Panick when inserting safety comment as suggested by undocumented_unsafe_blocks

[Dav1d23]

When using #![warn(clippy::undocumented_unsafe_blocks)], clippy reported

warning: unsafe block missing a safety comment
  --> src/unsafe_node.rs:26:13
   |
26 |             unsafe { ptr::NonNull::new_unchecked(Box::into_raw(Box::new(next))) }
   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
note: the lint level is defined here
  --> src/lib.rs:3:9
   |
3  | #![warn(clippy::undocumented_unsafe_blocks)]
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#undocumented_unsafe_blocks
help: consider adding a safety comment
   |
26 ~             // Safety: ...
27 +             unsafe { ptr::NonNull::new_unchecked(Box::into_raw(Box::new(next))) }
   |

I applied the suggestion, and I got:

thread 'rustc' panicked at 'assertion failed: self.start_pos.to_u32() + total_extra_bytes <= bpos.to_u32()', compiler/rustc_span/src/lib.rs:1677:9
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 0.1.58 (db9d1b2 2022-01-20)

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

cargo-clippy exited abnormally with code 101 at Sun Feb 13 15:07:40

The complete backtrace:

;RUST_BACKTRACE=1 cargo clippy
    Checking astack v0.1.0 (/home/david.petroni/PERSO/snippets/rust/astack)
thread 'rustc' panicked at 'assertion failed: self.start_pos.to_u32() + total_extra_bytes <= bpos.to_u32()', compiler/rustc_span/src/lib.rs:1677:9
stack backtrace:
   0: rust_begin_unwind
             at /rustc/db9d1b20bba1968c1ec1fc49616d4742c1725b4b/library/std/src/panicking.rs:498:5
   1: core::panicking::panic_fmt
             at /rustc/db9d1b20bba1968c1ec1fc49616d4742c1725b4b/library/core/src/panicking.rs:107:14
   2: core::panicking::panic
             at /rustc/db9d1b20bba1968c1ec1fc49616d4742c1725b4b/library/core/src/panicking.rs:48:5
   3: <rustc_span::SourceFile>::lookup_file_pos
   4: <rustc_span::SourceFile>::lookup_file_pos_with_col_display
   5: <clippy_lints::undocumented_unsafe_blocks::UndocumentedUnsafeBlocks>::block_has_safety_comment
   6: <clippy_lints::undocumented_unsafe_blocks::UndocumentedUnsafeBlocks as rustc_lint::passes::LateLintPass>::check_block
   7: <rustc_lint::late::LateLintPassObjects as rustc_lint::passes::LateLintPass>::check_block
   8: <rustc_lint::late::LateContextAndPass<rustc_lint::late::LateLintPassObjects> as rustc_hir::intravisit::Visitor>::visit_block
   9: <rustc_lint::late::LateContextAndPass<rustc_lint::late::LateLintPassObjects> as rustc_hir::intravisit::Visitor>::visit_expr
  10: rustc_hir::intravisit::walk_expr::<rustc_lint::late::LateContextAndPass<rustc_lint::late::LateLintPassObjects>>
  11: <rustc_lint::late::LateContextAndPass<rustc_lint::late::LateLintPassObjects> as rustc_hir::intravisit::Visitor>::visit_expr
  12: rustc_hir::intravisit::walk_expr::<rustc_lint::late::LateContextAndPass<rustc_lint::late::LateLintPassObjects>>
  13: <rustc_lint::late::LateContextAndPass<rustc_lint::late::LateLintPassObjects> as rustc_hir::intravisit::Visitor>::visit_expr
  14: <rustc_lint::late::LateContextAndPass<rustc_lint::late::LateLintPassObjects> as rustc_hir::intravisit::Visitor>::visit_stmt
  15: rustc_hir::intravisit::walk_block::<rustc_lint::late::LateContextAndPass<rustc_lint::late::LateLintPassObjects>>
  16: <rustc_lint::late::LateContextAndPass<rustc_lint::late::LateLintPassObjects> as rustc_hir::intravisit::Visitor>::visit_block
  17: <rustc_lint::late::LateContextAndPass<rustc_lint::late::LateLintPassObjects> as rustc_hir::intravisit::Visitor>::visit_expr
  18: <rustc_lint::late::LateContextAndPass<rustc_lint::late::LateLintPassObjects> as rustc_hir::intravisit::Visitor>::visit_nested_body
  19: <rustc_lint::late::LateContextAndPass<rustc_lint::late::LateLintPassObjects> as rustc_hir::intravisit::Visitor>::visit_fn
  20: rustc_hir::intravisit::walk_impl_item::<rustc_lint::late::LateContextAndPass<rustc_lint::late::LateLintPassObjects>>
  21: <rustc_lint::late::LateContextAndPass<rustc_lint::late::LateLintPassObjects> as rustc_hir::intravisit::Visitor>::visit_nested_impl_item
  22: rustc_hir::intravisit::walk_impl_item_ref::<rustc_lint::late::LateContextAndPass<rustc_lint::late::LateLintPassObjects>>
  23: rustc_hir::intravisit::walk_item::<rustc_lint::late::LateContextAndPass<rustc_lint::late::LateLintPassObjects>>
  24: <rustc_lint::late::LateContextAndPass<rustc_lint::late::LateLintPassObjects> as rustc_hir::intravisit::Visitor>::visit_nested_item
  25: rustc_hir::intravisit::walk_mod::<rustc_lint::late::LateContextAndPass<rustc_lint::late::LateLintPassObjects>>
  26: <rustc_lint::late::LateContextAndPass<rustc_lint::late::LateLintPassObjects> as rustc_hir::intravisit::Visitor>::visit_mod
  27: <rustc_lint::late::LateContextAndPass<rustc_lint::late::LateLintPassObjects> as rustc_hir::intravisit::Visitor>::visit_nested_item
  28: rustc_hir::intravisit::walk_mod::<rustc_lint::late::LateContextAndPass<rustc_lint::late::LateLintPassObjects>>
  29: <rustc_lint::late::LateContextAndPass<rustc_lint::late::LateLintPassObjects> as rustc_hir::intravisit::Visitor>::visit_mod
  30: <rustc_middle::hir::map::Map>::walk_toplevel_module::<rustc_lint::late::LateContextAndPass<rustc_lint::late::LateLintPassObjects>>
  31: rustc_lint::late::late_lint_pass_crate::<rustc_lint::late::LateLintPassObjects>
  32: rustc_lint::late::late_lint_crate::<rustc_lint::BuiltinCombinedLateLintPass>
  33: rustc_data_structures::sync::join::<rustc_lint::late::check_crate<rustc_lint::BuiltinCombinedLateLintPass, rustc_interface::passes::analysis::{closure#5}::{closure#0}::{closure#3}::{closure#0}::{closure#0}>::{closure#0}, rustc_lint::late::check_crate<rustc_lint::BuiltinCombinedLateLintPass, rustc_interface::passes::analysis::{closure#5}::{closure#0}::{closure#3}::{closure#0}::{closure#0}>::{closure#1}, (), ()>
  34: <core::panic::unwind_safe::AssertUnwindSafe<rustc_interface::passes::analysis::{closure#5}::{closure#0}> as core::ops::function::FnOnce<()>>::call_once
  35: <rustc_session::session::Session>::time::<(), rustc_interface::passes::analysis::{closure#5}>
  36: rustc_interface::passes::analysis
  37: <rustc_query_system::dep_graph::graph::DepGraph<rustc_middle::dep_graph::dep_node::DepKind>>::with_task::<rustc_middle::ty::context::TyCtxt, (), core::result::Result<(), rustc_errors::ErrorReported>>
  38: rustc_data_structures::stack::ensure_sufficient_stack::<(core::result::Result<(), rustc_errors::ErrorReported>, rustc_query_system::dep_graph::graph::DepNodeIndex), rustc_query_system::query::plumbing::execute_job<rustc_query_impl::plumbing::QueryCtxt, (), core::result::Result<(), rustc_errors::ErrorReported>>::{closure#3}>
  39: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<(), core::result::Result<(), rustc_errors::ErrorReported>>>
  40: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::analysis
  41: <rustc_interface::passes::QueryContext>::enter::<rustc_driver::run_compiler::{closure#1}::{closure#2}::{closure#3}, core::result::Result<(), rustc_errors::ErrorReported>>
  42: <rustc_interface::interface::Compiler>::enter::<rustc_driver::run_compiler::{closure#1}::{closure#2}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_errors::ErrorReported>>
  43: rustc_span::with_source_map::<core::result::Result<(), rustc_errors::ErrorReported>, rustc_interface::interface::create_compiler_and_run<core::result::Result<(), rustc_errors::ErrorReported>, rustc_driver::run_compiler::{closure#1}>::{closure#1}>
  44: <scoped_tls::ScopedKey<rustc_span::SessionGlobals>>::set::<rustc_interface::util::setup_callbacks_and_run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorReported>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorReported>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorReported>>
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 0.1.58 (db9d1b2 2022-01-20)

query stack during panic:
#0 [analysis] running analysis passes on this crate
end of query stack

[giraffate]

Thanks for the report!

It's a duplicate of #8020, so I'm closing this.

[Dav1d23]

Mb, I should have taken a look before opening a new ticket!

Thanks for taking care of this!