Linking error when using a public inherent method on a value of an unnameable type in an external crate.

[jseyfried]

For example, consider a crate demo:

pub fn f() -> foo::Bar { foo::Bar }

mod foo {
    pub struct Bar;
    impl Bar {
        pub fn baz(&self) {}
    }
}

and another crate that uses demo:

extern crate demo;

fn main() {
    demo::f().baz();
}

Here, demo::foo::Bar is unnameable in the other crate.
Compiling the other crate will cause an error:

error: linking with `cc` failed: exit code: 1
note: /home/ubuntu/demo/target/debug/examples/example.0.o: In function `example::main':
/home/ubuntu/demo/examples/example.rs:4: undefined reference to `foo::Bar::baz::h2fcc0e6532120868paa'
collect2: error: ld returned 1 exit status

[petrochenkov]

Duplicate of #16734

[jseyfried]

Thanks