Cross-compiling from Linux to Windows

[John-Nagle]

It almost works. But not quite.

Tried to build Rend3 on Linux with Windows target "i686-pc-windows-gnu". This fails because Tracy won't build.
Rust Tracy dev blames upstream C++ Tracy project and MinGW C++ environment. See

nagisa/rust_tracy_client#31

This isn't really a Rend3 problem. But perhaps Tracy inclusion in the project could be tied to a "tracy" feature gate.
I use this in my own code:

[features]
#   Feature "tracy" enables profiing with Tracy
tracy = ["tracy-client", "profiling/profile-with-tracy", "slscene/tracy"]

With a "tracy" feature gate I can better debug and report cross-compile problems.

When I compile my own application, with the "tracy" feature gate off, I get all the way to linking, and then fail.
The missing symbol needed is _Unwind_Resume, which is part of the C++ exception system.

This came up in some other Rust context at: rust-lang/rust#77394

This is probably a "need to install some library"/"missing dependency" problem. I'm using the current release Rust on Ubuntu 20.04 LTS, so in theory I'm current.

(I don't use Windows much and have only an old Windows 7 machine without MSVC.)

Attached entire compile.
crosscompilelinkfail.txt

[John-Nagle]

The _Unwind_Resume problem is known, but not fixed. It's not Rend3. See

rust-lang/rust#79489

[cwfitzgerald]

Tracy is already feature gated: https://github.com/BVE-Reborn/rend3/blob/trunk/examples/scene-viewer/Cargo.toml#L27-L28

Unfortunately I don't know much about cross compiling, I always use native builds through CI, so I'm not going to be much help here.

[John-Nagle]

Thanks. The undefined symbol isn't a Rend3 problem, anyway.

Where do I turn the feature off? It's apparently on by default if I just build "rend3" with its examples.

[John-Nagle]

Sorry, version problem. With the current Github Rend3, "tracy" is not loaded by default. So, past that problem.

[cwfitzgerald]

Great!

Going to close as the rest of this seems outside of rend3's jurisdiction

[John-Nagle]

It's not a Rend3 problem. Now that I have it working, though, here's what's required:

I've been able to run most of the Rend3 tests and my own application, cross-compiled from Linux to Windows and then run under Wine.

Notes:

• cargo build --target x86_64-pc-windows-gnu --examples --release

• Needs Wine 7.0 to run Rend3/WGPU. Wine 5.0, which ships with Ubuntu 20.04 LTS, has incompatibilities around GPU memory types, and WGPU startup can't find a supported GPU memory type.

• Needs these files copied to the executable directory for more complex Rend3 applications:

/usr/lib/gcc/x86_64-w64-mingw32/9.3-win32/libgcc_s_seh-1.dll
/usr/lib/gcc/x86_64-w64-mingw32/9.3-win32/libstdc++-6.dll

Rust is supposed to statically link the standard C++ libraries, but it doesn't for some C++ dependencies. Ref: Rust issue #67408

Sample output:

[John-Nagle]

Fixed dependency issue. I was still pulling in the deprecated "basis" package, which pulls in those DLLs. After revising my code to load the skybox without using "basis", the Windows executable ran under Wine 7.0 with no need to provide extra DLLs.

So Rend3 now cross-compiles nicely.

[cwfitzgerald]

Great to hear!