ICE on impossible trait object/associated type

[talchas]

trait Hack: std::ops::Add<Self, Output = Self> + Copy {}
fn takes_hack(x: &Hack<Output=i32>) {}```
(which can't work of course)

Gives:
thread 'rustc' panicked at 'assertion failed: !ty.needs_infer()', ../src/librustc_typeck/lib.rs:152
on playpen's nightly and on an older nightly:
   1:     0x7f2a73cac30e - sys::backtrace::write::h1e294cdf8b83f011srs
   2:     0x7f2a73cb44d4 - panicking::on_panic::h759b2622c5bddde1mdx
   3:     0x7f2a73c76ade - rt::unwind::begin_unwind_inner::hdb2ee52cd09f11c10Sw
   4:     0x7f2a73415651 - rt::unwind::begin_unwind::h16407102452406535252
   5:     0x7f2a73519747 - collect::convert_item::hee80771e2831a06bVHx
   6:     0x7f2a735164c7 - collect::collect_item_types::hb25670e75e1ace20iPw
   7:     0x7f2a735636c9 - check_crate::h699f9ca48d981e0dRWC
   8:     0x7f2a74211cc9 - driver::phase_3_run_analysis_passes::closure.15891
   9:     0x7f2a7421060b - middle::ty::ctxt<'tcx>::create_and_enter::h14877326799551551326
  10:     0x7f2a7420b5b1 - driver::phase_3_run_analysis_passes::h13027946853248993312
  11:     0x7f2a741ea80c - driver::compile_input::h1bb41626855952a5Tba
  12:     0x7f2a742d0e83 - run_compiler::hed8febc643a5bd02A7b
  13:     0x7f2a742ce85e - boxed::F.FnBox<A>::call_box::h3262743521461286850
  14:     0x7f2a742ce0a9 - rt::unwind::try::try_fn::h13012207966773460524
  15:     0x7f2a73d2f9d8 - rust_try_inner
  16:     0x7f2a73d2f9c5 - rust_try
  17:     0x7f2a73c9f647 - rt::unwind::try::inner_try::hcf9d4b2ce436da47TOw
  18:     0x7f2a742ce2bb - boxed::F.FnBox<A>::call_box::h5485760352730305604
  19:     0x7f2a73cb3131 - sys::thread::Thread::new::thread_start::h6bca3390d26c61e4GYv

[arielb1]

mini:

trait Foo<T:?Sized> {type S;}
trait Hack: Foo<Self> {}
fn takes_hack(x: &Hack<S=()>) {}
fn main() {}

This is non-object-safe, but the crash occurs in collect - needs to be prohibited earlier.

[apasel422]

@arielb1's test case no longer ICEs:

foo.rs:3:19: 3:29 error: the trait `Hack` cannot be made into an object [E0038]
foo.rs:3 fn takes_hack(x: &Hack<S=()>) {}
                           ^~~~~~~~~~
foo.rs:3:19: 3:29 help: run `rustc --explain E0038` to see a detailed explanation
foo.rs:3:19: 3:29 note: the trait cannot use `Self` as a type parameter in the supertrait listing

[arielb1]

duplicate of #28576 (is there a version of github search that doesn't suck?).

[arielb1]

I searched for needs_infer when I fixed #28576, but github search ignored me.