ICE: 'rustc' panicked at 'assertion failed: *start <= *end' in slice.rs:396

[mitchmindtree]

I'm getting the following ICE

mindTree:RustyJen Mitch$ cargo build                                                                               
   Compiling jen v0.0.0 (file:///Users/Mitch/Programming/Rust/RustyJen)                                            
error: internal compiler error: unexpected panic                                                                   
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 'assertion failed: *start <= *end', /Users/rustbuild/src/rust-buildbot/slave/nightly-mac/b
uild/src/libcore/slice.rs:396                                                                                      

when compiling my project against the latest OSX nightly rustc 0.13.0-nightly (221fc1e3c 2014-10-31 02:27:15 +0000).

[msiemens]

Could you run cargo build again with RUST_BACKTRACE=1 (= RUST_BACKTRACE=1 cargo build) and post the backtrace here?

[mitchmindtree]

oh, of course!

   Compiling jen v0.0.0 (file:///Users/Mitch/Programming/Rust/RustyJen)                                                    
error: internal compiler error: unexpected panic                                                                           
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 'assertion failed: *start <= *end', /Users/rustbuild/src/rust-buildbot/slave/nightly-mac/build/src
/libcore/slice.rs:396                                                                                                      

stack backtrace:                                                                                                           
   1:        0x10d976929 - rt::backtrace::imp::write::hfe87245730e40e498nq                                                 
   2:        0x10d979b6c - failure::on_fail::h250240fc1d2cc13cHEq                                                          
   3:        0x10dbdb395 - unwind::begin_unwind_inner::h629bbfd5c5c7ad4bSJd                                                
   4:        0x10dbdb02f - unwind::begin_unwind_fmt::h26eed6b8c9614d01kHd                                                  
   5:        0x10dbdad82 - rust_begin_unwind                                                                               
   6:        0x10dc315dc - panicking::panic_fmt::h9773bd98fc91f575h7j                                                      
   7:        0x10dc2806f - panicking::panic::hf2209879fd0a6385l4j                                                          
   8:        0x10aaee5eb - middle::typeck::check::vtable::check_object_safety::hd2ef41a3d3297642CBN                        
   9:        0x10ab588db - middle::typeck::check::FnCtxt<'a, 'tcx>::register_unsize_obligations::h93da532586d1f760GhX      
  10:        0x10ab58770 - middle::typeck::check::FnCtxt<'a, 'tcx>::register_autoref_obligations::hdcb3d01fc6bc2a0bEgX     
  11:        0x10ab58791 - middle::typeck::check::FnCtxt<'a, 'tcx>::register_autoref_obligations::hdcb3d01fc6bc2a0bEgX     
  12:        0x10ab345b7 - middle::typeck::check::FnCtxt<'a, 'tcx>::write_adjustment::h559300c55596d0cbIdX                 
  13:        0x10ab255fb - middle::typeck::check::FnCtxt<'a, 'tcx>::mk_assignty::h495121b0f62037e0xvX                      
  14:        0x10ab253c5 - middle::typeck::check::demand::coerce::h94b3644e227f71a2RPR                                     
  15:        0x10ab85f09 - middle::typeck::check::check_expr_coercable_to_type::closure.132412                             
  16:        0x10ab7ded6 - middle::typeck::check::check_expr_with_unifier::h69de001b4060f90bdJY                            
  17:        0x10abce4d3 - middle::typeck::check::check_decl_local::h0cae6d84e687454cWJ0                                   
  18:        0x10abce647 - middle::typeck::check::check_stmt::h46c2f90bba03a179WL0                                         
  19:        0x10ab49acf - middle::typeck::check::check_block_with_expected::hde19a8324d3b35305P0                          
  20:        0x10ab45862 - middle::typeck::check::check_fn::h6804afcefd6fc458pvV                                           
  21:        0x10ab44d8f - middle::typeck::check::check_bare_fn::hb7e7210980026133EkV                                      
  22:        0x10ab4c530 - middle::typeck::check::check_method_body::h36c9acd490135be6xPV                                  
  23:        0x10ab41d58 - middle::typeck::check::check_item::h39bec44c2e37ec07NEV                                         
  24:        0x10ab44462 - visit::Visitor::visit_mod::h8897482306723449792                                                 
  25:        0x10ab42fb0 - visit::walk_item::h18177613619592010200                                                         
  26:        0x10ab4446d - visit::Visitor::visit_mod::h8897482306723449792                                                 
  27:        0x10ab42fb0 - visit::walk_item::h18177613619592010200                                                         
  28:        0x10ab44bea - middle::typeck::check::check_item_types::h232f3854bb5459bfOjV                                   
  29:        0x10a6571a6 - util::common::time::h13516290540542203264                                                       
  30:        0x10ae04d7e - middle::typeck::check_crate::h6b2f140055619821A3n                                               
  31:        0x10ae6dadf - driver::driver::phase_3_run_analysis_passes::h9af5661d865aaa0elNA                               
  32:        0x10ae683a8 - driver::driver::compile_input::h64933a02c4abd95e6tA                                             
  33:        0x10aee5b88 - driver::run_compiler::h37c520fe594ec038KgE                                                      
  34:        0x10aee3dae - driver::run::closure.145405                                                                     
  35:        0x10a66f64b - task::TaskBuilder<S>::try_future::closure.103660                                                
  36:        0x10a66f543 - task::TaskBuilder<S>::spawn_internal::closure.103631                                            
  37:        0x10d69ba4d - task::NativeSpawner.Spawner::spawn::closure.8535                                                
  38:        0x10dc4124c - rust_try_inner                                                                                  
  39:        0x10dc41236 - rust_try                                                                                        
  40:        0x10dbd8a17 - unwind::try::h554e9d30ab8d9725cyd                                                               
  41:        0x10dbd88ac - task::Task::run::h39093ecd59554b49ZJc                                                           
  42:        0x10d69b873 - task::NativeSpawner.Spawner::spawn::closure.8472                                                
  43:        0x10dbda1c7 - thread::thread_start::h589be8c0a398d299e5c                                                      
  44:     0x7fff981f52fc - _pthread_body                                                                                   
  45:     0x7fff981f5279 - _pthread_body                                                                                   

[UberLambda]

I'm getting this too, on Linux x64:

error: internal compiler error: unexpected panic
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 'assertion failed: *start <= *end', /build/rust-git/src/rust/src/libcore/slice.rs:396

stack backtrace:
   1:     0x7fc07401d550 - rt::backtrace::imp::write::h6d7b51dbe08c7a90Weq
   2:     0x7fc074020650 - <unknown>
   3:     0x7fc078371330 - unwind::begin_unwind_inner::ha369021e3864117bdSd
   4:     0x7fc078370e50 - unwind::begin_unwind_fmt::h6c1ae8b41766cb91FPd
   5:     0x7fc078370e10 - rust_begin_unwind
   6:     0x7fc0783b4d60 - panicking::panic_fmt::h1f4102d9dbcc2a5dh7j
   7:     0x7fc0783b0610 - panicking::panic::h68bf04de05fcd341l4j
   8:     0x7fc078de3300 - middle::typeck::check::vtable::check_object_safety::h5e858634fb68b05e6zN
   9:     0x7fc078de2c40 - middle::typeck::check::vtable::check_object_cast::h76abd899d5e17912cqN
  10:     0x7fc078e3ae20 - <unknown>
  11:     0x7fc078e617a0 - <unknown>
  12:     0x7fc078e5fb30 - <unknown>
  13:     0x7fc078e5e7a0 - <unknown>
  14:     0x7fc078e617a0 - <unknown>
  15:     0x7fc078eaeba0 - middle::typeck::check::check_stmt::hd0a4ef48c8f354dcjI0
  16:     0x7fc078e2f060 - <unknown>
  17:     0x7fc078e617a0 - <unknown>
  18:     0x7fc078ddbf10 - middle::typeck::check::_match::check_match::haa2decc95e3c7268D2M
  19:     0x7fc078e617a0 - <unknown>
  20:     0x7fc078e2f060 - <unknown>
  21:     0x7fc078e2b0a0 - <unknown>
  22:     0x7fc078e2ade0 - <unknown>
  23:     0x7fc078e31d00 - <unknown>
  24:     0x7fc078e270c0 - middle::typeck::check::check_item::h9547b3316e8784c0aBV
  25:     0x7fc078e290e0 - <unknown>
  26:     0x7fc078e2a8b0 - middle::typeck::check::check_item_types::h88799901145244c6bgV
  27:     0x7fc0789b2a50 - <unknown>
  28:     0x7fc0790bed90 - middle::typeck::check_crate::h62ec16fdebb5bcbeQZn
  29:     0x7fc079122330 - driver::driver::phase_3_run_analysis_passes::h9af115960c945947BJA
  30:     0x7fc07911d0a0 - driver::driver::compile_input::h7fc95caa4ba569b2mqA
  31:     0x7fc0791a0660 - <unknown>
  32:     0x7fc0791a0550 - <unknown>
  33:     0x7fc0789cb380 - <unknown>
  34:     0x7fc0789cb170 - <unknown>
  35:     0x7fc0786b3a80 - <unknown>
  36:     0x7fc0783c29f0 - <unknown>
  37:     0x7fc0783c29e0 - rust_try
  38:     0x7fc07836eae0 - unwind::try::hca7256b355f2fe07xGd
  39:     0x7fc07836e970 - task::Task::run::hf4a989e4dbd46d6cnMc
  40:     0x7fc0786b37c0 - <unknown>
  41:     0x7fc0783701d0 - <unknown>
  42:     0x7fc0733ce250 - start_thread
  43:     0x7fc07804b3b9 - clone
  44:                0x0 - <unknown>

(Link to the full RUST_LOG=debug RUST_BACKTRACE=1 cargo build --verbose)

---

Rustc's version (installed from thestinger's Arch repos:

rustc 0.13.0-dev (fd5365748 2014-10-30 20:17:15 +0000)
binary: rustc
commit-hash: fd53657484d78d0b7c00ce3264d99c051cf07d26
commit-date: 2014-10-30 20:17:15 +0000
host: x86_64-unknown-linux-gnu
release: 0.13.0-dev

[parbo]

Same here:

$ RUST_BACKTRACE=1 cargo build
Compiling protobuf v0.0.1 (https://github.com/stepancheg/rust-protobuf.git#cd5c700d)
Compiling rust-crypto v0.1.0 (https://github.com/DaGenix/rust-crypto.git#bd9f0970)
Compiling nix v0.0.1 (https://github.com/carllerche/nix-rust#69437208)
error: internal compiler error: unexpected panic
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 'assertion failed: *start <= *end', /home/rustbuild/src/rust-buildbot/slave/nightly-linux/build/src/libcore/slice.rs:396

stack backtrace:
1: 0x7fb85e59daf0 - rt::backtrace::imp::write::h78410bf389422bb4Afq
2: 0x7fb85e5a0bf0 - failure::on_fail::h3d7a049ab1da182dXAq
3: 0x7fb862adfe30 - unwind::begin_unwind_inner::ha5ca26286b78bd8fdSd
4: 0x7fb862adf950 - unwind::begin_unwind_fmt::h9ff359c82ebbcec0FPd
5: 0x7fb862adf910 - rust_begin_unwind
6: 0x7fb862b2b1a0 - panicking::panic_fmt::h6d1e7e05d89e9577h7j
7: 0x7fb862b26a50 - panicking::panic::h9595095b841fe7bal4j
8: 0x7fb8635f2050 - middle::typeck::check::vtable::check_object_safety::h909babbc174b8351CBN
9: 0x7fb86365f600 - middle::typeck::check::FnCtxt<'a, 'tcx>::register_unsize_obligations::h7602815ae022d228GhX
10: 0x7fb86365f570 - middle::typeck::check::FnCtxt<'a, 'tcx>::register_autoref_obligations::h0590f015c52acbc0EgX
11: 0x7fb86365f570 - middle::typeck::check::FnCtxt<'a, 'tcx>::register_autoref_obligations::h0590f015c52acbc0EgX
12: 0x7fb86363aa80 - middle::typeck::check::FnCtxt<'a, 'tcx>::write_adjustment::h1396e48fc524a05dIdX
13: 0x7fb86362b520 - middle::typeck::check::FnCtxt<'a, 'tcx>::mk_assignty::ha58af6f758d897bdxvX
14: 0x7fb86362b210 - middle::typeck::check::demand::coerce::h48183cae82ca7869RPR
15: 0x7fb86368e000 - middle::typeck::check::check_expr_coercable_to_type::closure.132386
16: 0x7fb863684970 - middle::typeck::check::check_expr_with_unifier::h9021eb76dad51ef5dJY
17: 0x7fb863682dd0 - middle::typeck::check::check_argument_types::h1928dcb07649510889X
18: 0x7fb863684970 - middle::typeck::check::check_expr_with_unifier::h9021eb76dad51ef5dJY
19: 0x7fb8636501a0 - middle::typeck::check::check_block_with_expected::hbcf547bf91ace5705P0
20: 0x7fb86364b770 - middle::typeck::check::check_fn::hc80418f404e5c598pvV
21: 0x7fb86364b4b0 - middle::typeck::check::check_bare_fn::h1dd0be1cd95d0c63EkV
22: 0x7fb863652ca0 - middle::typeck::check::check_method_body::h131e48693ec30c1axPV
23: 0x7fb8636471c0 - middle::typeck::check::check_item::hfa9ed324eb120d1cNEV
24: 0x7fb86364ac30 - visit::Visitor::visit_mod::h4776340902026008023
25: 0x7fb863649760 - visit::walk_item::h1837381033057518270
26: 0x7fb86364af80 - middle::typeck::check::check_item_types::h7314688a92a7a43fOjV
27: 0x7fb863146590 - util::common::time::h1086293170624038403
28: 0x7fb86391db90 - middle::typeck::check_crate::h707090d761adfc72A3n
29: 0x7fb863987950 - driver::driver::phase_3_run_analysis_passes::h2dc7f682b53f78f9lNA
30: 0x7fb863982200 - driver::driver::compile_input::hb25c14dfa369b7d96tA
31: 0x7fb863a048b0 - driver::run_compiler::h3e5318d61e864690KgE
32: 0x7fb863a047a0 - driver::run::closure.145379
33: 0x7fb86315f370 - task::TaskBuilder::try_future::closure.103636
34: 0x7fb86315f160 - task::TaskBuilder::spawn_internal::closure.103607
35: 0x7fb862e2a1a0 - task::NativeSpawner.Spawner::spawn::closure.8435
36: 0x7fb862b38e30 - rust_try_inner
37: 0x7fb862b38e20 - rust_try
38: 0x7fb862add5e0 - unwind::try::h8c75b93d8c87f5c4xGd
39: 0x7fb862add470 - task::Task::run::h3855d187b4c0788fnMc
40: 0x7fb862e29ee0 - task::NativeSpawner.Spawner::spawn::closure.8373
41: 0x7fb862adecd0 - thread::thread_start::he45c6d58df77cc88C7c
42: 0x7fb85d949fe0 - start_thread
43: 0x7fb8627a9819 - __clone
44: 0x0 -

$ rustc --version=verbose
rustc 0.13.0-nightly (221fc1e 2014-10-31 02:27:15 +0000)
binary: rustc
commit-hash: 221fc1e
commit-date: 2014-10-31 02:27:15 +0000
host: x86_64-unknown-linux-gnu
release: 0.13.0-nightly

[alexcrichton]

cc @nick29581

[nrc]

@mitchmindtree @UberLambda @parbo would one of you mind posting the code that caused the ICE please? Even better would be if you could narrow down the code to a minimal test case which causes the crash. Thanks!

[parbo]

For me, it's just a new empty project (cargo new --git) which I added some dependencies to:

Cargo.toml:

[package]

name = "sprs"
version = "0.0.1"
authors = ["bohrarper@spotify.com>"]

[dependencies.protobuf]

git = "https://github.com/stepancheg/rust-protobuf.git"

[dependencies.rust-crypto]

git = "https://github.com/DaGenix/rust-crypto.git"

[dependencies.mio]

git = "https://github.com/carllerche/mio.git"

lib.rs:

extern crate crypto
extern crate mio
extern crate rust-protobuf

#[test]
fn it_works() {
}

[waterlink]

I have the same problem, but this happens only when I compile my tests/* code. So the problem is probably somewhere there. Code is available here: https://github.com/johnmq/raft-rs/tree/master/tests

And here is my backtrace:

RUST_BACKTRACE=1 cargo test
   Compiling raft_rs v0.0.1 (file:///home/user/github/waterlink/johnmq/raft-rs)
error: internal compiler error: unexpected panic
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 'assertion failed: *start <= *end', /home/rustbuild/src/rust-buildbot/slave/nightly-linux/build/src/libcore/slice.rs:396

stack backtrace:
   1:     0x7f8136dd9af0 - rt::backtrace::imp::write::h78410bf389422bb4Afq
   2:     0x7f8136ddcbf0 - failure::on_fail::h3d7a049ab1da182dXAq
   3:     0x7f813b31ee30 - unwind::begin_unwind_inner::ha5ca26286b78bd8fdSd
   4:     0x7f813b31e950 - unwind::begin_unwind_fmt::h9ff359c82ebbcec0FPd
   5:     0x7f813b31e910 - rust_begin_unwind
   6:     0x7f813b36a1a0 - panicking::panic_fmt::h6d1e7e05d89e9577h7j
   7:     0x7f813b365a50 - panicking::panic::h9595095b841fe7bal4j
   8:     0x7f813be31050 - middle::typeck::check::vtable::check_object_safety::h909babbc174b8351CBN
   9:     0x7f813be9e600 - middle::typeck::check::FnCtxt<'a, 'tcx>::register_unsize_obligations::h7602815ae022d228GhX
  10:     0x7f813be9e570 - middle::typeck::check::FnCtxt<'a, 'tcx>::register_autoref_obligations::h0590f015c52acbc0EgX
  11:     0x7f813be9e570 - middle::typeck::check::FnCtxt<'a, 'tcx>::register_autoref_obligations::h0590f015c52acbc0EgX
  12:     0x7f813be79a80 - middle::typeck::check::FnCtxt<'a, 'tcx>::write_adjustment::h1396e48fc524a05dIdX
  13:     0x7f813be6a520 - middle::typeck::check::FnCtxt<'a, 'tcx>::mk_assignty::ha58af6f758d897bdxvX
  14:     0x7f813be6a210 - middle::typeck::check::demand::coerce::h48183cae82ca7869RPR
  15:     0x7f813becd000 - middle::typeck::check::check_expr_coercable_to_type::closure.132386
  16:     0x7f813bec3970 - middle::typeck::check::check_expr_with_unifier::h9021eb76dad51ef5dJY
  17:     0x7f813bec1dd0 - middle::typeck::check::check_argument_types::h1928dcb07649510889X
  18:     0x7f813bec1610 - middle::typeck::check::check_method_argument_types::h20978a60653d31e5k8X
  19:     0x7f813bec3970 - middle::typeck::check::check_expr_with_unifier::h9021eb76dad51ef5dJY
  20:     0x7f813bf17500 - middle::typeck::check::check_stmt::h0b590f51bdc43b8bWL0
  21:     0x7f813be8f1a0 - middle::typeck::check::check_block_with_expected::hbcf547bf91ace5705P0
  22:     0x7f813bec3970 - middle::typeck::check::check_expr_with_unifier::h9021eb76dad51ef5dJY
  23:     0x7f813be8f1a0 - middle::typeck::check::check_block_with_expected::hbcf547bf91ace5705P0
  24:     0x7f813be8a770 - middle::typeck::check::check_fn::hc80418f404e5c598pvV
  25:     0x7f813bece970 - middle::typeck::check::check_expr_with_unifier::check_expr_fn::h2ca30ae5f2e571b43dZ
  26:     0x7f813bec3970 - middle::typeck::check::check_expr_with_unifier::h9021eb76dad51ef5dJY
  27:     0x7f813bec1dd0 - middle::typeck::check::check_argument_types::h1928dcb07649510889X
  28:     0x7f813bec3970 - middle::typeck::check::check_expr_with_unifier::h9021eb76dad51ef5dJY
  29:     0x7f813be8f1a0 - middle::typeck::check::check_block_with_expected::hbcf547bf91ace5705P0
  30:     0x7f813be8a770 - middle::typeck::check::check_fn::hc80418f404e5c598pvV
  31:     0x7f813be8a4b0 - middle::typeck::check::check_bare_fn::h1dd0be1cd95d0c63EkV
  32:     0x7f813be861c0 - middle::typeck::check::check_item::hfa9ed324eb120d1cNEV
  33:     0x7f813be89c30 - visit::Visitor::visit_mod::h4776340902026008023
  34:     0x7f813be88760 - visit::walk_item::h1837381033057518270
  35:     0x7f813be89f80 - middle::typeck::check::check_item_types::h7314688a92a7a43fOjV
  36:     0x7f813b985590 - util::common::time::h1086293170624038403
  37:     0x7f813c15cb90 - middle::typeck::check_crate::h707090d761adfc72A3n
  38:     0x7f813c1c6950 - driver::driver::phase_3_run_analysis_passes::h2dc7f682b53f78f9lNA
  39:     0x7f813c1c1200 - driver::driver::compile_input::hb25c14dfa369b7d96tA
  40:     0x7f813c2438b0 - driver::run_compiler::h3e5318d61e864690KgE
  41:     0x7f813c2437a0 - driver::run::closure.145379
  42:     0x7f813b99e370 - task::TaskBuilder<S>::try_future::closure.103636
  43:     0x7f813b99e160 - task::TaskBuilder<S>::spawn_internal::closure.103607
  44:     0x7f813b6691a0 - task::NativeSpawner.Spawner::spawn::closure.8435
  45:     0x7f813b377e30 - rust_try_inner
  46:     0x7f813b377e20 - rust_try
  47:     0x7f813b31c5e0 - unwind::try::h8c75b93d8c87f5c4xGd
  48:     0x7f813b31c470 - task::Task::run::h3855d187b4c0788fnMc
  49:     0x7f813b668ee0 - task::NativeSpawner.Spawner::spawn::closure.8373
  50:     0x7f813b31dcd0 - thread::thread_start::he45c6d58df77cc88C7c
  51:     0x7f8136189ea0 - start_thread
  52:     0x7f813afe5999 - __clone
  53:                0x0 - <unknown>

Could not compile `raft_rs`.

To learn more, run the command again with --verbose.

rustc --version=verbose
rustc 0.13.0-nightly (221fc1e3c 2014-10-31 02:27:15 +0000)
binary: rustc
commit-hash: 221fc1e3cdcc208e1bb7debcc2de27d47c847747
commit-date: 2014-10-31 02:27:15 +0000
host: x86_64-unknown-linux-gnu
release: 0.13.0-nightly

[waterlink]

I have done a bit of narrowing and got this:

Compiler fails when trying to understand this https://github.com/johnmq/raft-rs/blob/398307167cd7263e6e4a10fb9be287d415c0b902/tests/node.rs#L46

and this line calls this method: https://github.com/johnmq/raft-rs/blob/398307167cd7263e6e4a10fb9be287d415c0b902/src/node.rs#L133-L141

[waterlink]

And after playing around with my suspect code I was able to avoid this bug by replacing type annotations of my arguments with parametric types instead of traits. This commit shows it: johnmq/raft-rs@6ba292f .

Basically that means that this bug is related somehow to trait rules changes. If this helps somehow..

[stepancheg]

Minimal example:

use std::default::Default;

pub trait Message {
    fn new() -> Self { panic!(); }
}

fn new_instance<M : 'static + Message>() -> Box<Message + 'static> {
    let m: M = Default::default();
    box m as Box<Message>
}

fn main() {}

[hotgloupi]

Same issue here:

trait Command { fn name() -> &'static str; }
struct Init;
impl Command for Init { fn name() -> &'static str { "init" } }
fn main() {  let cmd = box Init as Box<Command>; }

with the backtrace:

task 'rustc' panicked at 'assertion failed: *start <= *end', /Users/rustbuild/src/rust-buildbot/slave/nightly-mac/build/src/libcore/slice.rs:396

stack backtrace:
   1:        0x10d65d619 - rt::backtrace::imp::write::h03fee16d4a0b6b41moq
   2:        0x10d66085c - failure::on_fail::h3e0f6b3c6c4bbcc3VEq
   3:        0x10d8c4f05 - unwind::begin_unwind_inner::h6c7f4532e72658d7SJd
   4:        0x10d8c4b9f - unwind::begin_unwind_fmt::h9863b25c438d6314kHd
   5:        0x10d8c48f2 - rust_begin_unwind
   6:        0x10d91b53c - panicking::panic_fmt::hc53a414d3d53805bi7j
   7:        0x10d911f6f - panicking::panic::h5cf45d77d6cb56acm4j
   8:        0x10a84c83b - middle::typeck::check::vtable::check_object_safety::h3ee32f70bc2a6910cvN
   9:        0x10a84bab4 - middle::typeck::check::vtable::check_object_cast::ha17cfa6c915c29failN
  10:        0x10a8b4954 - middle::typeck::check::check_cast::h212d4526506e607bdwW
  11:        0x10a8dcae4 - middle::typeck::check::check_expr_with_unifier::h153e2ccf9b0cb061XCY
  12:        0x10a92c583 - middle::typeck::check::check_decl_local::h4f8f86e796500762GD0
  13:        0x10a92c6f7 - middle::typeck::check::check_stmt::h7691c17f92d0623eGF0
  14:        0x10a8a7faf - middle::typeck::check::check_block_with_expected::heb9a0fb2300c4559PJ0
  15:        0x10a8a3d42 - middle::typeck::check::check_fn::h0449d63e5b4f3e3a9oV
  16:        0x10a8a326f - middle::typeck::check::check_bare_fn::hf2de12c52654551eoeV
  17:        0x10a89f18d - middle::typeck::check::check_item::hfaeea23703d7dd28xyV
  18:        0x10a8a30bf - middle::typeck::check::check_item_types::haaff85b74e988d92ydV
  19:        0x10a3b9556 - util::common::time::h11920059333862041717
  20:        0x10ab6359e - middle::typeck::check_crate::h50fcc5c8b39993f4LVn
  21:        0x10abcbbcf - driver::driver::phase_3_run_analysis_passes::h1425a4ca465c7b097DA
  22:        0x10abc62b8 - driver::driver::compile_input::h60bc42ef7fabbfd4SkA
  23:        0x10ac43ca8 - driver::run_compiler::h4031243f49082a9fw7D
  24:        0x10ac41ece - driver::run::closure.145349
  25:        0x10a3d181b - task::TaskBuilder<S>::try_future::closure.103709
  26:        0x10a3d1713 - task::TaskBuilder<S>::spawn_internal::closure.103680
  27:        0x10a35198d - task::NativeSpawner.Spawner::spawn::closure.8526
  28:        0x10d92b20c - rust_try_inner
  29:        0x10d92b1f6 - rust_try
  30:        0x10d8c2677 - unwind::try::hab84862d0081b274cyd
  31:        0x10d8c250c - task::Task::run::h39093ecd59554b49ZJc
  32:        0x10a3517b3 - task::NativeSpawner.Spawner::spawn::closure.8463
  33:        0x10d8c3d37 - thread::thread_start::h589be8c0a398d299e5c
  34:     0x7fff8bbe7899 - _pthread_body
  35:     0x7fff8bbe772a - _pthread_struct_init

[hotgloupi]

Is the example I gave unrelated ? Because it's still give me the same backtrace :/
It might be a good idea to add the above crashing snippets to rust test suite (If they are well formed).

Side question: Is the online compiler up-to-date (as a nightly build is) ?