display-buffer-same-window

display-buffer-same-window is a compiled Lisp function in `window.el'.

(display-buffer-same-window BUFFER ALIST)

Display BUFFER in the selected window.
This fails if ALIST has a non-nil `inhibit-same-window' entry, or
if the selected window is a minibuffer window or is dedicated to
another buffer; in that case, return nil. Otherwise, return the
selected window.