I was trying to build imgui-rs, to make a library that provides an interface between imgui and the 3DS system, to allow for easy creation of GUI applications, and i ran into a problem. (what little code i wrote is here)

imgui-rs, like many crates that wrap a C or C++ library, uses the cc crate to build the C dependency. The problem is that when the C dependency is being built, it targets the host system's architecture, because the CC, CXX and other standard environment variables aren't being overridden by cargo-3ds.

By manually setting the following environment variables, i was able to build the imgui-rs crate, the zstd crate and other C wrappers without any issues, linking or otherwise.

• CRATE_CC_NO_DEFAULTS=1 as documented here, to override the default build configuration (that would build for the host target).

• CXX=/opt/devkitpro/devkitARM/bin/arm-none-eabi-g++ (the path has to not be hardcoded, of course)

• CC=/opt/devkitpro/devkitARM/bin/arm-none-eabi-gcc (same thing here as before)

• All the variables in /opt/devkitpro/3dsvars.sh (same thing here with the path), as documented here

With all of these set, the crates build fine with no extra warnings or anything.