internal compiler error: Impl DefId { krate: 0, node: 12 }:u32.Stringify was matchable against Obligation(predicate=Binder(TraitPredicate(Stringify)),depth=0) but now is not

[huachaohuang]

• I tried this code:

trait Stringify {
    fn to_string(&self) -> String;
}

impl Stringify for u32 {
    fn to_string(&self) -> String { format!("u32: {}", *self) }
}

impl Stringify for f32 {
    fn to_string(&self) -> String { format!("f32: {}", *self) }
}

fn print<T: Stringify>(x: T) {
    println!("{}", x.to_string());
}

fn main() {
    print(5);
    print(5.0);
}

• I expected to see this happen:

u32: 5
f32: 5.0

• Instead, this happened:

error: internal compiler error: Impl DefId { krate: 0, node: 12 }:u32.Stringify was matchable against Obligation(predicate=Binder(TraitPredicate(Stringify)),depth=0) but now is not
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports
note: run with RUST_BACKTRACE=1 for a backtrace

Meta

rustc 1.0.0-nightly (199bdcf 2015-03-26) (built 2015-03-26)
binary: rustc
commit-hash: 199bdcf
commit-date: 2015-03-26
build-date: 2015-03-26
host: x86_64-apple-darwin
release: 1.0.0-nightly

• Backtrace:

thread 'rustc' panicked at 'Box<Any>', /Users/rustbuild/src/rust-buildbot/slave/nightly-dist-rustc-mac/build/src/libsyntax/diagnostic.rs:190

stack backtrace:
   1:        0x10cdac8b4 - sys::backtrace::write::h56b628caa3d9f4e2WBD
   2:        0x10cdd7a08 - panicking::on_panic::ha7bc09956d9f12916rJ
   3:        0x10ccf499e - rt::unwind::begin_unwind_inner::h5ef900798574fe5egaJ
   4:        0x10c4ec45e - rt::unwind::begin_unwind::h2748891250859470333
   5:        0x10c4ecc89 - diagnostic::Handler::bug::h57426bf76a5037d4pgB
   6:        0x10a06b4bf - middle::traits::select::SelectionContext<'cx, 'tcx>::rematch_impl::h3b4e834c3872ae21NVR
   7:        0x10a06ab56 - middle::infer::InferCtxt<'a, 'tcx>::try::h6881848181392734290
   8:        0x10a0510c4 - middle::traits::select::SelectionContext<'cx, 'tcx>::confirm_candidate::ha7bb241f7d3cdb480iR
   9:        0x10a025b8d - middle::traits::select::SelectionContext<'cx, 'tcx>::select::hb97262a482e0a260koP
  10:        0x10a0225e0 - middle::traits::fulfill::FulfillmentContext<'tcx>::select::hcffa8f4e81b26cc8HhN
  11:        0x10a021aee - middle::traits::fulfill::FulfillmentContext<'tcx>::select_where_possible::h0a2ed0d6733c5352VgN
  12:        0x10942d473 - check::vtable::select_fcx_obligations_where_possible::h796cff45179b9501A4b
  13:        0x10942cfc3 - check::vtable::select_all_fcx_obligations_and_apply_defaults::hfadb66c912bf39a2X0b
  14:        0x1094de47e - check::check_bare_fn::heb3c8094aebf74083nn
  15:        0x1094d68eb - check::check_item::h25c21617996c325dOGn
  16:        0x1095afed6 - check_crate::closure.35998
  17:        0x1095aad9a - check_crate::haa845b167eb64ccfOmC
  18:        0x1092e4477 - driver::phase_3_run_analysis_passes::h8f332883f9aa5c0arGa
  19:        0x1092ca4b7 - driver::compile_input::h0311d7070ac04983Rba
  20:        0x109384093 - run_compiler::hbe451b463527cb69s2b
  21:        0x109381bb5 - thunk::F.Invoke<A, R>::invoke::h777505636365567823
  22:        0x109380f77 - rt::unwind::try::try_fn::h5237749675862334843
  23:        0x10ce5dfa8 - rust_try_inner
  24:        0x10ce5df95 - rust_try
  25:        0x109381315 - thunk::F.Invoke<A, R>::invoke::h424791141543398798
  26:        0x10cdc299d - sys::thread::create::thread_start::h760927331a49c0e267H
  27:     0x7fff91d6b267 - _pthread_body
  28:     0x7fff91d6b1e4 - _pthread_start

[mitchmindtree]

I've also just run into this, here's the error and the backtrace.

error: internal compiler error: Impl DefId { krate: 2, node: 34078 } was matchable against Obligation(predicate=Binder(TraitPredicate(core::ops::Add<_>)),depth=1) but now is not
note: the compiler unexpectedly panicked. this is a bug.                                                                                                                         
note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports                                                                
note: run with `RUST_BACKTRACE=1` for a backtrace                                                                                                                                
thread 'rustc' panicked at 'Box<Any>', /Users/rustbuild/src/rust-buildbot/slave/nightly-dist-rustc-mac/build/src/libsyntax/diagnostic.rs:190                                     

stack backtrace:                                                                                                                                                                 
   1:        0x1121339f4 - sys::backtrace::write::h79b5fc37599ff6dfazD                                                                                                           
   2:        0x1121614b0 - panicking::on_panic::h56cd7321a5392f568oJ                                                                                                             
   3:        0x112071c8e - rt::unwind::begin_unwind_inner::h9b1dd02e7e9b2523i7I                                                                                                  
   4:        0x1118565ce - rt::unwind::begin_unwind::h5359193300489870763                                                                                                        
   5:        0x111856e19 - diagnostic::Handler::bug::h0696301796c915b4ShB                                                                                                        
   6:        0x10f3ae6be - middle::traits::select::SelectionContext<'cx, 'tcx>::rematch_impl::h00877b9f7d68b755V3R                                                               
   7:        0x10f3ae008 - middle::infer::InferCtxt<'a, 'tcx>::try::h1635483048343115861                                                                                         
   8:        0x10f38f454 - middle::traits::select::SelectionContext<'cx, 'tcx>::confirm_candidate::h2b843f592bb3d1ebJlR                                                          
   9:        0x10f3638e3 - middle::traits::select::SelectionContext<'cx, 'tcx>::select::h48941a5b9b6aeafbApP                                                                     
  10:        0x10f37363a - middle::traits::project::project_type::h27f6c84f9a43d3fbK5N                                                                                           
  11:        0x10f371017 - middle::traits::project::opt_normalize_projection_type::h7647720dfb8d8959mYN                                                                          
  12:        0x10f36aa36 - middle::traits::project::poly_project_and_unify_type::closure.81002                                                                                   
  13:        0x10f368a40 - middle::traits::project::poly_project_and_unify_type::h14c21863493f04758EN                                                                            
  14:        0x10f3602e6 - middle::traits::fulfill::FulfillmentContext<'tcx>::select::hd40ad264985439f7hhN                                                                       
  15:        0x10f35f928 - middle::traits::fulfill::FulfillmentContext<'tcx>::select_where_possible::h0ebb717f715533c9vgN                                                        
  16:        0x10e724d63 - check::vtable::select_fcx_obligations_where_possible::hbca02d457f2550e2r4b                                                                            
  17:        0x10e75d48d - check::FnCtxt<'a, 'tcx>::resolve_type_vars_if_possible::h4ae213f9cb49bdadLYo                                                                          
  18:        0x10e7d91ae - check::op::check_binop::h03b611fd681fb03fM6m                                                                                                          
  19:        0x10e81e5cc - check::check_expr_with_unifier::h17623262095715920792                                                                                                 
  20:        0x10e8484f2 - check::check_decl_local::hceee65fb94b47336eis                                                                                                         
  21:        0x10e7e8ad1 - check::check_block_with_expected::ha2448513d5fb9fb9kos                                                                                                
  22:        0x10e82bf51 - check::check_expr_with_unifier::h15858122413925670105                                                                                                 
  23:        0x10e713b05 - check::_match::check_match::closure.28752                                                                                                             
  24:        0x10e713811 - check::_match::check_match::h6e204581d7b2887c9mb                                                                                                      
  25:        0x10e81eba4 - check::check_expr_with_unifier::h17623262095715920792                                                                                                 
  26:        0x10e7e8e0b - check::check_block_with_expected::ha2448513d5fb9fb9kos                                                                                                
  27:        0x10e803584 - check::check_block_no_value::he84d13599fd37c5alns                                                                                                     
  28:        0x10e82be51 - check::check_expr_with_unifier::h15858122413925670105                                                                                                 
  29:        0x10e713b05 - check::_match::check_match::closure.28752                                                                                                             
  30:        0x10e713811 - check::_match::check_match::h6e204581d7b2887c9mb                                                                                                      
  31:        0x10e81eba4 - check::check_expr_with_unifier::h17623262095715920792                                                                                                 
  32:        0x10e8484f2 - check::check_decl_local::hceee65fb94b47336eis                                                                                                         
  33:        0x10e7e8ad1 - check::check_block_with_expected::ha2448513d5fb9fb9kos                                                                                                
  34:        0x10e81ec21 - check::check_expr_with_unifier::h17623262095715920792                                                                                                 
  35:        0x10e7e8e0b - check::check_block_with_expected::ha2448513d5fb9fb9kos                                                                                                
   36:        0x10e82bf51 - check::check_expr_with_unifier::h15858122413925670105    
  37:        0x10e713b05 - check::_match::check_match::closure.28752                
  38:        0x10e713811 - check::_match::check_match::h6e204581d7b2887c9mb         
  39:        0x10e81eba4 - check::check_expr_with_unifier::h17623262095715920792    
  40:        0x10e7e8e0b - check::check_block_with_expected::ha2448513d5fb9fb9kos   
  41:        0x10e82bf51 - check::check_expr_with_unifier::h15858122413925670105    
  42:        0x10e713b05 - check::_match::check_match::closure.28752                
  43:        0x10e713811 - check::_match::check_match::h6e204581d7b2887c9mb         
  44:        0x10e81eba4 - check::check_expr_with_unifier::h17623262095715920792    
  45:        0x10e7e8e0b - check::check_block_with_expected::ha2448513d5fb9fb9kos   
  46:        0x10e7c33e5 - check::check_fn::h7a50c890b5419d55G1n                    
  47:        0x10e7e395e - check::check_bare_fn::hb7403022fad4c11dfRn               
  48:        0x10e7db85f - check::check_item::hede794dfa708b89909n                  
  49:        0x10e7e1ec2 - visit::walk_item::h9731833736362995753                   
  50:        0x10e8b8ff1 - check_crate::closure.36204                               
  51:        0x10e8b3437 - check_crate::h2a80ddc71481fbe04wC                        
  52:        0x10e5d7287 - driver::phase_3_run_analysis_passes::h6b1a4d735c5454a3oGa
  53:        0x10e5bb9c5 - driver::compile_input::hc433cbaf5268b434Qba              
  54:        0x10e679b75 - run_compiler::hfdf6389c24d7bf2fp2b                       
  55:        0x10e67748f - thunk::F.Invoke<A, R>::invoke::h17962875359394492347     
  56:        0x10e6765b7 - rt::unwind::try::try_fn::h2161268800680238185            
  57:        0x1121e8028 - rust_try_inner                                           
  58:        0x1121e8015 - rust_try                                                 
  59:        0x10e676988 - thunk::F.Invoke<A, R>::invoke::h12486231582466062018     
  60:        0x11214a91d - sys::thread::create::thread_start::h5cc5a46a7850c86a84H  
  61:     0x7fff82c3e267 - _pthread_body                                            
  62:     0x7fff82c3e1e4 - _pthread_start                                           

Could not compile `elmesque`.                                                       

I haven't yet been able to isolate the culprit code, I'll keep searching and post it if I come across it. Just thought I'd share this first.

This occurred on rustc 1.0.0-nightly (6cf3b0b74 2015-03-30) (built 2015-03-30)

[mitchmindtree]

Not sure if this helps at all, but I was able to side-step this ICE in my own code by changing an incorrect generic integer to a correct generic float.

To be exact, I changed this (which should have been a compile error, but ICEd):

let mut half_prev_width = 0;

to this (which compiles fine):

let mut half_prev_width = 0.0;

The following is the block of code in which this occurred:

let multi = if let Direction::Right = direction { 1.0 } else { -1.0 };
let mut half_prev_width = 0;
for element in elements.into_iter() {
    let element = element.opacity(props.opacity * element.props.opacity);
    let half_width = width_of(&element) as f64 / 2.0;
    draw_element(element, matrix, g, draw_state);
    let x_trans = half_width + half_prev_width;
    let Transform2D(new_matrix) = Transform2D(matrix)
        .multiply(transform_2d::translation(x_trans * multi, 0.0));
    matrix = new_matrix;
    half_prev_width = half_width;
}

I think the error that rustc should have given was

error: mismatched types:
 expected `_`,
    found `f64`

Perhaps the ICE is related to the way this error is detected, or perhaps the way the generic number's type is inferred?

I tried recreating the ICE in a simpler playpen example to no avail. Hopefully this helps point someone in the right direction though!

[TimNN]

I can reproduce this error with the following test case (playpen):

fn main() {
    let _ = 0f32 * 0.0 * 0;
}

The ICE also happens with the operators + - / %.

Adding or removing any type suffix, changing the operand order or using two different operators fixes the ICE.

Version: rustc 1.0.0-nightly (00978a987 2015-04-18) (built 2015-04-18) on OS X

Backtrace:

error: internal compiler error: Impl DefId { krate: 2, node: 41567 } was matchable against Obligation(predicate=Binder(TraitPredicate(<f32 as core::ops::Mul<_>>)),depth=1) but now is not
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports
note: run with `RUST_BACKTRACE=1` for a backtrace
thread 'rustc' panicked at 'Box<Any>', /Users/rustbuild/src/rust-buildbot/slave/nightly-dist-rustc-mac/build/src/libsyntax/diagnostic.rs:230

stack backtrace:
   1:        0x103bf907f - sys::backtrace::write::h652639cd75f0c63cnSs
   2:        0x103c01612 - panicking::on_panic::h669c4ea43c1379a9CPw
   3:        0x103bb7815 - rt::unwind::begin_unwind_inner::h3fc7f8f4791b4491lxw
   4:        0x1033b700e - rt::unwind::begin_unwind::h3264207737224415616
   5:        0x1033b77b2 - diagnostic::Handler::bug::h43c0dbadc7c09da91wB
   6:        0x100f43f4b - middle::traits::select::SelectionContext<'cx, 'tcx>::rematch_impl::hdaa10e90cc7f94c6fyS
   7:        0x100f43ad8 - middle::infer::InferCtxt<'a, 'tcx>::commit_if_ok::h12400076273368149998
   8:        0x100f2dc2d - middle::traits::select::SelectionContext<'cx, 'tcx>::confirm_candidate::h287b4d911777ca83hQR
   9:        0x100f09198 - middle::traits::select::SelectionContext<'cx, 'tcx>::select::h4326d6c2fd759146URP
  10:        0x100f151dd - middle::traits::project::project_type::heec759ea04573f931yO
  11:        0x100f13b8b - middle::traits::project::opt_normalize_projection_type::h854a36e9d7fdc4baDrO
  12:        0x100f1033b - middle::traits::project::project_and_unify_type::h01572a7c3a6427d9xaO
  13:        0x100f0e5df - middle::infer::InferCtxt<'a, 'tcx>::commit_if_ok::h9136385102605535755
  14:        0x100f06519 - middle::traits::fulfill::FulfillmentContext<'tcx>::select::h8e12571e1c1d6e2a5JN
  15:        0x100f05f38 - middle::traits::fulfill::FulfillmentContext<'tcx>::select_where_possible::ha144bba9596c77dbjJN
  16:        0x1009a32a3 - check::vtable::select_fcx_obligations_where_possible::h11116134018e3c7eI0b
  17:        0x1009caef1 - check::FnCtxt<'a, 'tcx>::resolve_type_vars_if_possible::h2e09c238ad2631efOUo
  18:        0x100a2ba98 - check::op::check_binop::h63d2d3bb28d51501Qan
  19:        0x100a6a67e - check::check_expr_with_unifier::h13774552146527501464
  20:        0x100a911ab - check::check_decl_local::h05c9fe2a0c0769088bs
  21:        0x100a39bfa - check::check_block_with_expected::h638aab069ab365beeis
  22:        0x100a1b378 - check::check_fn::h9fa3978846dc7de3N4n
  23:        0x100a35379 - check::check_bare_fn::h43ce861f2a41909amUn
  24:        0x100a33466 - check::CheckItemBodiesVisitor<'a, 'tcx>.Visitor<'tcx>::visit_item::h9ea50cb814d6f016pRn
  25:        0x100afccea - check_crate::closure.38351
  26:        0x100af80f7 - check_crate::hb20169de249f4e69pCC
  27:        0x1003463c2 - driver::phase_3_run_analysis_passes::h48e7216953f4195erGa
  28:        0x10032819c - driver::compile_input::h8c0d6e2f0389eda0Qba
  29:        0x1003ef903 - run_compiler::h318b4521e91f682fD4b
  30:        0x1003ed42a - boxed::F.FnBox<A>::call_box::h15521220820018991817
  31:        0x1003ec8c7 - rt::unwind::try::try_fn::h6267384748210286924
  32:        0x103c8b3d8 - rust_try_inner
  33:        0x103c8b3c5 - rust_try
  34:        0x1003ecba0 - boxed::F.FnBox<A>::call_box::h12285395525992985164
  35:        0x103c0017d - sys::thread::create::thread_start::hbbc60a5321f29f07eVv
  36:     0x7fff932fe267 - _pthread_body
  37:     0x7fff932fe1e4 - _pthread_start

[arielb1]

Duplicate of #24325