ICE with `impl FnOnce...` in argument position. Unexpected panic.

[thedodd]

ICE when using impl FnOnce... in argument position on 1.25.0-nightly 2018-01-24. Unexpected panic.

A quick note, the offending argument is of type: impl FnOnce(_) -> Box<_> (omitting the concrete types with _). That said, I'm not sure if universal_impl_trait actually explicitly supports impl Trait in argument position for the fn family at this point in time.

code sample that causes the bug

Working example:

#[derive(Clone, StateData, NewMiddleware)]
pub struct CoreServices {
    pub header_value: Arc<String>,
}

impl Middleware for CoreServices {
    fn call<Chain>(self, mut state: State, chain: Chain) -> Box<HandlerFuture>
        where Chain: FnOnce(State) -> Box<HandlerFuture>,
    {
        state.put(self);
        let f = chain(state).and_then(move |(state, mut response)| {
            let data = state.borrow::<CoreServices>();
            let headers = response.headers_mut();
            let header_val = (*data.header_value).clone();
            headers.set_raw(String::from("X-Super-Header"), header_val);
            future::ok((state, response))
        });
        Box::new(f)
    }
}

The code which breaks it:

#[derive(Clone, StateData, NewMiddleware)]
pub struct CoreServices {
    pub header_value: Arc<String>,
}

impl Middleware for CoreServices {
    fn call(self, mut state: State, chain: impl FnOnce(State) -> Box<HandlerFuture>) -> Box<HandlerFuture>
    {
        state.put(self);
        let f = chain(state).and_then(move |(state, mut response)| {
            let data = state.borrow::<CoreServices>();
            let headers = response.headers_mut();
            let header_val = (*data.header_value).clone();
            headers.set_raw(String::from("X-Super-Header"), header_val);
            future::ok((state, response))
        });
        Box::new(f)
    }
}

I expected the code to compile. I have the following nightly features enabled:

#![feature(
    conservative_impl_trait,
    generators,
    nll,
    proc_macro,
    universal_impl_trait,
    use_nested_groups,
)]

meta

rustc info:

$ rustc --version --verbose
rustc 1.25.0-nightly (a0dcecff9 2018-01-24)
binary: rustc
commit-hash: a0dcecff90c45ad5d4eb60859e22bb3f1b03842a
commit-date: 2018-01-24
host: x86_64-apple-darwin
release: 1.25.0-nightly
LLVM version: 4.0

Backtrace:

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

note: rustc 1.25.0-nightly (a0dcecff9 2018-01-24) running on x86_64-apple-darwin

note: run with `RUST_BACKTRACE=1` for a backtrace

thread 'rustc' panicked at 'called `Option::unwrap()` on a `None` value', libcore/option.rs:335:21
stack backtrace:
   0:        0x10ca43eab - std::sys::unix::backtrace::tracing::imp::unwind_backtrace::ha9efc95a1760cacd
   1:        0x10ca50044 - std::sys_common::backtrace::print::hf5c8aa5eb53db16a
   2:        0x10ca436e0 - std::panicking::default_hook::{{closure}}::hdce9608c60053b8f
   3:        0x10ca433e3 - std::panicking::default_hook::hba09553cc28730a2
   4:        0x10ca43b66 - std::panicking::rust_panic_with_hook::h3639511a0c7cb848
   5:        0x10ca439be - std::panicking::begin_panic::h0e3595e70a446052
   6:        0x10ca43913 - std::panicking::begin_panic_fmt::h94f1111cdb67ea95
   7:        0x10ca43882 - rust_begin_unwind
   8:        0x10cab9df3 - core::panicking::panic_fmt::h7800179476794181
   9:        0x10cab9ce6 - core::panicking::panic::h4f9b253c2f9854a3
  10:        0x109dfacf9 - rustc_typeck::check::compare_method::compare_impl_method::h257f59c3b52215a2
  11:        0x109d86fda - rustc_typeck::check::check_item_type::h969b3c82c24011db
  12:        0x109d0da8f - rustc::hir::Crate::visit_all_item_likes::h14dadb1787741be5
  13:        0x109ddd868 - rustc_typeck::check_crate::h6ea8f3ed64500660
  14:        0x106649aba - <std::thread::local::LocalKey<T>>::with::hc97c0f695fc47a37
  15:        0x1066471ec - <std::thread::local::LocalKey<T>>::with::h5232c8db13d095a5
  16:        0x1066753e3 - rustc_driver::driver::compile_input::h13c6388277ea77a3
  17:        0x10668617c - rustc_driver::run_compiler::hebc5d6e3e17d092c
  18:        0x1066042d1 - std::sys_common::backtrace::__rust_begin_short_backtrace::he16271a6bff11c29
  19:        0x10ca72fbe - __rust_maybe_catch_panic
  20:        0x1065b8ddd - <F as alloc::boxed::FnBox<A>>::call_box::h838126c6997c937c
  21:        0x10ca52a67 - std::sys_common::thread::start_thread::hee6a12d8ac7037fd
  22:        0x10ca5eda8 - std::sys::unix::thread::Thread::new::thread_start::hca6ddd0e0fdf932d
  23:     0x7fff6b51d6c0 - _pthread_body
  24:     0x7fff6b51d56c - _pthread_start

[estebank]

No longer an ICE.

[durka]

The code given in the original issue does not ICE on the version specified. But a bunch of supporting code is missing (like the implementations of those procedural macros). @thedodd can you complete the bug report?

[thedodd]

It’s long enough ago that I would be in favor of closing this issue. The code has evolved enough that it would be quite difficult for me to reproduce the issue.

I’ll close this issue if that is all the same with you all.