rustc panic on invalid input (maybe due to name collision)?

[QuinnFreedman]

I made an error where I forgot to include the &self in this minimal trait example. Also, there were multiple trait methods with the same name. It seems like the combination of these things causes a rustc panic.

Code

trait Foo {
    fn f();
}

trait Bar {
    fn f();
}

struct Baz {}

impl Foo for Baz {
    fn f() {
        println!("F");
    }
}


fn main() {
    let b = Baz {};
    b.f();
    println!("Hello");
}

This is currently reproducible in this Rust Playground https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=eb7703a056233d9756edffd5eadcd3e6

Meta

rustc --version --verbose:

rustc 1.75.0 (82e1608df 2023-12-21) running on x86_64-unknown-linux-gnu

Error output

   Compiling playground v0.0.1 (/playground)
thread 'rustc' panicked at compiler/rustc_hir_typeck/src/method/suggest.rs:3299:28:
index out of bounds: the len is 0 but the index is 0
stack backtrace:
   0:     0x7fa49bc5262c - std::backtrace_rs::backtrace::libunwind::trace::ha637c64ce894333a
                               at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/../../backtrace/src/backtrace/libunwind.rs:104:5
   1:     0x7fa49bc5262c - std::backtrace_rs::backtrace::trace_unsynchronized::h47f62dea28e0c88d
                               at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7fa49bc5262c - std::sys_common::backtrace::_print_fmt::h9eef0abe20ede486
                               at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/sys_common/backtrace.rs:67:5
   3:     0x7fa49bc5262c - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hed7f999df88cc644
                               at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7fa49bca5630 - core::fmt::rt::Argument::fmt::h1539a9308b8d058d
                               at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/core/src/fmt/rt.rs:142:9
   5:     0x7fa49bca5630 - core::fmt::write::h3a39390d8560d9c9
                               at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/core/src/fmt/mod.rs:1120:17
   6:     0x7fa49bc4654f - std::io::Write::write_fmt::h5fc9997dfe05f882
                               at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/io/mod.rs:1762:15
   7:     0x7fa49bc52414 - std::sys_common::backtrace::_print::h894006fb5c6f3d45
                               at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7fa49bc52414 - std::sys_common::backtrace::print::h23a2d212c6fff936
                               at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7fa49bc550a7 - std::panicking::default_hook::{{closure}}::h8a1d2ee00185001a
  10:     0x7fa49bc54e0f - std::panicking::default_hook::h6038f2eba384e475
                               at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/panicking.rs:292:9
  11:     0x7fa49e7fe190 - std[409886f6357001f0]::panicking::update_hook::<alloc[c1b021ad36e35877]::boxed::Box<rustc_driver_impl[7d23c5715ff089db]::install_ice_hook::{closure#0}>>::{closure#0}
  12:     0x7fa49bc557e8 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h1f8f335eaa9cfaee
                               at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/alloc/src/boxed.rs:2021:9
  13:     0x7fa49bc557e8 - std::panicking::rust_panic_with_hook::h2b5517d590cab22e
                               at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/panicking.rs:783:13
  14:     0x7fa49bc5553e - std::panicking::begin_panic_handler::{{closure}}::h233112c06e0ef43e
                               at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/panicking.rs:657:13
  15:     0x7fa49bc52af6 - std::sys_common::backtrace::__rust_end_short_backtrace::h6e893f24d7ebbff8
                               at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/sys_common/backtrace.rs:170:18
  16:     0x7fa49bc552a2 - rust_begin_unwind
                               at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/panicking.rs:645:5
  17:     0x7fa49bca1d15 - core::panicking::panic_fmt::hbf0e066aabfa482c
                               at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/core/src/panicking.rs:72:14
  18:     0x7fa49bca1f32 - core::panicking::panic_bounds_check::h326a19b32dc06d6d
                               at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/core/src/panicking.rs:190:5
  19:     0x7fa49ea093a4 - rustc_hir_typeck[2eba1876834da1d1]::method::suggest::print_disambiguation_help
  20:     0x7fa49e9fdaa1 - <rustc_hir_typeck[2eba1876834da1d1]::fn_ctxt::FnCtxt>::note_candidates_on_method_error
  21:     0x7fa49e9f43f0 - <rustc_hir_typeck[2eba1876834da1d1]::fn_ctxt::FnCtxt>::report_no_match_method_error
  22:     0x7fa49ea18135 - <rustc_hir_typeck[2eba1876834da1d1]::fn_ctxt::FnCtxt>::report_method_error
  23:     0x7fa4a0591026 - <rustc_hir_typeck[2eba1876834da1d1]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  24:     0x7fa4a003f599 - <rustc_hir_typeck[2eba1876834da1d1]::fn_ctxt::FnCtxt>::check_block_with_expected
  25:     0x7fa4a05877a9 - <rustc_hir_typeck[2eba1876834da1d1]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  26:     0x7fa4a02824fe - rustc_hir_typeck[2eba1876834da1d1]::check::check_fn
  27:     0x7fa49fe1c353 - rustc_hir_typeck[2eba1876834da1d1]::typeck
  28:     0x7fa49fe1b7c7 - rustc_query_impl[664ae873a521fa7c]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[664ae873a521fa7c]::query_impl::typeck::dynamic_query::{closure#2}::{closure#0}, rustc_middle[aca4860da4e5a967]::query::erase::Erased<[u8; 8usize]>>
  29:     0x7fa49fbcc9ec - rustc_query_system[b5dcdc06a735d5f1]::query::plumbing::try_execute_query::<rustc_query_impl[664ae873a521fa7c]::DynamicConfig<rustc_query_system[b5dcdc06a735d5f1]::query::caches::VecCache<rustc_span[3d5dc97049ad8d50]::def_id::LocalDefId, rustc_middle[aca4860da4e5a967]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[664ae873a521fa7c]::plumbing::QueryCtxt, false>
  30:     0x7fa49fbcc6d0 - rustc_query_impl[664ae873a521fa7c]::query_impl::typeck::get_query_non_incr::__rust_end_short_backtrace
  31:     0x7fa49ff4a943 - rustc_hir_analysis[eb447668a4654582]::check_crate
  32:     0x7fa4a0154b59 - rustc_interface[fbb0cb4be6c0ba34]::passes::analysis
  33:     0x7fa4a0154575 - rustc_query_impl[664ae873a521fa7c]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[664ae873a521fa7c]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[aca4860da4e5a967]::query::erase::Erased<[u8; 1usize]>>
  34:     0x7fa4a05ec766 - rustc_query_system[b5dcdc06a735d5f1]::query::plumbing::try_execute_query::<rustc_query_impl[664ae873a521fa7c]::DynamicConfig<rustc_query_system[b5dcdc06a735d5f1]::query::caches::SingleCache<rustc_middle[aca4860da4e5a967]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[664ae873a521fa7c]::plumbing::QueryCtxt, false>
  35:     0x7fa4a05ec595 - rustc_query_impl[664ae873a521fa7c]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  36:     0x7fa4a08ce021 - rustc_interface[fbb0cb4be6c0ba34]::interface::run_compiler::<core[21cdcf8e8af4c2d9]::result::Result<(), rustc_span[3d5dc97049ad8d50]::ErrorGuaranteed>, rustc_driver_impl[7d23c5715ff089db]::run_compiler::{closure#1}>::{closure#0}
  37:     0x7fa4a08c915b - std[409886f6357001f0]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[fbb0cb4be6c0ba34]::util::run_in_thread_with_globals<rustc_interface[fbb0cb4be6c0ba34]::interface::run_compiler<core[21cdcf8e8af4c2d9]::result::Result<(), rustc_span[3d5dc97049ad8d50]::ErrorGuaranteed>, rustc_driver_impl[7d23c5715ff089db]::run_compiler::{closure#1}>::{closure#0}, core[21cdcf8e8af4c2d9]::result::Result<(), rustc_span[3d5dc97049ad8d50]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[21cdcf8e8af4c2d9]::result::Result<(), rustc_span[3d5dc97049ad8d50]::ErrorGuaranteed>>
  38:     0x7fa4a08c8fb3 - <<std[409886f6357001f0]::thread::Builder>::spawn_unchecked_<rustc_interface[fbb0cb4be6c0ba34]::util::run_in_thread_with_globals<rustc_interface[fbb0cb4be6c0ba34]::interface::run_compiler<core[21cdcf8e8af4c2d9]::result::Result<(), rustc_span[3d5dc97049ad8d50]::ErrorGuaranteed>, rustc_driver_impl[7d23c5715ff089db]::run_compiler::{closure#1}>::{closure#0}, core[21cdcf8e8af4c2d9]::result::Result<(), rustc_span[3d5dc97049ad8d50]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[21cdcf8e8af4c2d9]::result::Result<(), rustc_span[3d5dc97049ad8d50]::ErrorGuaranteed>>::{closure#1} as core[21cdcf8e8af4c2d9]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  39:     0x7fa49bc5f6a5 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hc7eafaff61e32df9
                               at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/alloc/src/boxed.rs:2007:9
  40:     0x7fa49bc5f6a5 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h6ba4a5de48dd2304
                               at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/alloc/src/boxed.rs:2007:9
  41:     0x7fa49bc5f6a5 - std::sys::unix::thread::Thread::new::thread_start::he469335aef763e45
                               at /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/sys/unix/thread.rs:108:17
  42:     0x7fa49bb77609 - start_thread
  43:     0x7fa49ba9a353 - clone
  44:                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 1.75.0 (82e1608df 2023-12-21) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type bin -C embed-bitcode=no -C codegen-units=1 -C debuginfo=2

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
#0 [typeck] type-checking `main`
#1 [analysis] running analysis passes on this crate
end of query stack
error: could not compile `playground` (bin "playground")

Backtrace

The compiler backtrace is in the error message. I'm not able to get a backtrace of my own code.

[Noratrieb]

Thank you for the report. This is a duplicate of #117728, which has been fixed in beta, so I'm closing this.
(next time, you could attempt to search for duplicates first by search for the file where the panic happened - but of course we'd rather have duplicates than missing reports, so don't worry if you don't :))