ICE: unelided lifetime in signature

[matthiaskrgr]

auto-reduced (treereduce-rust):

#![feature(min_generic_const_args)]
#![feature(inherent_associated_types)]
struct Foo<'a> {
    x: &'a (),
}

impl<'a> Foo<'a> {
    fn foo(_: [u8; Foo::X]) {}
}

fn main() {}

original:

struct Foo<'a> { x: &'a () }

impl<'a> Foo<'a> {
    const X: usize = 0;

    fn foo(_: [u8; Foo::X]) {}
}


fn main() {}

Version information

rustc 1.87.0-nightly (e6af292f9 2025-03-06)
binary: rustc
commit-hash: e6af292f91f21f12ac1aab6825efb7e1e3381cbb
commit-date: 2025-03-06
host: x86_64-unknown-linux-gnu
release: 1.87.0-nightly
LLVM version: 20.1.0

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc -Zcrate-attr=feature(min_generic_const_args) -Zcrate-attr=feature(inherent_associated_types)

Program output

warning: the feature `min_generic_const_args` is incomplete and may not be safe to use and/or cause compiler crashes
 --> <crate attribute>:1:9
  |
1 | feature(min_generic_const_args)
  |         ^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #132980 <https://github.com/rust-lang/rust/issues/132980> for more information
  = note: `#[warn(incomplete_features)]` on by default

warning: the feature `inherent_associated_types` is incomplete and may not be safe to use and/or cause compiler crashes
 --> <crate attribute>:1:9
  |
1 | feature(inherent_associated_types)
  |         ^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #8995 <https://github.com/rust-lang/rust/issues/8995> for more information

warning: struct `Foo` is never constructed
 --> /tmp/icemaker_global_tempdir.6nb7eU6SZYdW/rustc_testrunner_tmpdir_reporting.kLVtKi15t0YT/mvce.rs:1:8
  |
1 | struct Foo<'a> {
  |        ^^^
  |
  = note: `#[warn(dead_code)]` on by default

warning: associated function `foo` is never used
 --> /tmp/icemaker_global_tempdir.6nb7eU6SZYdW/rustc_testrunner_tmpdir_reporting.kLVtKi15t0YT/mvce.rs:6:8
  |
5 | impl<'a> Foo<'a> {
  | ---------------- associated function in this implementation
6 |     fn foo(_: [u8; Foo::X]) {}
  |        ^^^

warning: 4 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: unelided lifetime in signature
 --> /tmp/icemaker_global_tempdir.6nb7eU6SZYdW/rustc_testrunner_tmpdir_reporting.kLVtKi15t0YT/mvce.rs:6:20
  |
6 |     fn foo(_: [u8; Foo::X]) {}
  |                    ^^^
  |
note: delayed at compiler/rustc_hir_analysis/src/collect.rs:417:13
         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: <rustc_hir_analysis::collect::ItemCtxt as rustc_hir_analysis::hir_ty_lowering::HirTyLowerer>::re_infer
         5: <dyn rustc_hir_analysis::hir_ty_lowering::HirTyLowerer>::lower_path
         6: <dyn rustc_hir_analysis::hir_ty_lowering::HirTyLowerer>::lower_ty
         7: <dyn rustc_hir_analysis::hir_ty_lowering::HirTyLowerer>::lower_const_arg
         8: <dyn rustc_hir_analysis::hir_ty_lowering::HirTyLowerer>::lower_ty
         9: <dyn rustc_hir_analysis::hir_ty_lowering::HirTyLowerer>::lower_fn_ty
        10: rustc_hir_analysis::collect::lower_fn_sig_recovering_infer_ret_ty
        11: rustc_hir_analysis::collect::fn_sig
        12: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::fn_sig::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 24]>>
        13: <rustc_query_impl::query_impl::fn_sig::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_span::def_id::DefId)>>::call_once
        14: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::DefIdCache<rustc_middle::query::erase::Erased<[u8; 24]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, false>
        15: rustc_query_impl::query_impl::fn_sig::get_query_non_incr::__rust_end_short_backtrace
        16: rustc_middle::query::plumbing::query_get_at::<rustc_query_system::query::caches::DefIdCache<rustc_middle::query::erase::Erased<[u8; 24]>>>
        17: <rustc_hir_analysis::variance::constraints::ConstraintContext>::build_constraints_for_item
        18: rustc_hir_analysis::variance::crate_variances
        19: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::crate_variances::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 8]>>
        20: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 8]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, false>
        21: rustc_query_impl::query_impl::crate_variances::get_query_non_incr::__rust_end_short_backtrace
        22: rustc_hir_analysis::variance::variances_of
        23: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::variances_of::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 16]>>
        24: <rustc_query_impl::query_impl::variances_of::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_span::def_id::DefId)>>::call_once
        25: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::DefIdCache<rustc_middle::query::erase::Erased<[u8; 16]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, false>
        26: rustc_query_impl::query_impl::variances_of::get_query_non_incr::__rust_end_short_backtrace
        27: rustc_middle::query::plumbing::query_get_at::<rustc_query_system::query::caches::DefIdCache<rustc_middle::query::erase::Erased<[u8; 16]>>>
        28: rustc_hir_analysis::check::wfcheck::check_variances_for_type_defn
        29: rustc_hir_analysis::check::wfcheck::check_well_formed
        30: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 1]>>
        31: 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; 1]>, rustc_query_system::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, false>
        32: rustc_query_impl::query_impl::check_well_formed::get_query_non_incr::__rust_end_short_backtrace
        33: rustc_hir_analysis::check::wfcheck::check_mod_type_wf
        34: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::check_mod_type_wf::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 1]>>
        35: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::DefaultCache<rustc_span::def_id::LocalModDefId, rustc_middle::query::erase::Erased<[u8; 1]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, false>
        36: rustc_query_impl::query_impl::check_mod_type_wf::get_query_non_incr::__rust_end_short_backtrace
        37: rustc_hir_analysis::check_crate
        38: rustc_interface::passes::run_required_analyses
        39: rustc_interface::passes::analysis
        40: 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]>>
        41: 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>
        42: rustc_query_impl::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
        43: 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}
        44: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
        45: 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}, ()>
        46: <<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}
        47: std::sys::pal::unix::thread::Thread::new::thread_start
        48: <unknown>
        49: <unknown>
 --> /tmp/icemaker_global_tempdir.6nb7eU6SZYdW/rustc_testrunner_tmpdir_reporting.kLVtKi15t0YT/mvce.rs:6:20
  |
6 |     fn foo(_: [u8; Foo::X]) {}
  |                    ^^^

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 (e6af292f9 2025-03-06) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z crate-attr=feature(min_generic_const_args) -Z crate-attr=feature(inherent_associated_types) -Z dump-mir-dir=dir

query stack during panic:
end of query stack

@rustbot label +F-min_generic_const_args +F-inherent_associated_types