Rustdoc ICE - 'expected a const, but found another kind'

[tomBoddaert]

Code

use std::cmp::PartialEq;

type Dyn<Rhs> = dyn PartialEq<Rhs>;

Meta

rustc --version --verbose:

rustc 1.77.0-nightly (e51e98dde 2023-12-31)
binary: rustc
commit-hash: e51e98dde6a60637b6a71b8105245b629ac3fe77
commit-date: 2023-12-31
host: x86_64-unknown-linux-gnu
release: 1.77.0-nightly
LLVM version: 17.0.6

Error output

error: internal compiler error: compiler/rustc_middle/src/ty/generic_args.rs:184:43: expected a const, but found another kind

Backtrace

thread 'rustc' panicked at /rustc/e51e98dde6a60637b6a71b8105245b629ac3fe77/compiler/rustc_errors/src/lib.rs:1068:30:
Box<dyn Any>
stack backtrace:
   0: std::panicking::begin_panic::<rustc_errors::ExplicitBug>
   1: <rustc_errors::diagnostic_builder::BugAbort as rustc_errors::diagnostic_builder::EmissionGuarantee>::emit_producing_guarantee
   2: <rustc_errors::DiagCtxt>::bug::<alloc::string::String>
   3: rustc_middle::util::bug::opt_span_bug_fmt::<rustc_span::span_encoding::Span>::{closure#0}
   4: rustc_middle::ty::context::tls::with_opt::<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>::{closure#0}
   5: rustc_middle::ty::context::tls::with_context_opt::<rustc_middle::ty::context::tls::with_opt<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
   6: rustc_middle::util::bug::bug_fmt
   7: <rustc_middle::ty::generic_args::GenericArg>::expect_const
   8: rustdoc::clean::utils::ty_args_to_args
   9: rustdoc::clean::utils::external_path
  10: rustdoc::clean::clean_middle_ty
  11: rustdoc::clean::clean_maybe_renamed_item::{closure#1}
  12: rustdoc::clean::clean_doc_module
  13: rustdoc::core::run_global_ctxt
  14: rustdoc::main_args::{closure#1}::{closure#0}::{closure#0}
  15: rustc_interface::interface::run_compiler::<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustdoc::main_args::{closure#1}>::{closure#0}

rustc-ice file

thread 'rustc' panicked at /rustc/e51e98dde6a60637b6a71b8105245b629ac3fe77/compiler/rustc_errors/src/lib.rs:1068:30:
Box<dyn Any>
stack backtrace:
   0:     0x7ff635fe7d2e - std::backtrace_rs::backtrace::libunwind::trace::h44f4ca7c442c0986
                               at /rustc/e51e98dde6a60637b6a71b8105245b629ac3fe77/library/std/src/../../backtrace/src/backtrace/libunwind.rs:104:5
   1:     0x7ff635fe7d2e - std::backtrace_rs::backtrace::trace_unsynchronized::h08d378a2031b5c5b
                               at /rustc/e51e98dde6a60637b6a71b8105245b629ac3fe77/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7ff635fe7d2e - std::backtrace::Backtrace::create::hf208879ddad61a5f
                               at /rustc/e51e98dde6a60637b6a71b8105245b629ac3fe77/library/std/src/backtrace.rs:331:13
   3:     0x7ff635fe7c70 - std::backtrace::Backtrace::force_capture::h5b9c5cc42433e60b
                               at /rustc/e51e98dde6a60637b6a71b8105245b629ac3fe77/library/std/src/backtrace.rs:312:9
   4:     0x7ff632d66afc - std[59bbd359e4a0812d]::panicking::update_hook::<alloc[9e8bbef5278c9f16]::boxed::Box<rustc_driver_impl[f5f02e8ab7f89dcf]::install_ice_hook::{closure#0}>>::{closure#0}
   5:     0x7ff636003c06 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h0ebdda5c503ff158
                               at /rustc/e51e98dde6a60637b6a71b8105245b629ac3fe77/library/alloc/src/boxed.rs:2029:9
   6:     0x7ff636003c06 - std::panicking::rust_panic_with_hook::h4f38919015b1c60f
                               at /rustc/e51e98dde6a60637b6a71b8105245b629ac3fe77/library/std/src/panicking.rs:783:13
   7:     0x7ff632d9f1b4 - std[59bbd359e4a0812d]::panicking::begin_panic::<rustc_errors[b2b45e62fb4172dd]::ExplicitBug>::{closure#0}
   8:     0x7ff632d9b5b6 - std[59bbd359e4a0812d]::sys_common::backtrace::__rust_end_short_backtrace::<std[59bbd359e4a0812d]::panicking::begin_panic<rustc_errors[b2b45e62fb4172dd]::ExplicitBug>::{closure#0}, !>
   9:     0x7ff632d96856 - std[59bbd359e4a0812d]::panicking::begin_panic::<rustc_errors[b2b45e62fb4172dd]::ExplicitBug>
  10:     0x7ff632daa101 - <rustc_errors[b2b45e62fb4172dd]::diagnostic_builder::BugAbort as rustc_errors[b2b45e62fb4172dd]::diagnostic_builder::EmissionGuarantee>::emit_producing_guarantee
  11:     0x7ff633171ece - <rustc_errors[b2b45e62fb4172dd]::DiagCtxt>::bug::<alloc[9e8bbef5278c9f16]::string::String>
  12:     0x7ff63320e02b - rustc_middle[7d80ff9c88f366f3]::util::bug::opt_span_bug_fmt::<rustc_span[44814e3eac9e4a35]::span_encoding::Span>::{closure#0}
  13:     0x7ff6331f690a - rustc_middle[7d80ff9c88f366f3]::ty::context::tls::with_opt::<rustc_middle[7d80ff9c88f366f3]::util::bug::opt_span_bug_fmt<rustc_span[44814e3eac9e4a35]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  14:     0x7ff6331f67a8 - rustc_middle[7d80ff9c88f366f3]::ty::context::tls::with_context_opt::<rustc_middle[7d80ff9c88f366f3]::ty::context::tls::with_opt<rustc_middle[7d80ff9c88f366f3]::util::bug::opt_span_bug_fmt<rustc_span[44814e3eac9e4a35]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  15:     0x7ff631188960 - rustc_middle[7d80ff9c88f366f3]::util::bug::bug_fmt
  16:     0x7ff633200086 - <rustc_middle[7d80ff9c88f366f3]::ty::generic_args::GenericArg>::expect_const
  17:     0x55f51eac189a - rustdoc[60b03d8a22a2fa25]::clean::utils::ty_args_to_args
  18:     0x55f51eac1c4b - rustdoc[60b03d8a22a2fa25]::clean::utils::external_path
  19:     0x55f51ec1441b - rustdoc[60b03d8a22a2fa25]::clean::clean_middle_ty
  20:     0x55f51eae37c9 - rustdoc[60b03d8a22a2fa25]::clean::clean_maybe_renamed_item::{closure#1}
  21:     0x55f51eac9d5d - rustdoc[60b03d8a22a2fa25]::clean::clean_doc_module
  22:     0x55f51eaf4a79 - rustdoc[60b03d8a22a2fa25]::core::run_global_ctxt
  23:     0x55f51ec07666 - rustdoc[60b03d8a22a2fa25]::main_args::{closure#1}::{closure#0}::{closure#0}
  24:     0x55f51e9fe41d - rustc_interface[8dea96efab884454]::interface::run_compiler::<core[f50a4b4ddb6878bb]::result::Result<(), rustc_span[44814e3eac9e4a35]::ErrorGuaranteed>, rustdoc[60b03d8a22a2fa25]::main_args::{closure#1}>::{closure#0}
  25:     0x55f51e9c13a0 - std[59bbd359e4a0812d]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[8dea96efab884454]::util::run_in_thread_with_globals<rustc_interface[8dea96efab884454]::util::run_in_thread_pool_with_globals<rustc_interface[8dea96efab884454]::interface::run_compiler<core[f50a4b4ddb6878bb]::result::Result<(), rustc_span[44814e3eac9e4a35]::ErrorGuaranteed>, rustdoc[60b03d8a22a2fa25]::main_args::{closure#1}>::{closure#0}, core[f50a4b4ddb6878bb]::result::Result<(), rustc_span[44814e3eac9e4a35]::ErrorGuaranteed>>::{closure#0}, core[f50a4b4ddb6878bb]::result::Result<(), rustc_span[44814e3eac9e4a35]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[f50a4b4ddb6878bb]::result::Result<(), rustc_span[44814e3eac9e4a35]::ErrorGuaranteed>>
  26:     0x55f51ea0998e - <<std[59bbd359e4a0812d]::thread::Builder>::spawn_unchecked_<rustc_interface[8dea96efab884454]::util::run_in_thread_with_globals<rustc_interface[8dea96efab884454]::util::run_in_thread_pool_with_globals<rustc_interface[8dea96efab884454]::interface::run_compiler<core[f50a4b4ddb6878bb]::result::Result<(), rustc_span[44814e3eac9e4a35]::ErrorGuaranteed>, rustdoc[60b03d8a22a2fa25]::main_args::{closure#1}>::{closure#0}, core[f50a4b4ddb6878bb]::result::Result<(), rustc_span[44814e3eac9e4a35]::ErrorGuaranteed>>::{closure#0}, core[f50a4b4ddb6878bb]::result::Result<(), rustc_span[44814e3eac9e4a35]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[f50a4b4ddb6878bb]::result::Result<(), rustc_span[44814e3eac9e4a35]::ErrorGuaranteed>>::{closure#1} as core[f50a4b4ddb6878bb]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  27:     0x7ff63600db35 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hfced58be344e2c05
                               at /rustc/e51e98dde6a60637b6a71b8105245b629ac3fe77/library/alloc/src/boxed.rs:2015:9
  28:     0x7ff63600db35 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h7842a7154462ae57
                               at /rustc/e51e98dde6a60637b6a71b8105245b629ac3fe77/library/alloc/src/boxed.rs:2015:9
  29:     0x7ff63600db35 - std::sys::unix::thread::Thread::new::thread_start::ha365c5d9b9d0ac99
                               at /rustc/e51e98dde6a60637b6a71b8105245b629ac3fe77/library/std/src/sys/unix/thread.rs:108:17
  30:     0x7ff62fdbd9eb - <unknown>
  31:     0x7ff62fe417cc - <unknown>
  32:                0x0 - <unknown>


rustc version: 1.77.0-nightly (e51e98dde 2023-12-31)
platform: x86_64-unknown-linux-gnu

query stack during panic:
end of query stack

This ICE only occurs when running cargo doc or rustdoc src/main.rs with nightly. Defining the PartialEq trait manually did not trigger this, only the PartialEq in std/alloc/core.
Running a quick search on nightly versions, nightly-2023-12-11 (d86d65bbc 2023-12-10) works and nightly-2023-12-12 (21cce21d8 2023-12-11) fails with a similar backtrace (some items have been renamed / moved).