ICE with associated types: unbound path

[tomaka]

The version is rustc 0.12.0-nightly (9508faa22 2014-09-17 23:45:36 +0000)

Code:

trait Foo<T> {
    type Bar;
    fn get_bar() -> <Self as Foo<T>>::Bar;
}

Error:

C:\Users\Tomaka17\Projets\test\src\main.rs:5:34: 5:35 error: internal compiler e
rror: unbound path path(T)
C:\Users\Tomaka17\Projets\test\src\main.rs:5     fn get_bar() -> <Self as Foo<T>
>::Bar;
                                                                              ^
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-bugr
eport.html
note: run with `RUST_BACKTRACE=1` for a backtrace
task 'rustc' failed at 'Box<Any>', C:\bot\slave\nightly-win32\build\src\libsynta
x\ast_util.rs:751

(because of some issues with my shell I can't print a backtrace for now)

[japaric]

Backtrace:

ice.rs:5:34: 5:35 error: internal compiler error: unbound path path(T)
ice.rs:5     fn get_bar() -> <Self as Foo<T>>::Bar;
                                          ^
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>', /var/tmp/paludis/build/dev-lang-rust-scm/work/rust-scm/src/libsyntax/ast_util.rs:751

stack backtrace:
   1:     0x7f2c448aebd0 - rt::backtrace::imp::write::hc0f5116acb0fa00fiHq
   2:     0x7f2c448b1d90 - <unknown>
   3:     0x7f2c4506dd30 - unwind::begin_unwind_inner::hf187fcd15f4370d8MTd
   4:     0x7f2c43337e90 - <unknown>
   5:     0x7f2c43337de0 - diagnostic::SpanHandler::span_bug::hca7ebac09aed6025CPE
   6:     0x7f2c456210a0 - driver::session::Session::span_bug::h9bbd70985dcc1a1cYVx
   7:     0x7f2c456f77e0 - middle::typeck::astconv::ast_ty_to_prim_ty::h5f832d51acb46f2dMY0
   8:     0x7f2c45b87670 - <unknown>
   9:     0x7f2c45a29c90 - <unknown>
  10:     0x7f2c45b8bf30 - <unknown>
  11:     0x7f2c45b8be20 - <unknown>
  12:     0x7f2c45b8e980 - <unknown>
  13:     0x7f2c45b87670 - <unknown>
  14:     0x7f2c45b766a0 - <unknown>
  15:     0x7f2c45b58090 - <unknown>
  16:     0x7f2c45b31330 - middle::typeck::collect::convert::hde892ddbd942c261z3f
  17:     0x7f2c45b2a110 - middle::typeck::collect::collect_item_types::h34839250c10cab43q4e
  18:     0x7f2c45460220 - <unknown>
  19:     0x7f2c45cfa650 - middle::typeck::check_crate::h0dbc94139bb624b2WIk
  20:     0x7f2c45d674a0 - driver::driver::phase_3_run_analysis_passes::h777eed77d7f01cb9Ucx
  21:     0x7f2c45d62910 - driver::driver::compile_input::h1e1f68cd3c0db39eRTw
  22:     0x7f2c45de7990 - <unknown>
  23:     0x7f2c45de7870 - <unknown>
  24:     0x7f2c45479a10 - <unknown>
  25:     0x7f2c45479800 - <unknown>
  26:     0x7f2c467495b0 - <unknown>
  27:     0x7f2c450bcb00 - <unknown>
  28:     0x7f2c450bcaf0 - rust_try
  29:     0x7f2c4506b330 - unwind::try::h3fd431c8ae9db728uId
  30:     0x7f2c4506b190 - task::Task::run::h8df699a6a6fb1c6ecYc
  31:     0x7f2c46749320 - <unknown>
  32:     0x7f2c4506cd80 - <unknown>
  33:     0x7f2c44371fb0 - start_thread
  34:     0x7f2c44d3bf99 - clone
  35:                0x0 - <unknown>

Version:

rustc 0.12.0-pre (49dd8e8c3 2014-09-18 08:25:38 +0000)

According to -Z time-passes, the ICE occurs during the "type collecting" phase.

cc @pcwalton

[carllerche]

I think this may be the primary issue that I am hitting trying to use associated types at the moment.

[emberian]

Me too:

#![feature(associated_types)]
pub trait Transfer<S> {
    type R;
    fn transfer(&mut self) -> <Self as Transfer<S>>::R;
}

fn main(){}

gives:

foo.rs:4:49: 4:50 error: internal compiler error: unbound path path(S)
foo.rs:4     fn transfer(&mut self) -> <Self as Transfer<S>>::R;
                                                         ^
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
task 'rustc' panicked at 'Box<Any>', /home/rustbuild/src/rust-buildbot/slave/nightly-linux/build/src/libsyntax/diagnostic.rs:116

stack backtrace:
   1:     0x7f41fc192820 - rt::backtrace::imp::write::h8a05a2225574bd5ascq
   2:     0x7f41fc1958a0 - failure::on_fail::h3903c5b5788bc95c3xq
   3:     0x7f42006dea00 - unwind::begin_unwind_inner::h0919efe752d6fd357Rd
   4:     0x7f41fccdde40 - unwind::begin_unwind::h12448235468951990776
   5:     0x7f41fccdddc0 - diagnostic::SpanHandler::span_bug::h05cbb84cec88209aH6F
   6:     0x7f4200f96310 - middle::typeck::astconv::ast_ty_to_prim_ty::h9f95d12e1d973d81rR4
   7:     0x7f42013a38d0 - middle::typeck::astconv::ast_ty_to_ty::h12861914180600525724
   8:     0x7f4201068d60 - iter::Iterator::collect::h13337330953596778502
   9:     0x7f42013a6610 - middle::typeck::astconv::ast_path_substs::h13947801815788576546
  10:     0x7f42013a88c0 - middle::typeck::astconv::ast_path_to_trait_ref::h17933483232567598950
  11:     0x7f42013a9380 - middle::typeck::astconv::associated_ty_to_ty::h8004787093255996260
  12:     0x7f42013a38d0 - middle::typeck::astconv::ast_ty_to_ty::h12861914180600525724
  13:     0x7f420139b470 - middle::typeck::astconv::ty_of_method_or_bare_fn::h17568311308738250480
  14:     0x7f420137b230 - middle::typeck::collect::collect_trait_methods::ty_method_of_trait_method::hf39311a07abed50b7dk
  15:     0x7f4201357dd0 - middle::typeck::collect::convert::hde1a9421fe94c3ef0Uk
  16:     0x7f4201351640 - middle::typeck::collect::collect_item_types::h2377a8e9bb3d5ad9GUj
  17:     0x7f4200d3fbc0 - util::common::time::h6545073167695776246
  18:     0x7f42015378d0 - middle::typeck::check_crate::h0f9c9a0fae05a0bfJEp
  19:     0x7f42015a0940 - driver::driver::phase_3_run_analysis_passes::h46245b66b26614aeJoC
  20:     0x7f420159b7a0 - driver::driver::compile_input::he3b1257e173b8860u5B
  21:     0x7f420161e900 - driver::run_compiler::hd836d04808dd8d5eLVF
  22:     0x7f420161e7f0 - driver::run::closure.146540
  23:     0x7f4200d58b00 - task::TaskBuilder<S>::try_future::closure.104852
  24:     0x7f4200d588f0 - task::TaskBuilder<S>::spawn_internal::closure.104823
  25:     0x7f4200a25630 - task::NativeSpawner.Spawner::spawn::closure.8456
  26:     0x7f42007338c0 - rust_try_inner
  27:     0x7f42007338b0 - rust_try
  28:     0x7f42006dc380 - unwind::try::h32143614f9ac9c88PGd
  29:     0x7f42006dc210 - task::Task::run::h8c90cb04437a131dFMc
  30:     0x7f4200a25370 - task::NativeSpawner.Spawner::spawn::closure.8394
  31:     0x7f42006dda20 - thread::thread_start::h7bbfc46247c32113U7c
  32:     0x7f41fb544250 - start_thread
  33:     0x7f42003b83b9 - clone
  34:                0x0 - <unknown>

[nikomatsakis]

I have a fix for this issue but it requires PR #18743. I'll open the PR once that lands.

[nikomatsakis]

Branch is https://github.com/nikomatsakis/rust/tree/issue-17388-unbound-path-assoc-type