rust-lang / rust-lang/rust

[ICE]: `!infcx.next_trait_solver() || !type_outlives.has_non_rigid_aliases()`

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@bit-aloo is already working on this.

Since Aug 14, 2026.

-Zassumptions-on-binders C-bug F-type_alias_impl_trait I-ICE needs-triage requires-debug-assertions T-compiler WG-trait-system-refactor
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Description

auto-reduced (treereduce-rust):

//@compile-flags: -Zassumptions-on-binders
pub type Opaque<T> = impl Sized;

struct Ss<'a, T>(&'a Opaque<T>);

original:

#![feature(type_alias_impl_trait)]

pub type Opaque<T> = impl Sized;
#[define_opaque(Opaque)]
fn defining<T>() -> Opaque<T> {}

struct Ss<'a, T>(&'a Opaque<T>);

fn test<'a, T>(_: Ss<'a, T>) {
    // test that we have an implied bound `Opaque<T>: 'a` from fn signature
    None::<&'a Opaque<T>>;
}

fn main() {}

Version information

rustc 1.99.0-nightly (ba28ff76f 2026-08-13)
binary: rustc
commit-hash: ba28ff76f353a722f31c4f3dd2ac4e437d36411b
commit-date: 2026-08-13
host: x86_64-unknown-linux-gnu
release: 1.99.0-nightly
LLVM version: 23.1.0

Possibly related line of code:
https://github.com/rust-lang/rust/blob/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_trait_selection/src/regions.rs#L29-L41

Command:
/home/matthias/.rustup/toolchains/alt-master/bin/rustc -Zassumptions-on-binders

Program output 

error[E0658]: `impl Trait` in type aliases is unstable
 --> /tmp/icemaker_global_tempdir.gtr0zWeHfhZM/rustc_testrunner_tmpdir_reporting.JozKNqw5lH8t/mvce.rs:1:22
  |
1 | pub type Opaque<T> = impl Sized;
  |                      ^^^^^^^^^^
  |
  = note: see issue #63063 <https://github.com/rust-lang/rust/issues/63063> for more information
  = help: add `#![feature(type_alias_impl_trait)]` to the crate attributes to enable
  = note: this compiler was built on 2026-08-13; consider upgrading it if it is out of date

error[E0601]: `main` function not found in crate `mvce`
 --> /tmp/icemaker_global_tempdir.gtr0zWeHfhZM/rustc_testrunner_tmpdir_reporting.JozKNqw5lH8t/mvce.rs:3:33
  |
3 | struct Ss<'a, T>(&'a Opaque<T>);
  |                                 ^ consider adding a `main` function to `/tmp/icemaker_global_tempdir.gtr0zWeHfhZM/rustc_testrunner_tmpdir_reporting.JozKNqw5lH8t/mvce.rs`


thread 'rustc' (1623683) panicked at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_trait_selection/src/regions.rs:35:17:
assertion failed: !infcx.next_trait_solver() || !type_outlives.has_non_rigid_aliases()
stack backtrace:
   0:     0x7fc6411a09e0 - std[9c371471df126e17]::backtrace_rs::backtrace::libunwind::trace
                               at /rustc/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/std/src/../../backtrace/src/backtrace/libunwind.rs:117:9
   1:     0x7fc6411a09e0 - std[9c371471df126e17]::backtrace_rs::backtrace::trace_unsynchronized::<std[9c371471df126e17]::sys::backtrace::_print_fmt::{closure#1}>
                               at /rustc/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/std/src/../../backtrace/src/backtrace/mod.rs:66:14
   2:     0x7fc6411a09e0 - std[9c371471df126e17]::sys::backtrace::_print_fmt
                               at /rustc/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/std/src/sys/backtrace.rs:74:9
   3:     0x7fc6411a09e0 - <<std[9c371471df126e17]::sys::backtrace::BacktraceLock>::print::DisplayBacktrace as core[bbf77075108f009e]::fmt::Display>::fmt
                               at /rustc/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/std/src/sys/backtrace.rs:44:26
   4:     0x7fc63ca1758e - <core[bbf77075108f009e]::fmt::rt::Argument>::fmt
                               at /rustc/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/core/src/fmt/rt.rs:152:76
   5:     0x7fc63ca1758e - core[bbf77075108f009e]::fmt::write
   6:     0x7fc6411b7abc - core[bbf77075108f009e]::io::write::default_write_fmt::<std[9c371471df126e17]::sys::stdio::unix::Stderr>
                               at /rustc/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/core/src/io/write.rs:402:11
   7:     0x7fc6411b7abc - <std[9c371471df126e17]::sys::stdio::unix::Stderr as core[bbf77075108f009e]::io::write::Write>::write_fmt
                               at /rustc/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/core/src/io/write.rs:335:13
   8:     0x7fc64115f404 - <std[9c371471df126e17]::sys::backtrace::BacktraceLock>::print
                               at /rustc/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/std/src/sys/backtrace.rs:47:9
   9:     0x7fc64115f404 - std[9c371471df126e17]::panicking::default_hook::{closure#0}
                               at /rustc/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/std/src/panicking.rs:292:27
  10:     0x7fc64118cd31 - std[9c371471df126e17]::panicking::default_hook
                               at /rustc/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/std/src/panicking.rs:319:9
  11:     0x7fc63dd5aad8 - <alloc[935401a7a6a78f3f]::boxed::Box<dyn for<'a, 'b> core[bbf77075108f009e]::ops::function::Fn<(&'a std[9c371471df126e17]::panic::PanicHookInfo<'b>,), Output = ()> + core[bbf77075108f009e]::marker::Sync + core[bbf77075108f009e]::marker::Send> as core[bbf77075108f009e]::ops::function::Fn<(&std[9c371471df126e17]::panic::PanicHookInfo,)>>::call
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/alloc/src/boxed.rs:2332:9
  12:     0x7fc63dd5aad8 - rustc_driver_impl[acdaae3c03aca7f7]::install_ice_hook::{closure#1}
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_driver_impl/src/lib.rs:1483:17
  13:     0x7fc63dd5aad8 - <alloc[935401a7a6a78f3f]::boxed::Box<rustc_driver_impl[acdaae3c03aca7f7]::install_ice_hook::{closure#1}> as core[bbf77075108f009e]::ops::function::Fn<(&dyn for<'a, 'b> core[bbf77075108f009e]::ops::function::Fn<(&'a std[9c371471df126e17]::panic::PanicHookInfo<'b>,), Output = ()> + core[bbf77075108f009e]::marker::Sync + core[bbf77075108f009e]::marker::Send, &std[9c371471df126e17]::panic::PanicHookInfo)>>::call
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/alloc/src/boxed.rs:2332:9
  14:     0x7fc63dd5aad8 - std[9c371471df126e17]::panicking::update_hook::<alloc[935401a7a6a78f3f]::boxed::Box<rustc_driver_impl[acdaae3c03aca7f7]::install_ice_hook::{closure#1}>>::{closure#0}
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/std/src/panicking.rs:235:47
  15:     0x7fc64118d1ba - <alloc[935401a7a6a78f3f]::boxed::Box<dyn for<'a, 'b> core[bbf77075108f009e]::ops::function::Fn<(&'a std[9c371471df126e17]::panic::PanicHookInfo<'b>,), Output = ()> + core[bbf77075108f009e]::marker::Sync + core[bbf77075108f009e]::marker::Send> as core[bbf77075108f009e]::ops::function::Fn<(&std[9c371471df126e17]::panic::PanicHookInfo,)>>::call
                               at /rustc/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/alloc/src/boxed.rs:2332:9
  16:     0x7fc64118d1ba - std[9c371471df126e17]::panicking::panic_with_hook
                               at /rustc/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/std/src/panicking.rs:823:13
  17:     0x7fc64115f504 - std[9c371471df126e17]::panicking::panic_handler::{closure#0}
                               at /rustc/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/std/src/panicking.rs:681:13
  18:     0x7fc641152e19 - std[9c371471df126e17]::sys::backtrace::__rust_end_short_backtrace::<std[9c371471df126e17]::panicking::panic_handler::{closure#0}, !>
                               at /rustc/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/std/src/sys/backtrace.rs:182:18
  19:     0x7fc64116151d - __rustc[5f650fa12cddb854]::rust_begin_unwind
                               at /rustc/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/std/src/panicking.rs:679:5
  20:     0x7fc63ca182fc - core[bbf77075108f009e]::panicking::panic_fmt
                               at /rustc/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/core/src/panicking.rs:80:14
  21:     0x7fc63ca182c2 - core[bbf77075108f009e]::panicking::panic
                               at /rustc/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/core/src/panicking.rs:150:5
  22:     0x7fc640a896a3 - <rustc_infer[aeee14ecfd85b5b2]::infer::outlives::env::OutlivesEnvironment as rustc_trait_selection[f55def2dee19757a]::regions::OutlivesEnvironmentBuildExt>::new_with_implied_bounds_compat::<[rustc_middle[bba5799a2187c04b]::ty::Ty; 0usize]>
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_trait_selection/src/regions.rs:35:17
  23:     0x7fc640a896a3 - <rustc_infer[aeee14ecfd85b5b2]::infer::outlives::env::OutlivesEnvironment as rustc_trait_selection[f55def2dee19757a]::regions::OutlivesEnvironmentBuildExt>::new::<[rustc_middle[bba5799a2187c04b]::ty::Ty; 0usize]>
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_trait_selection/src/regions.rs:21:9
  24:     0x7fc640a896a3 - <rustc_infer[aeee14ecfd85b5b2]::infer::InferCtxt as rustc_trait_selection[f55def2dee19757a]::regions::InferCtxtRegionExt>::resolve_regions::<[rustc_middle[bba5799a2187c04b]::ty::Ty; 0usize]>
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_trait_selection/src/regions.rs:78:14
  25:     0x7fc640cc4308 - rustc_trait_selection[f55def2dee19757a]::traits::do_normalize_clauses
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_trait_selection/src/traits/mod.rs:402:25
  26:     0x7fc640cc7f36 - rustc_trait_selection[f55def2dee19757a]::traits::normalize_param_env_or_error
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_trait_selection/src/traits/mod.rs:565:28
  27:     0x7fc641012a26 - rustc_ty_utils[63c3368e28450b41]::ty::param_env
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_ty_utils/src/ty.rs:203:5
  28:     0x7fc64019316d - rustc_query_impl[7d3e9b7bad8a5be9]::query_vtables::param_env::invoke_provider_fn::__rust_begin_short_backtrace
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_query_impl/src/query_vtables.rs:130:46
  29:     0x7fc63fee9cfc - rustc_query_impl[7d3e9b7bad8a5be9]::execution::execute_job_non_incr::<rustc_middle[bba5799a2187c04b]::query::caches::DefIdCache<rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>>>::{closure#0}
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_query_impl/src/execution.rs:390:59
  30:     0x7fc63fee9cfc - rustc_middle[bba5799a2187c04b]::ty::context::tls::enter_context::<rustc_query_impl[7d3e9b7bad8a5be9]::execution::execute_job_non_incr<rustc_middle[bba5799a2187c04b]::query::caches::DefIdCache<rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>>>::{closure#0}, rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>>::{closure#0}
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_middle/src/ty/context/tls.rs:56:9
  31:     0x7fc63fee9cfc - <std[9c371471df126e17]::thread::local::LocalKey<core[bbf77075108f009e]::cell::Cell<*const ()>>>::try_with::<rustc_middle[bba5799a2187c04b]::ty::context::tls::enter_context<rustc_query_impl[7d3e9b7bad8a5be9]::execution::execute_job_non_incr<rustc_middle[bba5799a2187c04b]::query::caches::DefIdCache<rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>>>::{closure#0}, rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>>::{closure#0}, rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>>
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/std/src/thread/local.rs:464:12
  32:     0x7fc63fee9cfc - <std[9c371471df126e17]::thread::local::LocalKey<core[bbf77075108f009e]::cell::Cell<*const ()>>>::with::<rustc_middle[bba5799a2187c04b]::ty::context::tls::enter_context<rustc_query_impl[7d3e9b7bad8a5be9]::execution::execute_job_non_incr<rustc_middle[bba5799a2187c04b]::query::caches::DefIdCache<rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>>>::{closure#0}, rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>>::{closure#0}, rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>>
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/std/src/thread/local.rs:428:20
  33:     0x7fc63fee9cfc - rustc_middle[bba5799a2187c04b]::ty::context::tls::enter_context::<rustc_query_impl[7d3e9b7bad8a5be9]::execution::execute_job_non_incr<rustc_middle[bba5799a2187c04b]::query::caches::DefIdCache<rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>>>::{closure#0}, rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>>
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_middle/src/ty/context/tls.rs:53:9
  34:     0x7fc63fee9cfc - rustc_query_impl[7d3e9b7bad8a5be9]::execution::start_query::<rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>, rustc_query_impl[7d3e9b7bad8a5be9]::execution::execute_job_non_incr<rustc_middle[bba5799a2187c04b]::query::caches::DefIdCache<rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>>>::{closure#0}>::{closure#0}
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_query_impl/src/execution.rs:374:9
  35:     0x7fc63fee9cfc - rustc_middle[bba5799a2187c04b]::ty::context::tls::with_context::<rustc_query_impl[7d3e9b7bad8a5be9]::execution::start_query<rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>, rustc_query_impl[7d3e9b7bad8a5be9]::execution::execute_job_non_incr<rustc_middle[bba5799a2187c04b]::query::caches::DefIdCache<rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>>>::{closure#0}>::{closure#0}, rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>>::{closure#0}
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_middle/src/ty/context/tls.rs:86:36
  36:     0x7fc63fee9cfc - rustc_middle[bba5799a2187c04b]::ty::context::tls::with_context_opt::<rustc_middle[bba5799a2187c04b]::ty::context::tls::with_context<rustc_query_impl[7d3e9b7bad8a5be9]::execution::start_query<rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>, rustc_query_impl[7d3e9b7bad8a5be9]::execution::execute_job_non_incr<rustc_middle[bba5799a2187c04b]::query::caches::DefIdCache<rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>>>::{closure#0}>::{closure#0}, rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>>::{closure#0}, rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>>
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_middle/src/ty/context/tls.rs:75:18
  37:     0x7fc63fee9cfc - rustc_middle[bba5799a2187c04b]::ty::context::tls::with_context::<rustc_query_impl[7d3e9b7bad8a5be9]::execution::start_query<rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>, rustc_query_impl[7d3e9b7bad8a5be9]::execution::execute_job_non_incr<rustc_middle[bba5799a2187c04b]::query::caches::DefIdCache<rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>>>::{closure#0}>::{closure#0}, rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>>
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_middle/src/ty/context/tls.rs:86:5
  38:     0x7fc63fee9cfc - rustc_query_impl[7d3e9b7bad8a5be9]::execution::start_query::<rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>, rustc_query_impl[7d3e9b7bad8a5be9]::execution::execute_job_non_incr<rustc_middle[bba5799a2187c04b]::query::caches::DefIdCache<rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>>>::{closure#0}>
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_query_impl/src/execution.rs:361:5
  39:     0x7fc63fee9cfc - rustc_query_impl[7d3e9b7bad8a5be9]::execution::execute_job_non_incr::<rustc_middle[bba5799a2187c04b]::query::caches::DefIdCache<rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>>>
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_query_impl/src/execution.rs:390:17
  40:     0x7fc63fee9cfc - rustc_query_impl[7d3e9b7bad8a5be9]::execution::try_execute_query::<rustc_middle[bba5799a2187c04b]::query::caches::DefIdCache<rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>>, false>
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_query_impl/src/execution.rs:261:17
  41:     0x7fc6401934b3 - rustc_query_impl[7d3e9b7bad8a5be9]::execution::execute_query_non_incr_inner::<rustc_middle[bba5799a2187c04b]::query::caches::DefIdCache<rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>>>
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_query_impl/src/execution.rs:575:5
  42:     0x7fc6401934b3 - rustc_query_impl[7d3e9b7bad8a5be9]::query_vtables::param_env::execute_query_non_incr::__rust_end_short_backtrace
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_query_impl/src/query_vtables.rs:94:30
  43:     0x7fc63e063dc6 - rustc_middle[bba5799a2187c04b]::query::inner::query_get_at::<rustc_middle[bba5799a2187c04b]::query::caches::DefIdCache<rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 8usize]>>>
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_middle/src/query/inner.rs:45:17
  44:     0x7fc63e063dc6 - <rustc_middle[bba5799a2187c04b]::query::plumbing::TyCtxtAt>::param_env::<rustc_span[f1f70695bb4a1dca]::def_id::LocalDefId>
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_middle/src/query/plumbing.rs:564:46
  45:     0x7fc63e063dc6 - <rustc_middle[bba5799a2187c04b]::ty::context::TyCtxt>::param_env::<rustc_span[f1f70695bb4a1dca]::def_id::LocalDefId>
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_middle/src/query/plumbing.rs:552:39
  46:     0x7fc63e063dc6 - rustc_hir_analysis[1dd10e8ed87600ce]::check::wfcheck::enter_wf_checking_ctxt::<rustc_hir_analysis[1dd10e8ed87600ce]::check::wfcheck::check_type_defn::{closure#0}>
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_hir_analysis/src/check/wfcheck.rs:164:25
  47:     0x7fc63e27a019 - rustc_hir_analysis[1dd10e8ed87600ce]::check::wfcheck::check_type_defn
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_hir_analysis/src/check/wfcheck.rs:983:5
  48:     0x7fc63e25c91d - rustc_hir_analysis[1dd10e8ed87600ce]::check::check::check_item_type
  49:     0x7fc63e2802e7 - rustc_hir_analysis[1dd10e8ed87600ce]::check::wfcheck::check_well_formed
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_hir_analysis/src/check/wfcheck.rs:231:19
  50:     0x7fc640131a67 - rustc_query_impl[7d3e9b7bad8a5be9]::query_vtables::check_well_formed::invoke_provider_fn::__rust_begin_short_backtrace
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_query_impl/src/query_vtables.rs:130:46
  51:     0x7fc63feb0bc9 - rustc_query_impl[7d3e9b7bad8a5be9]::execution::execute_job_non_incr::<rustc_data_structures[a090a70c23a6db2c]::vec_cache::VecCache<rustc_span[f1f70695bb4a1dca]::def_id::LocalDefId, rustc_middle[bba5799a2187c04b]::query::erase::ErasedData<[u8; 1usize]>, rustc_middle[bba5799a2187c04b]::dep_graph::graph::DepNodeIndex>>::{closure#0}
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/compiler/rustc_query_impl/src/execution.rs:390:59
  


 153:     0x7fc63dd63019 - <core[bbf77075108f009e]::panic::unwind_safe::AssertUnwindSafe<std[9c371471df126e17]::thread::lifecycle::spawn_unchecked<rustc_interface[5649c42bcbf1bdf]::util::run_in_thread_with_globals<rustc_interface[5649c42bcbf1bdf]::util::run_in_thread_pool_with_globals<rustc_interface[5649c42bcbf1bdf]::interface::run_compiler<(), rustc_driver_impl[acdaae3c03aca7f7]::run_compiler::{closure#0}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1}::{closure#0}> as core[bbf77075108f009e]::ops::function::FnOnce<()>>::call_once
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/core/src/panic/unwind_safe.rs:275:9
 154:     0x7fc63dd63019 - std[9c371471df126e17]::panicking::catch_unwind::do_call::<core[bbf77075108f009e]::panic::unwind_safe::AssertUnwindSafe<std[9c371471df126e17]::thread::lifecycle::spawn_unchecked<rustc_interface[5649c42bcbf1bdf]::util::run_in_thread_with_globals<rustc_interface[5649c42bcbf1bdf]::util::run_in_thread_pool_with_globals<rustc_interface[5649c42bcbf1bdf]::interface::run_compiler<(), rustc_driver_impl[acdaae3c03aca7f7]::run_compiler::{closure#0}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1}::{closure#0}>, ()>
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/std/src/panicking.rs:576:43
 155:     0x7fc63dd63019 - std[9c371471df126e17]::panicking::catch_unwind::<(), core[bbf77075108f009e]::panic::unwind_safe::AssertUnwindSafe<std[9c371471df126e17]::thread::lifecycle::spawn_unchecked<rustc_interface[5649c42bcbf1bdf]::util::run_in_thread_with_globals<rustc_interface[5649c42bcbf1bdf]::util::run_in_thread_pool_with_globals<rustc_interface[5649c42bcbf1bdf]::interface::run_compiler<(), rustc_driver_impl[acdaae3c03aca7f7]::run_compiler::{closure#0}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1}::{closure#0}>>
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/std/src/panicking.rs:544:19
 156:     0x7fc63dd63019 - std[9c371471df126e17]::panic::catch_unwind::<core[bbf77075108f009e]::panic::unwind_safe::AssertUnwindSafe<std[9c371471df126e17]::thread::lifecycle::spawn_unchecked<rustc_interface[5649c42bcbf1bdf]::util::run_in_thread_with_globals<rustc_interface[5649c42bcbf1bdf]::util::run_in_thread_pool_with_globals<rustc_interface[5649c42bcbf1bdf]::interface::run_compiler<(), rustc_driver_impl[acdaae3c03aca7f7]::run_compiler::{closure#0}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1}::{closure#0}>, ()>
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/std/src/panic.rs:359:14
 157:     0x7fc63dd63019 - std[9c371471df126e17]::thread::lifecycle::spawn_unchecked::<rustc_interface[5649c42bcbf1bdf]::util::run_in_thread_with_globals<rustc_interface[5649c42bcbf1bdf]::util::run_in_thread_pool_with_globals<rustc_interface[5649c42bcbf1bdf]::interface::run_compiler<(), rustc_driver_impl[acdaae3c03aca7f7]::run_compiler::{closure#0}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1}
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/std/src/thread/lifecycle.rs:68:26
 158:     0x7fc63dd63019 - <std[9c371471df126e17]::thread::lifecycle::spawn_unchecked<rustc_interface[5649c42bcbf1bdf]::util::run_in_thread_with_globals<rustc_interface[5649c42bcbf1bdf]::util::run_in_thread_pool_with_globals<rustc_interface[5649c42bcbf1bdf]::interface::run_compiler<(), rustc_driver_impl[acdaae3c03aca7f7]::run_compiler::{closure#0}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[bbf77075108f009e]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
                               at /rustc-dev/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/core/src/ops/function.rs:250:5
 159:     0x7fc64119c5df - <alloc[935401a7a6a78f3f]::boxed::Box<dyn core[bbf77075108f009e]::ops::function::FnOnce<(), Output = ()> + core[bbf77075108f009e]::marker::Send> as core[bbf77075108f009e]::ops::function::FnOnce<()>>::call_once
                               at /rustc/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/alloc/src/boxed.rs:2318:9
 160:     0x7fc64119c5df - <std[9c371471df126e17]::sys::thread::unix::Thread>::new::thread_start
                               at /rustc/ba28ff76f353a722f31c4f3dd2ac4e437d36411b/library/std/src/sys/thread/unix.rs:123:17
 161:     0x7fc63b097739 - <unknown>
 162:     0x7fc63b11bedc - <unknown>
 163:                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 1.99.0-nightly (ba28ff76f 2026-08-13) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z assumptions-on-binders -Z dump-mir-dir=dir

query stack during panic:
#0 [param_env] computing normalized predicates of `Ss`
#1 [check_well_formed] checking that `Ss` is well-formed
#2 [check_type_wf] checking that types are well-formed
#3 [analysis] running analysis passes on crate `mvce`
end of query stack
error: aborting due to 2 previous errors

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

@rustbot label +F-type_alias_impl_trait

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