bug#81537: 32.0.50; Fixing icomplete-in-buffer requiring users to advice-add

Version: 32.1

Juri Linkov [02/Aug  6:16pm +03] wrote:
>> We've discussed this before and Eshel and Juri suggested that the thing
>> to do is make icomplete-in-buffer a proper completion-in-region-function
>> value, instead of hanging off the default completion infrastructure as
>> it does now.
>
> Shouldn't the UI of icomplete-in-buffer be the same as the UI
> of icomplete in the minibuffer?  That is, only when the user
> types TAB, it should display the *Completions* buffer,
> either in the minibuffer or in the regular buffer.
> But otherwise on typing characters it should display inline
> candidates immediately, without requiring to type TAB,
> i.e. something like 'completion-preview-mode' already does.

I think I've figured out an implementation of this.
Installed and closing, thanks both.

--
diff --git a/lisp/minibuffer.el b/lisp/minibuffer.el
index 7ef6f1383ab..24156ded8b3 100644
--- a/lisp/minibuffer.el
+++ b/lisp/minibuffer.el
@@ -1581,6 +1581,9 @@ completion--in-boundaries-p
          (end (+ (length string) (cdr boundaries))))
     (>= start pos end)))
 
+(defun completion--icomplete-in-buffer-p ()
+  (eq (bound-and-true-p icomplete--in-region-buffer) (current-buffer)))
+
 (defun completion--do-completion (beg end &optional
                                       try-completion-function expect-exact)
   "Do the completion and return a summary of what happened.
@@ -1686,6 +1689,7 @@ completion--do-completion
               (minibuffer-force-complete beg end))
              ((or completed only-changed-boundaries)
               (cond
+               ((completion--icomplete-in-buffer-p)) ; Bug#81537.
                ((pcase completion-auto-help
                   ('visible (minibuffer--completions-visible))
                   ('always t))
@@ -1699,14 +1703,16 @@ completion--do-completion
                                           'exact 'unknown))))))
              ;; Show the completion table, if requested.
              ((not exact)
-	      (if (pcase completion-auto-help
-                    ('lazy (eq this-command last-command))
-                    (_ completion-auto-help))
+	      (if (if (or (eq completion-auto-help 'lazy)
+                          (completion--icomplete-in-buffer-p)) ; Bug#81537.
+                      (eq this-command last-command)
+                    completion-auto-help)
                   (minibuffer-completion-help beg end)
                 (completion--message "Next char not unique")))
              ;; If the last exact completion and this one were the same, it
              ;; means we've already given a "Complete, but not unique" message
-             ;; and the user's hit TAB again, so now we give him help.
+             ;; and the user's hit TAB again, so now we give him help
+             ;; (even if `completion--icomplete-in-buffer-p' is non-nil).
              (t
               (when (and (eq this-command last-command) completion-auto-help)
                 (minibuffer-completion-help beg end))
@@ -1774,12 +1780,18 @@ completion--in-region-1
    (t (prog1 (pcase (completion--do-completion beg end)
                (#b000 nil)
                (_     t))
-        (if (window-live-p minibuffer-scroll-window)
-            (and (eq completion-auto-select t)
-                 (eq t (frame-visible-p (window-frame minibuffer-scroll-window)))
-                 ;; When the completion list window was displayed, select it.
-                 (switch-to-completions))
-          (completion-in-region-mode -1))))))
+        ;; FIXME: This part of the fix for bug#81537 reintroduces
+        ;; bug#67001 for `icomplete-in-region' users.  It's not as bad
+        ;; for them because Icomplete users probably expect to have to
+        ;; C-g out of completion before using other bindings, but maybe
+        ;; we can still fix it.  --spwhitton
+        (unless (completion--icomplete-in-buffer-p)
+          (if (window-live-p minibuffer-scroll-window)
+              (and (eq completion-auto-select t)
+                   (eq t (frame-visible-p (window-frame minibuffer-scroll-window)))
+                   ;; When the completion list window was displayed, select it.
+                   (switch-to-completions))
+            (completion-in-region-mode -1)))))))
 
 (defun completion--cache-all-sorted-completions (beg end comps)
   (add-hook 'after-change-functions
-- 
Sean Whitton