ICE: begin <= end (12 <= 11) when slicing 'Self::Assoc<'_>'

[matthiaskrgr]

snippet:

trait MemoryUnit {
    extern "C" fn read_word(&mut self) -> u8;
    extern "C" fn read_dword(Self::Assoc<'_>) -> u16;
}

struct ROM {}

impl MemoryUnit for ROM {
    extern "C" fn read_dword(&'s self) -> u16 {
        let a16 = self.read_word() as u16;
        let b16 = self.read_word() as u16;

        (b16 << 8) | a16
    }
}

Version information

rustc 1.78.0-nightly (384d26fc7 2024-02-29)
binary: rustc
commit-hash: 384d26fc7e3bdd7687cc17b2662b091f6017ec2a
commit-date: 2024-02-29
host: x86_64-unknown-linux-gnu
release: 1.78.0-nightly
LLVM version: 18.1.0

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

Program output

error[E0261]: use of undeclared lifetime name `'s`
 --> /tmp/icemaker_global_tempdir.TDgy1iqr90fd/rustc_testrunner_tmpdir_reporting.nnRae760BqGM/mvce.rs:9:31
  |
9 |     extern "C" fn read_dword(&'s self) -> u16 {
  |                               ^^ undeclared lifetime
  |
help: consider introducing lifetime `'s` here
  |
9 |     extern "C" fn read_dword<'s>(&'s self) -> u16 {
  |                             ++++
help: consider introducing lifetime `'s` here
  |
8 | impl<'s> MemoryUnit for ROM {
  |     ++++

warning: anonymous parameters are deprecated and will be removed in the next edition
 --> /tmp/icemaker_global_tempdir.TDgy1iqr90fd/rustc_testrunner_tmpdir_reporting.nnRae760BqGM/mvce.rs:3:30
  |
3 |     extern "C" fn read_dword(Self::Assoc<'_>) -> u16;
  |                              ^^^^^^^^^^^^^^^ help: try naming the parameter or explicitly ignoring it: `_: Self::Assoc<'_>`
  |
  = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2018!
  = note: for more information, see issue #41686 <https://github.com/rust-lang/rust/issues/41686>
  = note: `#[warn(anonymous_parameters)]` on by default

error[E0601]: `main` function not found in crate `mvce`
  --> /tmp/icemaker_global_tempdir.TDgy1iqr90fd/rustc_testrunner_tmpdir_reporting.nnRae760BqGM/mvce.rs:15:2
   |
15 | }
   |  ^ consider adding a `main` function to `/tmp/icemaker_global_tempdir.TDgy1iqr90fd/rustc_testrunner_tmpdir_reporting.nnRae760BqGM/mvce.rs`

error[E0220]: associated type `Assoc` not found for `Self`
 --> /tmp/icemaker_global_tempdir.TDgy1iqr90fd/rustc_testrunner_tmpdir_reporting.nnRae760BqGM/mvce.rs:3:36
  |
3 |     extern "C" fn read_dword(Self::Assoc<'_>) -> u16;
  |                                    ^^^^^ associated type `Assoc` not found

error[E0185]: method `read_dword` has a `&self` declaration in the impl, but not in the trait
 --> /tmp/icemaker_global_tempdir.TDgy1iqr90fd/rustc_testrunner_tmpdir_reporting.nnRae760BqGM/mvce.rs:9:5
  |
3 |     extern "C" fn read_dword(Self::Assoc<'_>) -> u16;
  |     ------------------------------------------------- trait method declared without `&self`
...
9 |     extern "C" fn read_dword(&'s self) -> u16 {
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `&self` used in impl

error[E0046]: not all trait items implemented, missing: `read_word`
 --> /tmp/icemaker_global_tempdir.TDgy1iqr90fd/rustc_testrunner_tmpdir_reporting.nnRae760BqGM/mvce.rs:8:1
  |
2 |     extern "C" fn read_word(&mut self) -> u8;
  |     ----------------------------------------- `read_word` from trait
...
8 | impl MemoryUnit for ROM {
  | ^^^^^^^^^^^^^^^^^^^^^^^ missing `read_word` in implementation

thread 'rustc' panicked at compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs:1368:48:
begin <= end (12 <= 11) when slicing `Self::Assoc<'_>`
stack backtrace:
   0:     0x7f752178cd36 - std::backtrace_rs::backtrace::libunwind::trace::h3a19003a2649a042
                               at /rustc/384d26fc7e3bdd7687cc17b2662b091f6017ec2a/library/std/src/../../backtrace/src/backtrace/libunwind.rs:104:5
   1:     0x7f752178cd36 - std::backtrace_rs::backtrace::trace_unsynchronized::hafb8387fdb677ced
                               at /rustc/384d26fc7e3bdd7687cc17b2662b091f6017ec2a/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f752178cd36 - std::sys_common::backtrace::_print_fmt::h773b2eb83e893aac
                               at /rustc/384d26fc7e3bdd7687cc17b2662b091f6017ec2a/library/std/src/sys_common/backtrace.rs:68:5
   3:     0x7f752178cd36 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hf9c4b0aaffae0e26
                               at /rustc/384d26fc7e3bdd7687cc17b2662b091f6017ec2a/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7f75217ddc8c - core::fmt::rt::Argument::fmt::hd27bd8720fbe360b
                               at /rustc/384d26fc7e3bdd7687cc17b2662b091f6017ec2a/library/core/src/fmt/rt.rs:142:9
   5:     0x7f75217ddc8c - core::fmt::write::h302aead198f704a5
                               at /rustc/384d26fc7e3bdd7687cc17b2662b091f6017ec2a/library/core/src/fmt/mod.rs:1120:17
   6:     0x7f752178159f - std::io::Write::write_fmt::h47ac46bdbb511a9b
                               at /rustc/384d26fc7e3bdd7687cc17b2662b091f6017ec2a/library/std/src/io/mod.rs:1846:15
   7:     0x7f752178cae4 - std::sys_common::backtrace::_print::hbe00a1350460cf41
                               at /rustc/384d26fc7e3bdd7687cc17b2662b091f6017ec2a/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7f752178cae4 - std::sys_common::backtrace::print::hfc2bd9d3d47d4566
                               at /rustc/384d26fc7e3bdd7687cc17b2662b091f6017ec2a/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7f752178f81b - std::panicking::default_hook::{{closure}}::hb9ff0341655a5c73
  10:     0x7f752178f577 - std::panicking::default_hook::hf368561d0cd93e13
                               at /rustc/384d26fc7e3bdd7687cc17b2662b091f6017ec2a/library/std/src/panicking.rs:292:9
  11:     0x7f75246a4a7c - std[fbb42328cecafc22]::panicking::update_hook::<alloc[c93a5f242b466a42]::boxed::Box<rustc_driver_impl[9cf1776aae3c094]::install_ice_hook::{closure#0}>>::{closure#0}
  12:     0x7f752178ff80 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h2e1de234f5eaee61
                               at /rustc/384d26fc7e3bdd7687cc17b2662b091f6017ec2a/library/alloc/src/boxed.rs:2030:9
  13:     0x7f752178ff80 - std::panicking::rust_panic_with_hook::he0aaa3480ffc94b9
                               at /rustc/384d26fc7e3bdd7687cc17b2662b091f6017ec2a/library/std/src/panicking.rs:783:13
  14:     0x7f752178fcc2 - std::panicking::begin_panic_handler::{{closure}}::h8a6e565b7e092d89
                               at /rustc/384d26fc7e3bdd7687cc17b2662b091f6017ec2a/library/std/src/panicking.rs:657:13
  15:     0x7f752178d216 - std::sys_common::backtrace::__rust_end_short_backtrace::h396ef3d27803de1f
                               at /rustc/384d26fc7e3bdd7687cc17b2662b091f6017ec2a/library/std/src/sys_common/backtrace.rs:171:18
  16:     0x7f752178f9f4 - rust_begin_unwind
                               at /rustc/384d26fc7e3bdd7687cc17b2662b091f6017ec2a/library/std/src/panicking.rs:645:5
  17:     0x7f75217da1a5 - core::panicking::panic_fmt::h08e652d54c9df8f0
                               at /rustc/384d26fc7e3bdd7687cc17b2662b091f6017ec2a/library/core/src/panicking.rs:72:14
  18:     0x7f75217e23b8 - core::str::slice_error_fail_rt::h2b2d3394853a6979
  19:     0x7f75217e2207 - core::str::slice_error_fail::hef6f34374c73c39c
                               at /rustc/384d26fc7e3bdd7687cc17b2662b091f6017ec2a/library/core/src/str/mod.rs:91:9
  20:     0x7f75244b0753 - rustc_borrowck[f1c2b069dd61b1a9]::diagnostics::mutability_errors::suggest_ampmut_self
  21:     0x7f75244af392 - <rustc_borrowck[f1c2b069dd61b1a9]::MirBorrowckCtxt>::suggest_make_local_mut
  22:     0x7f75230ef759 - <rustc_borrowck[f1c2b069dd61b1a9]::MirBorrowckCtxt>::report_mutability_error
  23:     0x7f7526865418 - rustc_borrowck[f1c2b069dd61b1a9]::do_mir_borrowck
  24:     0x7f752681485e - rustc_borrowck[f1c2b069dd61b1a9]::mir_borrowck
  25:     0x7f7526814317 - rustc_query_impl[1640d3938b91755e]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[1640d3938b91755e]::query_impl::mir_borrowck::dynamic_query::{closure#2}::{closure#0}, rustc_middle[29894b38651fd55d]::query::erase::Erased<[u8; 8usize]>>
  26:     0x7f7525baa770 - rustc_query_system[9c626cf6262cf6c2]::query::plumbing::try_execute_query::<rustc_query_impl[1640d3938b91755e]::DynamicConfig<rustc_query_system[9c626cf6262cf6c2]::query::caches::VecCache<rustc_span[e214f2a58174522b]::def_id::LocalDefId, rustc_middle[29894b38651fd55d]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[1640d3938b91755e]::plumbing::QueryCtxt, false>
  27:     0x7f7525baa34c - rustc_query_impl[1640d3938b91755e]::query_impl::mir_borrowck::get_query_non_incr::__rust_end_short_backtrace
  28:     0x7f75266ae98c - rustc_interface[c8c0a49aa2897191]::passes::analysis
  29:     0x7f75266ae499 - rustc_query_impl[1640d3938b91755e]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[1640d3938b91755e]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[29894b38651fd55d]::query::erase::Erased<[u8; 1usize]>>
  30:     0x7f75267326a5 - rustc_query_system[9c626cf6262cf6c2]::query::plumbing::try_execute_query::<rustc_query_impl[1640d3938b91755e]::DynamicConfig<rustc_query_system[9c626cf6262cf6c2]::query::caches::SingleCache<rustc_middle[29894b38651fd55d]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[1640d3938b91755e]::plumbing::QueryCtxt, false>
  31:     0x7f7526732409 - rustc_query_impl[1640d3938b91755e]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  32:     0x7f7526739f3c - rustc_interface[c8c0a49aa2897191]::interface::run_compiler::<core[3e98a99d3b4a7fa7]::result::Result<(), rustc_span[e214f2a58174522b]::ErrorGuaranteed>, rustc_driver_impl[9cf1776aae3c094]::run_compiler::{closure#0}>::{closure#0}
  33:     0x7f75269de105 - std[fbb42328cecafc22]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[c8c0a49aa2897191]::util::run_in_thread_with_globals<rustc_interface[c8c0a49aa2897191]::util::run_in_thread_pool_with_globals<rustc_interface[c8c0a49aa2897191]::interface::run_compiler<core[3e98a99d3b4a7fa7]::result::Result<(), rustc_span[e214f2a58174522b]::ErrorGuaranteed>, rustc_driver_impl[9cf1776aae3c094]::run_compiler::{closure#0}>::{closure#0}, core[3e98a99d3b4a7fa7]::result::Result<(), rustc_span[e214f2a58174522b]::ErrorGuaranteed>>::{closure#0}, core[3e98a99d3b4a7fa7]::result::Result<(), rustc_span[e214f2a58174522b]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[3e98a99d3b4a7fa7]::result::Result<(), rustc_span[e214f2a58174522b]::ErrorGuaranteed>>
  34:     0x7f75269ddf32 - <<std[fbb42328cecafc22]::thread::Builder>::spawn_unchecked_<rustc_interface[c8c0a49aa2897191]::util::run_in_thread_with_globals<rustc_interface[c8c0a49aa2897191]::util::run_in_thread_pool_with_globals<rustc_interface[c8c0a49aa2897191]::interface::run_compiler<core[3e98a99d3b4a7fa7]::result::Result<(), rustc_span[e214f2a58174522b]::ErrorGuaranteed>, rustc_driver_impl[9cf1776aae3c094]::run_compiler::{closure#0}>::{closure#0}, core[3e98a99d3b4a7fa7]::result::Result<(), rustc_span[e214f2a58174522b]::ErrorGuaranteed>>::{closure#0}, core[3e98a99d3b4a7fa7]::result::Result<(), rustc_span[e214f2a58174522b]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[3e98a99d3b4a7fa7]::result::Result<(), rustc_span[e214f2a58174522b]::ErrorGuaranteed>>::{closure#1} as core[3e98a99d3b4a7fa7]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  35:     0x7f7521799955 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h1310005556baa0fc
                               at /rustc/384d26fc7e3bdd7687cc17b2662b091f6017ec2a/library/alloc/src/boxed.rs:2016:9
  36:     0x7f7521799955 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h55d902c3660dd7c9
                               at /rustc/384d26fc7e3bdd7687cc17b2662b091f6017ec2a/library/alloc/src/boxed.rs:2016:9
  37:     0x7f7521799955 - std::sys::pal::unix::thread::Thread::new::thread_start::h5bd490f6a8b2e778
                               at /rustc/384d26fc7e3bdd7687cc17b2662b091f6017ec2a/library/std/src/sys/pal/unix/thread.rs:108:17
  38:     0x7f752158155a - <unknown>
  39:     0x7f75215fea3c - <unknown>
  40:                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: rustc 1.78.0-nightly (384d26fc7 2024-02-29) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [mir_borrowck] borrow-checking `<impl at /tmp/icemaker_global_tempdir.TDgy1iqr90fd/rustc_testrunner_tmpdir_reporting.nnRae760BqGM/mvce.rs:8:1: 8:24>::read_dword`
#1 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 5 previous errors; 1 warning emitted

Some errors have detailed explanations: E0046, E0185, E0220, E0261, E0601.
For more information about an error, try `rustc --explain E0046`.

[matthiaskrgr]

#120550 cc @oli-obk