error[E0658]: trait aliases are experimental --> /tmp/icemaker_global_tempdir.9RJGbLHtZS3f/rustc_testrunner_tmpdir_reporting.K3JbY4FM9GbA/mvce.rs:1:1 | 1 | trait F = Fn() -> Self; | ^^^^^^^^^^^^^^^^^^^^^^^ | = note: see issue #41517 <https://github.com/rust-lang/rust/issues/41517> for more information = help: add `#![feature(trait_alias)]` to the crate attributes to enable = note: this compiler was built on 2025-03-24; consider upgrading it if it is out of date error[E0601]: `main` function not found in crate `mvce` --> /tmp/icemaker_global_tempdir.9RJGbLHtZS3f/rustc_testrunner_tmpdir_reporting.K3JbY4FM9GbA/mvce.rs:3:30 | 3 | fn _f3<Fut>(a: dyn F<Fut>) {} | ^ consider adding a `main` function to `/tmp/icemaker_global_tempdir.9RJGbLHtZS3f/rustc_testrunner_tmpdir_reporting.K3JbY4FM9GbA/mvce.rs` error[E0107]: trait alias takes 0 generic arguments but 1 generic argument was supplied --> /tmp/icemaker_global_tempdir.9RJGbLHtZS3f/rustc_testrunner_tmpdir_reporting.K3JbY4FM9GbA/mvce.rs:3:20 | 3 | fn _f3<Fut>(a: dyn F<Fut>) {} | ^----- help: remove the unnecessary generics | | | expected 0 generic arguments | note: trait alias defined here, with 0 generic parameters --> /tmp/icemaker_global_tempdir.9RJGbLHtZS3f/rustc_testrunner_tmpdir_reporting.K3JbY4FM9GbA/mvce.rs:1:7 | 1 | trait F = Fn() -> Self; | ^ error: internal compiler error: compiler/rustc_infer/src/infer/canonical/canonicalizer.rs:404:17: encountered a fresh type during canonicalization thread 'rustc' panicked at compiler/rustc_infer/src/infer/canonical/canonicalizer.rs:404:17: Box<dyn Any> stack backtrace: 0: 0x7cb472c372f3 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h2760fe8863421f5c 1: 0x7cb473405b11 - core::fmt::write::h3dac15c2c2ecb533 2: 0x7cb4747adcd1 - std::io::Write::write_fmt::h075eef10e49b35aa 3: 0x7cb472c37152 - std::sys::backtrace::BacktraceLock::print::hfd69c92aba7c12c8 4: 0x7cb472c39a0a - std::panicking::default_hook::{{closure}}::h08503484e559a2f9 5: 0x7cb472c3958f - std::panicking::default_hook::h141fa4f2c715ef5e 6: 0x7cb471cb0250 - std[89bc5ccdd7126a22]::panicking::update_hook::<alloc[285974f900039e31]::boxed::Box<rustc_driver_impl[bd7fc35b05314b57]::install_ice_hook::{closure#1}>>::{closure#0} 7: 0x7cb472c3a283 - std::panicking::rust_panic_with_hook::h226a3fc30a0b89e9 8: 0x7cb471cedb71 - std[89bc5ccdd7126a22]::panicking::begin_panic::<rustc_errors[533322d0018a48b8]::ExplicitBug>::{closure#0} 9: 0x7cb471ce1d36 - std[89bc5ccdd7126a22]::sys::backtrace::__rust_end_short_backtrace::<std[89bc5ccdd7126a22]::panicking::begin_panic<rustc_errors[533322d0018a48b8]::ExplicitBug>::{closure#0}, !> 10: 0x7cb471cde88b - std[89bc5ccdd7126a22]::panicking::begin_panic::<rustc_errors[533322d0018a48b8]::ExplicitBug> 11: 0x7cb471cf7411 - <rustc_errors[533322d0018a48b8]::diagnostic::BugAbort as rustc_errors[533322d0018a48b8]::diagnostic::EmissionGuarantee>::emit_producing_guarantee 12: 0x7cb47232ecaa - rustc_middle[a1c7959211e9dd4e]::util::bug::opt_span_bug_fmt::<rustc_span[6d7120c72a98845f]::span_encoding::Span>::{closure#0} 13: 0x7cb47230a67a - rustc_middle[a1c7959211e9dd4e]::ty::context::tls::with_opt::<rustc_middle[a1c7959211e9dd4e]::util::bug::opt_span_bug_fmt<rustc_span[6d7120c72a98845f]::span_encoding::Span>::{closure#0}, !>::{closure#0} 14: 0x7cb47230a4eb - rustc_middle[a1c7959211e9dd4e]::ty::context::tls::with_context_opt::<rustc_middle[a1c7959211e9dd4e]::ty::context::tls::with_opt<rustc_middle[a1c7959211e9dd4e]::util::bug::opt_span_bug_fmt<rustc_span[6d7120c72a98845f]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !> 15: 0x7cb4702fbde0 - rustc_middle[a1c7959211e9dd4e]::util::bug::bug_fmt 16: 0x7cb473c78e90 - <rustc_infer[a2306f7a6093687f]::infer::canonical::canonicalizer::Canonicalizer as rustc_type_ir[e2203e1e22965ec]::fold::TypeFolder<rustc_middle[a1c7959211e9dd4e]::ty::context::TyCtxt>>::fold_ty 17: 0x7cb473c75bbf - <rustc_infer[a2306f7a6093687f]::infer::canonical::canonicalizer::Canonicalizer as rustc_type_ir[e2203e1e22965ec]::fold::TypeFolder<rustc_middle[a1c7959211e9dd4e]::ty::context::TyCtxt>>::fold_ty 18: 0x7cb474701fd7 - rustc_trait_selection[44c579af88ade2df]::traits::outlives_bounds::implied_outlives_bounds 19: 0x7cb473aab842 - <rustc_infer[a2306f7a6093687f]::infer::outlives::env::OutlivesEnvironment as rustc_trait_selection[44c579af88ade2df]::regions::OutlivesEnvironmentBuildExt>::new_with_implied_bounds_compat::<core[b9c58c49076e5645]::iter::adapters::copied::Copied<indexmap[306b0dcaefb62a11]::set::iter::Iter<rustc_middle[a1c7959211e9dd4e]::ty::Ty>>> 20: 0x7cb473aaae89 - rustc_hir_analysis[44fec3f23cf762cf]::check::wfcheck::check_item_fn 21: 0x7cb4738f1918 - rustc_hir_analysis[44fec3f23cf762cf]::check::wfcheck::check_well_formed 22: 0x7cb4738efa87 - rustc_query_impl[b86e1ec47b6ca816]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[b86e1ec47b6ca816]::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle[a1c7959211e9dd4e]::query::erase::Erased<[u8; 1usize]>> 23: 0x7cb4738ef517 - rustc_query_system[af38d3c28df6173e]::query::plumbing::try_execute_query::<rustc_query_impl[b86e1ec47b6ca816]::DynamicConfig<rustc_data_structures[36b80869008ebc33]::vec_cache::VecCache<rustc_span[6d7120c72a98845f]::def_id::LocalDefId, rustc_middle[a1c7959211e9dd4e]::query::erase::Erased<[u8; 1usize]>, rustc_query_system[af38d3c28df6173e]::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl[b86e1ec47b6ca816]::plumbing::QueryCtxt, false> 24: 0x7cb4738ef003 - rustc_query_impl[b86e1ec47b6ca816]::query_impl::check_well_formed::get_query_non_incr::__rust_end_short_backtrace 25: 0x7cb4738ec495 - rustc_hir_analysis[44fec3f23cf762cf]::check::wfcheck::check_mod_type_wf 26: 0x7cb4738ec2b5 - rustc_query_impl[b86e1ec47b6ca816]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[b86e1ec47b6ca816]::query_impl::check_mod_type_wf::dynamic_query::{closure#2}::{closure#0}, rustc_middle[a1c7959211e9dd4e]::query::erase::Erased<[u8; 1usize]>> 27: 0x7cb4744d0b53 - rustc_query_system[af38d3c28df6173e]::query::plumbing::try_execute_query::<rustc_query_impl[b86e1ec47b6ca816]::DynamicConfig<rustc_query_system[af38d3c28df6173e]::query::caches::DefaultCache<rustc_span[6d7120c72a98845f]::def_id::LocalModDefId, rustc_middle[a1c7959211e9dd4e]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[b86e1ec47b6ca816]::plumbing::QueryCtxt, false> 28: 0x7cb4744d08ca - rustc_query_impl[b86e1ec47b6ca816]::query_impl::check_mod_type_wf::get_query_non_incr::__rust_end_short_backtrace 29: 0x7cb47374d817 - rustc_hir_analysis[44fec3f23cf762cf]::check_crate 30: 0x7cb4737e475d - rustc_interface[5d0158996fce411b]::passes::run_required_analyses 31: 0x7cb4742775de - rustc_interface[5d0158996fce411b]::passes::analysis 32: 0x7cb4742775b3 - rustc_query_impl[b86e1ec47b6ca816]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[b86e1ec47b6ca816]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[a1c7959211e9dd4e]::query::erase::Erased<[u8; 0usize]>> 33: 0x7cb47451867a - rustc_query_system[af38d3c28df6173e]::query::plumbing::try_execute_query::<rustc_query_impl[b86e1ec47b6ca816]::DynamicConfig<rustc_query_system[af38d3c28df6173e]::query::caches::SingleCache<rustc_middle[a1c7959211e9dd4e]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[b86e1ec47b6ca816]::plumbing::QueryCtxt, false> 34: 0x7cb474518378 - rustc_query_impl[b86e1ec47b6ca816]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace 35: 0x7cb4746def7c - rustc_interface[5d0158996fce411b]::passes::create_and_enter_global_ctxt::<core[b9c58c49076e5645]::option::Option<rustc_interface[5d0158996fce411b]::queries::Linker>, rustc_driver_impl[bd7fc35b05314b57]::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0} 36: 0x7cb4744ff6e2 - rustc_interface[5d0158996fce411b]::interface::run_compiler::<(), rustc_driver_impl[bd7fc35b05314b57]::run_compiler::{closure#0}>::{closure#1} 37: 0x7cb474437a08 - std[89bc5ccdd7126a22]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[5d0158996fce411b]::util::run_in_thread_with_globals<rustc_interface[5d0158996fce411b]::util::run_in_thread_pool_with_globals<rustc_interface[5d0158996fce411b]::interface::run_compiler<(), rustc_driver_impl[bd7fc35b05314b57]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()> 38: 0x7cb4744382f4 - <<std[89bc5ccdd7126a22]::thread::Builder>::spawn_unchecked_<rustc_interface[5d0158996fce411b]::util::run_in_thread_with_globals<rustc_interface[5d0158996fce411b]::util::run_in_thread_pool_with_globals<rustc_interface[5d0158996fce411b]::interface::run_compiler<(), rustc_driver_impl[bd7fc35b05314b57]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[b9c58c49076e5645]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0} 39: 0x7cb4744396eb - std::sys::pal::unix::thread::Thread::new::thread_start::ha2b3be6e9515328e 40: 0x7cb46e2a370a - <unknown> 41: 0x7cb46e327aac - <unknown> 42: 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 1.87.0-nightly (90f5eab95 2025-03-24) running on x86_64-unknown-linux-gnu query stack during panic: #0 [check_well_formed] checking that `_f3` is well-formed #1 [check_mod_type_wf] checking that types are well-formed in top-level module #2 [analysis] running analysis passes on this crate end of query stack error: aborting due to 4 previous errors Some errors have detailed explanations: E0107, E0601, E0658. For more information about an error, try `rustc --explain E0107`.