Add support for crt-static

[Dirreke]

This pull request updates the build script to select the appropriate MSVC runtime library based on whether the crt-static target feature is enabled. This ensures that the correct runtime linkage is used for static or dynamic CRT builds.

[lovasoa]

Hello and thank you for the pr ! Could you give me some context about what this does?

Is it meant to add support for building static executables on windows? If so, then could you also add this to the ci matrix, so that static windows binaries are tested and this does not regress in the future?

[Dirreke]

Hi, thank you for the review.

Rust exposes crt-static as a target feature, and on MSVC this affects whether native code should be built against the static or dynamic C runtime. In build scripts, this is available through CARGO_CFG_TARGET_FEATURE, which is what this patch checks. When crt-static is enabled, the native side should use MultiThreaded (/MT); otherwise it should use MultiThreadedDLL (/MD).

So this change is mainly about keeping the Rust side and the CMake-built native library consistent, and avoiding CRT mismatch during linking.

This patch simply makes that choice explicit:

• with crt-static: CMAKE_MSVC_RUNTIME_LIBRARY=MultiThreaded
• without it: CMAKE_MSVC_RUNTIME_LIBRARY=MultiThreadedDLL or I can remove it to keep default value.

As for CI, I’d prefer to keep this PR scoped to the runtime-selection fix itself for now. Since this change mainly aligns the native build with Rust’s existing target configuration, I’m not sure adding a dedicated CI entry is necessary at this stage. But if you insist, I'm good to add.

[lovasoa]

Understood !

For reading the feature, is crt-static special in some way, or can we read it like all other features in the build script ?

Could we simplify this to

 .define("CMAKE_MSVC_RUNTIME_LIBRARY", if cfg!(feature = "crt-static") { "MultiThreaded" } else { "MultiThreadedDLL" })