ICE:cannot relate bound region

[hebiyan]

'rustc -v' output: rustc 0.12.0-pre (641b1980a 2014-09-09 04:26:18 +0000)

os: Mac OS X 10.9.4

'uname -a' output:

Darwin server.gideon001.private 13.3.0 Darwin Kernel Version 13.3.0: Tue Jun  3 21:27:35 PDT 2014; root:xnu-2422.110.17~1/RELEASE_X86_64 x86_64

code:

fn main () {
    let addf: <'r>|int|:'r -> Box<|int|:'r -> int> = 
        |n:int|  {box |m:int| -> int {n + m }};

    println!("{}", (*addf(2))(3));
}

RUST_BACKTRACE=1 rustc output:

cl.rs:4:9: 4:47 error: internal compiler error: cannot relate bound region: ReLateBound (10, BrNamed (syntax::ast::DefId{krate: 0u32, node: 26u32}, 'r)) <= ReInfer (0)
cl.rs:4         |n:int|  {box |m:int| -> int {n + m }};
                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
note: the compiler hit an unexpected failure path. this is a bug.
note: we would appreciate a bug report: http://doc.rust-lang.org/complement-bugreport.html
note: run with `RUST_BACKTRACE=1` for a backtrace
task 'rustc' failed at 'Box<Any>', /Users/gideon/tools/rust/rust/src/libsyntax/ast_util.rs:776

stack backtrace:
   1:        0x110d45925 - rt::backtrace::imp::write::hc34efde930f36017Lhr
   2:        0x110d48c61 - failure::on_fail::h3bc40b5494fc9081Fyr
   3:        0x110ffba35 - unwind::begin_unwind_inner::h82cdbb3cd9ec0b01b0d
   4:        0x1103c2c6a - unwind::begin_unwind::h3453961218879215225
   5:        0x1103c2be5 - diagnostic::SpanHandler::span_bug::h1b86fed0ce30aee8YaF
   6:        0x10d8e49c7 - driver::session::Session::span_bug::h64074688fe14108d1IE
   7:        0x10de03e21 - middle::typeck::infer::region_inference::RegionVarBindings<'a, 'tcx>::make_subregion::h60507627917bb1c6jUc
   8:        0x10de1348f - middle::typeck::infer::sub::Sub<'f, 'tcx>.Combine<'tcx>::regions::h8af2cb6ad62249fefAf
   9:        0x10de13115 - middle::typeck::infer::sub::Sub<'f, 'tcx>.Combine<'tcx>::contraregions::hd6337c74f4ce1730Fzf
  10:        0x10ddb3cc5 - middle::typeck::infer::sub::Sub<'f, 'tcx>.Combine<'tcx>::tys::h4ff6780852b0589dNIf
  11:        0x10ddb1750 - middle::typeck::infer::coercion::Coerce<'f, 'tcx>::subtype::h3ece1fef911cabeeMn6
  12:        0x10ddb150c - middle::typeck::infer::coercion::Coerce<'f, 'tcx>::coerce_borrowed_fn::h969fec4a98356fe5h76
  13:        0x10ddb12e1 - middle::typeck::infer::coercion::Coerce<'f, 'tcx>::tys::closure.134706
  14:        0x10ddae4c4 - middle::typeck::infer::coercion::Coerce<'f, 'tcx>::unpack_actual_value::h948805772714329226
  15:        0x10ddadf79 - middle::typeck::infer::coercion::Coerce<'f, 'tcx>::tys::hb38bc87449217190If6
  16:        0x10de21648 - middle::typeck::infer::mk_coercety::closure.136784
  17:        0x10de212d0 - middle::typeck::infer::InferCtxt<'a, 'tcx>::commit_if_ok::closure.136776
  18:        0x10de21147 - middle::typeck::infer::InferCtxt<'a, 'tcx>::commit_unconditionally::h11340877979196374766
  19:        0x10dd4c305 - middle::typeck::infer::mk_coercety::hc4de794711c1d371Bgi
  20:        0x10dcf3565 - middle::typeck::check::FnCtxt<'a, 'tcx>::mk_assignty::h476edb1f6652be36yTY
  21:        0x10dcf33bd - middle::typeck::check::demand::coerce::h7c31b43dc8bb8462mxT
  22:        0x10dd5bc6a - middle::typeck::check::check_expr_coercable_to_type::closure.133678
  23:        0x10dd543ef - middle::typeck::check::check_expr_with_unifier::h6d5b3dc20f73aee9F3Z
  24:        0x10dda8474 - middle::typeck::check::check_decl_local::h5a935f957a31a756w61
  25:        0x10dda86c8 - middle::typeck::check::check_stmt::h372cfadc360693a0E81
  26:        0x10dd16662 - middle::typeck::check::check_block_with_expected::h22fe190983b7dfe2Rc2
  27:        0x10dd11d58 - middle::typeck::check::check_fn::hb51a901c65978ab9OLW
  28:        0x10dd112c9 - middle::typeck::check::check_bare_fn::h3d757c7ca707a846sAW
  29:        0x10dd09f8d - middle::typeck::check::check_item::h13627fd0014f8964mgX
  30:        0x10dd110ad - middle::typeck::check::check_item_types::h56a54a78d1f84672rzW
  31:        0x10d740b86 - util::common::time::h6774358895183961009
  32:        0x10df221f8 - middle::typeck::check_crate::h79d3f57e66bdaf51xgp
  33:        0x10dfde766 - driver::driver::phase_3_run_analysis_passes::h821dbd7bfc00cf7e6YD
  34:        0x10dfd94b2 - driver::driver::compile_input::h7817fa347452fba6JKD
  35:        0x10e064a0a - driver::run_compiler::ha557cce5753da6b01CH
  36:        0x10e062e16 - driver::main_args::closure.148073
  37:        0x10d758d6b - task::TaskBuilder<S>::try_future::closure.100105
  38:        0x10d758c73 - task::TaskBuilder<S>::spawn_internal::closure.100076
  39:        0x110bcd6cd - task::spawn_opts::closure.8474
  40:        0x11105e1cc - rust_try_inner
  41:        0x11105e1b6 - rust_try
  42:        0x110ff8ed7 - unwind::try::h083fe44507311ba0lOd
  43:        0x110ff8d4c - task::Task::run::h91e4f0552d7b8b33L0c
  44:        0x110bcd522 - task::spawn_opts::closure.8413
  45:        0x110ffa97a - thread::thread_start::h4f6e4374d46c14dbSld
  46:     0x7fff8bf53899 - _pthread_body
  47:     0x7fff8bf5372a - _pthread_struct_init

[Gankra]

I think I'm getting this ICE on the latest nightly in collect-rs:

unused manifest key: profile.build.debug
       Fresh traverse v0.0.2
   Compiling collect v0.0.6 (file:///C:/users/alexis/documents/github/collect-rs)
     Running `rustc C:\users\alexis\documents\github\collect-rs\src\lib.rs --crate-name collect --crate-type lib --cfg ndebug --test -C metadata=507ed9788c885314 -C extra-filename=-507ed9788c885314 --out-dir C:\users\alexis\documents\github\collect-rs\target --emit=dep-info,link -L C:\users\alexis\documents\github\collect-rs\target -L C:\users\alexis\documents\github\collect-rs\target\deps --extern traverse=C:\users\alexis\documents\github\collect-rs\target\deps/libtraverse-c0a1cc9151073bab.rlib`
C:\users\alexis\documents\github\collect-rs\src\tree\set.rs:1036:5: 1042:6 error: internal compiler error: cannot relate bound region: ReLateBound(DebruijnIndex { depth: 1 }, BrAnon(0)) <= ReLateBound(DebruijnIndex { depth: 2 }, BrAnon(0))
C:\users\alexis\documents\github\collect-rs\src\tree\set.rs:1036     impl<'a, 'b> FnMut(&int) -> bool for Counter<'a, 'b> {
C:\users\alexis\documents\github\collect-rs\src\tree\set.rs:1037         extern "rust-call" fn call_mut(&mut self, (&x,): (&int,)) -> bool {
C:\users\alexis\documents\github\collect-rs\src\tree\set.rs:1038             assert_eq!(x, self.expected[*self.i]);
C:\users\alexis\documents\github\collect-rs\src\tree\set.rs:1039             *self.i += 1;
C:\users\alexis\documents\github\collect-rs\src\tree\set.rs:1040             true
C:\users\alexis\documents\github\collect-rs\src\tree\set.rs:1041         }
                                                                 ...
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: http://doc.rust-lang.org/complement-bugreport.html
note: run with `RUST_BACKTRACE=1` for a backtrace
thread 'rustc' panicked at 'Box<Any>', C:\bot\slave\nightly-win-64\build\src\libsyntax\diagnostic.rs:123

stack backtrace:
   1:         0x69bef7f8 - sys::backtrace::write::h5b0ba28ad71857afeQt
   2:         0x69c021e9 - rt::unwind::register::h91aefd9b472076aecGz
   3:         0x69b82fcb - rt::unwind::begin_unwind_inner::h04b772eae7a7fc7bJDz
   4:         0x6f8acd56 - diagnostic::SpanHandler::span_bug::h90408fcd1499494fwZF
   5:         0x6f8acd00 - diagnostic::SpanHandler::span_bug::h90408fcd1499494fwZF
   6:           0x972a31 - middle::infer::region_inference::RegionVarBindings<$u{27}a$C$$u{20}$u{27}tcx$GT$::make_subregion::h2d032b24a1882941bAw
   7:           0x90f621 - middle::infer::region_inference::RegionVarBindings<$u{27}a$C$$u{20}$u{27}tcx$GT$::make_eqregion::h2d032b24a1882941zzw
   8:           0x90f4a3 - middle::infer::equate::Equate<$u{27}f$C$$u{20}$u{27}tcx$GT$.Combine$LT$$u{27}tcx$GT$::regions::hc467de7375d80198Akr
   9:           0x908f8f - middle::infer::equate::Equate<$u{27}f$C$$u{20}$u{27}tcx$GT$.Combine$LT$$u{27}tcx$GT$::tys::h912a5dd2b206dbe1Frr
  10:           0x921c09 - middle::ty::mk_unboxed_closure::hcc6ac3bf2616fcf0sv2
  11:           0x9095c5 - middle::infer::equate::Equate<$u{27}f$C$$u{20}$u{27}tcx$GT$.Combine$LT$$u{27}tcx$GT$::tys::h912a5dd2b206dbe1Frr
  12:           0x91f43a - util::ppaux::ty..BoundRegion.Repr<$u{27}tcx$GT$::repr::hbe9f644adb44adbbPbt
  13:           0x91efd3 - util::ppaux::ty..BoundRegion.Repr<$u{27}tcx$GT$::repr::hbe9f644adb44adbbPbt
  14:           0x91eca2 - util::ppaux::ty..BoundRegion.Repr<$u{27}tcx$GT$::repr::hbe9f644adb44adbbPbt
  15:           0x99113e - middle::infer::InferCtxt<$u{27}a$C$$u{20}$u{27}tcx$GT$::sub_trait_refs::h390adbc09a3b494bgyB
  16:           0xa00c4e - middle::ty::TraitRef<$u{27}tcx$GT$...std..cmp..PartialEq::eq::h543edb6d2ba7d3b3ruZ
  17:           0xa0ca51 - middle::ty::GenericBounds<$u{27}tcx$GT$::is_empty::hc31f5ae763726d73PQ1
  18:           0xa07660 - middle::traits::select::Candidate<$u{27}tcx$GT$.Repr$LT$$u{27}tcx$GT$::repr::h48b108f0ecd54c0dbPS
  19:           0x9f8055 - middle::ty::TraitRef<$u{27}tcx$GT$.RegionEscape::has_regions_escaping_depth::he874f51e3eb2d51fZQ7
  20:           0x9f4b4c - middle::traits::select::SelectionContext<$u{27}cx$C$$u{20}$u{27}tcx$GT$::select::hf1da19fa1e7dadc9ZoQ
  21:           0x9ee4cd - middle::traits::select::SelectionContext<$u{27}cx$C$$u{20}$u{27}tcx$GT$::new::hd2f65bc2e1895228nnQ
  22:           0x8c7a83 - middle::traits::fulfill::FulfillmentContext<$u{27}tcx$GT$::select_all_or_error::hcc757e1ded501152KKP
  23:         0x6d4db274
  24:         0x6d54dbe0 - check::method::CandidateSource...std..cmp..PartialOrd::ge::he78261c7d2364bd3edi
  25:         0x6d552623 - check::wf::CheckTypeWellFormedVisitor<$u{27}ccx$C$$u{20}$u{27}tcx$GT$.Visitor$LT$$u{27}v$GT$::visit_item::h83ad74d1a29d2d8c58i
  26:         0x6d553f9f - check::wf::CheckTypeWellFormedVisitor<$u{27}ccx$C$$u{20}$u{27}tcx$GT$.Visitor$LT$$u{27}v$GT$::visit_item::h83ad74d1a29d2d8c58i
  27:         0x6d5526f6 - check::wf::CheckTypeWellFormedVisitor<$u{27}ccx$C$$u{20}$u{27}tcx$GT$.Visitor$LT$$u{27}v$GT$::visit_item::h83ad74d1a29d2d8c58i
  28:         0x6d553f9f - check::wf::CheckTypeWellFormedVisitor<$u{27}ccx$C$$u{20}$u{27}tcx$GT$.Visitor$LT$$u{27}v$GT$::visit_item::h83ad74d1a29d2d8c58i
  29:         0x6d5526f6 - check::wf::CheckTypeWellFormedVisitor<$u{27}ccx$C$$u{20}$u{27}tcx$GT$.Visitor$LT$$u{27}v$GT$::visit_item::h83ad74d1a29d2d8c58i
  30:         0x6d553f9f - check::wf::CheckTypeWellFormedVisitor<$u{27}ccx$C$$u{20}$u{27}tcx$GT$.Visitor$LT$$u{27}v$GT$::visit_item::h83ad74d1a29d2d8c58i
  31:         0x6d5526f6 - check::wf::CheckTypeWellFormedVisitor<$u{27}ccx$C$$u{20}$u{27}tcx$GT$.Visitor$LT$$u{27}v$GT$::visit_item::h83ad74d1a29d2d8c58i
  32:         0x6d8273db - check_crate::hd1761d8b5c95808dQZy
  33:         0x6d822422 - check_crate::hd1761d8b5c95808dQZy
  34:         0x70b227ae - driver::phase_3_run_analysis_passes::h50b942faf81eb47bIta
  35:         0x70b03695 - driver::compile_input::hd01226bf772688afvba
  36:         0x70ca3e95 - run::h9cdc49dc8c011aeedYb
  37:         0x70ca05b9 - run::h9cdc49dc8c011aeedYb
  38:         0x69c6648c - rust_try
  39:         0x69c66469 - rust_try
  40:         0x70ca0d0f - run::h9cdc49dc8c011aeedYb
  41:         0x69bf4ee7 - sys::tcp::TcpListener::bind::hb1b42652ff0a60d9Fqw
  42:     0x7ffcd28616ad - BaseThreadInitThunk

Could not compile `collect`.

Caused by:
  Process didn't exit successfully: `rustc C:\users\alexis\documents\github\collect-rs\src\lib.rs --crate-name collect --crate-type lib --cfg ndebug --test -C metadata=507ed9788c885314 -C extra-filename=-507ed9788c885314 --out-dir C:\users\alexis\documents\github\collect-rs\target --emit=dep-info,link -L C:\users\alexis\documents\github\collect-rs\target -L C:\users\alexis\documents\github\collect-rs\target\deps --extern traverse=C:\users\alexis\documents\github\collect-rs\target\deps/libtraverse-c0a1cc9151073bab.rlib` (status=101)

This is of course hidden behind a second ICE about for loop debug info. Good way to start the day.

Haven't had a chance to creduce.

[Gankra]

Small code:

#![feature(unboxed_closures)]

struct Counter<'a, 'b> {
    i: &'a mut uint,
    expected: &'b [int],
}

impl<'a, 'b> FnMut(&int) -> bool for Counter<'a, 'b> {
    extern "rust-call" fn call_mut(&mut self, (&x,): (&int,)) -> bool {
        assert_eq!(x, self.expected[*self.i]);
        *self.i += 1;
        true
    }
}

fn main() {}

[Gankra]

Tiny code:

struct Counter;

impl FnMut(&int) -> bool for Counter {
    extern "rust-call" fn call_mut(&mut self, (&x,): (&int,)) -> bool {}
}

Run by cargo test with this as main.rs.

Using rustc 0.13.0-nightly (34d680009 2014-12-22 00:12:47 +0000)

[Gankra]

@nikomatsakis Showed me that it was actually https://github.com/rust-lang/rust/issues/19982

[tamird]

Crazy, this ICEs with cargo test, but not with cargo build.

[Gankra]

It ICEs only on test because the snippet I posted is is missing a fn main() {} declaration, and the compiler errors out there first.