88fe75af - rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::mir_for_ctfe::get_query_non_incr::__rust_end_short_backtrace
  51:     0x7f8b88fe76f0 - <rustc_const_eval[f76452ba52d780f5]::interpret::eval_context::InterpCx<rustc_const_eval[f76452ba52d780f5]::const_eval::machine::CompileTimeMachine>>::load_mir
  52:     0x7f8b862184f2 - rustc_const_eval[f76452ba52d780f5]::const_eval::eval_queries::eval_to_allocation_raw_provider
  53:     0x7f8b88fe8e76 - rustc_query_impl[85a0e4e3d1ea5e51]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::eval_to_allocation_raw::dynamic_query::{closure#2}::{closure#0}, rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 24usize]>>
  54:     0x7f8b88fe8692 - rustc_query_system[5ff4688cf420f9ff]::query::plumbing::try_execute_query::<rustc_query_impl[85a0e4e3d1ea5e51]::DynamicConfig<rustc_query_system[5ff4688cf420f9ff]::query::caches::DefaultCache<rustc_middle[75f727fe079a4f22]::ty::ParamEnvAnd<rustc_middle[75f727fe079a4f22]::mir::interpret::GlobalId>, rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 24usize]>>, false, false, false>, rustc_query_impl[85a0e4e3d1ea5e51]::plumbing::QueryCtxt, false>
  55:     0x7f8b88fe826f - rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::eval_to_allocation_raw::get_query_non_incr::__rust_end_short_backtrace
  56:     0x7f8b88fdaeaf - rustc_const_eval[f76452ba52d780f5]::const_eval::valtrees::eval_to_valtree
  57:     0x7f8b88fdacc3 - <rustc_const_eval[f76452ba52d780f5]::provide::{closure#0} as core[72d89f67a2ed16cb]::ops::function::FnOnce<(rustc_middle[75f727fe079a4f22]::ty::context::TyCtxt, rustc_middle[75f727fe079a4f22]::ty::ParamEnvAnd<rustc_middle[75f727fe079a4f22]::mir::interpret::GlobalId>)>>::call_once
  58:     0x7f8b88fdac7a - rustc_query_impl[85a0e4e3d1ea5e51]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::eval_to_valtree::dynamic_query::{closure#2}::{closure#0}, rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 24usize]>>
  59:     0x7f8b88fdac3b - <rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::eval_to_valtree::dynamic_query::{closure#2} as core[72d89f67a2ed16cb]::ops::function::FnOnce<(rustc_middle[75f727fe079a4f22]::ty::context::TyCtxt, rustc_middle[75f727fe079a4f22]::ty::ParamEnvAnd<rustc_middle[75f727fe079a4f22]::mir::interpret::GlobalId>)>>::call_once
  60:     0x7f8b88fe876d - rustc_query_system[5ff4688cf420f9ff]::query::plumbing::try_execute_query::<rustc_query_impl[85a0e4e3d1ea5e51]::DynamicConfig<rustc_query_system[5ff4688cf420f9ff]::query::caches::DefaultCache<rustc_middle[75f727fe079a4f22]::ty::ParamEnvAnd<rustc_middle[75f727fe079a4f22]::mir::interpret::GlobalId>, rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 24usize]>>, false, false, false>, rustc_query_impl[85a0e4e3d1ea5e51]::plumbing::QueryCtxt, false>
  61:     0x7f8b88fe808a - rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::eval_to_valtree::get_query_non_incr::__rust_end_short_backtrace
  62:     0x7f8b891d21c2 - rustc_middle[75f727fe079a4f22]::query::plumbing::query_get_at::<rustc_query_system[5ff4688cf420f9ff]::query::caches::DefaultCache<rustc_middle[75f727fe079a4f22]::ty::ParamEnvAnd<rustc_middle[75f727fe079a4f22]::mir::interpret::GlobalId>, rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 24usize]>>>
  63:     0x7f8b891d1c28 - <rustc_middle[75f727fe079a4f22]::ty::context::TyCtxt>::const_eval_global_id_for_typeck
  64:     0x7f8b891d0bbe - <rustc_middle[75f727fe079a4f22]::ty::context::TyCtxt>::const_eval_resolve_for_typeck
  65:     0x7f8b891d084a - <rustc_middle[75f727fe079a4f22]::ty::consts::Const>::eval
  66:     0x7f8b891d033c - <rustc_trait_selection[fd550b6f72b0e0c6]::traits::normalize::AssocTypeNormalizer as rustc_type_ir[c12c9ed35f9c7001]::fold::TypeFolder<rustc_middle[75f727fe079a4f22]::ty::context::TyCtxt>>::fold_const
  67:     0x7f8b87e117f3 - <rustc_middle[75f727fe079a4f22]::ty::Term as rustc_type_ir[c12c9ed35f9c7001]::fold::TypeFoldable<rustc_middle[75f727fe079a4f22]::ty::context::TyCtxt>>::try_fold_with::<rustc_trait_selection[fd550b6f72b0e0c6]::traits::normalize::AssocTypeNormalizer>
  68:     0x7f8b87f06468 - <rustc_trait_selection[fd550b6f72b0e0c6]::traits::normalize::AssocTypeNormalizer as rustc_type_ir[c12c9ed35f9c7001]::fold::TypeFolder<rustc_middle[75f727fe079a4f22]::ty::context::TyCtxt>>::fold_binder::<rustc_type_ir[c12c9ed35f9c7001]::predicate::ExistentialPredicate<rustc_middle[75f727fe079a4f22]::ty::context::TyCtxt>>
  69:     0x7f8b88fb7a17 - <rustc_middle[75f727fe079a4f22]::ty::Ty as rustc_type_ir[c12c9ed35f9c7001]::fold::TypeSuperFoldable<rustc_middle[75f727fe079a4f22]::ty::context::TyCtxt>>::try_super_fold_with::<rustc_trait_selection[fd550b6f72b0e0c6]::traits::normalize::AssocTypeNormalizer>
  70:     0x7f8b88e5d2b9 - <rustc_hir_analysis[f9d0127424903d94]::check::wfcheck::WfCheckingCtxt>::normalize::<rustc_middle[75f727fe079a4f22]::ty::Ty>
  71:     0x7f8b88e5bd60 - rustc_hir_analysis[f9d0127424903d94]::check::wfcheck::check_fn_or_method
  72:     0x7f8b88e5e2f5 - rustc_hir_analysis[f9d0127424903d94]::check::wfcheck::check_item_fn
  73:     0x7f8b85f37f61 - rustc_hir_analysis[f9d0127424903d94]::check::wfcheck::check_well_formed
  74:     0x7f8b88d1a3c7 - rustc_query_impl[85a0e4e3d1ea5e51]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 1usize]>>
  75:     0x7f8b88d1a63e - rustc_query_system[5ff4688cf420f9ff]::query::plumbing::try_execute_query::<rustc_query_impl[85a0e4e3d1ea5e51]::DynamicConfig<rustc_query_system[5ff4688cf420f9ff]::query::caches::VecCache<rustc_hir[bda7baf23f46ef3e]::hir_id::OwnerId, rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[85a0e4e3d1ea5e51]::plumbing::QueryCtxt, false>
  76:     0x7f8b88d1a3a2 - rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::check_well_formed::get_query_non_incr::__rust_end_short_backtrace
  77:     0x7f8b88d1b153 - rustc_hir_analysis[f9d0127424903d94]::check::wfcheck::check_mod_type_wf
  78:     0x7f8b88d1af91 - rustc_query_impl[85a0e4e3d1ea5e51]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::check_mod_type_wf::dynamic_query::{closure#2}::{closure#0}, rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 1usize]>>
  79:     0x7f8b896aa5bb - rustc_query_system[5ff4688cf420f9ff]::query::plumbing::try_execute_query::<rustc_query_impl[85a0e4e3d1ea5e51]::DynamicConfig<rustc_query_system[5ff4688cf420f9ff]::query::caches::DefaultCache<rustc_span[a0fd5433b72e73f5]::def_id::LocalModDefId, rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[85a0e4e3d1ea5e51]::plumbing::QueryCtxt, false>
  80:     0x7f8b896aa36d - rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::check_mod_type_wf::get_query_non_incr::__rust_end_short_backtrace
  81:     0x7f8b88c73a49 - rustc_hir_analysis[f9d0127424903d94]::check_crate
  82:     0x7f8b88c70705 - rustc_interface[21c67170a9071fc5]::passes::run_required_analyses
  83:     0x7f8b895166de - rustc_interface[21c67170a9071fc5]::passes::analysis
  84:     0x7f8b895166b1 - rustc_query_impl[85a0e4e3d1ea5e51]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 1usize]>>
  85:     0x7f8b896ae22e - rustc_query_system[5ff4688cf420f9ff]::query::plumbing::try_execute_query::<rustc_query_impl[85a0e4e3d1ea5e51]::DynamicConfig<rustc_query_system[5ff4688cf420f9ff]::query::caches::SingleCache<rustc_middle[75f727fe079a4f22]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[85a0e4e3d1ea5e51]::plumbing::QueryCtxt, false>
  86:     0x7f8b896adf8f - rustc_query_impl[85a0e4e3d1ea5e51]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  87:     0x7f8b89500bbc - rustc_interface[21c67170a9071fc5]::interface::run_compiler::<core[72d89f67a2ed16cb]::result::Result<(), rustc_span[a0fd5433b72e73f5]::ErrorGuaranteed>, rustc_driver_impl[bd499d3fdd772cd8]::run_compiler::{closure#0}>::{closure#1}
  88:     0x7f8b895c8850 - std[1fc20c4bf4345a88]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[21c67170a9071fc5]::util::run_in_thread_with_globals<rustc_interface[21c67170a9071fc5]::util::run_in_thread_pool_with_globals<rustc_interface[21c67170a9071fc5]::interface::run_compiler<core[72d89f67a2ed16cb]::result::Result<(), rustc_span[a0fd5433b72e73f5]::ErrorGuaranteed>, rustc_driver_impl[bd499d3fdd772cd8]::run_compiler::{closure#0}>::{closure#1}, core[72d89f67a2ed16cb]::result::Result<(), rustc_span[a0fd5433b72e73f5]::ErrorGuaranteed>>::{closure#0}, core[72d89f67a2ed16cb]::result::Result<(), rustc_span[a0fd5433b72e73f5]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[72d89f67a2ed16cb]::result::Result<(), rustc_span[a0fd5433b72e73f5]::ErrorGuaranteed>>
  89:     0x7f8b895c8eba - <<std[1fc20c4bf4345a88]::thread::Builder>::spawn_unchecked_<rustc_interface[21c67170a9071fc5]::util::run_in_thread_with_globals<rustc_interface[21c67170a9071fc5]::util::run_in_thread_pool_with_globals<rustc_interface[21c67170a9071fc5]::interface::run_compiler<core[72d89f67a2ed16cb]::result::Result<(), rustc_span[a0fd5433b72e73f5]::ErrorGuaranteed>, rustc_driver_impl[bd499d3fdd772cd8]::run_compiler::{closure#0}>::{closure#1}, core[72d89f67a2ed16cb]::result::Result<(), rustc_span[a0fd5433b72e73f5]::ErrorGuaranteed>>::{closure#0}, core[72d89f67a2ed16cb]::result::Result<(), rustc_span[a0fd5433b72e73f5]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[72d89f67a2ed16cb]::result::Result<(), rustc_span[a0fd5433b72e73f5]::ErrorGuaranteed>>::{closure#1} as core[72d89f67a2ed16cb]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  90:     0x7f8b895c92ab - std::sys::pal::unix::thread::Thread::new::thread_start::hfd4e0f9214174c65
  91:     0x7f8b8ad4739d - <unknown>
  92:     0x7f8b8adcc49c - <unknown>
  93:                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: please make sure that you have updated to the latest nightly

note: rustc 1.83.0-nightly (8c2c9a9ef 2024-09-15) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [typeck] type-checking `take1::{constant#0}`
#1 [check_match] match-checking `take1::{constant#0}`
end of query stack
error: aborting due to 4 previous errors; 1 warning emitted

Some errors have detailed explanations: E0308, E0601, E0658.
For more information about an error, try `rustc --explain E0308`.

Regression in nightly-2024-03-12
commit[0] 2024-03-10: Auto merge of #122306 - workingjubilee:backtrace-0.3.70, r=workingjubilee
commit[1] 2024-03-10: Auto merge of #122312 - matthiaskrgr:rollup-0p8y7gg, r=matthiaskrgr
commit[2] 2024-03-11: Auto merge of #122132 - nnethercote:diag-renaming3, r=nnethercote
commit[3] 2024-03-11: Auto merge of #121752 - mu001999:dead_code/improve, r=pnkfelix
commit[4] 2024-03-11: Auto merge of #122050 - erikdesjardins:sret, r=nikic
commit[5] 2024-03-11: Auto merge of #117156 - jmillikin:os-unix-socket-ext, r=Amanieu,dtolnay
commit[6] 2024-03-11: Auto merge of #122331 - jhpratt:rollup-cbl8xsy, r=jhpratt
commit[7] 2024-03-11: Auto merge of #122305 - Nilstrieb:target-tiers, r=davidtwco
commit[8] 2024-03-11: Auto merge of #122140 - oli-obk:track_errors13, r=davidtwco
commit[9] 2024-03-11: Auto merge of #122338 - workingjubilee:rollup-xzpt4v4, r=workingjubilee
commit[10] 2024-03-11: Auto merge of #121796 - oli-obk:eager_opaque_checks3, r=lcnr
commit[11] 2024-03-11: Auto merge of #112267 - lqd:win-1cgu, r=Kobzol

cc #123456, #123140, #125957 (all different symptoms, same root cause)

When I compile the auto-reduced sample code with:

% rustc -v -V
rustc 1.94.0 (4a4ef49 2026-03-02)
binary: rustc
commit-hash: 4a4ef49
commit-date: 2026-03-02
host: aarch64-apple-darwin
release: 1.94.0
LLVM version: 21.1.8

I get the following output:

% rustc src/main.rs 
error[E0658]: associated const equality is incomplete
 --> src/main.rs:5:21
  |
5 | fn take1(_: Project<SELF = {}>) {}
  |                     ^^^^^^^^^
  |
  = note: see issue #132980 <https://github.com/rust-lang/rust/issues/132980> for more information

warning: trait objects without an explicit `dyn` are deprecated
 --> src/main.rs:5:13
  |
5 | fn take1(_: Project<SELF = {}>) {}
  |             ^^^^^^^^^^^^^^^^^^
  |
  = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
  = note: for more information, see <https://doc.rust-lang.org/edition-guide/rust-2021/warnings-promoted-to-error.html>
  = note: `#[warn(bare_trait_objects)]` (part of `#[warn(rust_2021_compatibility)]`) on by default
help: if this is a dyn-compatible trait, use `dyn`
  |
5 | fn take1(_: dyn Project<SELF = {}>) {}
  |             +++

error[E0038]: the trait `Project` is not dyn compatible
 --> src/main.rs:5:13
  |
5 | fn take1(_: Project<SELF = {}>) {}
  |             ^^^^^^^^^^^^^^^^^^ `Project` is not dyn compatible
  |
note: for a trait to be dyn compatible it needs to allow building a vtable
      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
 --> src/main.rs:2:11
  |
1 | trait Project {
  |       ------- this trait is not dyn compatible...
2 |     const SELF: Self;
  |           ^^^^ ...because it contains this associated `const`
  = help: consider moving `SELF` to another trait

error[E0277]: the size for values of type `(dyn Project + 'static)` cannot be known at compilation time
 --> src/main.rs:5:13
  |
5 | fn take1(_: Project<SELF = {}>) {}
  |             ^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
  |
  = help: the trait `Sized` is not implemented for `(dyn Project + 'static)`
help: you can use `impl Trait` as the argument type
  |
5 | fn take1(_: impl Project<SELF = {}>) {}
  |             ++++
help: function arguments must have a statically known size, borrowed types always have a known size
  |
5 | fn take1(_: &dyn Project<SELF = {}>) {}
  |             ++++

error[E0308]: mismatched types
 --> src/main.rs:5:28
  |
5 | fn take1(_: Project<SELF = {}>) {}
  |                            ^^ expected fresh type, found `()`
  |
  = note:   expected type `FreshTy(0)`
          found unit type `()`

error: internal compiler error: /rustc-dev/4a4ef493e3a1488c6e321570238084b38948f6db/compiler/rustc_infer/src/infer/relate/generalize.rs:501:17: unexpected infer type: FreshTy(0)


thread 'rustc' (102846) panicked at /rustc-dev/4a4ef493e3a1488c6e321570238084b38948f6db/compiler/rustc_infer/src/infer/relate/generalize.rs:501:17:
Box<dyn Any>
stack backtrace:
   0:        0x1111a7634 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::hcde33371d8bba08b
   1:        0x10e3f81fc - core::fmt::write::h8a52dffc4df6d016
   2:        0x111161260 - std::io::Write::write_fmt::h2fd0abc6933d662d
   3:        0x111179ea4 - std::panicking::default_hook::{{closure}}::h1af7615be47c43ab
   4:        0x111179dac - std::panicking::default_hook::hdcc779fdbf67ae29
   5:        0x10f043378 - std[b190ad38c85ed59a]::panicking::update_hook::<alloc[cec09d4d3689febe]::boxed::Box<rustc_driver_impl[185e3967a9919f9d]::install_ice_hook::{closure#1}>>::{closure#0}
   6:        0x11117a2d0 - std::panicking::panic_with_hook::h455d3ea9bab4bcbd
   7:        0x10f0c7588 - std[b190ad38c85ed59a]::panicking::begin_panic::<rustc_errors[95ffe445a7b7fe12]::ExplicitBug>::{closure#0}
   8:        0x10f0b0ef0 - std[b190ad38c85ed59a]::sys::backtrace::__rust_end_short_backtrace::<std[b190ad38c85ed59a]::panicking::begin_panic<rustc_errors[95ffe445a7b7fe12]::ExplicitBug>::{closure#0}, !>
   9:        0x113f498f4 - std[b190ad38c85ed59a]::panicking::begin_panic::<rustc_errors[95ffe445a7b7fe12]::ExplicitBug>
  10:        0x113f4a438 - <rustc_errors[95ffe445a7b7fe12]::diagnostic::BugAbort as rustc_errors[95ffe445a7b7fe12]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
  11:        0x113fb8d10 - rustc_middle[1dd1fc2248f63b22]::util::bug::opt_span_bug_fmt::<rustc_span[40bc6320bb32000f]::span_encoding::Span>::{closure#0}
  12:        0x10fd23714 - rustc_middle[1dd1fc2248f63b22]::ty::context::tls::with_opt::<rustc_middle[1dd1fc2248f63b22]::util::bug::opt_span_bug_fmt<rustc_span[40bc6320bb32000f]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  13:        0x10fcfc71c - rustc_middle[1dd1fc2248f63b22]::ty::context::tls::with_context_opt::<rustc_middle[1dd1fc2248f63b22]::ty::context::tls::with_opt<rustc_middle[1dd1fc2248f63b22]::util::bug::opt_span_bug_fmt<rustc_span[40bc6320bb32000f]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  14:        0x113fbcf00 - rustc_middle[1dd1fc2248f63b22]::util::bug::bug_fmt
  15:        0x10f8bdc9c - <rustc_infer[6c4201f777a84977]::infer::relate::generalize::Generalizer as rustc_type_ir[2c11913eb1716827]::relate::TypeRelation<rustc_middle[1dd1fc2248f63b22]::ty::context::TyCtxt>>::tys::{closure#0}
  16:        0x10f86eed4 - <rustc_infer[6c4201f777a84977]::infer::InferCtxt>::generalize::<rustc_middle[1dd1fc2248f63b22]::ty::Ty, rustc_type_ir[2c11913eb1716827]::ty_kind::TyVid>
  17:        0x10f86f228 - <rustc_infer[6c4201f777a84977]::infer::InferCtxt>::instantiate_ty_var::<rustc_infer[6c4201f777a84977]::infer::relate::type_relating::TypeRelating>
  18:        0x10f8f1c10 - <rustc_infer[6c4201f777a84977]::infer::relate::type_relating::TypeRelating as rustc_type_ir[2c11913eb1716827]::relate::TypeRelation<rustc_middle[1dd1fc2248f63b22]::ty::context::TyCtxt>>::tys
  19:        0x10f55212c - <rustc_infer[6c4201f777a84977]::infer::at::At>::sup::<rustc_middle[1dd1fc2248f63b22]::ty::Ty>
  20:        0x10f729818 - <rustc_hir_typeck[61143b3384822dff]::coercion::Coerce>::unify_raw
  21:        0x10f544ce4 - <rustc_hir_typeck[61143b3384822dff]::coercion::Coerce>::unify_and::<core[a936a58af82ee723]::iter::adapters::flatten::FlatMap<core[a936a58af82ee723]::option::IntoIter<(rustc_middle[1dd1fc2248f63b22]::ty::adjustment::Adjustment, rustc_middle[1dd1fc2248f63b22]::ty::adjustment::Adjustment)>, [rustc_middle[1dd1fc2248f63b22]::ty::adjustment::Adjustment; 2usize], <rustc_hir_typeck[61143b3384822dff]::coercion::Coerce>::coerce_unsized::{closure#1}>>
  22:        0x10f728fa0 - <rustc_hir_typeck[61143b3384822dff]::coercion::Coerce>::coerce
  23:        0x10f6d8794 - <rustc_hir_typeck[61143b3384822dff]::fn_ctxt::FnCtxt>::coerce
  24:        0x10f669ad0 - <rustc_hir_typeck[61143b3384822dff]::fn_ctxt::FnCtxt>::demand_coerce_diag
  25:        0x10f61e4e8 - rustc_hir_typeck[61143b3384822dff]::typeck_with_inspect::{closure#0}
  26:        0x10f6377bc - rustc_hir_typeck[61143b3384822dff]::typeck
  27:        0x1105e2e00 - rustc_query_impl[def6bb11db1f9526]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[def6bb11db1f9526]::query_impl::typeck::dynamic_query::{closure#2}::{closure#0}, rustc_middle[1dd1fc2248f63b22]::query::erase::Erased<[u8; 8usize]>>
  28:        0x1106663c8 - rustc_query_system[23a19f823f15ce6c]::query::plumbing::try_execute_query::<rustc_query_impl[def6bb11db1f9526]::DynamicConfig<rustc_data_structures[fafc8b92dea7f144]::vec_cache::VecCache<rustc_hir_id[5eec3bb7a05ee6b5]::OwnerId, rustc_middle[1dd1fc2248f63b22]::query::erase::Erased<[u8; 8usize]>, rustc_query_system[23a19f823f15ce6c]::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl[def6bb11db1f9526]::plumbing::QueryCtxt, false>
  29:        0x1107698a0 - rustc_query_impl[def6bb11db1f9526]::query_impl::typeck::get_query_non_incr::__rust_end_short_backtrace
  30:        0x10f6361c8 - rustc_hir_typeck[61143b3384822dff]::used_trait_imports
  31:        0x1105dfa18 - rustc_query_impl[def6bb11db1f9526]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[def6bb11db1f9526]::query_impl::used_trait_imports::dynamic_query::{closure#2}::{closure#0}, rustc_middle[1dd1fc2248f63b22]::query::erase::Erased<[u8; 8usize]>>
  32:        0x1106663c8 - rustc_query_system[23a19f823f15ce6c]::query::plumbing::try_execute_query::<rustc_query_impl[def6bb11db1f9526]::DynamicConfig<rustc_data_structures[fafc8b92dea7f144]::vec_cache::VecCache<rustc_hir_id[5eec3bb7a05ee6b5]::OwnerId, rustc_middle[1dd1fc2248f63b22]::query::erase::Erased<[u8; 8usize]>, rustc_query_system[23a19f823f15ce6c]::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl[def6bb11db1f9526]::plumbing::QueryCtxt, false>
  33:        0x11074c144 - rustc_query_impl[def6bb11db1f9526]::query_impl::used_trait_imports::get_query_non_incr::__rust_end_short_backtrace
  34:        0x10f3af14c - rustc_hir_analysis[7f434dfda0d33b75]::check_unused::check_unused_traits
  35:        0x1105dfb40 - rustc_query_impl[def6bb11db1f9526]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[def6bb11db1f9526]::query_impl::check_unused_traits::dynamic_query::{closure#2}::{closure#0}, rustc_middle[1dd1fc2248f63b22]::query::erase::Erased<[u8; 0usize]>>
  36:        0x1105fba64 - rustc_query_system[23a19f823f15ce6c]::query::plumbing::try_execute_query::<rustc_query_impl[def6bb11db1f9526]::DynamicConfig<rustc_query_system[23a19f823f15ce6c]::query::caches::SingleCache<rustc_middle[1dd1fc2248f63b22]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[def6bb11db1f9526]::plumbing::QueryCtxt, false>
  37:        0x11074cc10 - rustc_query_impl[def6bb11db1f9526]::query_impl::check_unused_traits::get_query_non_incr::__rust_end_short_backtrace
  38:        0x10f3553e8 - rustc_hir_analysis[7f434dfda0d33b75]::check_crate
  39:        0x10f9b3ed0 - rustc_interface[8731d2cac67c9b74]::passes::analysis
  40:        0x1105e2e98 - rustc_query_impl[def6bb11db1f9526]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[def6bb11db1f9526]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[1dd1fc2248f63b22]::query::erase::Erased<[u8; 0usize]>>
  41:        0x1105fba64 - rustc_query_system[23a19f823f15ce6c]::query::plumbing::try_execute_query::<rustc_query_impl[def6bb11db1f9526]::DynamicConfig<rustc_query_system[23a19f823f15ce6c]::query::caches::SingleCache<rustc_middle[1dd1fc2248f63b22]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[def6bb11db1f9526]::plumbing::QueryCtxt, false>
  42:        0x11076a3b8 - rustc_query_impl[def6bb11db1f9526]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  43:        0x10eff6b40 - rustc_interface[8731d2cac67c9b74]::passes::create_and_enter_global_ctxt::<core[a936a58af82ee723]::option::Option<rustc_interface[8731d2cac67c9b74]::queries::Linker>, rustc_driver_impl[185e3967a9919f9d]::run_compiler::{closure#0}::{closure#2}>
  44:        0x10f041a9c - rustc_interface[8731d2cac67c9b74]::interface::run_compiler::<(), rustc_driver_impl[185e3967a9919f9d]::run_compiler::{closure#0}>::{closure#1}
  45:        0x10f037d9c - std[b190ad38c85ed59a]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[8731d2cac67c9b74]::util::run_in_thread_with_globals<rustc_interface[8731d2cac67c9b74]::util::run_in_thread_pool_with_globals<rustc_interface[8731d2cac67c9b74]::interface::run_compiler<(), rustc_driver_impl[185e3967a9919f9d]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  46:        0x10f048ff4 - <std[b190ad38c85ed59a]::thread::lifecycle::spawn_unchecked<rustc_interface[8731d2cac67c9b74]::util::run_in_thread_with_globals<rustc_interface[8731d2cac67c9b74]::util::run_in_thread_pool_with_globals<rustc_interface[8731d2cac67c9b74]::interface::run_compiler<(), rustc_driver_impl[185e3967a9919f9d]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[a936a58af82ee723]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  47:        0x111170530 - std::sys::thread::unix::Thread::new::thread_start::hb5c7d2a38fab9e31
  48:        0x18cb17c08 - __pthread_cond_wait

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 1.94.0 (4a4ef493e 2026-03-02) running on aarch64-apple-darwin

query stack during panic:
#0 [typeck] type-checking `take1::{constant#0}`
#1 [used_trait_imports] finding used_trait_imports `take1::{constant#0}`
... and 2 other queries... use `env RUST_BACKTRACE=1` to see the full query stack
error: aborting due to 5 previous errors; 1 warning emitted

Noting that this is using rust edition 2015, I tried compiling with the latest edition 2024, which produced:

rustc --edition=2024 src/main.rs
error[E0658]: associated const equality is incomplete
 --> src/main.rs:5:21
  |
5 | fn take1(_: Project<SELF = {}>) {}
  |                     ^^^^^^^^^
  |
  = note: see issue #132980 <https://github.com/rust-lang/rust/issues/132980> for more information

error[E0782]: expected a type, found a trait
 --> src/main.rs:5:13
  |
5 | fn take1(_: Project<SELF = {}>) {}
  |             ^^^^^^^^^^^^^^^^^^
  |
  = note: `Project<SELF = {}>` is dyn-incompatible, otherwise a trait object could be used
help: use a new generic type parameter, constrained by `Project<SELF = {}>`
  |
5 - fn take1(_: Project<SELF = {}>) {}
5 + fn take1<T: Project<SELF = {}>>(_: T) {}
  |
help: you can also use an opaque type, but users won't be able to specify the type parameter when calling the `fn`, having to rely exclusively on type inference
  |
5 | fn take1(_: impl Project<SELF = {}>) {}
  |             ++++

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0658, E0782.
For more information about an error, try `rustc --explain E0658`.

Which does not panic, neither does 2021 but 2018 does.

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ICE: `asked to assemble auto trait candidates of unexpected type: FreshTy(0)` #130411

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ICE: asked to assemble auto trait candidates of unexpected type: FreshTy(0) #130411

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matthiaskrgr commented on Sep 15, 2024

fmease commented on Sep 15, 2024

RodBurman commented on Mar 18, 2026

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ICE: `asked to assemble auto trait candidates of unexpected type: FreshTy(0)` #130411