I was trying to debug Rust in CLion when I was greeted with the aforementioned
I updated my toolchain setting to use the suggested default as such:
As well as Ömer Erden's answer it is worth pointing out that Jetbarins now has an article about how to configure Clion for Rust complete with some tips on what settings are applicable to Rust development.
Debugging Rust Code in CLion
Particularly this paragraph is relevant to the question:
On Windows, go to Settings | Build, Execution, Deployment | Toolchain and set either Cygwin or MinGW as your working environment. Then, run
rustup toolchain listand check the first line: it should be one of the gnu versions matching the bitness of the debugger. For example, if you’re working on MinGW (32-bit), the default toolchain should be i686-pc-windows-gnu. If you’re on MinGW64, it should be x86_64-pc-windows-gnu. You can set the appropriate toolchain by runningrustup default.