Compiler panic while running rayon demo

[ndaniels]

Trying the Rayon nbody demo with the current nightly on MacOS 10.13.3 caused a compiler panic.

I executed the following from bash prompt:

cargo +nightly run --release -- nbody visualize

And received the following, apparently when compiling cgmath:

thread 'rustc' panicked at 'assertion failed: `(left != right)` left: `ParamEnv(Binder(ProjectionPredicate(ProjectionTy { substs: Slice([S, S]), item_def_id: DefId(2/0:885 ~ core[6938]::ops[0]::arith[0]::Add[0]::Output[0]) }, S)))`, right: `ParamEnv(Binder(ProjectionPredicate(ProjectionTy { substs: Slice([S, S]), item_def_id: DefId(2/0:885 ~ core[6938]::ops[0]::arith[0]::Add[0]::Output[0]) }, S)))`', librustc/traits/project.rs:146:17 note: Run with `RUST_BACKTRACE=1` for a backtrace.

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rustc --version --verbose:

rustc --version --verbose rustc 1.24.0 (4d90ac38c 2018-02-12) binary: rustc commit-hash: 4d90ac38c0b61bb69470b61ea2cccea0df48d9e5 commit-date: 2018-02-12 host: x86_64-apple-darwin release: 1.24.0 LLVM version: 4.0

rustc +nightly --version --verbose:

binary: rustc
commit-hash: bedbad61195d2eae69b43eca49c6d3e2aee8f208
commit-date: 2018-02-26
host: x86_64-apple-darwin
release: 1.26.0-nightly
LLVM version: 6.0```



Backtrace:

   Compiling cocoa v0.13.0
thread 'rustc' panicked at 'assertion failed: `(left != right)`
  left: `ParamEnv(Binder(ProjectionPredicate(ProjectionTy { substs: Slice([S, S]), item_def_id: DefId(2/0:885 ~ core[6938]::ops[0]::arith[0]::Add[0]::Output[0]) }, S)))`,
 right: `ParamEnv(Binder(ProjectionPredicate(ProjectionTy { substs: Slice([S, S]), item_def_id: DefId(2/0:885 ~ core[6938]::ops[0]::arith[0]::Add[0]::Output[0]) }, S)))`', librustc/traits/project.rs:146:17
stack backtrace:
   0:        0x106621323 - std::sys::unix::backtrace::tracing::imp::unwind_backtrace::h78255b011393efc6
   1:        0x106618a92 - std::sys_common::backtrace::_print::h068788d7ab321c64
   2:        0x10661e10d - std::panicking::default_hook::{{closure}}::h707de483218d106c
   3:        0x10661dd98 - std::panicking::default_hook::ha4b75b184472ef99
   4:        0x104c04fa0 - core::ops::function::Fn::call::h622a21864f3755f4
   5:        0x10661e5d0 - std::panicking::rust_panic_with_hook::h8e832f9bf3226352
   6:        0x10661e3ca - std::panicking::begin_panic_fmt::heebe356c4dcb17fb
   7:        0x104f321bf - rustc::traits::project::ProjectionTyCandidateSet::push_candidate::h777952838de6649f
   8:        0x104f36d79 - rustc::traits::project::opt_normalize_projection_type::h4e2a3fb7470ec768
   9:        0x104f326c2 - rustc::traits::project::poly_project_and_unify_type::{{closure}}::h9534d6dd7cffc586
  10:        0x104f322b6 - rustc::traits::project::poly_project_and_unify_type::h5c5c79ac648f1cae
  11:        0x104f2fd93 - <rustc::traits::fulfill::FulfillProcessor<'a, 'b, 'gcx, 'tcx> as rustc_data_structures::obligation_forest::ObligationProcessor>::process_obligation::h470b336fd79eeb80
  12:        0x104f2ebe8 - rustc::traits::fulfill::FulfillmentContext::select::h2241f3e06a4c0ed0
  13:        0x104f2dbe6 - rustc::traits::fulfill::FulfillmentContext::select_all_or_error::h5407d27f7846e56f
  14:        0x103eb85b0 - rustc_typeck::check::compare_method::compare_predicate_entailment::h1e2e8e86f71cddff
  15:        0x103ed65e2 - rustc_typeck::check::check_impl_items_against_trait::heb5073227ba5d86e
  16:        0x103ecfa9f - rustc_typeck::check::check_item_type::h09ca81f3691ac3b1
  17:        0x103f1abbc - rustc_typeck::check_crate::{{closure}}::hc575e80d425c94f0
  18:        0x103f16342 - rustc_typeck::check_crate::h1ee02350b3b6a17b
  19:        0x1038bcc54 - rustc::ty::context::TyCtxt::create_and_enter::ha895fab321dd8998
  20:        0x103924952 - rustc_driver::driver::compile_input::h09390d3c8da066cd
  21:        0x10394089e - rustc_driver::run_compiler::hf1b7fcf47f029bd5
  22:        0x10386b0c5 - std::sys_common::backtrace::__rust_begin_short_backtrace::hb34e4b4b9070b735
  23:        0x10663903e - __rust_maybe_catch_panic
  24:        0x1038a6915 - <F as alloc::boxed::FnBox<A>>::call_box::ha23cd4726d1af3ed
  25:        0x10662ddbb - std::sys::unix::thread::Thread::new::thread_start::h0ccdb6055298a0f4
  26:     0x7fff7ff706c0 - _pthread_body
  27:     0x7fff7ff7056c - _pthread_start

[shssoichiro]

Confirmed with latest nightly on Linux. I can start investigating.

Edit: Works on 2018-02-24 nightly and 1.24.0 stable (or rather, stable makes it past the cgmath dependency and fails at requiring a nightly-only feature elsewhere), so this is a regression from stable.

[ishitatsuyuki]

Duplicate of #48551