panic during build of unrust: region_obligations not empty

[kevinw]

panic while compiling the unrust crate with nightly

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rustc --version --verbose:

rustc 1.28.0-nightly (cbc4c8380 2018-06-22)
binary: rustc
commit-hash: cbc4c8380fb92a719ae9be40f9da44ca7e3e2f3f
commit-date: 2018-06-22
host: x86_64-apple-darwin
release: 1.28.0-nightly
LLVM version: 6.0

Backtrace:

computer:conetracing kevin$ RUST_BACKTRACE=1 cargo build --verbose
       Fresh void v1.0.2
       Fresh libc v0.2.40
       Fresh lazy_static v1.0.0
       Fresh ucd-util v0.1.1
       Fresh glob v0.2.11
       Fresh cfg-if v0.1.3
       Fresh utf8-ranges v1.0.0
       Fresh unicode-width v0.1.4
       Fresh unicode-xid v0.1.0
       Fresh bitflags v1.0.3
       Fresh vec_map v0.8.1
       Fresh strsim v0.7.0
       Fresh ansi_term v0.11.0
       Fresh foreign-types-shared v0.1.1
       Fresh peeking_take_while v0.1.2
       Fresh block v0.1.6
       Fresh adler32 v1.0.2
       Fresh byteorder v1.2.3
       Fresh lazy_static v0.2.11
       Fresh approx v0.1.1
       Fresh serde v1.0.55
       Fresh lzw v0.10.0
       Fresh hound v3.4.0
       Fresh fnv v1.0.6
       Fresh typed-arena v1.3.0
       Fresh futures v0.1.21
       Fresh obj v0.8.2
       Fresh unreachable v1.0.0
       Fresh memchr v2.0.1
       Fresh memchr v1.0.2
       Fresh atty v0.2.10
       Fresh which v1.0.5
       Fresh malloc_buf v0.0.6
       Fresh time v0.1.40
       Fresh rand v0.4.2
       Fresh shared_library v0.1.8
       Fresh regex-syntax v0.5.6
       Fresh log v0.4.1
       Fresh textwrap v0.9.0
       Fresh proc-macro2 v0.2.3
       Fresh proc-macro2 v0.3.8
       Fresh xml-rs v0.7.0
       Fresh foreign-types v0.3.2
       Fresh inflate v0.4.2
       Fresh deflate v0.7.18
       Fresh thread_local v0.3.5
       Fresh aho-corasick v0.6.4
       Fresh nom v4.0.0
       Fresh nom v3.2.1
       Fresh objc v0.2.2
       Fresh libloading v0.4.3
       Fresh khronos_api v2.2.0
       Fresh log v0.3.9
       Fresh clap v2.31.2
       Fresh quote v0.4.2
       Fresh quote v0.5.2
       Fresh core-foundation-sys v0.5.1
       Fresh num-traits v0.2.4
       Fresh regex v0.2.11
       Fresh uni-glsl v0.1.0 (file:///Users/kevin/src/unrust/uni-glsl)
       Fresh cexpr v0.2.3
       Fresh gl_generator v0.9.0
       Fresh clang-sys v0.21.2
       Fresh gl_generator v0.6.1
       Fresh syn v0.13.10
       Fresh core-foundation v0.5.1
       Fresh num-integer v0.1.38
       Fresh num-traits v0.1.43
       Fresh env_logger v0.4.3
       Fresh serde_derive v1.0.55
       Fresh num-derive v0.2.1
       Fresh unrust-derive v0.1.0 (file:///Users/kevin/src/unrust/unrust-derive)
       Fresh core-graphics v0.13.0
       Fresh num-iter v0.1.37
       Fresh num-rational v0.1.42
       Fresh cgmath v0.16.1
       Fresh bindgen v0.32.3
       Fresh cocoa v0.14.0
       Fresh png v0.12.0
       Fresh gleam v0.5.0
       Fresh gl v0.6.5
       Fresh winit v0.13.1
       Fresh image v0.19.0
       Fresh cgl v0.2.2
       Fresh webgl v0.1.0 (file:///Users/kevin/src/unrust/webgl)
       Fresh coreaudio-sys v0.2.2 (file:///Users/kevin/src/coreaudio-sys)
       Fresh glutin v0.15.0
       Fresh coreaudio-rs v0.9.1 (file:///Users/kevin/src/coreaudio-rs)
       Fresh uni-app v0.1.0 (file:///Users/kevin/src/unrust/uni-app)
       Fresh cpal v0.8.1 (file:///Users/kevin/src/cpal)
       Fresh uni-pad v0.1.0 (file:///Users/kevin/src/unrust/uni-pad)
       Fresh uni-snd v0.1.0 (file:///Users/kevin/src/unrust/uni-snd)
   Compiling unrust v0.1.1 (file:///Users/kevin/src/unrust)
     Running `rustc --crate-name unrust /Users/kevin/src/unrust/src/lib.rs --crate-type lib --emit=dep-info,link -C debuginfo=2 --cfg 'feature="default"' -C metadata=51b65ca54940ec8f -C extra-filename=-51b65ca54940ec8f --out-dir /Users/kevin/src/conetracing/target/debug/deps -C incremental=/Users/kevin/src/conetracing/target/debug/incremental -L dependency=/Users/kevin/src/conetracing/target/debug/deps --extern bitflags=/Users/kevin/src/conetracing/target/debug/deps/libbitflags-c990d7bd8f03d465.rlib --extern cgmath=/Users/kevin/src/conetracing/target/debug/deps/libcgmath-31b6271ae6e769e9.rlib --extern fnv=/Users/kevin/src/conetracing/target/debug/deps/libfnv-4abe3704733a22f9.rlib --extern futures=/Users/kevin/src/conetracing/target/debug/deps/libfutures-203db50c8c9d93bc.rlib --extern hound=/Users/kevin/src/conetracing/target/debug/deps/libhound-fc016b1814fdc0e4.rlib --extern image=/Users/kevin/src/conetracing/target/debug/deps/libimage-1967be20c5d5813c.rlib --extern lazy_static=/Users/kevin/src/conetracing/target/debug/deps/liblazy_static-891d049fce5a0893.rlib --extern obj=/Users/kevin/src/conetracing/target/debug/deps/libobj-548dea30b3de4279.rlib --extern typed_arena=/Users/kevin/src/conetracing/target/debug/deps/libtyped_arena-4d76a44c7a34bd2d.rlib --extern uni_app=/Users/kevin/src/conetracing/target/debug/deps/libuni_app-21a4577913886d3a.rlib --extern uni_glsl=/Users/kevin/src/conetracing/target/debug/deps/libuni_glsl-c13d623c07b38b9e.rlib --extern uni_pad=/Users/kevin/src/conetracing/target/debug/deps/libuni_pad-f38219fdc25cf95f.rlib --extern uni_snd=/Users/kevin/src/conetracing/target/debug/deps/libuni_snd-3a36a8cd30199129.rlib --extern unrust_derive=/Users/kevin/src/conetracing/target/debug/deps/libunrust_derive-d5c490821a959f43.dylib --extern webgl=/Users/kevin/src/conetracing/target/debug/deps/libwebgl-e12cd4b26b69fa11.rlib`
thread 'main' panicked at 'region_obligations not empty: [
    (
        NodeId(
            2868
        ),
        RegionObligation(sub_region='_#1r, sup_type=engine::asset::asset_database::AssetDatabaseContext<FS>)
    )
]', librustc/infer/mod.rs:1057:9
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
   1: std::sys_common::backtrace::print
   2: std::panicking::default_hook::{{closure}}
   3: std::panicking::default_hook
   4: rustc::util::common::panic_hook
   5: std::panicking::rust_panic_with_hook
   6: std::panicking::continue_panic_fmt
   7: std::panicking::begin_panic_fmt
   8: rustc::infer::InferCtxt::take_and_reset_region_constraints
   9: rustc_mir::borrow_check::nll::type_check::TypeChecker::prove_predicates
  10: <rustc_mir::borrow_check::nll::type_check::TypeVerifier<'a, 'b, 'gcx, 'tcx> as rustc::mir::visit::Visitor<'tcx>>::visit_constant
  11: <rustc_mir::borrow_check::nll::type_check::TypeVerifier<'a, 'b, 'gcx, 'tcx> as rustc::mir::visit::Visitor<'tcx>>::visit_mir
  12: rustc_mir::borrow_check::nll::type_check::type_check_internal
  13: rustc_mir::borrow_check::nll::compute_regions
  14: rustc_mir::borrow_check::do_mir_borrowck
  15: rustc::ty::context::tls::with_related_context
  16: rustc::infer::InferCtxtBuilder::enter
  17: rustc_mir::borrow_check::mir_borrowck
  18: rustc::ty::query::__query_compute::mir_borrowck
  19: rustc::ty::query::<impl rustc::ty::query::config::QueryAccessors<'tcx> for rustc::ty::query::queries::mir_borrowck<'tcx>>::compute
  20: rustc::ty::context::tls::with_context
  21: rustc::dep_graph::graph::DepGraph::with_task_impl
  22: rustc::ty::context::tls::with_related_context
  23: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::force_query_with_job
  24: rustc::ty::query::plumbing::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::get_query
  25: rustc::ty::query::<impl rustc::ty::context::TyCtxt<'a, 'tcx, 'lcx>>::mir_borrowck
  26: rustc::ty::<impl rustc::ty::context::TyCtxt<'a, 'gcx, 'tcx>>::par_body_owners
  27: rustc::util::common::time
  28: rustc::ty::context::tls::enter_context
  29: <std::thread::local::LocalKey<T>>::with
  30: rustc::ty::context::TyCtxt::create_and_enter
  31: rustc_driver::driver::compile_input
  32: rustc_driver::run_compiler_with_pool
  33: <scoped_tls::ScopedKey<T>>::set
  34: <scoped_tls::ScopedKey<T>>::set
  35: syntax::with_globals
  36: <std::panic::AssertUnwindSafe<F> as core::ops::function::FnOnce<()>>::call_once
  37: __rust_maybe_catch_panic
  38: rustc_driver::run
  39: rustc_driver::main
  40: std::rt::lang_start::{{closure}}
  41: std::panicking::try::do_call
  42: __rust_maybe_catch_panic
  43: std::rt::lang_start_internal
  44: main
query stack during panic:
#0 [mir_borrowck] processing `<engine::asset::asset_database::AssetDatabase<FS, F> as std::ops::Deref>::deref`
end of query stack

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/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.28.0-nightly (cbc4c8380 2018-06-22) running on x86_64-apple-darwin

note: compiler flags: -C debuginfo=2 -C incremental --crate-type lib

note: some of the compiler flags provided by cargo are hidden

error: Could not compile `unrust`.

Caused by:
  process didn't exit successfully: `rustc --crate-name unrust /Users/kevin/src/unrust/src/lib.rs --crate-type lib --emit=dep-info,link -C debuginfo=2 --cfg feature="default" -C metadata=51b65ca54940ec8f -C extra-filename=-51b65ca54940ec8f --out-dir /Users/kevin/src/conetracing/target/debug/deps -C incremental=/Users/kevin/src/conetracing/target/debug/incremental -L dependency=/Users/kevin/src/conetracing/target/debug/deps --extern bitflags=/Users/kevin/src/conetracing/target/debug/deps/libbitflags-c990d7bd8f03d465.rlib --extern cgmath=/Users/kevin/src/conetracing/target/debug/deps/libcgmath-31b6271ae6e769e9.rlib --extern fnv=/Users/kevin/src/conetracing/target/debug/deps/libfnv-4abe3704733a22f9.rlib --extern futures=/Users/kevin/src/conetracing/target/debug/deps/libfutures-203db50c8c9d93bc.rlib --extern hound=/Users/kevin/src/conetracing/target/debug/deps/libhound-fc016b1814fdc0e4.rlib --extern image=/Users/kevin/src/conetracing/target/debug/deps/libimage-1967be20c5d5813c.rlib --extern lazy_static=/Users/kevin/src/conetracing/target/debug/deps/liblazy_static-891d049fce5a0893.rlib --extern obj=/Users/kevin/src/conetracing/target/debug/deps/libobj-548dea30b3de4279.rlib --extern typed_arena=/Users/kevin/src/conetracing/target/debug/deps/libtyped_arena-4d76a44c7a34bd2d.rlib --extern uni_app=/Users/kevin/src/conetracing/target/debug/deps/libuni_app-21a4577913886d3a.rlib --extern uni_glsl=/Users/kevin/src/conetracing/target/debug/deps/libuni_glsl-c13d623c07b38b9e.rlib --extern uni_pad=/Users/kevin/src/conetracing/target/debug/deps/libuni_pad-f38219fdc25cf95f.rlib --extern uni_snd=/Users/kevin/src/conetracing/target/debug/deps/libuni_snd-3a36a8cd30199129.rlib --extern unrust_derive=/Users/kevin/src/conetracing/target/debug/deps/libunrust_derive-d5c490821a959f43.dylib --extern webgl=/Users/kevin/src/conetracing/target/debug/deps/libwebgl-e12cd4b26b69fa11.rlib` (exit code: 101)

[FraGag]

Probably a duplicate of #51649.

[estebank]

Closing as per the fixed duplicate. Feel free to reopen if you see this problem again!