ICE Unimplemented selecting <Inner as FooTrait> during trans

[dbalchev]

Compiled on Windows 8.1 with 64-bit compiler rustc 0.12.0-nightly (b5ba2f5 2014-10-06 20:27:14 +0000).

struct Inner {
    x:int
}
type Foo = Box<Inner>;

struct Bar;

trait FooTrait {
    fn foo_fun(&self);
}
trait BarTrait {
    fn bar_fun(&Self, &FooTrait);
}
impl FooTrait for Foo {
    fn foo_fun(&self) {

    }
}
impl BarTrait for Bar {
    fn bar_fun(b:&Bar, f: &FooTrait) {

    }
}

fn main() {
    BarTrait::bar_fun(&Bar, &box Inner{x:72});
}

Errors:
bughunt.rs:1:1: 1:1 error: internal compiler error: Encountered error Unimplemented selecting <Inner as FooTrait> during trans
bughunt.rs:1

         ^

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

Backtrace:
task 'rustc' failed at 'Box', C:\bot\slave\nightly-win-64\build\src\libsyntax\diagnostic.rs:113

stack backtrace:
1: 0x66be29a8 - ZN2rt9backtrace3imp5write20hc5b481d5cd57af2aE9qE
2: 0x66be641b - ZN2rt4init20hffee7254612f46fffnrE
3: 0x668461cd - ZN6unwind18begin_unwind_inner20h484cd690c7389d13QhdE
4: 0x6a675f76 - ZN10diagnostic11SpanHandler8span_bug20h61400d8c039e9bc6GMFE
5: 0x6a675f20 - ZN10diagnostic11SpanHandler8span_bug20h61400d8c039e9bc6GMFE
6: 0x6d4c437a - ZN6driver7session7Session8span_bug20h2168907c2e4ca091kyxE
7: 0x6d6eccf6 - ZN6middle5trans6common18fulfill_obligation20heb3710fb7ef945524B6E
8: 0x6d76abbb - ZN6middle5trans5type_4Type6vtable20hd46d323115ea795edrvE
9: 0x6d76c320 - ZN4util5ppaux17ty..BareFnTy.Repr4repr20h89c8f0a6d9a94237TIGE
10: 0x6d6d0e03 - ZN6middle5trans4meth10get_vtable20h3e74db9548c22210KGkE
11: 0x6d6cff80 - ZN6middle2ty34AutoAdjustment...std..clone..Clone5clone20h9b1b6280b278f7184syE
12: 0x6d6d207a - ZN6middle2ty9unsize_ty20h89062c559ef98902zfGE
13: 0x6d6d2208 - ZN6middle2ty7mk_rptr20h0c96f17a65cdda7dwiEE
14: 0x6d6cf59a - ZN6middle2ty34AutoAdjustment...std..clone..Clone5clone20h9b1b6280b278f7184syE
15: 0x6d6cee3c - ZN6middle2ty34AutoAdjustment...std..clone..Clone5clone20h9b1b6280b278f7184syE
16: 0x6d693572 - ZN6middle5trans4expr5trans20ha48b94e0db233834pN2E
17: 0x6d6c41c4 - ZN6middle5trans6callee10trans_args20h88999b8991f24ca4kk2E
18: 0x6d699a70 - ZN6middle5trans6callee16trans_call_inner20hf94d81b3cc0dc994nZ1E
19: 0x6d6bd5e0 - ZN6middle5trans6callee10trans_call20h61df90c183273a62IT1E
20: 0x6d6cce3b - ZN6middle2ty9expr_kind20h949e0064a45a1e82ilGE
21: 0x6d691723 - ZN6middle5trans4expr10trans_into20h96733f5255894c9dvJ2E
22: 0x6d690ad0 - ZN6middle5trans11controlflow15trans_stmt_semi20h65a5128923d5c87e9VYE
23: 0x6d6901b9 - ZN6middle5trans11controlflow10trans_stmt20h6a327ed75a825439WRYE
24: 0x6d691969 - ZN6middle5trans11controlflow11trans_block20hc018d4181ef5114d2WYE
25: 0x6d735c90 - ZN6middle5trans4base13trans_closure20hfb78e3f15b7b784dTQeE
26: 0x6d68411d - ZN6middle5trans4base8trans_fn20h94c1533573410e77h2eE
27: 0x6d6817ec - ZN6middle5trans4base10trans_item20h7a9c36ad77c3fd91AlfE
28: 0x6d73f009 - ZN6middle5trans4base11trans_crate20ha6d41362f46fe1abQlgE
29: 0x6db6daf9 - ZN6driver6driver25phase_4_translate_to_llvm20hc8eefbd8dad9706cjZwE
30: 0x6db661f4 - ZN6driver6driver13compile_input20h0eef3c908953a111ewwE
31: 0x6dbe2dff - ZN6driver7monitor20hcdaa282087678b71SaBE
32: 0x6dbe1170 - ZN6driver7monitor20hcdaa282087678b71SaBE
33: 0x6d33bf55 - ZN6driver6driver35OutputFilenames...std..clone..Clone5clone20h22daf11eed536512ElxE
34: 0x6d33be97 - ZN6driver6driver35OutputFilenames...std..clone..Clone5clone20h22daf11eed536512ElxE
35: 0x7072945c - ZN4task10spawn_opts20hae91090f93dc8031FteE
36: 0x668aab5f - rust_try
37: 0x668aab39 - rust_try
38: 0x6684432e - ZN6unwind3try20hba110656f3557a7bU4cE
39: 0x66844189 - ZN4task4Task3run20hdb858a047ca67fa4kzcE
40: 0x707292b6 - ZN4task10spawn_opts20hae91090f93dc8031FteE
41: 0x66845807 - ZN4task11BlockedTask14cast_from_uint20hffe040d42c989c01XRcE
42: 0x7ff9177a16ad - BaseThreadInitThunk

Edit: The bug persists on compiler version: rustc 0.13.0-nightly (15dd90b 2014-10-30 00:27:02 +0000)

Edit 2: after some tracing with RUST_LOG=rustc::middle::traits::select=5, the following is reached

        if candidates.len() == 0 {
            return Err(Unimplemented);
        }

with candidates.len() = 0.
link to line: https://github.com/rust-lang/rust/blob/master/src/librustc/middle/traits/select.rs#L835
the error is printed by this line:

rust/src/librustc/middle/trans/common.rs

Line 850 in 77f44d4

format!("Encountered error `{}` selecting `{}` during trans",

[dbalchev]

As of rustc 0.13.0-nightly (8bca470 2014-12-08 00:12:30 +0000) the bug is fixed.