I still spend most of my day writing C and I doubt that is going to change any time soon. But that doesn’t mean you should have to!
Builder got a number of late arriving improvements around Rust support, so now would be a good time to go test them before the 40 release is out.
Yesterday I landed a long awaited feature that will find the common Flatpak SDK ancestors. This was needed to resolve the branch name for SDK extensions like org.freedesktop.Sdk.Extension.rust-stable. Your project might use org.gnome.Sdk//3.38 but the branch for rust-stable is 20.08 (coming from org.freedesktop.Sdk//20.08). Terribly annoying, but hey, now it’s fixed.
Furthermore, Builder can use rust-analyzer¹ as bundled by the org.freedesktop.Sdk.Extension.rust-stable SDK so that is one less thing you need to install or manage. It will pick up all the same dependencies as your project because it will run from within your projects build container. It will see everything your build system does, and in the same way.
Just create a new project using the “GNOME Application” template, select “Rust” as the language, and Run.
¹ rust-analyzer provides diagnostics, auto-completion, and more.