error: internal compiler error: get_unique_type_id_of_type() - unexpected type: closure, ty_unboxed_closure

[emk]

It's September 22, and I just download today's compiler using rustup.sh. I tried to compile this modified version of rust-replace-map, using FnOnce:

#![feature(unboxed_closures, overloaded_calls)]

//! Exposes `replace_map`, for replacing values at mutable memory locations.

use std::ptr;

/// Replace the value at a mutable memory location with the value
/// produced by the passed in closure.
///
/// Does not create an intermediate value, so is more efficient and
/// ergonomic in cases where producing a value to pass to mem::replace
/// is hard.
pub fn replace_map<'a, T, F>(src: &mut T, prod: F)
where F: FnOnce(T) -> T {
    // Read the value, pass it to prod, then write-over src.
    //
    // Safe because the value originally behind src is dropped
    // inside of prod and is then immediately written over.
    unsafe { *src = prod(ptr::read(src as *mut T as *const T)); }
}

#[test] fn test_works() {
    let mut a = 7u;
    let b = &mut a;

    replace_map(b, |: x: uint| x * 2);
    assert_eq!(*b, 14u);
}

…and got:

error: internal compiler error: get_unique_type_id_of_type() - unexpected type: closure, ty_unboxed_closure(syntax::ast::DefId{krate: 0u32, node: 67u32}, ReScope(64u32))
note: the compiler hit an unexpected failure path. this is a bug.
note: we would appreciate a bug report: http://doc.rust-lang.org/complement-bugreport.html
note: run with `RUST_BACKTRACE=1` for a backtrace
task 'rustc' failed at 'Box<Any>', /home/rustbuild/src/rust-buildbot/slave/nightly-linux/build/src/libsyntax/diagnostic.rs:169

stack backtrace:
   1:     0x7ff33e8faf00 - rt::backtrace::imp::write::hb40e767174eadc9blLq
   2:     0x7ff33e8fe0c0 - failure::on_fail::hab6209505fea7a58N6q
   3:     0x7ff34300df80 - unwind::begin_unwind_inner::h3a7e8417aad82c7eMTd
   4:     0x7ff33f6a8450 - unwind::begin_unwind::h2392538768877619269
   5:     0x7ff33f6a8bc0 - diagnostic::Handler::bug::hbcf500f6b0a7b557wjF
   6:     0x7ff343660780 - driver::session::Session::bug::h0f635b08aa66c6feeQx
   7:     0x7ff343b05fa0 - middle::trans::debuginfo::TypeMap::get_unique_type_id_of_type::h233deb54704247ccivp
   8:     0x7ff343b0f6d0 - middle::trans::debuginfo::type_metadata::hb53e934b117efcaftOr
   9:     0x7ff343ab60a0 - middle::trans::debuginfo::create_function_debug_context::h7fc6b788d4b1d265rfq
  10:     0x7ff343a2fe60 - middle::trans::base::new_fn_ctxt::h611243317f012711AFe
  11:     0x7ff343aba2b0 - middle::trans::base::trans_closure::hd7b21130af57d114T6e
  12:     0x7ff343a00cf0 - middle::trans::base::trans_fn::hba6c6098eff914846hf
  13:     0x7ff343a013d0 - middle::trans::monomorphize::monomorphic_fn::h111314500f9ac8aadtY
  14:     0x7ff343a383a0 - middle::trans::callee::trans_fn_ref_with_substs::h927366ab2c3f6092XP1
  15:     0x7ff343a35cf0 - middle::trans::callee::trans_fn_ref::h6176864c3298571axE1
  16:     0x7ff343a3db50 - middle::trans::callee::trans_call::closure.123725
  17:     0x7ff343a16130 - middle::trans::callee::trans_call_inner::ha373276fc0d46583Fb2
  18:     0x7ff343a3d8b0 - middle::trans::callee::trans_call::ha3d5b5ce354777b1051
  19:     0x7ff343a4c630 - middle::trans::expr::trans_rvalue_dps_unadjusted::hf457bf80e76e66462i4
  20:     0x7ff343a0e5c0 - middle::trans::expr::trans_into::ha20572ab8748555eMV2
  21:     0x7ff343a0d9c0 - middle::trans::controlflow::trans_stmt_semi::h5634a3e832fd1190x3Y
  22:     0x7ff343a0d0e0 - middle::trans::controlflow::trans_stmt::h669538f418e4814fuZY
  23:     0x7ff343a0ea90 - middle::trans::controlflow::trans_block::h98e6c8ac340121b9q4Y
  24:     0x7ff343aba2b0 - middle::trans::base::trans_closure::hd7b21130af57d114T6e
  25:     0x7ff343a00cf0 - middle::trans::base::trans_fn::hba6c6098eff914846hf
  26:     0x7ff3439fe110 - middle::trans::base::trans_item::h13a70584bb385db8fBf
  27:     0x7ff343ac5510 - middle::trans::base::trans_crate::he94a02318e5d0e54kzg
  28:     0x7ff343ee6b90 - driver::driver::phase_4_translate_to_llvm::hfa5c9eb34e10ce6cchx
  29:     0x7ff343eddf50 - driver::driver::compile_input::h644c4bcdb8d4fa416Nw
  30:     0x7ff343f5fe40 - driver::run_compiler::hd9154f69e0f25652kFA
  31:     0x7ff343f5fd20 - driver::main_args::closure.146572
  32:     0x7ff34368fe70 - task::TaskBuilder<S>::try_future::closure.101814
  33:     0x7ff34368fc60 - task::TaskBuilder<S>::spawn_internal::closure.101785
  34:     0x7ff34335d540 - task::spawn_opts::closure.8457
  35:     0x7ff343064390 - rust_try_inner
  36:     0x7ff343064380 - rust_try
  37:     0x7ff34300b580 - unwind::try::haa9a6e4d3a3bf10cuId
  38:     0x7ff34300b3e0 - task::Task::run::h18e39631c20de002cYc
  39:     0x7ff34335d2b0 - task::spawn_opts::closure.8397
  40:     0x7ff34300cfd0 - thread::thread_start::hfdbefd9910b77f41rid
  41:     0x7ff33dcabdc0 - start_thread
  42:                0x0 - <unknown>

[emk]

This appears to be a regression of #17021, on almost exactly the same code.