Typenum ICE during car

[jpoler]

When I attempt to build docs, building the typenum docs throws an ICE.

I tried the following docs command:

cargo +nightly doc --open --all

You can use this repo to reproduce:

https://github.com/jpoler/typenum-ice

I expected the docs to build and open in my browser.

Instead, this happened:

 Documenting typenum v1.10.0
error: internal compiler error: librustc/traits/structural_impls.rs:178: impossible case reached

thread '<unnamed>' panicked at 'Box<Any>', librustc_errors/lib.rs:578:9
note: Run with `RUST_BACKTRACE=1` for a backtrace.

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: rustc 1.30.0-nightly (7e8ca9f8b 2018-08-03) running on x86_64-unknown-linux-gnu

error: Could not document `typenum`.

Caused by:
  process didn't exit successfully: `rustdoc --crate-name typenum /home/ash/.cargo/registry/src/github.com-1ecc6299db9ec823/typenum-1.10.0/src/lib.rs --cap-lints allow -o /home/ash/src-tmp/doc-ice/target/doc -L dependency=/home/ash/src-tmp/doc-ice/target/debug/deps` (exit code: 1)

Backtrace:

thread '<unnamed>' panicked at 'Box<Any>', librustc_errors/lib.rs:578:9
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
             at libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
   1: std::sys_common::backtrace::print
             at libstd/sys_common/backtrace.rs:71
             at libstd/sys_common/backtrace.rs:59
   2: std::panicking::default_hook::{{closure}}
             at libstd/panicking.rs:211
   3: std::panicking::default_hook
             at libstd/panicking.rs:227
   4: std::panicking::rust_panic_with_hook
             at libstd/panicking.rs:475
   5: std::panicking::begin_panic
   6: rustc_errors::Handler::bug
   7: rustc::session::opt_span_bug_fmt::{{closure}}
   8: rustc::ty::context::tls::with_opt::{{closure}}
   9: rustc::ty::context::tls::with_context_opt
  10: rustc::ty::context::tls::with_opt
  11: rustc::session::opt_span_bug_fmt
  12: rustc::session::bug_fmt
  13: rustc::traits::structural_impls::<impl rustc::ty::context::Lift<'tcx> for rustc::traits::SelectionError<'a>>::lift_to_tcx
  14: rustc::ty::context::TyCtxt::lift_to_global
  15: rustc::traits::select::SelectionContext::candidate_from_obligation
  16: rustc::traits::select::SelectionContext::evaluate_stack
  17: rustc::traits::select::SelectionContext::evaluate_predicate_recursively
  18: rustc::infer::InferCtxt::probe
  19: <&'a mut I as core::iter::iterator::Iterator>::next
  20: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T, I>>::from_iter
  21: rustc::traits::select::SelectionContext::candidate_from_obligation_no_cache
  22: rustc::traits::select::SelectionContext::candidate_from_obligation
  23: rustc::traits::select::SelectionContext::evaluate_stack
  24: rustc::traits::select::SelectionContext::evaluate_predicate_recursively
  25: rustc::infer::InferCtxt::probe
  26: <&'a mut I as core::iter::iterator::Iterator>::next
  27: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T, I>>::from_iter
  28: rustc::traits::select::SelectionContext::candidate_from_obligation_no_cache
  29: rustc::traits::select::SelectionContext::candidate_from_obligation
  30: rustc::traits::select::SelectionContext::evaluate_stack
  31: rustc::traits::select::SelectionContext::evaluate_predicate_recursively
  32: rustc::infer::InferCtxt::probe
  33: <&'a mut I as core::iter::iterator::Iterator>::next
  34: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T, I>>::from_iter
  35: rustc::traits::select::SelectionContext::candidate_from_obligation_no_cache
  36: rustc::traits::select::SelectionContext::candidate_from_obligation
  37: rustc::traits::select::SelectionContext::evaluate_stack
  38: rustc::traits::select::SelectionContext::evaluate_predicate_recursively
  39: rustc::infer::InferCtxt::probe
  40: <&'a mut I as core::iter::iterator::Iterator>::next
  41: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T, I>>::from_iter
  42: rustc::traits::select::SelectionContext::candidate_from_obligation_no_cache
  43: rustc::traits::select::SelectionContext::candidate_from_obligation
  44: rustc::traits::select::SelectionContext::evaluate_stack
  45: rustc::traits::select::SelectionContext::evaluate_predicate_recursively
  46: rustc::infer::InferCtxt::probe
  47: <&'a mut I as core::iter::iterator::Iterator>::next
  48: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T, I>>::from_iter
  49: rustc::traits::select::SelectionContext::candidate_from_obligation_no_cache
  50: rustc::traits::select::SelectionContext::candidate_from_obligation
  51: rustc::traits::select::SelectionContext::evaluate_stack
  52: rustc::traits::select::SelectionContext::evaluate_predicate_recursively
  53: rustc::infer::InferCtxt::probe
  54: <&'a mut I as core::iter::iterator::Iterator>::next
  55: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T, I>>::from_iter
  56: rustc::traits::select::SelectionContext::candidate_from_obligation_no_cache
  57: rustc::traits::select::SelectionContext::candidate_from_obligation
  58: rustc::traits::select::SelectionContext::evaluate_stack
  59: rustc::traits::select::SelectionContext::evaluate_predicate_recursively
  60: rustc::infer::InferCtxt::probe
  61: <&'a mut I as core::iter::iterator::Iterator>::next
  62: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T, I>>::from_iter
  63: rustc::traits::select::SelectionContext::candidate_from_obligation_no_cache
  64: rustc::traits::select::SelectionContext::candidate_from_obligation
  65: rustc::traits::select::SelectionContext::evaluate_stack
  66: rustc::traits::select::SelectionContext::evaluate_predicate_recursively
  67: rustc::infer::InferCtxt::probe
  68: <&'a mut I as core::iter::iterator::Iterator>::next
  69: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T, I>>::from_iter
  70: rustc::traits::select::SelectionContext::candidate_from_obligation_no_cache
  71: rustc::traits::select::SelectionContext::candidate_from_obligation
  72: rustc::traits::select::SelectionContext::evaluate_stack
  73: rustc::traits::select::SelectionContext::evaluate_predicate_recursively
  74: rustc::infer::InferCtxt::probe
  75: <&'a mut I as core::iter::iterator::Iterator>::next
  76: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T, I>>::from_iter
  77: rustc::traits::select::SelectionContext::candidate_from_obligation_no_cache
  78: rustc::traits::select::SelectionContext::candidate_from_obligation
  79: rustc::traits::select::SelectionContext::evaluate_stack
  80: rustc::traits::select::SelectionContext::evaluate_predicate_recursively
  81: rustc::infer::InferCtxt::probe
  82: <&'a mut I as core::iter::iterator::Iterator>::next
  83: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T, I>>::from_iter
  84: rustc::traits::select::SelectionContext::candidate_from_obligation_no_cache
  85: rustc::traits::select::SelectionContext::candidate_from_obligation
  86: rustc::traits::select::SelectionContext::evaluate_stack
  87: rustc::traits::select::SelectionContext::evaluate_predicate_recursively
  88: rustc::infer::InferCtxt::probe
  89: <&'a mut I as core::iter::iterator::Iterator>::next
  90: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T, I>>::from_iter
  91: rustc::traits::select::SelectionContext::candidate_from_obligation_no_cache
  92: rustc::traits::select::SelectionContext::candidate_from_obligation
  93: rustc::traits::select::SelectionContext::evaluate_stack
  94: rustc::traits::select::SelectionContext::evaluate_predicate_recursively
  95: rustc::infer::InferCtxt::probe
  96: <&'a mut I as core::iter::iterator::Iterator>::next
  97: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T, I>>::from_iter
  98: rustc::traits::select::SelectionContext::candidate_from_obligation_no_cache
  99: rustc::traits::select::SelectionContext::candidate_from_obligation

[VictorKoenders]

Seems to be a duplicate of #52873

[dtolnay]

Closing as a duplicate of #52873.