ICE: DefID [...] was matchable against Obligation [...] but now is not

[tyler569]

I don't really know what could be causing this bug, but this code

struct Test;

impl Add<i32, i32> for Test {
    fn add(&self, othr: &i32) -> i32 {
        othr + 1
    }
}

impl Add<f64, f64> for Test {
    fn add(&self, othr: &f64) -> f64 {
        othr + 2.0
    }
}

fn main() {
    let f = Test;
    println!("f + 3:   {}", f + 3);
    println!("f + 3.0: {}", f + 3.0);
}

using this version of rustc,

rustc 0.13.0-nightly (0a5e7f359 2014-11-03 23:16:55 +0000)
binary: rustc
commit-hash: 0a5e7f35949d18f312dca90af73e56aced6f2b0e
commit-date: 2014-11-03 23:16:55 +0000
host: x86_64-apple-darwin
release: 0.13.0-nightly

on Mac OS X 10.10
causes

[tyler@mac ~]$ RUST_BACKTRACE=1 rustc test.rs
error: internal compiler error: Impl DefId { krate: 0, node: 7 }:Test.Add<i32, i32> was matchable against Obligation(trait_ref=<_ as core::ops::Add<_, _>>,depth=0) but now is not
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>', /Users/rustbuild/src/rust-buildbot/slave/nightly-mac/build/src/libsyntax/diagnostic.rs:175

stack backtrace:
   1:        0x10a2997ff - rt::backtrace::imp::write::h41ac48e0092ef821Kqq
   2:        0x10a29c987 - failure::on_fail::h3381510cd10c9a61zHq
   3:        0x10a4f5495 - unwind::begin_unwind_inner::h8667451db5084e88EKd
   4:        0x109a88897 - unwind::begin_unwind::h574859237947728247
   5:        0x109a890d3 - diagnostic::Handler::bug::h6b8e7fd2f9430272TgG
   6:        0x10733a9c1 - middle::traits::select::SelectionContext<'cx, 'tcx>::rematch_impl::h88c48df6dbcc8ecfbkZ
   7:        0x1073294ab - middle::traits::select::SelectionContext<'cx, 'tcx>::confirm_candidate::h66ce271d2e7c254er0Y
   8:        0x107321837 - middle::traits::select::SelectionContext<'cx, 'tcx>::select::h1fe5e22ffd93df8bVuX
   9:        0x107320746 - middle::traits::fulfill::FulfillmentContext::select::hb3fa38b300468ae1f2W
  10:        0x10731ffbc - middle::traits::fulfill::FulfillmentContext::select_where_possible::hc2e2275050ef1b1eu1W
  11:        0x107235782 - middle::traits::fulfill::FulfillmentContext::select_all_or_error::h5af4c7aa23325766hZW
  12:        0x1074a1638 - middle::typeck::check::vtable::select_all_fcx_obligations_or_error::h2aa8ac2036bfa6468aO
  13:        0x1074f679b - middle::typeck::check::check_bare_fn::heec9ab1513e561178IV
  14:        0x1074f25dd - middle::typeck::check::check_item::h88a198c1ca5a907bh3V
  15:        0x1074f65df - middle::typeck::check::check_item_types::h153b2b615101bfcaiIV
  16:        0x106ffcbc6 - util::common::time::h7711944396490138833
  17:        0x1077bd73e - middle::typeck::check_crate::hd52e86e35ee1a30a3uo
  18:        0x10782696f - driver::driver::phase_3_run_analysis_passes::h340df4cdb996da5a8hB
  19:        0x107821198 - driver::driver::compile_input::h02967bf5608361a5TYA
  20:        0x10789fd3c - driver::run_compiler::h3ec9fe79d927cfd96OE
  21:        0x10789e1ce - driver::run::closure.145814
  22:        0x10701552b - task::TaskBuilder<S>::try_future::closure.104091
  23:        0x107015423 - task::TaskBuilder<S>::spawn_internal::closure.104062
  24:        0x106f93c7d - task::NativeSpawner.Spawner::spawn::closure.8516
  25:        0x10a55468c - rust_try_inner
  26:        0x10a554676 - rust_try
  27:        0x10a4f2c67 - unwind::try::h7be47cb819f03817Yyd
  28:        0x10a4f2afc - task::Task::run::hd977e1132c48b8d6LKc
  29:        0x106f93aa3 - task::NativeSpawner.Spawner::spawn::closure.8453
  30:        0x10a4f4327 - thread::thread_start::ha9ae96309fe3363b05c
  31:     0x7fff8c73d2fc - _pthread_body
  32:     0x7fff8c73d279 - _pthread_body

Apologies if this is an incorrect format or non-relevant, I've never really submitted a bug report to a large project before.

Addendum:
Adding "f64" to the second println!:

struct Test;

impl Add<i32, i32> for Test {
    fn add(&self, othr: &i32) -> i32 {
        othr + 1
    }
}

impl Add<f64, f64> for Test {
    fn add(&self, othr: &f64) -> f64 {
        othr + 2.0
    }
}

fn main() {
    let f = Test;
    println!("f + 3:   {}", f + 3);
    println!("f + 3.0: {}", f + 3.0f64);
}

compiles and runs as expected

[tyler@mac ~]$ ./test
f + 3:   4
f + 3.0: 5

[steveklabnik]

I tried to reproduce, but am bad at the Add trait. Once I updated the syntax for associated types, it failed with 'conflicting implementations.'

[paholg]

@steveklabnik I believe I have reproduced this bug with associated types (or at least stumbled upon a very similar one).

use std::ops::Add;

trait Scalar {}
impl Scalar for f64 {}

struct Bob;

impl<RHS: Scalar> Add<RHS> for Bob {
    type Output = Bob;
    fn add(self, rhs: RHS) -> Bob { self }
}

fn main() {
    let b = Bob;
    b + 3.5;
    // Internal compiler error (should be type error?):
    b + 3;
}

playpen link

[veddan]

I ran into to it when accidentally using a float to index (&xs[5.] instead of &xs[5..]). However, copying the offending code verbatim to a new file didn't reproduce the error.

thread 'rustc' panicked at 'Box<Any>', /home/viktor/Documents/rust/rust/src/libsyntax/diagnostic.rs:191

stack backtrace:
1:      0x7fc4fb7689f8 - sys::backtrace::write::ha29d830caaf281c1kHC
2:      0x7fc4fb793f17 - panicking::on_panic::hd4b7cfa54ce15a47uUI
3:      0x7fc4fb6cba63 - rt::unwind::begin_unwind_inner::ha80e7d5af5095813CzI
4:      0x7fc4f8a6521d - rt::unwind::begin_unwind::h14288175298002166887
5:      0x7fc4f8a65972 - diagnostic::Handler::bug::hfe9a62f5ab542276osB
6:      0x7fc4f96a8ca1 - middle::traits::select::SelectionContext<'cx, 'tcx>::rematch_impl::h888ed2605974267aWuT
7:      0x7fc4f96a851f - middle::infer::InferCtxt<'a, 'tcx>::commit_if_ok::h8758431782731900545
8:      0x7fc4f96892ef - middle::traits::select::SelectionContext<'cx, 'tcx>::confirm_candidate::h680de60fb1bd61adSMS
9:      0x7fc4f965c86a - middle::traits::select::SelectionContext<'cx, 'tcx>::select::h105c655576bbde6e9NQ
10:     0x7fc4f966c33a - middle::traits::project::project_type::hf3dcf4dd73f443504tP
11:     0x7fc4f9669d71 - middle::traits::project::opt_normalize_projection_type::h72ea40d2d30b32b8GmP
12:     0x7fc4f9663e1a - middle::traits::project::poly_project_and_unify_type::closure.83715
13:     0x7fc4f9661ccc - middle::traits::project::poly_project_and_unify_type::h07927f85d5854b03P2O
14:     0x7fc4f965893b - middle::traits::fulfill::FulfillmentContext<'tcx>::select::h841d140980122122YEO
15:     0x7fc4f9657f2b - middle::traits::fulfill::FulfillmentContext<'tcx>::select_where_possible::h486388f4f6bf28bccEO
16:     0x7fc4fa3bdcb8 - check::vtable::select_fcx_obligations_where_possible::h9b2c69b3fe91faa2h4b
17:     0x7fc4fa3f622a - check::FnCtxt<'a, 'tcx>::resolve_type_vars_if_possible::h075b04892164c50b5Wo
18:     0x7fc4fa3a14b7 - check::structurally_resolved_type::h764154d1245e2f783xt
19:     0x7fc4fa4d0f9f - check::check_expr_with_unifier::h15570588596475525203
20:     0x7fc4fa47010a - check::op::check_binop::h97ec7d0b9e582ed693m
21:     0x7fc4fa4c7856 - check::check_expr_with_unifier::h11880991079361711379
22:     0x7fc4fa4c886e - check::check_expr_with_unifier::h11880991079361711379
23:     0x7fc4fa4af7a3 - check::check_expr_with_unifier::h13671224543324200731
24:     0x7fc4fa4990e8 - check::check_expr_with_unifier::check_then_else::hc4434b21966ece39ANq
25:     0x7fc4fa4c11f4 - check::check_expr_with_unifier::h1254672801148009773
26:     0x7fc4fa47e3f1 - check::check_block_with_expected::hf352b795571d241fUns
27:     0x7fc4fa4c13b3 - check::check_expr_with_unifier::h1254672801148009773
28:     0x7fc4fa3ad3de - check::_match::check_match::closure.28881
29:     0x7fc4fa3ad112 - check::_match::check_match::h2624ec058d33fc6aZmb
30:     0x7fc4fa4c1357 - check::check_expr_with_unifier::h1254672801148009773
31:     0x7fc4fa47e3f1 - check::check_block_with_expected::hf352b795571d241fUns
32:     0x7fc4fa4ce903 - check::check_expr_with_unifier::h15570588596475525203
33:     0x7fc4fa47e123 - check::check_block_with_expected::hf352b795571d241fUns
34:     0x7fc4fa45b969 - check::check_fn::haaf9eb020ec080d90Zn
35:     0x7fc4fa47905c - check::check_bare_fn::he93355dfc3534a69zPn
36:     0x7fc4fa472f24 - check::check_item::he0e731c9541337aak8n
37:     0x7fc4fa477662 - visit::walk_item::h16976416926307002031
38:     0x7fc4fa47766d - visit::walk_item::h16976416926307002031
39:     0x7fc4fa54c991 - check_crate::closure.36438
40:     0x7fc4fa546ed3 - check_crate::h60772f272ea0d698asC
41:     0x7fc4fbdea80d - driver::phase_3_run_analysis_passes::h71b6dad7a437d3fcgGa
42:     0x7fc4fbdce665 - driver::compile_input::h617a4fae1fdc397dQba
43:     0x7fc4fbe85c65 - run_compiler::h85ca2893f7ce8fe6S4b
44:     0x7fc4fbe8357d - boxed::F.FnBox<A>::call_box::h8037565825972556017
45:     0x7fc4fbe82ab9 - rt::unwind::try::try_fn::h15794509059050188955
46:     0x7fc4fb8109b8 - rust_try_inner
47:     0x7fc4fb8109a5 - rust_try
48:     0x7fc4fbe82d8b - boxed::F.FnBox<A>::call_box::h677285017824924912
49:     0x7fc4fb77ef01 - sys::thread::create::thread_start::he70b0e4e639cf402MuH
50:     0x7fc4f57cd0a3 - start_thread
51:     0x7fc4fb32d06c - clone
52:                0x0 - <unknown>

[tamird]

triage: still reproduces

[arielb1]

Duplicate of #24352