ICE: FulfillmentError, MismatchedProjectionTypes

[gmorenz]

Testcase currently relying on the most recent ncollide and nphysics3d from crates.io. When I get some time later today I'll try to reduce it more.

Code:

extern crate ncollide;
extern crate nphysics3d;

use ncollide::shape::Ball;
use nphysics3d::object::RigidBody;

fn main() {
    RigidBody::new_dynamic(Ball::new(1.0f32), 1.0f32, 0.0f32, 1.0f32);
}

Error:

error: internal compiler error: ../src/librustc/infer/mod.rs:564: Encountered errors `[FulfillmentError(Obligation(predicate=Binder(ProjectionPredicate(ProjectionTy { trait_ref: <nalgebra::structs::vector::Vector3<f32> as ncollide::ncollide_math::Vector>, item_name: Scalar(3937) }, <<nalgebra::structs::point::Point3<f32> as ncollide::ncollide_math::Point>::Vect as ncollide::ncollide_math::Vector>::Scalar)),depth=2),MismatchedProjectionTypes(Sorts(ExpectedFound { expected: f32, found: <<nalgebra::structs::point::Point3<f32> as ncollide::ncollide_math::Point>::Vect as ncollide::ncollide_math::Vector>::Scalar })))]` fulfilling during trans
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

thread 'rustc' panicked at 'Box<Any>', ../src/libsyntax/errors/mod.rs:537
stack backtrace:
   1:     0x7fcc05a63610 - std::sys::backtrace::tracing::imp::write::h9fb600083204ae7f
   2:     0x7fcc05a70d5b - std::panicking::default_hook::_$u7b$$u7b$closure$u7d$$u7d$::hca543c34f11229ac
   3:     0x7fcc05a708fc - std::panicking::default_hook::hc2c969e7453d080c
   4:     0x7fcc05a3628f - std::sys_common::unwind::begin_unwind_inner::h30e12d15ce2b2e25
   5:     0x7fcc04538ea8 - std::sys_common::unwind::begin_unwind::h24c4c0fa2cfe995a
   6:     0x7fcc04538e4b - syntax::errors::Handler::span_bug::h1878d6587b8bfd95
   7:     0x7fcc0456dac2 - rustc::session::opt_span_bug_fmt::_$u7b$$u7b$closure$u7d$$u7d$::hf0fb5697f8f25f40
   8:     0x7fcc0456d9b2 - rustc::session::span_bug_fmt::h4591bcbadfc38558
   9:     0x7fcc0458204c - rustc_trans::common::fulfill_obligation::hb97500cd4d49823c
  10:     0x7fcc0457aa99 - rustc_trans::callee::Callee::def::ha169529fef0048b5
  11:     0x7fcc0467c11e - _<std..option..Option<T>>::map::h54e7f9a0f99f0360
  12:     0x7fcc0467bf0a - _<std..vec..Vec<T> as std..iter..FromIterator<T>>::from_iter::he173b9fb2f4cc1c2
  13:     0x7fcc0467b7c3 - rustc_trans::meth::get_vtable::_$u7b$$u7b$closure$u7d$$u7d$::hd7ec4b80d346f375
  14:     0x7fcc0467c942 - _<std..iter..FlatMap<I, U, F> as std..iter..Iterator>::next::ha090509351b98638
  15:     0x7fcc0467cb83 - _<std..vec..Vec<T>>::extend_desugared::hfc30acdd7688509c
  16:     0x7fcc0467c609 - core::iter::iterator::Iterator::collect::h42fa202d3651b5e6
  17:     0x7fcc0457c822 - rustc_trans::base::unsized_info::hd31be9e24e239b50
  18:     0x7fcc04641a66 - rustc_trans::expr::coerce_unsized::h6fa5deecc673f1b4
  19:     0x7fcc045eb860 - rustc_trans::expr::trans::h4425e9280a87b757
  20:     0x7fcc045a1faf - rustc_trans::expr::trans_into::he1315719b2222c7c
  21:     0x7fcc045a0d24 - rustc_trans::expr::trans_adt::hde3664923fa8f9ee
  22:     0x7fcc045a043d - rustc_trans::base::trans_named_tuple_constructor::hf968d51ee4f7b842
  23:     0x7fcc04579ab2 - rustc_trans::callee::Callee::call::h54d29fdb586ad3c4
  24:     0x7fcc0463e8b3 - rustc_trans::expr::trans_rvalue_dps_unadjusted::h4d8aac465b9b8fed
  25:     0x7fcc045a267d - rustc_trans::expr::trans_into::he1315719b2222c7c
  26:     0x7fcc0459a1cd - rustc_trans::controlflow::trans_block::h4fad28c271095568
  27:     0x7fcc04598c85 - rustc_trans::base::trans_closure::h83a389352ac0be25
  28:     0x7fcc0459a8f3 - rustc_trans::base::trans_fn::h9423938066432dd9
  29:     0x7fcc045d6fba - rustc_trans::callee::get_fn::h691a55e881985779
  30:     0x7fcc0457ad60 - rustc_trans::callee::Callee::def::ha169529fef0048b5
  31:     0x7fcc0467c11e - _<std..option..Option<T>>::map::h54e7f9a0f99f0360
  32:     0x7fcc0467bf0a - _<std..vec..Vec<T> as std..iter..FromIterator<T>>::from_iter::he173b9fb2f4cc1c2
  33:     0x7fcc0467b7c3 - rustc_trans::meth::get_vtable::_$u7b$$u7b$closure$u7d$$u7d$::hd7ec4b80d346f375
  34:     0x7fcc0467c942 - _<std..iter..FlatMap<I, U, F> as std..iter..Iterator>::next::ha090509351b98638
  35:     0x7fcc0467cb83 - _<std..vec..Vec<T>>::extend_desugared::hfc30acdd7688509c
  36:     0x7fcc0467c609 - core::iter::iterator::Iterator::collect::h42fa202d3651b5e6
  37:     0x7fcc0457c822 - rustc_trans::base::unsized_info::hd31be9e24e239b50
  38:     0x7fcc04641a66 - rustc_trans::expr::coerce_unsized::h6fa5deecc673f1b4
  39:     0x7fcc045eb860 - rustc_trans::expr::trans::h4425e9280a87b757
  40:     0x7fcc04645761 - rustc_trans::expr::trans_imm_cast::hf3533ccfb48f0b29
  41:     0x7fcc0463b828 - rustc_trans::expr::trans_unadjusted::hee333a5a427a7dc8
  42:     0x7fcc045eae31 - rustc_trans::expr::trans::h4425e9280a87b757
  43:     0x7fcc045e9bbe - rustc_trans::callee::trans_args::h9cc59c5a5b26cbc0
  44:     0x7fcc04579ec6 - rustc_trans::callee::Callee::call::h54d29fdb586ad3c4
  45:     0x7fcc0463e8b3 - rustc_trans::expr::trans_rvalue_dps_unadjusted::h4d8aac465b9b8fed
  46:     0x7fcc045a267d - rustc_trans::expr::trans_into::he1315719b2222c7c
  47:     0x7fcc045a0d24 - rustc_trans::expr::trans_adt::hde3664923fa8f9ee
  48:     0x7fcc0463d60a - rustc_trans::expr::trans_rvalue_dps_unadjusted::h4d8aac465b9b8fed
  49:     0x7fcc045a267d - rustc_trans::expr::trans_into::he1315719b2222c7c
  50:     0x7fcc0459a1cd - rustc_trans::controlflow::trans_block::h4fad28c271095568
  51:     0x7fcc04598c85 - rustc_trans::base::trans_closure::h83a389352ac0be25
  52:     0x7fcc0459a8f3 - rustc_trans::base::trans_fn::h9423938066432dd9
  53:     0x7fcc045d6fba - rustc_trans::callee::get_fn::h691a55e881985779
  54:     0x7fcc0457ad60 - rustc_trans::callee::Callee::def::ha169529fef0048b5
  55:     0x7fcc0463e671 - rustc_trans::expr::trans_rvalue_dps_unadjusted::h4d8aac465b9b8fed
  56:     0x7fcc0463b648 - rustc_trans::expr::trans_unadjusted::hee333a5a427a7dc8
  57:     0x7fcc045eae31 - rustc_trans::expr::trans::h4425e9280a87b757
  58:     0x7fcc045e9bbe - rustc_trans::callee::trans_args::h9cc59c5a5b26cbc0
  59:     0x7fcc04579ec6 - rustc_trans::callee::Callee::call::h54d29fdb586ad3c4
  60:     0x7fcc0463e8b3 - rustc_trans::expr::trans_rvalue_dps_unadjusted::h4d8aac465b9b8fed
  61:     0x7fcc045a267d - rustc_trans::expr::trans_into::he1315719b2222c7c
  62:     0x7fcc0459a1cd - rustc_trans::controlflow::trans_block::h4fad28c271095568
  63:     0x7fcc04598c85 - rustc_trans::base::trans_closure::h83a389352ac0be25
  64:     0x7fcc0459a8f3 - rustc_trans::base::trans_fn::h9423938066432dd9
  65:     0x7fcc045d6fba - rustc_trans::callee::get_fn::h691a55e881985779
  66:     0x7fcc0457ad60 - rustc_trans::callee::Callee::def::ha169529fef0048b5
  67:     0x7fcc0463e671 - rustc_trans::expr::trans_rvalue_dps_unadjusted::h4d8aac465b9b8fed
  68:     0x7fcc0463b648 - rustc_trans::expr::trans_unadjusted::hee333a5a427a7dc8
  69:     0x7fcc045eae31 - rustc_trans::expr::trans::h4425e9280a87b757
  70:     0x7fcc0461e166 - rustc_trans::controlflow::trans_stmt_semi::h1cfba097d89a5175
  71:     0x7fcc04599ea0 - rustc_trans::controlflow::trans_block::h4fad28c271095568
  72:     0x7fcc04598c85 - rustc_trans::base::trans_closure::h83a389352ac0be25
  73:     0x7fcc0459a8f3 - rustc_trans::base::trans_fn::h9423938066432dd9
  74:     0x7fcc045a4e91 - rustc_trans::base::trans_item::hdc785ae68a9e6500
  75:     0x7fcc045beecb - _<base..TransItemsWithinModVisitor<'a, 'tcx> as rustc..hir..intravisit..Visitor<'v>>::visit_item::h22c1c36dec64effa
  76:     0x7fcc045ad7cb - rustc_trans::base::trans_crate::h6ed1dbd6e572a8c2
  77:     0x7fcc05fc86ff - rustc_driver::driver::phase_4_translate_to_llvm::hd7579aae98641824
  78:     0x7fcc05fc6d8f - rustc_driver::driver::compile_input::_$u7b$$u7b$closure$u7d$$u7d$::he3c6b6ab9afe28dd
  79:     0x7fcc05fc3630 - rustc_driver::driver::phase_3_run_analysis_passes::_$u7b$$u7b$closure$u7d$$u7d$::h06c776ef4d1c70b6
  80:     0x7fcc05fbcf5e - rustc::ty::context::TyCtxt::create_and_enter::hb0e0e916c7274a64
  81:     0x7fcc05f8f90d - rustc_driver::driver::compile_input::h0629572e6f316b31
  82:     0x7fcc05f7053c - rustc_driver::run_compiler::h8902aebf8b1849a8
  83:     0x7fcc05f6dc41 - std::sys_common::unwind::try::try_fn::h4c74456035d0fcc7
  84:     0x7fcc05a60deb - __rust_try
  85:     0x7fcc05a60d7d - std::sys_common::unwind::inner_try::h47a4d9cd4a369dcd
  86:     0x7fcc05f6e48a - _<F as std..boxed..FnBox<A>>::call_box::h27f542a39f1d61ef
  87:     0x7fcc05a6eef4 - std::sys::thread::Thread::new::thread_start::h6f266e069bf4ec2b
  88:     0x7fcbfd7f6423 - start_thread
  89:     0x7fcc056cdcbc - clone
  90:                0x0 - <unknown>

error: Could not compile `pong`.

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

[sebcrozet]

I investigated this further and ended up with the following test case independent from ncollide/nphysics. It causes an ICE on both beta (rustc 1.9.0-beta.2 (87cb733 2016-05-04)) and nigthly (rustc 1.10.0-nightly (8da2bca 2016-04-28))( and compiles fine on stable. The ICE will appear with and without --release. This might be related to #33096.

I can try to compile this on master but it will take some time before I can download the repo and compile rustc manually.

use std::marker::PhantomData;

struct TheType<T> {
    t: PhantomData<T>
}

pub trait TheTrait {
    type TheAssociatedType;
}

impl TheTrait for () {
    type TheAssociatedType = ();
}

pub trait Shape<P: TheTrait> {
    fn doit(&self) {
    }
}

impl<P: TheTrait> Shape<P> for TheType<P::TheAssociatedType> {
}

fn main() {
    let ball = TheType { t: PhantomData };
    let handle: &Shape<()> = &ball;
}

This will compile fine, without any ICE if we do at least one of the following:

• Implement the .doit(...) method explicitly on impl<...> Shape<...> for TheType<...>:

impl<P: TheTrait> Shape<P> for TheType<P::TheAssociatedType> {
    fn doit(&self) {
   }
}

• Remove the associated type in the impl, i.e., replace impl<P: TheTrait> Shape<P> for TheType<P::TheAssociatedType> with impl<P: TheTrait> Shape<P> for TheType<()> (or anything else, including P itself instead of ()).
• Remove the cast to a &Shape<...> trait-object at the end of the main.

[sanxiyn]

Fixed by #33478.