ICE in clippy

[yan-zaretskiy]

Trying to run cargo clippy on my code today, I got

thread 'rustc' panicked at 'index out of bounds: the len is 4 but the index is 4', src/tools/clippy/clippy_lints/src/unnested_or_patterns.rs:403:27
stack backtrace:
   0:        0x10f48951e - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h13e6f26430148ff2
   1:        0x10f4c1f5c - core::fmt::write::h45a9bd04db15c24f
   2:        0x10f47a659 - std::io::Write::write_fmt::h8ae61696f13218d5
   3:        0x10f48df45 - std::panicking::default_hook::{{closure}}::hc98fe2390b6284e5
   4:        0x10f48dc82 - std::panicking::default_hook::h9a63cea866a4c14a
   5:        0x107d7ae32 - clippy_driver::report_clippy_ice::h5d9e7083c9c7365d
   6:        0x10f48e5fd - std::panicking::rust_panic_with_hook::h4d446ca45c8e1faa
   7:        0x10f48e1a2 - rust_begin_unwind
   8:        0x10f4e521f - core::panicking::panic_fmt::hda969e68cfcc1b10
   9:        0x10f4e51e6 - core::panicking::panic_bounds_check::h09b5dc2ffa04f0cf
  10:        0x107f7d433 - clippy_lints::unnested_or_patterns::eq_pre_post::hedce6be0a05cf1a1
  11:        0x10801f8ba - <alloc::vec::DrainFilter<T,F> as core::iter::traits::iterator::Iterator>::next::hb4962a33bf061c5d
  12:        0x107f7b096 - <clippy_lints::unnested_or_patterns::unnest_or_patterns::Visitor as rustc_ast::mut_visit::MutVisitor>::visit_pat::h60806b54d29096d8
  13:        0x107f7a0dd - clippy_lints::unnested_or_patterns::lint_unnested_or_patterns::h5b8a4d1c2f13fadf
  14:        0x10bb4ec23 - <rustc_lint::early::EarlyLintPassObjects as rustc_lint::passes::EarlyLintPass>::check_arm::h0babd5ff79ce58e4
  15:        0x1086ab6be - rustc_ast::visit::walk_expr::h97e76480f5144919
  16:        0x108663867 - <rustc_lint::early::EarlyContextAndPass<T> as rustc_ast::visit::Visitor>::visit_expr::h4b47e9ab3967cb67
  17:        0x1086ab774 - rustc_ast::visit::walk_expr::h97e76480f5144919
  18:        0x108663867 - <rustc_lint::early::EarlyContextAndPass<T> as rustc_ast::visit::Visitor>::visit_expr::h4b47e9ab3967cb67
  19:        0x1086abdbf - rustc_ast::visit::walk_expr::h97e76480f5144919
  20:        0x108663867 - <rustc_lint::early::EarlyContextAndPass<T> as rustc_ast::visit::Visitor>::visit_expr::h4b47e9ab3967cb67
  21:        0x1086abdbf - rustc_ast::visit::walk_expr::h97e76480f5144919
  22:        0x108663867 - <rustc_lint::early::EarlyContextAndPass<T> as rustc_ast::visit::Visitor>::visit_expr::h4b47e9ab3967cb67
  23:        0x108663af7 - <rustc_lint::early::EarlyContextAndPass<T> as rustc_ast::visit::Visitor>::visit_local::h74043354c7c706e8
  24:        0x1086ab5b4 - rustc_ast::visit::walk_expr::h97e76480f5144919
  25:        0x108663867 - <rustc_lint::early::EarlyContextAndPass<T> as rustc_ast::visit::Visitor>::visit_expr::h4b47e9ab3967cb67
  26:        0x1086a71f4 - rustc_ast::visit::walk_fn::h55031f4d5a60b400
  27:        0x1086a3037 - rustc_ast::visit::walk_assoc_item::hbf628ce1f1f9957e
  28:        0x1086aced0 - rustc_ast::visit::walk_item::h7a136d18b8588e0c
  29:        0x1086a876c - rustc_ast::visit::walk_mod::hfbde1f9aff7e959b
  30:        0x1086ac30c - rustc_ast::visit::walk_item::h7a136d18b8588e0c
  31:        0x1086a876c - rustc_ast::visit::walk_mod::hfbde1f9aff7e959b
  32:        0x10863f4fb - rustc_lint::early::early_lint_crate::hdf7efd504097e6ab
  33:        0x10863de7b - rustc_lint::early::check_ast_crate::haad559391831f24a
  34:        0x1086b3021 - rustc_session::utils::<impl rustc_session::session::Session>::time::h5e7252e0109052eb
  35:        0x108622795 - rustc_interface::passes::BoxedResolver::access::{{closure}}::hc4a3435e78c7ad36
  36:        0x10867c778 - rustc_interface::passes::configure_and_expand::{{closure}}::h00aafd017f5e3ca5
  37:        0x1086224c9 - rustc_interface::passes::BoxedResolver::access::h8fb09d2d154da189
  38:        0x10863b27d - rustc_interface::queries::Queries::lower_to_hir::haf4b7b12b1399e6e
  39:        0x10863be6f - rustc_interface::queries::Queries::global_ctxt::h71bc8858bfbb1f2b
  40:        0x108490d46 - rustc_interface::queries::<impl rustc_interface::interface::Compiler>::enter::h7b04855e89777cfa
  41:        0x10851b51e - rustc_span::with_source_map::heb2b51a1f3d09b82
  42:        0x108491d0a - rustc_interface::interface::create_compiler_and_run::h0dccc09f3a41f199
  43:        0x1084b9e79 - scoped_tls::ScopedKey<T>::set::h237c5aede1b35167
  44:        0x1084dc3e7 - std::sys_common::backtrace::__rust_begin_short_backtrace::h7836bf6fd1bfeba7
  45:        0x10849ef1c - core::ops::function::FnOnce::call_once{{vtable.shim}}::h2c6f48c5993204b0
  46:        0x10f49bb9d - std::sys::unix::thread::Thread::new::thread_start::h545d31fdf79b3d9e
  47:     0x7fff73dff2eb - AssociationsManager::_map
  48:     0x7fff73e02249 - AssociationsManager::_map

error: internal compiler error: unexpected panic

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust-clippy/issues/new

note: Clippy version: clippy 0.0.212 (346aec9b0 2020-07-11)

query stack during panic:
end of query stack

Let me know if there's something else I can assist you with in figuring this out.

[flip1995]

Can you give a minimal example or share the code base? Otherwise this is nearly impossible to debug.

[flip1995]

Nvm, this was already fixed in #5784. I try to get this into nightly Clippy ASAP.

[flip1995]

I just noticed, that this fix is already in the current nightly. So updating your toolchain should solve this problem.

[yan-zaretskiy]

rustup update skips a bunch of nightly versions, could explain why I still see the issue...

[flip1995]

That's because rustfmt is currently missing in nightly. If you don't need rustfmt, you can rustup component remove rustfmt --toolchain=nightly and then rustup update.