I'm starting to really wish there was a GC-free (or at least) GC optional version of Nim. Nim with Rust's memory semantics would just be the best of everything.
As for optional GC, didn't D haven't something along those lines?
AFAIK, most libraries won't handle that situation gracefully as they don't expect it.
It just didn't work out mixing Frameworks compiled in different modes, many times leading to crashes.
For example:
proc printf(formatstr: cstring) {.header: "<stdio.h>", importc: "printf", varargs.}
I'd be interested in seeing a comparison of higher level language features rather than performance (which is generally a result of data structure choices, etc). Stuff like package managers, concurrency primitives, cross compiler support, memory management, and general syntax.