choose-completion: Retain the suffix after completion boundary

* lisp/minibuffer.el (completion-base-suffix):
Remove as not optimal after all (bug#48356).
(completion--replace): Use insert-before-markers-and-inherit.
(minibuffer-completion-help): Don't set completion-base-affixes,
implement the same logic more optimally by local search and
querying for field boundaries.  Also fix the problem with
completion table, predicate and extra-props being looked up in the
wrong buffer.
(minibuffer-next-completion, minibuffer-choose-completion):
Don't bind completion-use-base-affixes anymore.

* lisp/simple.el (completion-base-affixes)
(completion-use-base-affixes): Remove.
(completion-list-insert-choice-function):
Don't pass them through anymore.

2 files changed, 42 insertions, 78 deletions

diff --git a/lisp/minibuffer.el b/lisp/minibuffer.el
index ad6a0928cda..61395577035 100644
--- a/lisp/minibuffer.el
+++ b/lisp/minibuffer.el
@@ -112,20 +112,6 @@ the closest directory separators."
     (cons (or (cadr boundaries) 0)
           (or (cddr boundaries) (length suffix)))))
 
-(defun completion-base-suffix (start end collection predicate)
-  "Return suffix of completion of buffer text between START and END.
-COLLECTION and PREDICATE are, respectively, the completion's
-completion table and predicate, as in `completion-boundaries' (which see).
-Value is a substring of buffer text between point and END.  It is
-the completion suffix that follows the completion boundary."
-  (let ((suffix (buffer-substring (point) end)))
-    (substring
-     suffix
-     (cdr (completion-boundaries (buffer-substring start (point))
-                                 collection
-                                 predicate
-                                 suffix)))))
-
 (defun completion-metadata (string table pred)
   "Return the metadata of elements to complete at the end of STRING.
 This metadata is an alist.  Currently understood keys are:
@@ -1377,7 +1363,7 @@ Moves point to the end of the new text."
       (setq newtext (substring newtext 0 (- suffix-len))))
     (goto-char beg)
     (let ((length (- end beg)))         ;Read `end' before we insert the text.
-      (insert-and-inherit newtext)
+      (insert-before-markers-and-inherit newtext)
       (delete-region (point) (+ (point) length)))
     (forward-char suffix-len)))
 
@@ -2598,17 +2584,23 @@ The candidate will still be chosen by `choose-completion' unless
              (base-size (or (cdr last) 0))
              (prefix (unless (zerop base-size) (substring string 0 base-size)))
              (minibuffer-completion-base (substring string 0 base-size))
-             (base-prefix (buffer-substring (minibuffer--completion-prompt-end)
-                                            (+ start base-size)))
-             (base-suffix (concat (completion-base-suffix start end
-                                                          minibuffer-completion-table
-                                                          minibuffer-completion-predicate)
-                                  (buffer-substring end (point-max))))
+             (ctable minibuffer-completion-table)
+             (cpred minibuffer-completion-predicate)
+             (cprops completion-extra-properties)
+             (field-end
+              (save-excursion
+                (forward-char
+                 (cdr (completion-boundaries (buffer-substring start (point))
+                                             ctable
+                                             cpred
+                                             (buffer-substring (point) end))))
+                (point-marker)))
+             (field-char (and (< field-end end) (char-after field-end)))
              (all-md (completion--metadata (buffer-substring-no-properties
                                             start (point))
                                            base-size md
-                                           minibuffer-completion-table
-                                           minibuffer-completion-predicate))
+                                           ctable
+                                           cpred))
              (ann-fun (completion-metadata-get all-md 'annotation-function))
              (aff-fun (completion-metadata-get all-md 'affixation-function))
              (sort-fun (completion-metadata-get all-md 'display-sort-function))
@@ -2687,38 +2679,31 @@ The candidate will still be chosen by `choose-completion' unless
 
                       (with-current-buffer standard-output
                         (setq-local completion-base-position
-                             (list (+ start base-size)
-                                   ;; FIXME: We should pay attention to completion
-                                   ;; boundaries here, but currently
-                                   ;; completion-all-completions does not give us the
-                                   ;; necessary information.
-                                   end))
-                        (setq-local completion-base-affixes
-                                    (list base-prefix base-suffix))
+                                    (list (+ start base-size) field-end))
                         (setq-local completion-list-insert-choice-function
-                             (let ((ctable minibuffer-completion-table)
-                                   (cpred minibuffer-completion-predicate)
-                                   (cprops completion-extra-properties))
                                (lambda (start end choice)
-                                 (if (and (stringp start) (stringp end))
-                                     (progn
-                                       (delete-minibuffer-contents)
-                                       (insert start choice)
-                                       ;; Keep point after completion before suffix
-                                       (save-excursion (insert
-                                                        (completion--merge-suffix
-                                                         choice
-                                                         (1- (length choice))
-                                                         end))))
-                                   (unless (or (zerop (length prefix))
-                                               (equal prefix
-                                                      (buffer-substring-no-properties
-                                                       (max (point-min)
-                                                            (- start (length prefix)))
-                                                       start)))
-                                     (message "*Completions* out of date"))
-                                   ;; FIXME: Use `md' to do quoting&terminator here.
-                                   (completion--replace start end choice))
+                                 (unless (or (zerop (length prefix))
+                                             (equal prefix
+                                                    (buffer-substring-no-properties
+                                                     (max (point-min)
+                                                          (- start (length prefix)))
+                                                     start)))
+                                   (message "*Completions* out of date"))
+                                 (when (> (point) end)
+                                   ;; Completion suffix has changed, have to adapt.
+                                   (setq end (+ end
+                                                (cdr (completion-boundaries
+                                                      (concat prefix choice) ctable cpred
+                                                      (buffer-substring end (point))))))
+                                   ;; Stopped before some field boundary.
+                                   (when (> (point) end)
+                                     (setq field-char (char-after end))))
+                                 (when (and field-char
+                                            (= (aref choice (1- (length choice)))
+                                               field-char))
+                                   (setq end (1+ end)))
+                                 ;; FIXME: Use `md' to do quoting&terminator here.
+                                 (completion--replace start end choice)
                                  (let* ((minibuffer-completion-table ctable)
                                         (minibuffer-completion-predicate cpred)
                                         (completion-extra-properties cprops)
@@ -2729,7 +2714,7 @@ The candidate will still be chosen by `choose-completion' unless
                                    ;; completion is not finished.
                                    (completion--done result
                                                      (if (eq (car bounds) (length result))
-                                                         'exact 'finished)))))))
+                                                         'exact 'finished))))))
 
                       (display-completion-list completions nil group-fun)))))
           nil)))
@@ -4877,8 +4862,7 @@ insert the selected completion candidate to the minibuffer."
           (next-line-completion (or n 1))
         (next-completion (or n 1)))
       (when auto-choose
-        (let ((completion-use-base-affixes t)
-              (completion-auto-deselect nil))
+        (let ((completion-auto-deselect nil))
           (choose-completion nil t t))))))
 
 (defun minibuffer-previous-completion (&optional n)
@@ -4916,8 +4900,7 @@ If NO-QUIT is non-nil, insert the completion candidate at point to the
 minibuffer, but don't quit the completions window."
   (interactive "P")
   (with-minibuffer-completions-window
-    (let ((completion-use-base-affixes t))
-      (choose-completion nil no-exit no-quit))))
+    (choose-completion nil no-exit no-quit)))
 
 (defun minibuffer-choose-completion-or-exit (&optional no-exit no-quit)
   "Choose the completion from the minibuffer or exit the minibuffer.
diff --git a/lisp/simple.el b/lisp/simple.el
index a459f6ecfd2..deab52c4201 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -9858,16 +9858,6 @@ Its value is a list of the form (START END) where START is the place
 where the completion should be inserted and END (if non-nil) is the end
 of the text to replace.  If END is nil, point is used instead.")
 
-(defvar completion-base-affixes nil
-  "Base context of the text corresponding to the shown completions.
-This variable is used in the *Completions* buffer.
-Its value is a list of the form (PREFIX SUFFIX) where PREFIX is the text
-before the place where completion should be inserted, and SUFFIX is the text
-after the completion.")
-
-(defvar completion-use-base-affixes nil
-  "Non-nil means to restore original prefix and suffix in the minibuffer.")
-
 (defvar completion-list-insert-choice-function #'completion--replace
   "Function to use to insert the text chosen in *Completions*.
 Called with three arguments (BEG END TEXT), it should replace the text
@@ -10128,7 +10118,6 @@ minibuffer, but don't quit the completions window."
   (with-current-buffer (window-buffer (posn-window (event-start event)))
     (let ((buffer completion-reference-buffer)
           (base-position completion-base-position)
-          (base-affixes completion-base-affixes)
           (insert-function completion-list-insert-choice-function)
           (completion-no-auto-exit (if no-exit t completion-no-auto-exit))
           (choice
@@ -10161,13 +10150,7 @@ minibuffer, but don't quit the completions window."
       (with-current-buffer buffer
         (choose-completion-string
          choice buffer
-         ;; Don't allow affixes to replace the whole buffer when not
-         ;; in the minibuffer.  Thus check for `completion-in-region-mode'
-         ;; to ignore non-nil value of `completion-use-base-affixes' set by
-         ;; `minibuffer-choose-completion'.
-         (or (and (not completion-in-region-mode)
-                  completion-use-base-affixes base-affixes)
-             base-position
+         (or base-position
              ;; If all else fails, just guess.
              (list (choose-completion-guess-base-position choice)))
          insert-function)))))
@@ -10323,11 +10306,9 @@ Called from `temp-buffer-show-hook'."
                 (buffer-substring (minibuffer-prompt-end) (point)))))))
     (with-current-buffer standard-output
       (let ((base-position completion-base-position)
-            (base-affixes completion-base-affixes)
             (insert-fun completion-list-insert-choice-function))
         (completion-list-mode)
         (setq-local completion-base-position base-position)
-        (setq-local completion-base-affixes base-affixes)
         (setq-local completion-list-insert-choice-function insert-fun))
       (setq-local completion-reference-buffer mainbuf)
       (if base-dir (setq default-directory base-dir))