"assertion failed: !projection_ty.has_escaping_regions()" with closure and associated type

[eefriedman]

trait Inner {
    type T;
}

impl<'a> Inner for &'a i32 {
    type T = i32;
}

fn main() {
  let x = |x| -> <&i32 as Inner>::T { *x };
}

error: internal compiler error: unexpected panic
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 'assertion failed: !projection_ty.has_escaping_regions()', src/librustc/middle/traits/fulfill.rs:149
stack backtrace:
   1:     0x7f52b131fecc - sys::backtrace::tracing::imp::write::h75096aefc5daabfdQDt
   2:     0x7f52b13285ba - panicking::log_panic::h074efb00ffa0c687aqx
   3:     0x7f52b12de5ba - sys_common::unwind::begin_unwind_inner::h581753ef184fd220ivs
   4:     0x7f52aed28e6f - sys_common::unwind::begin_unwind::h9428703455056690702
   5:     0x7f52aefdea53 - middle::traits::fulfill::FulfillmentContext<'tcx>::normalize_projection_type::h5f52e43af4f9c0059sT
   6:     0x7f52afe1e47d - check::FnCtxt<'a, 'tcx>::normalize_associated_type::hbdbae43be670d320p2q
   7:     0x7f52afdee027 - check::FnCtxt<'a, 'tcx>.AstConv<'tcx>::projected_ty::ha20b0a56cb63ce59UHq
   8:     0x7f52afe763fe - astconv::qpath_to_ty::hb88bde258a783395Jbx
   9:     0x7f52afe5d16b - astconv::finish_resolving_def_to_ty::hb7f9bf159e1148faXmx
  10:     0x7f52afe2411f - astconv::ast_ty_to_ty::h38cf5ea0249ba76dLox
  11:     0x7f52afdec81c - check::closure::check_expr_closure::h1d04c5c814757366txm
  12:     0x7f52afe40fa8 - check::check_expr_with_unifier::h42356118614520124
  13:     0x7f52afe60663 - check::check_decl_initializer::h334ede296ceea5c193t
  14:     0x7f52afe606e4 - check::check_decl_local::h12b21c5d281a63ecn5t
  15:     0x7f52afe607e3 - check::check_stmt::hf4ecae8c0ba1e88bg7t
  16:     0x7f52afe1a3d0 - check::check_block_with_expected::hcab69be31983aac8dbu
  17:     0x7f52afdee6e6 - check::check_fn::h3e98663611e2442aHMp
  18:     0x7f52afe139d9 - check::check_bare_fn::hc36ed50f1eba9146ABp
  19:     0x7f52afe11198 - check::check_item_body::h8962f1dd30f4a7dcx3p
  20:     0x7f52afecf9c2 - check_crate::h8a914941619a715a7qE
  21:     0x7f52b1838c75 - driver::phase_3_run_analysis_passes::closure.22365
  22:     0x7f52b1835877 - middle::ty::context::ctxt<'tcx>::create_and_enter::h3781535353480941046
  23:     0x7f52b18308a3 - driver::phase_3_run_analysis_passes::h8173353897596142097
  24:     0x7f52b1812857 - driver::compile_input::h23b288fcb72aa11acca
  25:     0x7f52b1901639 - run_compiler::h0000145acc5f7b5dbxc
  26:     0x7f52b18febf8 - sys_common::unwind::try::try_fn::h15957305491151013021
  27:     0x7f52b131d538 - __rust_try
  28:     0x7f52b130d15b - sys_common::unwind::try::inner_try::he55d5a78f340f1afQrs
  29:     0x7f52b18fef20 - boxed::F.FnBox<A>::call_box::h10013595788438212684
  30:     0x7f52b1326c13 - sys::thread::Thread::new::thread_start::hac6bae05f2c08abbTLw
  31:     0x7f52aa915181 - start_thread
  32:     0x7f52b0f8a47c - __clone
  33:                0x0 - <unknown>

[arielb1]

duplicate of #27901