Nim works quite well with GDB. I've tried it. It can generate metadata that GDB can use.

It's not perfect, but for my uses it has been alright (but then I'm ususally the kind of person who prefers to use debug printing and just studying the code)

Nim also shows very nice stack traces on uncaught exceptions so that also reduces the need to fire up GDB.

Simple example of GDB debugging: http://hookrace.net/blog/what-makes-nim-practical/#debugging...

An LLVM backend was recently announced. If that matures then the debugging issue will be simplified.