I have a function that's broken until debugging: it returns nil which it shouldn't. After I flag it for debug and unflag it, it works correctly from then on.


  • What is that function? I have no explanation other than some obscure bug but we'll need details if that is the case.
    – NickD
    Commented Feb 3 at 15:41
  • Show your code, please.
    – Drew
    Commented Feb 3 at 17:17

1 Answer 1


Sorry guys, the answer was clear in hindsight: edebug also evals it so Emacs will run the function in interpreted mode, not in compiled mode.

That's the biggest reason it can behave different.

If you have the same problem, check if just using eval-defun has the same effect.

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