Understood, here is the recipe.
1. Install hydra from GNU Elpa in emacs -Q.
2. Evaluate the below
(defhydra hydra-test (:color teal
:columns 7)
"Test Hydra"
("<SPC>" (message "Pressed space") "Space")
("<s-SPC>" (message "Pressed super space") "Super Space")
("q" (message "Pressed q") "q")
("r" (message "Pressed r") "r")
("s" (message "Pressed s") "s")
("t" (message "Pressed t") "t")
("u" (message "Pressed u") "u")
("v" (message "Pressed v") "v")
("w" (message "Pressed w") "w")
("x" (message "Pressed x") "x")
("y" (message "Pressed y") "y")
("z" (message "Pressed z") "z")
("A" (message "Pressed A") "A")
("B" (message "Pressed B") "B")
("C" (message "Pressed C") "C")
("D" (message "Pressed D") "D")
("E" (message "Pressed E") "E")
("F" (message "Pressed F") "F")
("G" (message "Pressed G") "G")
("H" (message "Pressed H") "H")
("I" (message "Pressed I") "I")
("J" (message "Pressed J") "J")
("K" (message "Pressed K") "K")
("L" (message "Pressed L") "L")
("M" (message "Pressed M") "M")
("N" (message "Pressed N") "N")
("O" (message "Pressed O") "O")
("P" (message "Pressed P") "P")
("Q" (message "Pressed Q") "Q")
("R" (message "Pressed R") "R")
("S" (message "Pressed S") "S")
("T" (message "Pressed T") "T")
("U" (message "Pressed U") "U")
("V" (message "Pressed V") "V")
("W" (message "Pressed W") "W")
("X" (message "Pressed X") "X")
("Y" (message "Pressed Y") "Y")
("Z" (message "Pressed Z") "Z")
("C-g" nil "cancel" :color blue))
(global-set-key (kbd "C-c l") #'hydra-test/body)
3. Press "C-c l"
I cannot quite place what's special about the above test hydra, but once you press C-c l, you will see:
and the hydra will be unresponsive.. you won't be able to exist that Hydra window at the bottom (of course, you can kill it.. but the hydra won't be possible to quit any more).
I have copied Oleh so that he can provide more insight into how this format commit affects hydra, and what that "binding stack not balanced" error means.
- I do not get this error if I reduce the number of elements/heads of that test hydra.
- I do not get this error if I remove the head with "<s-SPC>" binding: ("<s-SPC>" (message "Pressed super space") "Super Space")
I arrive to above test hydra only by trial.
Another issue caused by the format speed-up commit, that I cannot recreate in a recipe is that once emacs started up with my config, I would see the echo area 3-line tall, which is odd, and I've never seen.
Sure. I just thought this commit was too experimental, as it made my emacs session 100% unusable, and rebuilding was my only option.