Linking fails when only a lib's static variables are used and none of its functions are called.

[briansmith]

Program:

extern crate test_1_lib;

fn main() {
    // Uncomment this function call to make linking succeed:
    // test_1_lib::some_function();

    vec![0u8; test_1_lib::SOME_VALUE.some_member];
}

test_1_lib:

pub struct SomeType {
    pub some_member: usize,
}

pub static SOME_VALUE: SomeType = SomeType {
    some_member: 1,
};

pub fn some_function() { }

The full test case is available at https://github.com/briansmith/rust-bug-2.

To reproduce:

git clone https://github.com/briansmith/rust-bug-2
cd bin
cargo build

Linking fails with:

test_1_bin.0.o : error LNK2019: unresolved external symbol __imp__ZN10SOME_VALUE20hc1593d2370c9bbcfiaaE referenced in fu
nction _ZN4main20hf3c40dca13f06b85faaE
C:\<REDACTED>\test_1_bin.exe : fatal error LNK1120: 1 unresolved externals

Notice that the program only uses a static variable, and no functions, from the
library crate. If you uncomment the function call in
bin/src/test_1_bin.rs then linking succeeds.

Reproduced with (on x86_64-pc-windows-msvc):

• rustc 1.3.0 (9a92aaf 2015-09-15) / cargo 0.4.0-nightly (553b363 2015-08-03) (built 2015-08-03)
• rustc 1.4.0-nightly (fd302a9 2015-08-27) / cargo 0.5.0-nightly (53e51d5 2015-08-26)
• rustc 1.5.0-nightly (7beebbe 2015-10-22) / cargo 0.6.0-nightly (e1ed995 2015-10-22)

[wthrowe]

Appears to be Windows-specific. (Compiles successfully with 1.3.0 on 64bit Linux.)

[retep998]

Duplicate of #27438

[alexcrichton]

@briansmith when testing on beta/stable, are you sure you used the right compiler? This should have been fixed by #28646 which is present on both the beta/stable compilers, and I have verified myself that the x86_64-pc-windows-msvc beta/stable compilers work where the stable one does not. If it's still broken for you, though, that sounds like a problem!

[briansmith]

@briansmith when testing on beta/stable, are you sure you used the right compiler?

I guess you mean "beta/nightly" everywhere you wrote "beta/stable."

I did not test beta. I did test an old 1.4 nightly that failed. But, guess I did not properly test the current 1.5 nightly, because I just tried again and it succeeds. So, I think that this is fixed in Nightly 1.5 based on my testing. Again, I did not test the 1.4 beta.