The gud.el library uses display-buffer incorrectly, by passing a list of
functions as its second argument, instead of as a nested list.
CORRECT:
(display-buffer buffer
'((display-buffer-reuse-window
display-buffer-in-previous-window
display-buffer-same-window display-buffer-pop-up-window)))
INCORRECT (how gud does it):
(display-buffer buffer
'(display-buffer-reuse-window
display-buffer-in-previous-window
display-buffer-same-window display-buffer-pop-up-window))
This causes "wrong-type-argument: listp
display-buffer-in-previous-window" error. However, it appears Emacs
handles malformed alists by just ignoring them, so Doom will do the
same.
Reported by @maskray
a406b2d0c8