ICE: trait object trait bounds reference Self

[matthiaskrgr]

auto-reduced (treereduce-rust):

trait FromResidual<R = <Self as Try>::Residual> {}

trait Try {
    type Residual;
}

fn w<U>() {
    let b: &dyn FromResidual = &();
}

fn main() {}

original:

trait FromResidual<R = <Self as Try>::Residual> {
    fn y(self) -> isize;
}

trait Try {
    type Residual;
}

fn w<U>() {
    let b: &dyn FromResidual = &();
    //~^ ERROR: the trait `FromResidual` is not dyn compatible
    //~| ERROR: the trait `FromResidual` is not dyn compatible
}

fn main() {}

Version information

rustc 1.86.0-nightly (3cd8fcbf8 2025-01-23)
binary: rustc
commit-hash: 3cd8fcbf87bd28a1f31be000ca906fb66f4d451d
commit-date: 2025-01-23
host: x86_64-unknown-linux-gnu
release: 1.86.0-nightly
LLVM version: 19.1.7

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

Program output

warning: trait `FromResidual` is never used
 --> /tmp/icemaker_global_tempdir.48NMtvPAjGxe/rustc_testrunner_tmpdir_reporting.LRiH8Fwh0jxX/mvce.rs:1:7
  |
1 | trait FromResidual<R = <Self as Try>::Residual> {}
  |       ^^^^^^^^^^^^
  |
  = note: `#[warn(dead_code)]` on by default

warning: trait `Try` is never used
 --> /tmp/icemaker_global_tempdir.48NMtvPAjGxe/rustc_testrunner_tmpdir_reporting.LRiH8Fwh0jxX/mvce.rs:3:7
  |
3 | trait Try {
  |       ^^^

warning: function `w` is never used
 --> /tmp/icemaker_global_tempdir.48NMtvPAjGxe/rustc_testrunner_tmpdir_reporting.LRiH8Fwh0jxX/mvce.rs:7:4
  |
7 | fn w<U>() {
  |    ^

warning: 3 warnings emitted

note: no errors encountered even though delayed bugs were created

note: those delayed bugs will now be shown as internal compiler errors

error: internal compiler error: trait object trait bounds reference `Self`
 --> /tmp/icemaker_global_tempdir.48NMtvPAjGxe/rustc_testrunner_tmpdir_reporting.LRiH8Fwh0jxX/mvce.rs:8:17
  |
8 |     let b: &dyn FromResidual = &();
  |                 ^^^^^^^^^^^^
  |
note: delayed at compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs:245:51
         0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
         1: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
         2: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
         3: <rustc_errors::DiagCtxtHandle>::span_delayed_bug::<rustc_span::span_encoding::Span, &str>
         4: <dyn rustc_hir_analysis::hir_ty_lowering::HirTyLowerer>::lower_trait_object_ty
         5: <dyn rustc_hir_analysis::hir_ty_lowering::HirTyLowerer>::lower_ty
         6: <dyn rustc_hir_analysis::hir_ty_lowering::HirTyLowerer>::lower_ty
         7: <rustc_hir_typeck::gather_locals::GatherLocalsVisitor as rustc_hir::intravisit::Visitor>::visit_local
         8: <rustc_hir_typeck::gather_locals::GatherLocalsVisitor as rustc_hir::intravisit::Visitor>::visit_expr
         9: rustc_hir_typeck::check::check_fn
        10: rustc_hir_typeck::typeck_with_inspect::{closure#0}
        11: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::typeck::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 8]>>
        12: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::Erased<[u8; 8]>, rustc_query_system::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, false>
        13: rustc_query_impl::query_impl::typeck::get_query_non_incr::__rust_end_short_backtrace
        14: <rustc_middle::hir::map::Map>::par_body_owners::<rustc_hir_analysis::check_crate::{closure#4}>::{closure#0}
        15: rustc_hir_analysis::check_crate
        16: rustc_interface::passes::run_required_analyses
        17: rustc_interface::passes::analysis
        18: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 0]>>
        19: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 0]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, false>
        20: rustc_query_impl::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
        21: rustc_interface::passes::create_and_enter_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
        22: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
        23: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
        24: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
        25: std::sys::pal::unix::thread::Thread::new::thread_start
        26: <unknown>
        27: <unknown>
 --> /tmp/icemaker_global_tempdir.48NMtvPAjGxe/rustc_testrunner_tmpdir_reporting.LRiH8Fwh0jxX/mvce.rs:8:17
  |
8 |     let b: &dyn FromResidual = &();
  |                 ^^^^^^^^^^^^

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 (3cd8fcbf8 2025-01-23) running on x86_64-unknown-linux-gnu

query stack during panic:
end of query stack

[matthiaskrgr]

regression in #133830 cc @compiler-errors

[matthiaskrgr]

trait A<C = <Self as D>::E> {}

trait D {
    type E;
}

fn f() {
    let B: dyn A = todo!();
}

fn main() {}