Linux -> Windows Cross Compilation broken

[abbec]

This change 198621c#diff-26e81435323b9d11b39a44aa6f5adf5b3d863e3b2b149d6c2777b925ca8694b9R53 seems to break cross-compilation from Linux. It seems the build script is run with the equivalent of cfg!(unix), not cfg!(windows).

[kennykerr]

Have you actually tried to build for Windows on Linux? I'm not sure that's ever worked. That would require libs for Windows that a Linux-based linker could use to resolve imports, not to mention a C++ compiler that can cross compile for Windows on Linux. Not saying that's not possible, but I'd be surprised if that worked before this change. Also, I would imagine this problem would eventually go away once DLL imports are implemented.

[kennykerr]

Anyway, I deal with the issue of the build script not necessarily using the target compiler by checking the CARGO_CFG_TARGET_ARCH environment variable when copying architecture-specific dependencies. We could in theory use the
CARGO_CFG_TARGET_OS environment variable in a similar way to identify the target OS if we end up supporting something like this, but I'm not sure that's going to be something we need to support.

[abbec]

Hmm what do you mean? We use a mingw cross compiler on Linux to build for Windows and that works fine (except for this crate). Using the winapi crate works but I thought I would give this one a try but if it is not supported for this crate then so be it :)

[kennykerr]

That works because the winapi crate generates its own lib files. The windows crate doesn't do that, but as we have folks working on DLL imports we will soon not need lib files at all. So yes, I'd love to support that scenario eventually.

[kennykerr]

I'll leave this open for now while noting that it is blocked on rust-lang/rust#58713.

[abbec]

Cool, thanks! :)