I use AUCTeX pretty heavily; in fact, it was one of the first things I ever used in Emacs, way before I learned any Elisp or did any serious (or less serious) programming. Some time ago I noticed that sometimes (and I’m not sure what triggers this, though I have some suspicions) the word
Compiling will stay in the modeline forever. It bugged me a bit, so I asked about it on the mailing list, and Oleh Krehel (of Ivy and Lispy fame) shared this simple solution:
compilation-in-progress nil). It’s not really a clean solution, but it works.