Linking C library in Windows

[makarr]

I've been using the C API on Mac and Linux without issues but when I try to link on Windows I get "unresolved symbol" errors that seem to refer to Windows system libraries. With rustup==1.72.0 I get 32 errors, while with rustup==1.69.0 I get 29 errors, so maybe the problem lies on their end. I am making sure to set the RUSTFLAGS env variable following a previous issue.

Meanwhile I can build and run resvg.exe on Windows without any problems. Perplexing!

I setup a simple test repo here: https://github.com/makarr/resvg_lib_test

Even if the fault does not lie with resvg I would be thrilled if someone could explain how to get the C API to work on Windows.

[RazrFalcon]

Here are the Win libraries tools/viewsvg links:

-lWs2_32 -lAdvapi32 -lBcrypt -lUserenv -lNtdll

I do plan to write build instructions eventually: #564 But I'm not using Windows, so I'm not sure what happens in your case. I would assume you have to link Win libraries (for some reason) required by Rust std, because resvg by itself doesn't need any.

[makarr]

Steps to build resvg C library:

1. Install Rust on Windows 10. (Rust version 1.72.0)
2. git clone https://github.com/RazrFalcon/resvg.git
3. cd resvg/c-api
4. $ENV:RUSTFLAGS = "-lWs2_32 -lAdvapi32 -lBcrypt -lUserenv -lNtdll -C target-feature=+crt-static"
5. cargo build --release

Steps to reproduce issue:

1. Install CMake (>= 3.22) on Windows 10
2. git clone https://github.com/makarr/resvg_lib_test.git
3. Copy resvg\target\release\resvg.lib to resvg_lib_test\resvg
4. cd resvg_lib_test
5. cmake -S . -B build
6. cmake --build build

[RazrFalcon]

You have to link those libs to your executable, not to Rust/resvg. For some reason, afaiu, Rust doesn't propagate those library dependencies to the final binary. Maybe because of Windows, maybe because you use static linking. I don't know. I don't have Windows to test it.

You might want to ask about it in Rust/Cargo repos. This is not a resvg issue, but rather the way Rust builds C libraries on Windows. I don't think there is anything I can do on my side. At least I'm not aware of it.

PS: Passing libs to $ENV:RUSTFLAGS has no effect anyway.

[makarr]

You're 100% right. Fixed it by linking the Windows system libraries in CMake. Closing the issue.