Unboxed closures ICE: Expected(expected EBML doc with tag EsEnumVid but found tag 27)

[carllerche]

This issue assumes the presence of PR #18144 (otherwise, it hits the issue resolved by the PR.

Reproducing requires building an rlib and then using the rlib:

foo.rs:

#![crate_type = "lib"]
#![feature(unboxed_closures)]

pub trait Foo<M: Send> : Send {
    fn receive(&mut self, msg: M);
}

pub struct Both<M, F> {
    m: M,
    f: F,
}

pub fn repro2<M: Send, F: Foo<M>>(both: Both<M, F>) {
    box move |:| {
        let Both { m, mut f } = both;
        f.receive(m);
    };
}

pub fn repro1<M: Send + Clone, F: Foo<M>>(foo: F, msg: M) {
    repro2(Both { m: msg, f: foo });
}

and using the lib:

extern crate foo;

use foo::Foo;

pub struct MyFoo;

impl Foo<&'static str> for MyFoo {
    fn receive(&mut self, msg: &'static str) {
        println!("hello: {}", msg);
    }
}

pub fn main() {
    foo::repro1(MyFoo, "Hello");
}

output:

$ rustc -L . ice.rs
error: internal compiler error: unexpected failure
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 'called `Result::unwrap()` on an `Err` value: Expected(expected EBML doc with tag EsEnumVid but found tag 27)', /Users/carllerche/Code/oss/rust/src/libcore/result.rs:789

[nikomatsakis]

clearly a metadata issue

[bkoropoff]

#16790 is also an unboxed closure metadata bug. I don't think there's been much cross-crate testing of the feature yet, so I expect there are a bunch of issues like this to shake out.

[nikomatsakis]

cc @bkoropoff

[nikomatsakis]

oops, sorry, github was being slow and I didn't see the comment.