ICE with non-procedure type in 'do' expression

[KokaKiwi]

When I compile this:

type Cb<'self> = 'self |buf: &[u8]| -> bool;
// type Cb = proc(&[u8]) -> bool; // Works with this.

fn bug(cb: Cb) -> bool
{
    let arg = "hello";

    cb(arg.as_bytes())
}

fn main()
{
    do bug |s| {
        true
    };
}

Rust output this:

rustc -o bug bug.rs
bug.rs:12:7: 14:5 error: last argument in `do` call has non-procedure type: |&[u8]| -> bool
bug.rs:12     do bug |s| {
bug.rs:13         true
bug.rs:14     };
task 'rustc' failed at 'assertion failed: !ty::type_needs_infer(ty)', /build/rust-git/src/rust/src/librustc/middle/typeck/mod.rs:241
error: internal compiler error: unexpected failure
This message reflects a bug in the Rust compiler. 
We would appreciate a bug report: https://github.com/mozilla/rust/wiki/HOWTO-submit-a-Rust-bug-report
note: the compiler hit an unexpected failure path. this is a bug
note: try running with RUST_LOG=rustc=1 to get further details and report the results to github.com/mozilla/rust/issues
task '<main>' failed at 'explicit failure', /build/rust-git/src/rust/src/librustc/lib.rs:395
Makefile:6: recipe for target 'bug' failed
make: *** [bug] Error 101

This seems to me to be a lack of type checking, but I'm not sure.

PS: I'm using latest nightly Rust build from thestinger Arch repo.

[LeoTestard]

This is not a bug. The do form has changed, and is now only valid for proc functions.

I agree that the compiler should not fail on an ICE but instead display the error message and exit, but the new way to write this is:

bug(|x| {
    // ...
});

[KokaKiwi]

Yep I already know that, I posted this issue because of the ICE, not because the error message ;)
Even if the dev did a mistake, the compiler should not crash :)

[luqmana]

Closing this since the do-syntax is gone now.