index out of bounds ICE in `repeat_once` lint

[Nadrieril]

Message:

thread 'rustc' panicked at 'index out of bounds: the len is 1 but the index is 1', src/tools/clippy/clippy_lints/src/repeat_once.rs:44:93
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

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 (18bf6b4 2020-10-07)

error: could not compile `abnf_to_pest`.

Backtrace

thread 'rustc' panicked at 'index out of bounds: the len is 1 but the index is 1', src/tools/clippy/clippy_lints/src/repeat_once.rs:44:93 stack backtrace: 0: rust_begin_unwind at /rustc/18bf6b4f01a6feaf7259ba7cdae58031af1b7b39/library/std/src/panicking.rs:475 1: core::panicking::panic_fmt at /rustc/18bf6b4f01a6feaf7259ba7cdae58031af1b7b39/library/core/src/panicking.rs:85 2: core::panicking::panic_bounds_check at /rustc/18bf6b4f01a6feaf7259ba7cdae58031af1b7b39/library/core/src/panicking.rs:62 3: ::check_expr 4: ::check_expr 5: as rustc_hir::intravisit::Visitor>::visit_expr 6: rustc_hir::intravisit::walk_expr 7: as rustc_hir::intravisit::Visitor>::visit_expr 8: rustc_hir::intravisit::walk_expr 9: as rustc_hir::intravisit::Visitor>::visit_expr 10: rustc_hir::intravisit::walk_expr 11: as rustc_hir::intravisit::Visitor>::visit_expr 12: rustc_hir::intravisit::walk_expr 13: as rustc_hir::intravisit::Visitor>::visit_expr 14: rustc_hir::intravisit::walk_expr 15: as rustc_hir::intravisit::Visitor>::visit_expr 16: as rustc_hir::intravisit::Visitor>::visit_nested_body 17: as rustc_hir::intravisit::Visitor>::visit_fn 18: rustc_hir::intravisit::walk_impl_item 19: rustc_hir::intravisit::Visitor::visit_nested_impl_item 20: rustc_hir::intravisit::walk_item 21: rustc_hir::intravisit::Visitor::visit_nested_item 22: rustc_hir::intravisit::walk_crate 23: rustc_lint::late::late_lint_pass_crate 24: rustc_lint::late::late_lint_crate 25: rustc_data_structures::sync::join 26: rustc_session::utils::::time 27: as core::ops::function::FnOnce<()>>::call_once 28: rustc_session::utils::::time 29: rustc_interface::passes::analysis 30: rustc_middle::ty::query:: for rustc_middle::ty::que ry::queries::analysis>::compute 31: rustc_middle::dep_graph::::with_deps 32: rustc_query_system::dep_graph::graph::DepGraph::with_task_impl 33: rustc_data_structures::stack::ensure_sufficient_stack 34: rustc_query_system::query::plumbing::get_query_impl 35: rustc_interface::queries::::enter 36: rustc_span::with_source_map 37: rustc_interface::interface::create_compiler_and_run 38: scoped_tls::ScopedKey::set note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

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 (18bf6b4 2020-10-07)

query stack during panic:
#0 [analysis] running analysis passes on this crate
end of query stack
error: could not compile abnf_to_pest.

You can see the CI error here

The line that causes the problem is that one. If I comment it out the crash stops happening.

[ebroto]

Thanks for your report!

This was fixed in #5948 but did not make it to 1.47. It should be fixed in the current beta.

There's rust-lang/rust#77750 so in case there is a point release, the fix for this would make it.