Nightly panics `<rustc_errors::diagnostic_builder::DiagnosticBuilder<'a> as core::ops::Drop>::drop`

[dpc]

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

note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports

note: run with `RUST_BACKTRACE=1` for a backtrace

thread 'rustc' panicked at 'explicit panic', /checkout/src/librustc_errors/diagnostic_builder.rs:192
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
stack backtrace:
   0: <rustc_errors::diagnostic_builder::DiagnosticBuilder<'a> as core::ops::Drop>::drop
   1: syntax::parse::parser::Parser::parse_impl_item
   2: syntax::parse::parser::Parser::parse_item_impl
   3: syntax::parse::parser::Parser::parse_item_
   4: syntax::parse::parser::Parser::parse_item
   5: syntax::parse::parser::Parser::parse_mod_items
   6: syntax::parse::parser::Parser::parse_crate_mod
   7: syntax::parse::parse_crate_from_file
   8: rustc_driver::driver::phase_1_parse_input::{{closure}}
   9: rustc_driver::driver::phase_1_parse_input
  10: rustc_driver::driver::compile_input
  11: rustc_driver::run_compiler
  12: std::panicking::try::do_call
  13: __rust_maybe_catch_panic
             at /checkout/src/libpanic_unwind/lib.rs:98
  14: <F as alloc::boxed::FnBox<A>>::call_box
  15: std::sys::imp::thread::Thread::new::thread_start
             at /checkout/src/liballoc/boxed.rs:650
             at /checkout/src/libstd/sys_common/thread.rs:21
             at /checkout/src/libstd/sys/unix/thread.rs:84
  16: start_thread
  17: clone

error: Could not compile `slog-atomic`.

To learn more, run the command again with --verbose.

while compiling slog-atomic = "2.0.0-3.1" with the following change (I was just testing errors in Vim and introduced random error):

diff --git a/lib.rs b/lib.rs
index 6ac461e..ac47c1b 100644
--- a/lib.rs
+++ b/lib.rs
@@ -59,7 +59,7 @@ impl<O, E> AtomicSwitchCtrl<O, E> {
                 -> Arc<Box<SendSyncRefUnwindSafeDrain<Ok = O, Err = E>>> {
         self.0.set(drain)
     }
-
+s
     /// Get a `AtomicSwitch` drain controlled by this `AtomicSwitchCtrl`
     pub fn drain(&self) -> AtomicSwitch<O, E> {
         AtomicSwitch(self.0.clone())

[TimNN]

Probably a duplicate of #41161.