I've just found out a way to add "peek definition" functionality to Emacs by installing rtags. I installed rtags through Emacs, and everything seemed to go fine. However, I've run into some trouble: the basic command of rtags-start-process-unless-running to start rtags isn't working. If I try to run it in the minibuffer it just says No catch for tag: --cl-block-nil--, t

I'm using Linux (Arch), if that has any bearing on the problem. I'm just not sure what I should be looking for with an error like this, because I know very little about Lisp. Any guidance would be much appreciated. Here is the backtrace (Sorry if I'm missing something obvious, but this is one of the first times I've even seen the backtrace to Lisp).

Debugger entered--Lisp error: (no-catch --cl-block-nil-- t)
  throw(--cl-block-nil-- t)
  eval((rtags-start-process-unless-running) nil)
  funcall-interactively(eval-last-sexp nil)
  call-interactively(eval-last-sexp nil nil)
  • 1
    Looks like a bug in rtags, so I'd recommend you file a bug report with the authors.
    – Stefan
    Commented Apr 29, 2020 at 4:24
  • @Stefan Okay thanks! It looks to be the case. I posted a bug report. Commented Apr 29, 2020 at 5:12

1 Answer 1


Looks like its just a bug in RTags (at least when installed through Emacs). The package I had the problem with was installed from melpa-stable, and was Rtags 2.38. I tried installing a version 20200221.38 from melpa instead, and it seems to work now.

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