linker error when returning (and using) a struct that is not exported

[mttnff]

I just came across a linker error, which should probably give an error during compilation instead. Minimal example:

lib.rs:

mod stuff {
    pub struct MyStruct(u8);

    //some very useful struct
    impl MyStruct {
        pub fn new() -> MyStruct { MyStruct(42) }
        pub fn get_data(self) -> u8 { self.0 }
    }
}

use stuff::MyStruct;

pub fn foo() -> MyStruct {
    MyStruct::new()
}

When adding a binary target bin/exe.rs like this:

extern crate crash;

fn main() {
    //linker error here
    let n = crash::foo().get_data();
    println!("Got: {}",n);
}

I get the following linker error on cargo build or cargo build --bin exe:

note: /.../crash/target/debug/exe.0.o: In function `exe::main':
/.../crash/src/bin/exe.rs:5: undefined reference to `stuff::_$LT$impl$GT$::get_data::hda4b62b5e3688f36taa'
collect2: error: ld returned 1 exit status

I am not familiar with the way rust handles modules, but I think this should indeed not work, so the compiler should probably give an error here.

Note that this compiles (and runs) fine if pub mod stuff is used instead of mod stuff, or if pub use stuff::MyStruct is used, which would make MyStruct accessible.

Compiler versions used:

rustc 1.6.0 (c30b771ad 2016-01-19)
rustc 1.8.0-nightly (3623797eb 2016-02-07)
cargo 0.7.0-nightly (1af03be 2015-12-08)

[sfackler]

This is definitely a bug, but you should be able to get things to work by using pub use stuff::MyStruct instead of use stuff::MyStruct.

[petrochenkov]

Duplicate of #16734

[mttnff]

Indeed, sorry for missing out on that.