Generic Tuple-like Structs do not work cross-crate

[auroranockert]

First the crate testcrate.rs,

pub struct V2<T>(T, T);

then the actual test,

extern mod testcrate;

fn main() {
    let f = testcrate::V2(1.0f32, 2.0f32);
}

This gives the unexpected error,

test-run.rs:4:26: 4:32 error: mismatched types: expected `BUG[0]` but found `f32` (expected type parameter but found f32)
test-run.rs:4     let f = testcrate::V2(1.0f32, 2.0f32);
                                        ^~~~~~
test-run.rs:4:34: 4:40 error: mismatched types: expected `BUG[0]` but found `f32` (expected type parameter but found f32)
test-run.rs:4     let f = testcrate::V2(1.0f32, 2.0f32);
                                                ^~~~~~
error: aborting due to 2 previous errors
rust: task failed at 'explicit failure', /Users/Jens/Code/Git/rust/src/libsyntax/diagnostic.rs:96
rust: task failed at 'explicit failure', /Users/Jens/Code/Git/rust/src/librustc/rustc.rs:360
rust: domain main @0x7fd292008410 root task failed

[auroranockert]

@graydon: Just so you know what's going on with SIMD shuffles, I tried, but implementing it with #[lang=…] and generics is blocked bug.

[huonw]

Part of #7435, presumably.

Nominating for feature complete.

[SimonSapin]

I got bitten by this.

If fixing it is not easy, it would be good to at least have a less cryptic error message. Switching to structs with fields is easy enough… once you know that tuple-like structs are the problem. It took me a while to figure out.

[catamorphism]

Accepted for production-ready

[pnkfelix]

(should we try to improve the error message sooner than "production-ready" ... probably worth considering ....)

[alexcrichton]

@blake2-ppc has noticed that this has been fixed, flagging as needstest.

[alexcrichton]

false alarm

[pzol]

Visiting for triage.

Works. Would suggest to close it.
test performed:

testcrate.rs:

pub struct V2<T>(T, T);

rustc --crate-type lib testcrate.rs

main.rs:

extern crate testcrate;

fn main() {
    let f = testcrate::V2(1.0f32, 2.0f32);
}

rustc -L . main.rs

[sfackler]

Flagging as needstest