Overhaul annotation-function to match affixation-functionscratch/annotation-function-improvements

* doc/lispref/minibuf.texi (Programmed Completion): Rework
annotation-function and affixation-function.

* lisp/help-fns.el (help--symbol-completion-table-annotation): Rename
from help--symbol-completion-table-affixation.
(help--symbol-completion-table): Use
help--symbol-completion-table-annotation.

* lisp/minibuffer.el (minibuffer-completion-help): Interpret
annotation-function with more sophistication.

* lisp/simple.el (read-extended-command): Use
read-extended-command--annotation
(read-extended-command--annotation): Rename from
read-extended-command--affixation

1 files changed, 14 insertions, 5 deletions

diff --git a/lisp/minibuffer.el b/lisp/minibuffer.el
index e04f1040b38..966613aa99c 100644
--- a/lisp/minibuffer.el
+++ b/lisp/minibuffer.el
@@ -2251,11 +2251,20 @@ variables.")
                               (funcall aff-fun completions)))
                        (ann-fun
                         (setq completions
-                              (mapcar (lambda (s)
-                                        (let ((ann (funcall ann-fun s)))
-                                          (if ann (list s ann) s)))
-                                      completions))))
-
+                              (mapcar
+                               (lambda (s)
+                                 (let* ((ann (funcall ann-fun s))
+                                        (prefix-hint
+                                         (and ann
+                                              (get-text-property 0 'prefix ann)))
+                                        (suffix-hint
+                                         (and ann
+                                              (get-text-property 0 'suffix ann))))
+                                   (cond (prefix-hint
+                                          (list s prefix-hint (or suffix-hint "")))
+                                         (ann (list s ann))
+                                         (t s))))
+                               completions))))
                       (with-current-buffer standard-output
                         (setq-local completion-base-position
                              (list (+ start base-size)