Add function minibuffer-restore-windows (bug#45072)

* lisp/minibuffer.el (minibuffer-restore-windows): New function
that removes the completions buffer.  Add it to minibuffer-exit-hook.
* src/minibuf.c (read-minibuffer-restore-windows): Mention
minibuffer-restore-windows.

etc/NEWS

@@ -180,6 +180,8 @@ nor t.
 
 +++
 ** New user option 'read-minibuffer-restore-windows'.
+When customized to nil, it uses 'minibuffer-restore-windows' in
+'minibuffer-exit-hook' to remove only the *Completions* window.
 
 +++
 ** New system for displaying documentation for groups of functions.

lisp/minibuffer.el

@@ -2328,6 +2328,16 @@ variables.")
   (setq deactivate-mark nil)
   (throw 'exit nil))
 
+(defun minibuffer-restore-windows ()
+  "Restore some windows on exit from minibuffer.
+When `read-minibuffer-restore-windows' is nil, then this function
+added to `minibuffer-exit-hook' will remove at least the window
+with the *Completions* buffer."
+  (unless read-minibuffer-restore-windows
+    (minibuffer-hide-completions)))
+
+(add-hook 'minibuffer-exit-hook 'minibuffer-restore-windows)
+
 (defun minibuffer-quit-recursive-edit ()
   "Quit the command that requested this recursive edit without error.
 Like `abort-recursive-edit' without aborting keyboard macro

src/minibuf.c

@@ -2535,8 +2535,11 @@ instead. */);
 If this is non-nil (the default), reading input with the minibuffer will
 restore, on exit, the window configurations of the frame where the
 minibuffer was entered from and, if it is different, the frame that owns
-the associated minibuffer window.  If this is nil, no such restorations
-are done.  */);
+the associated minibuffer window.
+
+If this is nil, no such restorations are done.
+But still `minibuffer-restore-windows' in `minibuffer-exit-hook'
+will remove the window with the *Completions* buffer.  */);
   read_minibuffer_restore_windows = true;
 
   defsubr (&Sactive_minibuffer_window);