Nightly rustc panic when compiling a simple no_std program about rust HOT 2 OPEN

Looks like cg_clif cc @bjorn3

from rust.

You are compiling for riscv64gc-unknown-none-elf. It looks like the target_lexicon crate doesn't know that the binary format for that target is ELF and instead returns that the binary format is unknown. This then results in cranelift-object returning an error that it doesn't know how to create object files for this binary format and in turn cg_clif panics as it didn't expect an error. @sunfishcode should target-lexicon return ELF as object file for all -none targets? That is already the default when the OS is not recognized and I don't think we have any targets with an object file format other than ELF except for the wasm, windows, apple, ibm and vxworks targets all of which aren't matched by the -none case anyway.

from rust.