LLVM Segmentation fault - destructuring newtype with closure

[pfalabella]

this code:

struct GradFn<F: Fn() -> uint>(F);

fn main() {
    let GradFn(x_squared) : GradFn<_> = GradFn(|| -> uint { 2u });
    let _  = x_squared();
}

ICEs with:

Global is external, but doesn't have external or weak linkage!
i64 (%closure*)* @_ZN4main19unboxed_closure.944E
invalid linkage type for function declaration
i64 (%closure*)* @_ZN4main19unboxed_closure.944E
LLVM ERROR: Broken module found, compilation aborted!
Segmentation fault

$ rustc --version --verbose
rustc 0.13.0-nightly (34d680009 2014-12-22 00:12:47 +0000)
binary: rustc
commit-hash: 34d680009205de2302b902d8f9f5f7ae7a042f1a
commit-date: 2014-12-22 00:12:47 +0000
host: x86_64-pc-windows-gnu
release: 0.13.0-nightly

[pfalabella]

I thought this was due to what @japaric says in this comment, but it's not.
Even changing the declaration of the closure to use |&: |, to make sure the compiler sees it as an unboxed closure, like this:

#![feature(unboxed_closures)]
struct GradFn<F: Fn() -> uint>(F);

fn main() {
    let g = GradFn(|&:| 2u);
    let GradFn(f) = g; // LLVM error
    println!("{}", f.call(()));
}

I get the same LLVM error.
Note that a struct with one named element, instead of the newtype, works as expected:

#![feature(unboxed_closures)]
struct GradFn<F: Fn() -> uint> {f: F} // just named the element

fn main() {
    let g = GradFn{f: |&:| 2u };
    let GradFn { f } = g; // destructuring instead of accessing the element by name
                                   // to keep code as similar as possible as the previous one 
    println!("{}", f.call(())); // compiles and prints 2   
}

[zslayton]

I'm running into this issue as well. As an additional data point, I wanted to mention that the destructuring appears to work fine if the closure that's supplied to the struct is declared in advance.

For example:

struct GradFn<F: Fn() -> usize>(F);

fn main() {
    let grad_fn = || -> usize { 2us };
    let GradFn(x_squared) : GradFn<_> = GradFn(grad_fn);
    let _  = x_squared();
}

Playpen

Version information:

$ rustc --version --verbose
rustc 1.0.0-nightly (74b874071 2015-02-08 00:24:03 +0000)
binary: rustc
commit-hash: 74b8740719c1b427f79b67d6bc51e9d448dd9c49
commit-date: 2015-02-08 00:24:03 +0000
host: x86_64-unknown-linux-gnu
release: 1.0.0-nightly

[pfalabella]

this is now working correctly for me (on c4fe7d6 2015-02-23)

[frewsxcv]

All of the codeblocks in this issue are working for me with 1.0 beta2. Can this be closed?