ICE: `assertion failed: !ty.has_non_region_infer()`

[matthiaskrgr]

auto-reduced (treereduce-rust):

use std::ops::Add;

struct Container<S: Data>(S);

trait Data {
    type Elem;
}

impl<A, S> Add<Container<S>> for f32
where
    f32: Add<A, Output = A>,
    S:,
{
}

impl<'a, A, S> Add<&'a Container<S>> for f32
where
    f32: Add<A>,
    S: Data<Elem = A>,
{
    type Output = Container<Vec<<f32 as Add<A>>::Output>>;
    fn add(self, _rhs: &Container<Data>) -> Self::Output {}
}

original:

use std::ops::Add;

struct Container<S: Data>(S);

trait Data {
    type Elem;
}

impl<A> Data for Vec<A> {
    type Elem = A;
}

impl<A, S> Add<Container<S>> for f32
where
    f32: Add<A, Output=A>,
    S: Data<Elem=A>,
{
    impl<A> Data for Vec<A> {
    type Elem = A;
}
    fn add(self, _rhs: Container<S>) -> Container<S> {
        unimplemented!()
    }
}

impl<'a, A, S> Add<&'a Container<S>> for f32
where
      f32: Add<A>,
      S: Data<Elem=A>,
{
    type Output = Container<Vec<<f32 as Add<A>>::Output>>;
    fn add(self, _rhs: &Container<Data>) -> Self::Output {
        unimplemented!()
    }
}

Version information

rustc 1.86.0-nightly (dcfa38fe2 2025-01-05)
binary: rustc
commit-hash: dcfa38fe234de9304169afc6638e81d0dd222c06
commit-date: 2025-01-05
host: x86_64-unknown-linux-gnu
release: 1.86.0-nightly
LLVM version: 19.1.6

Possibly related line of code:

rust/compiler/rustc_trait_selection/src/traits/outlives_bounds.rs

Lines 48 to 60 in dcfa38f

	// We do not expect existential variables in implied bounds.
	// We may however encounter unconstrained lifetime variables
	// in very rare cases.
	//
	// See `ui/implied-bounds/implied-bounds-unconstrained-2.rs` for
	// an example.
	assert!(!ty.has_non_region_infer());
	let mut canonical_var_values = OriginalQueryValues::default();
	let input = ImpliedOutlivesBounds { ty };
	let canonical = infcx.canonicalize_query(param_env.and(input), &mut canonical_var_values);
	let implied_bounds_result = if compat {
	infcx.tcx.implied_outlives_bounds_compat(canonical)

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

Program output

error[E0601]: `main` function not found in crate `mvce`
  --> /tmp/icemaker_global_tempdir.eJbTZCOAMNoj/rustc_testrunner_tmpdir_reporting.9QYtHLbbaWJb/mvce.rs:23:2
   |
23 | }
   |  ^ consider adding a `main` function to `/tmp/icemaker_global_tempdir.eJbTZCOAMNoj/rustc_testrunner_tmpdir_reporting.9QYtHLbbaWJb/mvce.rs`

warning: trait objects without an explicit `dyn` are deprecated
  --> /tmp/icemaker_global_tempdir.eJbTZCOAMNoj/rustc_testrunner_tmpdir_reporting.9QYtHLbbaWJb/mvce.rs:22:35
   |
22 |     fn add(self, _rhs: &Container<Data>) -> Self::Output {}
   |                                   ^^^^
   |
   = 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 a dyn-compatible trait, use `dyn`
   |
22 |     fn add(self, _rhs: &Container<dyn Data>) -> Self::Output {}
   |                                   +++

error[E0191]: the value of the associated type `Elem` in `Data` must be specified
  --> /tmp/icemaker_global_tempdir.eJbTZCOAMNoj/rustc_testrunner_tmpdir_reporting.9QYtHLbbaWJb/mvce.rs:22:35
   |
6  |     type Elem;
   |     --------- `Elem` defined here
...
22 |     fn add(self, _rhs: &Container<Data>) -> Self::Output {}
   |                                   ^^^^ help: specify the associated type: `Data<Elem = Type>`

error[E0207]: the type parameter `A` is not constrained by the impl trait, self type, or predicates
 --> /tmp/icemaker_global_tempdir.eJbTZCOAMNoj/rustc_testrunner_tmpdir_reporting.9QYtHLbbaWJb/mvce.rs:9:6
  |
9 | impl<A, S> Add<Container<S>> for f32
  |      ^ unconstrained type parameter


thread 'rustc' panicked at compiler/rustc_trait_selection/src/traits/outlives_bounds.rs:54:5:
assertion failed: !ty.has_non_region_infer()
stack backtrace:
   0:     0x7b44522d47ca - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::hadf8e2df861efce2
   1:     0x7b4452a135e6 - core::fmt::write::h7a55e8c402e63d48
   2:     0x7b44539127d1 - std::io::Write::write_fmt::h3751c3424aa517d0
   3:     0x7b44522d4622 - std::sys::backtrace::BacktraceLock::print::hda228978e42208f7
   4:     0x7b44522d6bc7 - std::panicking::default_hook::{{closure}}::hd850557dd952fc8c
   5:     0x7b44522d69b0 - std::panicking::default_hook::hb302f704a65842a5
   6:     0x7b4451452928 - std[3100b7b695602b1a]::panicking::update_hook::<alloc[5f744d0bf49b6096]::boxed::Box<rustc_driver_impl[736abb8093ca35b1]::install_ice_hook::{closure#1}>>::{closure#0}
   7:     0x7b44522d7413 - std::panicking::rust_panic_with_hook::ha601460835d6d839
   8:     0x7b44522d70d6 - std::panicking::begin_panic_handler::{{closure}}::h81a3663d6cb5d12c
   9:     0x7b44522d4c99 - std::sys::backtrace::__rust_end_short_backtrace::h4ff0aa96a7064803
  10:     0x7b44522d6dcd - rust_begin_unwind
  11:     0x7b444ef9e9e0 - core::panicking::panic_fmt::h6dfbe1ba47369a2f
  12:     0x7b444fafa15c - core::panicking::panic::h24ba62daf6026c27
  13:     0x7b4453786400 - rustc_trait_selection[a36a1e16c88a6dc2]::traits::outlives_bounds::implied_outlives_bounds
  14:     0x7b445312cb37 - <rustc_infer[9bafcf6fc3bf205d]::infer::outlives::env::OutlivesEnvironment>::with_bounds::<core[5eafa33fb0699880]::iter::adapters::flatten::FlatMap<indexmap[5764fe6e3edd7c17]::set::iter::Iter<rustc_middle[ccb2eb78bedf1942]::ty::Ty>, alloc[5f744d0bf49b6096]::vec::Vec<rustc_middle[ccb2eb78bedf1942]::traits::query::OutlivesBound>, <rustc_infer[9bafcf6fc3bf205d]::infer::InferCtxt as rustc_trait_selection[a36a1e16c88a6dc2]::traits::outlives_bounds::InferCtxtExt>::implied_bounds_tys::{closure#0}>>
  15:     0x7b4453148e2b - rustc_hir_analysis[48e47dfc185f7fea]::check::compare_impl_item::compare_impl_item
  16:     0x7b44531476d5 - rustc_query_impl[ac2bab59562664c7]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[ac2bab59562664c7]::query_impl::compare_impl_item::dynamic_query::{closure#2}::{closure#0}, rustc_middle[ccb2eb78bedf1942]::query::erase::Erased<[u8; 1usize]>>
  17:     0x7b4453131c23 - rustc_query_system[9e3640c263c85fee]::query::plumbing::try_execute_query::<rustc_query_impl[ac2bab59562664c7]::DynamicConfig<rustc_data_structures[52740ce709e2e05d]::vec_cache::VecCache<rustc_span[8e152531e0bcd89e]::def_id::LocalDefId, rustc_middle[ccb2eb78bedf1942]::query::erase::Erased<[u8; 1usize]>, rustc_query_system[9e3640c263c85fee]::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl[ac2bab59562664c7]::plumbing::QueryCtxt, false>
  18:     0x7b4453131601 - rustc_query_impl[ac2bab59562664c7]::query_impl::compare_impl_item::get_query_non_incr::__rust_end_short_backtrace
  19:     0x7b4453c06b3a - rustc_hir_analysis[48e47dfc185f7fea]::check::check::check_impl_items_against_trait
  20:     0x7b4453124d0f - rustc_hir_analysis[48e47dfc185f7fea]::check::check::check_item_type
  21:     0x7b4453133580 - rustc_hir_analysis[48e47dfc185f7fea]::check::wfcheck::check_well_formed
  22:     0x7b4453132463 - rustc_query_impl[ac2bab59562664c7]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[ac2bab59562664c7]::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle[ccb2eb78bedf1942]::query::erase::Erased<[u8; 1usize]>>
  23:     0x7b4453131f05 - rustc_query_system[9e3640c263c85fee]::query::plumbing::try_execute_query::<rustc_query_impl[ac2bab59562664c7]::DynamicConfig<rustc_data_structures[52740ce709e2e05d]::vec_cache::VecCache<rustc_span[8e152531e0bcd89e]::def_id::LocalDefId, rustc_middle[ccb2eb78bedf1942]::query::erase::Erased<[u8; 1usize]>, rustc_query_system[9e3640c263c85fee]::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl[ac2bab59562664c7]::plumbing::QueryCtxt, false>
  24:     0x7b4453131981 - rustc_query_impl[ac2bab59562664c7]::query_impl::check_well_formed::get_query_non_incr::__rust_end_short_backtrace
  25:     0x7b445312edac - rustc_hir_analysis[48e47dfc185f7fea]::check::wfcheck::check_mod_type_wf
  26:     0x7b445312ebcb - rustc_query_impl[ac2bab59562664c7]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[ac2bab59562664c7]::query_impl::check_mod_type_wf::dynamic_query::{closure#2}::{closure#0}, rustc_middle[ccb2eb78bedf1942]::query::erase::Erased<[u8; 1usize]>>
  27:     0x7b445397a1c8 - rustc_query_system[9e3640c263c85fee]::query::plumbing::try_execute_query::<rustc_query_impl[ac2bab59562664c7]::DynamicConfig<rustc_query_system[9e3640c263c85fee]::query::caches::DefaultCache<rustc_span[8e152531e0bcd89e]::def_id::LocalModDefId, rustc_middle[ccb2eb78bedf1942]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[ac2bab59562664c7]::plumbing::QueryCtxt, false>
  28:     0x7b4453979f70 - rustc_query_impl[ac2bab59562664c7]::query_impl::check_mod_type_wf::get_query_non_incr::__rust_end_short_backtrace
  29:     0x7b4452dc2378 - rustc_hir_analysis[48e47dfc185f7fea]::check_crate
  30:     0x7b4452e950a8 - rustc_interface[21548936fe144d05]::passes::run_required_analyses
  31:     0x7b445391665e - rustc_interface[21548936fe144d05]::passes::analysis
  32:     0x7b445391662f - rustc_query_impl[ac2bab59562664c7]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[ac2bab59562664c7]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[ccb2eb78bedf1942]::query::erase::Erased<[u8; 0usize]>>
  33:     0x7b445397f7d5 - rustc_query_system[9e3640c263c85fee]::query::plumbing::try_execute_query::<rustc_query_impl[ac2bab59562664c7]::DynamicConfig<rustc_query_system[9e3640c263c85fee]::query::caches::SingleCache<rustc_middle[ccb2eb78bedf1942]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[ac2bab59562664c7]::plumbing::QueryCtxt, false>
  34:     0x7b445397f50e - rustc_query_impl[ac2bab59562664c7]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  35:     0x7b445393ecde - rustc_interface[21548936fe144d05]::passes::create_and_enter_global_ctxt::<core[5eafa33fb0699880]::option::Option<rustc_interface[21548936fe144d05]::queries::Linker>, rustc_driver_impl[736abb8093ca35b1]::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
  36:     0x7b4453958524 - rustc_interface[21548936fe144d05]::interface::run_compiler::<(), rustc_driver_impl[736abb8093ca35b1]::run_compiler::{closure#0}>::{closure#1}
  37:     0x7b4453806187 - std[3100b7b695602b1a]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[21548936fe144d05]::util::run_in_thread_with_globals<rustc_interface[21548936fe144d05]::util::run_in_thread_pool_with_globals<rustc_interface[21548936fe144d05]::interface::run_compiler<(), rustc_driver_impl[736abb8093ca35b1]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  38:     0x7b4453806624 - <<std[3100b7b695602b1a]::thread::Builder>::spawn_unchecked_<rustc_interface[21548936fe144d05]::util::run_in_thread_with_globals<rustc_interface[21548936fe144d05]::util::run_in_thread_pool_with_globals<rustc_interface[21548936fe144d05]::interface::run_compiler<(), rustc_driver_impl[736abb8093ca35b1]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[5eafa33fb0699880]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  39:     0x7b4453807c01 - std::sys::pal::unix::thread::Thread::new::thread_start::he5122ef3561b8e92
  40:     0x7b444dca339d - <unknown>
  41:     0x7b444dd2849c - <unknown>
  42:                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 1.86.0-nightly (dcfa38fe2 2025-01-05) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [compare_impl_item] checking assoc item `<impl at /tmp/icemaker_global_tempdir.eJbTZCOAMNoj/rustc_testrunner_tmpdir_reporting.9QYtHLbbaWJb/mvce.rs:16:1: 19:23>::add` is compatible with trait definition
#1 [check_well_formed] checking that `<impl at /tmp/icemaker_global_tempdir.eJbTZCOAMNoj/rustc_testrunner_tmpdir_reporting.9QYtHLbbaWJb/mvce.rs:16:1: 19:23>` is well-formed
#2 [check_mod_type_wf] checking that types are well-formed in top-level module
#3 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 3 previous errors; 1 warning emitted

Some errors have detailed explanations: E0191, E0207, E0601.
For more information about an error, try `rustc --explain E0191`.

[matthiaskrgr]

bisection points to #131239

[lqd]

cc PR author @VulnBandit

[cyrgani]

partial reduction that is hopefully conceptually simpler because it has less overlap:

trait Add {
    type Output;
    fn add(_: (), _: Self::Output) {}
}

trait IsSame<Lhs> {
    type Assoc;
}

trait Data {
    type Elem;
}

impl<B> IsSame<i16> for f32 where f32: IsSame<B, Assoc = B> {}

impl<A> Add for i64
where
    f32: IsSame<A>,
    i8: Data<Elem = A>,
{
    type Output = <f32 as IsSame<A>>::Assoc;
    fn add(_: Data, _: Self::Output) {}
}

[cyrgani]

the ICE is fixed with RUSTFLAGS=-Znext-solver
@rustbot label:fixed-by-next-solver

[rustbot]

Error: Label fixed-by-next-solver can only be set by Rust team members

Please file an issue on GitHub at triagebot if there's a problem with this bot, or reach out on #t-infra on Zulip.