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[ICE]: assumptions on binders: failed to resolve instance for <dyn Derived<()> as Derived<()>>::is_derived #157729

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#158404
Open
[ICE]: assumptions on binders: failed to resolve instance for <dyn Derived<()> as Derived<()>>::is_derived#157729
#158404
Labels
-Zassumptions-on-bindersUnstable option: `-Zassumptions-on-bindersC-bugCategory: This is a bug.I-ICEIssue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️T-compilerRelevant to the compiler team, which will review and decide on the PR/issue.WG-trait-system-refactorThe Rustc Trait System Refactor Initiative (-Znext-solver)needs-triageThis issue may need triage. Remove it if it has been sufficiently triaged.

Description

@matthiaskrgr
matthiaskrgr
opened on Jun 10, 2026

Code

//@compile-flags: -Zassumptions-on-binders -Znext-solver=globally
// Regression test for #77653
// When monomorphizing `f` we need to prove `dyn Derived<()>: Base<()>`. This
// requires us to normalize the `Base<<() as Proj>::S>` to `Base<()>` when
// comparing the supertrait `Derived<()>` to the expected trait.

//@ build-pass
//@ revisions: current next
//@ ignore-compare-mode-next-solver (explicit revisions)
//@[next] compile-flags: -Znext-solver

trait Proj {
    type S;
}

impl Proj for () {
    type S = ();
}

impl Proj for i32 {
    type S = i32;
}

trait Base<T> {
    fn is_base(&self);
}

trait Derived<B: Proj>: Base<B::S> + Base<()> {
    fn is_derived(&self);
}

fn f<P: Proj>(obj: &dyn Derived<P>) {
    obj.is_derived();
    Base::<P::S>::is_base(obj);
    Base::<()>::is_base(obj);
}

fn main() {
    let x: fn(_) = f::<()>;
    let x: fn(_) = f::<i32>;
}

Meta

rustc --version --verbose:

rustc 1.98.0-nightly (beae78130 2026-06-09)
binary: rustc
commit-hash: beae781308e9ddef13074a03faf57ca2fac59a5b
commit-date: 2026-06-09
host: x86_64-unknown-linux-gnu
release: 1.98.0-nightly
LLVM version: 22.1.6

Error output

<output>
Backtrace 

error: internal compiler error: /rustc-dev/beae781308e9ddef13074a03faf57ca2fac59a5b/compiler/rustc_middle/src/ty/instance.rs:569:21: failed to resolve instance for <dyn Derived<()> as Derived<()>>::is_derived
  --> a.rs:32:5
   |
32 |     obj.is_derived();
   |     ^^^^^^^^^^^^^^^^


thread 'rustc' (1430124) panicked at /rustc-dev/beae781308e9ddef13074a03faf57ca2fac59a5b/compiler/rustc_middle/src/ty/instance.rs:569:21:
Box<dyn Any>
stack backtrace:
   0:     0x7fd0880a0dd9 - <<std[210f122337a7df4c]::sys::backtrace::BacktraceLock>::print::DisplayBacktrace as core[56696922243b1362]::fmt::Display>::fmt
   1:     0x7fd088817988 - core[56696922243b1362]::fmt::write
   2:     0x7fd0880b6e66 - <std[210f122337a7df4c]::sys::stdio::unix::Stderr as std[210f122337a7df4c]::io::Write>::write_fmt
   3:     0x7fd08807656e - std[210f122337a7df4c]::panicking::default_hook::{closure#0}
   4:     0x7fd088093d33 - std[210f122337a7df4c]::panicking::default_hook
   5:     0x7fd086e840d1 - std[210f122337a7df4c]::panicking::update_hook::<alloc[87f39702ba754b16]::boxed::Box<rustc_driver_impl[17e5fc0182803539]::install_ice_hook::{closure#1}>>::{closure#0}
   6:     0x7fd088094012 - std[210f122337a7df4c]::panicking::panic_with_hook
   7:     0x7fd086eb1d41 - std[210f122337a7df4c]::panicking::begin_panic::<rustc_errors[c58c3e91abb3cebc]::ExplicitBug>::{closure#0}
   8:     0x7fd086eaaab6 - std[210f122337a7df4c]::sys::backtrace::__rust_end_short_backtrace::<std[210f122337a7df4c]::panicking::begin_panic<rustc_errors[c58c3e91abb3cebc]::ExplicitBug>::{closure#0}, !>
   9:     0x7fd086ea8a47 - std[210f122337a7df4c]::panicking::begin_panic::<rustc_errors[c58c3e91abb3cebc]::ExplicitBug>
  10:     0x7fd086ebcd71 - <rustc_errors[c58c3e91abb3cebc]::diagnostic::BugAbort as rustc_errors[c58c3e91abb3cebc]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
  11:     0x7fd0875245ec - <rustc_errors[c58c3e91abb3cebc]::DiagCtxtHandle>::span_bug::<rustc_span[1164d50c362b2714]::span_encoding::Span, alloc[87f39702ba754b16]::string::String>
  12:     0x7fd08754fa66 - rustc_middle[f785d3947f0fb584]::util::bug::opt_span_bug_fmt::<rustc_span[1164d50c362b2714]::span_encoding::Span>::{closure#0}
  13:     0x7fd08754fbf2 - rustc_middle[f785d3947f0fb584]::ty::context::tls::with_opt::<rustc_middle[f785d3947f0fb584]::util::bug::opt_span_bug_fmt<rustc_span[1164d50c362b2714]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  14:     0x7fd08753e77b - rustc_middle[f785d3947f0fb584]::ty::context::tls::with_context_opt::<rustc_middle[f785d3947f0fb584]::ty::context::tls::with_opt<rustc_middle[f785d3947f0fb584]::util::bug::opt_span_bug_fmt<rustc_span[1164d50c362b2714]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  15:     0x7fd084b3f618 - rustc_middle[f785d3947f0fb584]::util::bug::span_bug_fmt::<rustc_span[1164d50c362b2714]::span_encoding::Span>
  16:     0x7fd0897f4748 - <rustc_middle[f785d3947f0fb584]::ty::instance::Instance>::expect_resolve
  17:     0x7fd0892bd669 - <rustc_monomorphize[ccd7379517a8b282]::collector::MirUsedCollector as rustc_middle[f785d3947f0fb584]::mir::visit::Visitor>::visit_terminator
  18:     0x7fd0892b6a03 - rustc_monomorphize[ccd7379517a8b282]::collector::items_of_instance
  19:     0x7fd0892b6411 - rustc_query_impl[6a84ebe04ccf7fcc]::query_impl::items_of_instance::invoke_provider_fn::__rust_begin_short_backtrace
  20:     0x7fd0892b30ae - rustc_query_impl[6a84ebe04ccf7fcc]::execution::try_execute_query::<rustc_middle[f785d3947f0fb584]::query::caches::DefaultCache<(rustc_middle[f785d3947f0fb584]::ty::instance::Instance, rustc_middle[f785d3947f0fb584]::mono::CollectionMode), rustc_middle[f785d3947f0fb584]::query::erase::ErasedData<[u8; 32usize]>>, false>
  21:     0x7fd0892b2d17 - rustc_query_impl[6a84ebe04ccf7fcc]::query_impl::items_of_instance::execute_query_non_incr::__rust_end_short_backtrace
  22:     0x7fd0897276f1 - rustc_monomorphize[ccd7379517a8b282]::collector::collect_items_rec
  23:     0x7fd0897294f7 - rustc_monomorphize[ccd7379517a8b282]::collector::collect_items_rec
  24:     0x7fd08971f13f - rustc_monomorphize[ccd7379517a8b282]::collector::collect_crate_mono_items::{closure#1}::{closure#0}
  25:     0x7fd08971fdf7 - rustc_monomorphize[ccd7379517a8b282]::partitioning::collect_and_partition_mono_items
  26:     0x7fd08971faaa - rustc_query_impl[6a84ebe04ccf7fcc]::query_impl::collect_and_partition_mono_items::invoke_provider_fn::__rust_begin_short_backtrace
  27:     0x7fd0899d27ae - rustc_query_impl[6a84ebe04ccf7fcc]::execution::try_execute_query::<rustc_middle[f785d3947f0fb584]::query::caches::SingleCache<rustc_middle[f785d3947f0fb584]::query::erase::ErasedData<[u8; 24usize]>>, false>
  28:     0x7fd0899d2544 - rustc_query_impl[6a84ebe04ccf7fcc]::query_impl::collect_and_partition_mono_items::execute_query_non_incr::__rust_end_short_backtrace
  29:     0x7fd089a9eef2 - rustc_codegen_ssa[b5faf784774b9c59]::base::codegen_crate::<rustc_codegen_llvm[d170d6b482ddc43e]::LlvmCodegenBackend, rustc_codegen_llvm[d170d6b482ddc43e]::ModuleLlvm>
  30:     0x7fd089a9ec0d - <rustc_codegen_llvm[d170d6b482ddc43e]::LlvmCodegenBackend as rustc_codegen_ssa[b5faf784774b9c59]::traits::backend::CodegenBackend>::codegen_crate
  31:     0x7fd089987b5c - <rustc_interface[fcb53972e547428a]::queries::Linker>::codegen_and_build_linker
  32:     0x7fd0899821da - rustc_interface[fcb53972e547428a]::interface::run_compiler::<(), rustc_driver_impl[17e5fc0182803539]::run_compiler::{closure#0}>::{closure#1}
  33:     0x7fd089a0547a - std[210f122337a7df4c]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[fcb53972e547428a]::util::run_in_thread_with_globals<rustc_interface[fcb53972e547428a]::util::run_in_thread_pool_with_globals<rustc_interface[fcb53972e547428a]::interface::run_compiler<(), rustc_driver_impl[17e5fc0182803539]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  34:     0x7fd089a0522d - <std[210f122337a7df4c]::thread::lifecycle::spawn_unchecked<rustc_interface[fcb53972e547428a]::util::run_in_thread_with_globals<rustc_interface[fcb53972e547428a]::util::run_in_thread_pool_with_globals<rustc_interface[fcb53972e547428a]::interface::run_compiler<(), rustc_driver_impl[17e5fc0182803539]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[56696922243b1362]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  35:     0x7fd08975ec92 - <std[210f122337a7df4c]::sys::thread::unix::Thread>::new::thread_start
  36:     0x7fd082e981b9 - <unknown>
  37:     0x7fd082f1d21c - <unknown>
  38:                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: please attach the file at `/tmp/assumptions/rustc-ice-2026-06-10T20_20_57-1430114.txt` to your bug report

note: rustc 1.98.0-nightly (beae78130 2026-06-09) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z assumptions-on-binders -Z next-solver=globally

query stack during panic:
#0 [items_of_instance] collecting items used by `f::<()>`
#1 [collect_and_partition_mono_items] collect_and_partition_mono_items
end of query stack
error: aborting due to 1 previous error; 2 warnings emitted

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    -Zassumptions-on-bindersUnstable option: `-Zassumptions-on-bindersC-bugCategory: This is a bug.I-ICEIssue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️T-compilerRelevant to the compiler team, which will review and decide on the PR/issue.WG-trait-system-refactorThe Rustc Trait System Refactor Initiative (-Znext-solver)needs-triageThis issue may need triage. Remove it if it has been sufficiently triaged.

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