ICE on call/deref of bottom

[bkoropoff]

Code

fn main() {
    return { return () } ();
}

Output

test.rs:2:12: 2:28 error: multiple applicable methods in scope [E0034]
test.rs:2     return { return () } ();
                     ^~~~~~~~~~~~~~~~
test.rs:2:12: 2:28 note: candidate #1 is `core::ops::fn() -> Result.FnMut<(), Result>::call_mut`
test.rs:2     return { return () } ();
                     ^~~~~~~~~~~~~~~~
test.rs:2:12: 2:28 note: candidate #2 is `core::ops::fn(A0: A0) -> Result.FnMut<(A0,), Result>::call_mut`
test.rs:2     return { return () } ();
                     ^~~~~~~~~~~~~~~~
test.rs:2:12: 2:28 note: candidate #3 is `core::ops::fn(A0: A0, A1: A1) -> Result.FnMut<(A0, A1), Result>::call_mut`
test.rs:2     return { return () } ();
                     ^~~~~~~~~~~~~~~~
test.rs:2:12: 2:28 note: candidate #4 is `core::ops::fn(A0: A0, A1: A1, A2: A2) -> Result.FnMut<(A0, A1, A2), Result>::call_mut`
test.rs:2     return { return () } ();
                     ^~~~~~~~~~~~~~~~
test.rs:2:12: 2:28 note: candidate #5 is `core::ops::fn(A0: A0, A1: A1, A2: A2, A3: A3) -> Result.FnMut<(A0, A1, A2, A3), Result>::call_mut`
test.rs:2     return { return () } ();
                     ^~~~~~~~~~~~~~~~
test.rs:2:12: 2:28 note: candidate #6 is `core::ops::fn(A0: A0, A1: A1, A2: A2, A3: A3, A4: A4) -> Result.FnMut<(A0, A1, A2, A3, A4), Result>::call_mut`
test.rs:2     return { return () } ();
                     ^~~~~~~~~~~~~~~~
test.rs:2:12: 2:28 note: candidate #7 is `core::ops::fn(A0: A0, A1: A1, A2: A2, A3: A3, A4: A4, A5: A5) -> Result.FnMut<(A0, A1, A2, A3, A4, A5), Result>::call_mut`
test.rs:2     return { return () } ();
                     ^~~~~~~~~~~~~~~~
test.rs:2:12: 2:28 note: candidate #8 is `core::ops::fn(A0: A0, A1: A1, A2: A2, A3: A3, A4: A4, A5: A5, A6: A6) -> Result.FnMut<(A0, A1, A2, A3, A4, A5, A6), Result>::call_mut`
test.rs:2     return { return () } ();
                     ^~~~~~~~~~~~~~~~
test.rs:2:12: 2:28 note: candidate #9 is `core::ops::fn(A0: A0, A1: A1, A2: A2, A3: A3, A4: A4, A5: A5, A6: A6, A7: A7) -> Result.FnMut<(A0, A1, A2, A3, A4, A5, A6, A7), Result>::call_mut`
test.rs:2     return { return () } ();
                     ^~~~~~~~~~~~~~~~
test.rs:2:12: 2:28 note: candidate #10 is `core::ops::fn(A0: A0, A1: A1, A2: A2, A3: A3, A4: A4, A5: A5, A6: A6, A7: A7, A8: A8)
    -> Result.FnMut<(A0, A1, A2, A3, A4, A5, A6, A7, A8), Result>::call_mut`
test.rs:2     return { return () } ();
                     ^~~~~~~~~~~~~~~~
test.rs:2:12: 2:28 note: candidate #11 is `core::ops::fn
    (A0: A0, A1: A1, A2: A2, A3: A3, A4: A4, A5: A5, A6: A6, A7: A7, A8: A8,
     A9: A9) -> Result.FnMut<(A0, A1, A2, A3, A4, A5, A6, A7, A8, A9), Result>::call_mut`
test.rs:2     return { return () } ();
                     ^~~~~~~~~~~~~~~~
test.rs:2:12: 2:28 note: candidate #12 is `core::ops::fn
    (A0: A0, A1: A1, A2: A2, A3: A3, A4: A4, A5: A5, A6: A6, A7: A7, A8: A8,
     A9: A9, A10: A10) -> Result.FnMut<(A0, A1, A2, A3, A4, A5, A6, A7, A8, A9, A10), Result>::call_mut`
test.rs:2     return { return () } ();
                     ^~~~~~~~~~~~~~~~
test.rs:2:12: 2:28 note: candidate #13 is `core::ops::fn
    (A0: A0, A1: A1, A2: A2, A3: A3, A4: A4, A5: A5, A6: A6, A7: A7, A8: A8,
     A9: A9, A10: A10, A11: A11) -> Result.FnMut<(A0, A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11), Result>::call_mut`
test.rs:2     return { return () } ();
                     ^~~~~~~~~~~~~~~~
test.rs:2:12: 2:28 note: candidate #14 is `core::ops::fn
    (A0: A0, A1: A1, A2: A2, A3: A3, A4: A4, A5: A5, A6: A6, A7: A7, A8: A8,
     A9: A9, A10: A10, A11: A11, A12: A12) -> Result.FnMut<(A0, A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12), Result>::call_mut`
test.rs:2     return { return () } ();
                     ^~~~~~~~~~~~~~~~
test.rs:2:12: 2:28 note: candidate #15 is `core::ops::fn
    (A0: A0, A1: A1, A2: A2, A3: A3, A4: A4, A5: A5, A6: A6, A7: A7, A8: A8,
     A9: A9, A10: A10, A11: A11, A12: A12, A13: A13) -> Result.FnMut<(A0, A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13), Result>::call_mut`
test.rs:2     return { return () } ();
                     ^~~~~~~~~~~~~~~~
test.rs:2:12: 2:28 note: candidate #16 is `core::ops::fn
    (A0: A0, A1: A1, A2: A2, A3: A3, A4: A4, A5: A5, A6: A6, A7: A7, A8: A8,
     A9: A9, A10: A10, A11: A11, A12: A12, A13: A13, A14: A14) -> Result.FnMut<(A0, A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14),
      Result>::call_mut`
test.rs:2     return { return () } ();
                     ^~~~~~~~~~~~~~~~
test.rs:2:12: 2:28 note: candidate #17 is `core::ops::fn
    (A0: A0, A1: A1, A2: A2, A3: A3, A4: A4, A5: A5, A6: A6, A7: A7, A8: A8,
     A9: A9, A10: A10, A11: A11, A12: A12, A13: A13, A14: A14, A15: A15)
    -> Result.FnMut<(A0, A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14, A15),
      Result>::call_mut`
test.rs:2     return { return () } ();
                     ^~~~~~~~~~~~~~~~
test.rs:2:12: 2:28 error: internal compiler error: &mut ! was a subtype of &mut fn() -> <generic #0> but now is not?
test.rs:2     return { return () } ();
                     ^~~~~~~~~~~~~~~~
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/bkoropoff/Source/rust/src/libsyntax/ast_util.rs:784

stack backtrace:
   1:     0x7fc590d8a890 - rt::backtrace::imp::write::hfc9a3eeca6becfa7J7p
   2:     0x7fc590d8db90 - failure::on_fail::h207b145abcb1be86Ysq
   3:     0x7fc591553c00 - unwind::begin_unwind_inner::h31ee34186ed144ecVTd
   4:     0x7fc58d608660 - unwind::begin_unwind::h3182066330090709700
   5:     0x7fc58d6085a0 - diagnostic::SpanHandler::span_bug::hec3e0cc32b293820p0C
   6:     0x7fc591ad5fd0 - driver::session::Session::span_bug::h2dbacbf3b5f10a225Qx
   7:     0x7fc591ed7670 - middle::typeck::check::method::LookupContext<'a>::bug::h822098f00e352717wzQ
   8:     0x7fc591ed7700 - middle::typeck::check::method::LookupContext<'a>::consider_candidates::h8005a88e5d219fe40GP
   9:     0x7fc591ed5280 - middle::typeck::check::method::LookupContext<'a>::search_for_method::h24a51267e373f9fcqBP
  10:     0x7fc591ed6930 - middle::typeck::check::method::LookupContext<'a>::search_for_some_kind_of_autorefd_method::hf1b4e5205b429638PuP
  11:     0x7fc591ed0090 - middle::typeck::check::method::LookupContext<'a>::search_for_autoptrd_method::ha1d862fd7dee0298tsP
  12:     0x7fc591ecef90 - middle::typeck::check::method::LookupContext<'a>::search_step::h6a067abc559e1565sBO
  13:     0x7fc591ecc3d0 - middle::typeck::check::method::LookupContext<'a>::search::he4b843362403cf7aVzO
  14:     0x7fc591ecd420 - middle::typeck::check::method::lookup_in_trait::h2dd16f8b92589564hpO
  15:     0x7fc591f20f00 - middle::typeck::check::check_expr_with_unifier::h490595390fe04f852IT
  16:     0x7fc591f20f00 - middle::typeck::check::check_expr_with_unifier::h490595390fe04f852IT
  17:     0x7fc591f829a0 - middle::typeck::check::check_stmt::h8f0b5746e66a5c3eKMV
  18:     0x7fc591eea5d0 - middle::typeck::check::check_block_with_expected::h798e07ed4f900ecaVQV
  19:     0x7fc591ee6030 - middle::typeck::check::check_fn::h136863052baa3867IZQ
  20:     0x7fc591ee5d50 - middle::typeck::check::check_bare_fn::h855041f1bc5c3416jPQ
  21:     0x7fc591eded00 - middle::typeck::check::check_item::h3372d8c113cb6225WnR
  22:     0x7fc591ee5b50 - middle::typeck::check::check_item_types::hace6547f392b091dBOQ
  23:     0x7fc59190f7a0 - util::common::time::h9504726944636004855
  24:     0x7fc592100160 - middle::typeck::check_crate::h67c61b23653b9589Kci
  25:     0x7fc5921d4c90 - driver::driver::phase_3_run_analysis_passes::h8152f29332f19308iJw
  26:     0x7fc5921cfbb0 - driver::driver::compile_input::hfe9d9d96ad380951Xuw
  27:     0x7fc59227ea30 - driver::run_compiler::h4cedc40f963c25efSEz
  28:     0x7fc59227e940 - driver::main_args::closure.$x22closure$x22$LP$138592$RP$
  29:     0x7fc592291d50 - task::TaskBuilder<S>::try_future::closure.$x22closure$x22$LP$139736$RP$
  30:     0x7fc592291b30 - task::TaskBuilder<S>::spawn_internal::closure.$x22closure$x22$LP$139713$RP$
  31:     0x7fc592c7a1b0 - task::spawn_opts::closure.$x22closure$x22$LP$8216$RP$
  32:     0x7fc5915aada0 - rust_try
  33:     0x7fc591550ee0 - unwind::try::h8ff3ad5ffa6101160Hd
  34:     0x7fc591550c40 - task::Task::run::h7ab33a0b74628f4aQSc
  35:     0x7fc592c79fa0 - task::spawn_opts::closure.$x22closure$x22$LP$8162$RP$
  36:     0x7fc591552cb0 - thread::thread_start::hd9ff33059d311002Ufd
  37:     0x7fc59082ee70 - start_thread
  38:     0x7fc591222db9 - clone
  39:                0x0 - <unknown>

[emberian]

@pcwalton looks like there's some weirdness with overloaded call and bottom.

[bkoropoff]

Program can be simplified further. Basically anything that tries to call bottom will blow up:

fn main() {
    (return ())();
}

[huonw]

This is broken with normal methods and field accesses too, so I guess it's not necessarily due to overloaded calls specifically:

• fn main() { return.x }
• fn main() { return.x() }

[bkoropoff]

Updated title to better reflect issue

[huonw]

This is very similar to #13847.