ICE assertion failed: self.is_collecting_in_band_lifetimes'

[withkittens]

I tried the code on Rust Playground (link). The issue should be here:

impl<'_> TryFrom<&'_ str> for Subject<'_> {
    type Error = SubjectError;
    
    fn try_from(s: &str) -> Subject {
        Subject { inner: Cow::Borrowed(s) }
    }
}

More specifically, seems like the compiler doesn't like impl<'_>.

Expected

Errors reported (wrong return type, maybe something about lifetimes).

Actual Result

Instead, the compiler ICE'd:

   Compiling playground v0.0.1 (file:///playground)
thread 'main' panicked at 'assertion failed: self.is_collecting_in_band_lifetimes', librustc/hir/lowering.rs:738:9
note: Run with `RUST_BACKTRACE=1` for a backtrace.

...

note: rustc 1.29.0-nightly (960f6046c 2018-07-08) running on x86_64-unknown-linux-gnu

note: compiler flags: -C codegen-units=1 -C debuginfo=2 --crate-type bin

Backtrace

Gathered on Windows (rustc 1.29.0-nightly (9fd3d78 2018-07-07) x86_64-pc-windows-msvc):

thread 'main' panicked at 'assertion failed: self.is_collecting_in_band_lifetimes', librustc\hir\lowering.rs:738:9
stack backtrace:
   0: <std::sys::windows::args::Args as core::ops::drop::Drop>::drop
   1: <std::sys::windows::dynamic_lib::DynamicLibrary as core::ops::drop::Drop>::drop
   2: std::panicking::take_hook
   3: std::panicking::take_hook
   4: <rustc::ty::SymbolName as core::fmt::Display>::fmt
   5: std::panicking::rust_panic_with_hook
   6: <rustc::hir::intravisit::IdRange as core::fmt::Debug>::fmt
   7: <rustc::hir::lowering::LoweringContext::lower_async_fn_ret_ty::AsyncFnLifetimeCollector<'r, 'a> as rustc::hir::intravisit::Visitor<'v>>::visit_lifetime
   8: rustc::ty::context::TypeckTables::expr_ty
   9: <unknown>
  10: <rustc::hir::lowering::LoweringContext::lower_async_fn_ret_ty::AsyncFnLifetimeCollector<'r, 'a> as rustc::hir::intravisit::Visitor<'v>>::visit_lifetime
  11: rustc::hir::lowering::LoweringContext::lower_item
  12: <rustc::hir::lowering::LoweringContext::lower_crate::ItemLowerer<'lcx, 'interner> as syntax::visit::Visitor<'lcx>>::visit_item
  13: rustc::hir::lowering::lower_crate
  14: <rustc_driver::derive_registrar::Finder as rustc::hir::itemlikevisit::ItemLikeVisitor<'v>>::visit_item
  15: rustc_driver::driver::count_nodes
  16: rustc_driver::driver::compile_input
  17: rustc_driver::run_compiler
  18: rustc_driver::target_features::add_configuration
  19: <unknown>
  20: _rust_maybe_catch_panic
  21: rustc_driver::profile::dump
  22: rustc_driver::main
  23: <unknown>
  24: std::panicking::update_panic_count
  25: _rust_maybe_catch_panic
  26: std::rt::lang_start_internal
  27: <unknown>
  28: <unknown>
  29: BaseThreadInitThunk
  30: RtlUserThreadStart
query stack during panic:
end of query stack

[withkittens]

Duplicate of #52098.