Rustc panics on division of f64 and i32

[dmner]

Tried to find a simple example from my horrible scratch code, the code shouldn't compile due to the division of int and float but the compiler panics instead of erroring out.

I tried this code:

extern crate time;

fn main() {
    let max = 10;
    let mut total : f64 = 0.0;
    for i in 1..max {
        let start_time = time::precise_time_ns();
        // operation here
        let end_time = time::precise_time_ns();
        let duration = (end_time - start_time) as f64 / 1000000.0;
        println!("Time diff: {} ms", duration);
        total += duration;
    }
    println!("Avg: {}", total / max);
}

I expected to see this happen: warning about the division such as:

error: the trait `core::ops::Div<_>` is not implemented for the type `f64` [E0277]

That error occurs if you remove the for loop.

Instead, this happened: rustc panicked

error: internal compiler error: Impl DefId { krate: 2, node: 42138 } was matchable against Obligation(predicate=Binder(TraitPredicate(core::ops::Div<_>)),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>', C:/bot/slave/nightly-dist-rustc-win-64/build/src/libsyntax\diagnostic.rs:190

Meta

rustc --version --verbose:

rustc 1.0.0-nightly (083b8a404 2015-04-05) (built 2015-04-05)
binary: rustc
commit-hash: 083b8a40413eb3dfec7430150b8895f6c8bbafca
commit-date: 2015-04-05
build-date: 2015-04-05
host: x86_64-pc-windows-gnu
release: 1.0.0-nightly

Backtrace:

stack backtrace:
   1:         0x7120a6f3 - sys::backtrace::write::h44450b400aabf2c7DUC
   2:         0x7121fc81 - rt::unwind::register::hf93dcfca71eaeedaBtI
   3:         0x711836e0 - rt::unwind::begin_unwind_inner::h1c26c49e466c04e9LqI
   4:           0x6f4e29 - diagnostic::SpanHandler::span_bug::h13d9b44f0a605030nnB
   5:           0x6f5465 - diagnostic::Handler::bug::hb88abd22760a97693sB
   6:          0x1081af1 - middle::ty::substd_enum_variants::h652b7145d0050673Vq7
   7:          0x1081373 - middle::ty::substd_enum_variants::h652b7145d0050673Vq7
   8:          0x10637b7 - middle::ty::TraitPredicate<'tcx>.RegionEscape::has_regions_escaping_depth::h4332861124e51a36iR9
   9:          0x10386c8 - middle::traits::select::SelectionContext<'cx, 'tcx>::select::h5152e335d3335b0b3NQ
  10:          0x1047018 - middle::traits::select::SelectionContext<'cx, 'tcx>::closure_typer::h2ad939045ad278ffONQ
  11:          0x1045277 - middle::ty::Predicate<'tcx>...std..cmp..PartialEq::ne::hb9348ef9ca6483fdT92
  12:          0x103f626 - middle::ty::Predicate<'tcx>...std..cmp..PartialEq::ne::hb9348ef9ca6483fdT92
  13:          0x103d7b7 - middle::ty::ProjectionPredicate<'tcx>...std..clone..Clone::clone::ha5e6eda673804f45iv3
  14:          0x10348cf - middle::traits::fulfill::FulfillmentContext<'tcx>::select_new_obligations::h18d2468924b2bc20xDO
  15:          0x1033f2b - middle::traits::fulfill::FulfillmentContext<'tcx>::select_where_possible::h43612618c609155c6DO
  16:          0x16947de - check::FnCtxt<'a, 'tcx>.ty..ClosureTyper<'tcx>::closure_upvars::h4d2d960d8f47db518Hn
  17:          0x16caee6 - check::LvaluePreference...std..fmt..Debug::fmt::h8786612addfd7375tMp
  18:          0x17401c1 - check::callee::CallResolution<'tcx>.Repr<'tcx>::repr::h04de2749584f8541lqm
  19:          0x17950bf - check::UnresolvedTypeAction...std..clone..Clone::clone::h4af893540a13f8a1lQp
  20:          0x1791ea1 - check::UnresolvedTypeAction...std..clone..Clone::clone::h4af893540a13f8a1lQp
  21:          0x177688b - check::UnresolvedTypeAction...std..clone..Clone::clone::h4af893540a13f8a1lQp
  22:          0x17804d8 - check::UnresolvedTypeAction...std..clone..Clone::clone::h4af893540a13f8a1lQp
  23:          0x177bb14 - check::UnresolvedTypeAction...std..clone..Clone::clone::h4af893540a13f8a1lQp
  24:          0x168468b - check::FnCtxt<'a, 'tcx>.ty..ClosureTyper<'tcx>::closure_upvars::h4d2d960d8f47db518Hn
  25:          0x1795635 - check::UnresolvedTypeAction...std..clone..Clone::clone::h4af893540a13f8a1lQp
  26:          0x1760a08 - check::UnresolvedTypeAction...std..clone..Clone::clone::h4af893540a13f8a1lQp
  27:          0x1734829 - check::callee::CallResolution<'tcx>.DeferredCallResolution<'tcx>::resolve::hcc66066c231187905rm
  28:          0x1730f8f - check::FnCtxt<'a, 'tcx>.AstConv<'tcx>::projected_ty::hb45c2700a7bbe868pVo
  29:          0x172f0dd - check::FnCtxt<'a, 'tcx>.AstConv<'tcx>::projected_ty::hb45c2700a7bbe868pVo
  30:          0x175d18a - check::UnresolvedTypeAction...std..clone..Clone::clone::h4af893540a13f8a1lQp
  31:          0x1734829 - check::callee::CallResolution<'tcx>.DeferredCallResolution<'tcx>::resolve::hcc66066c231187905rm
  32:          0x1730f8f - check::FnCtxt<'a, 'tcx>.AstConv<'tcx>::projected_ty::hb45c2700a7bbe868pVo
  33:          0x172f0dd - check::FnCtxt<'a, 'tcx>.AstConv<'tcx>::projected_ty::hb45c2700a7bbe868pVo
  34:          0x179b84b - check::UnresolvedTypeAction...std..clone..Clone::clone::h4af893540a13f8a1lQp
  35:          0x174d1c1 - check::GatherLocalsVisitor<'a, 'tcx>.Visitor<'tcx>::visit_item::hceaf85db2079e370EZn
  36:          0x172b502 - check::FnCtxt<'a, 'tcx>.AstConv<'tcx>::projected_ty::hb45c2700a7bbe868pVo
  37:          0x174849f - check::CheckItemTypesVisitor<'a, 'tcx>.Visitor<'tcx>::visit_ty::h052b2547f6a9f346sMn
  38:          0x17425a2 - check::CheckItemTypesVisitor<'a, 'tcx>.Visitor<'tcx>::visit_item::h3825f10c694ef4b96Ln
  39:          0x1814d98 - check_crate::h0c1ffccf36595c1a1oC
  40:          0x180f18c - check_crate::h0c1ffccf36595c1a1oC
  41:         0x652df97b - driver::phase_3_run_analysis_passes::h4f4155770758209cgGa
  42:         0x652c2c72 - driver::compile_input::h26f65b3844aecdf5Qba
  43:         0x65376df3 - run_compiler::hbef16719e0bfa262S4b
  44:         0x65374bff - run::hb658b94f918c924fy4b
  45:         0x65373fda - run::hb658b94f918c924fy4b
  46:         0x7125946c - rust_try
  47:         0x71259449 - rust_try
  48:         0x653742c1 - run::hb658b94f918c924fy4b
  49:         0x712139d4 - sys::tcp::TcpListener::bind::h2dcec942e16be4c4OSG
  50:     0x7ffa967b13d2 - BaseThreadInitThunk

[oli-obk]

minimized:

fn main() {
    let max = 10;
    let total : f64 = 1.0 as f64 / 1000000.0;
    println!("Avg: {}", total / max);
}

yields

error: internal compiler error: Impl DefId { krate: 2, node: 42129 } was matchable against Obligation(predicate=Binder(TraitPredicate(core::ops::Div<_>)),depth=1) but now is not

---

if you remove the as f64

fn main() {
    let max = 10;
    let total : f64 = 1.0 / 1000000.0;
    println!("Avg: {}", total / max);
}

you get the correct error:

<anon>:4:25: 4:36 error: the trait `core::ops::Div<_>` is not implemented for the type `f64` [E0277]
<anon>:4     println!("Avg: {}", total / max);
                                 ^~~~~~~~~~~

[hauleth]

It happens if we use as _ before division operator (example). Doesn't limited only to f64 so it looks like bug in parser.

[dmner]

More examples based on Hauleth's:

Doesn't happen if you divide by an integer (example).
Doesn't happen if you explicitly cast the second float to f32 (example)

[sinkuu]

I hit mostly same ICE when multiplying. Somehow I couldn't get backtraces (if I set RUST_BACKTRACE rustc crashes with Illegal instruction).

fn main() {
    let x: f32 = 0.0;
    let c = x * 1.0;
    let q = c as f32 * 1;
}

error: internal compiler error: Impl DefId { krate: 2, node: 40695 } was matchable against Obligation(predicate=Binder(TraitPredicate(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>', /home/rustbuild/src/rust-buildbot/slave/nightly-dist-rustc-linux/build/src/libsyntax/diagnostic.rs:209

Looks like this ICE happens when using same operator twice. Doesn't happen if I change one of operators to +, but happens if I change both:

fn main() {
    let x: f32 = 0.0;
    let c = x + 1.0;
    let q = c as f32 + 1;
}

error: internal compiler error: Impl DefId { krate: 2, node: 37931 } 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>', /home/rustbuild/src/rust-buildbot/slave/nightly-dist-rustc-linux/build/src/libsyntax/diagnostic.rs:209

[crumblingstatue]

I've run into this problem too. Test case:

fn main() {
    let foo: f32 = 10.;
    let bar = foo / 2.;
    bar / 4;
}