From 24e550570554b3ae89d9621d6602fd3f993a7d29 Mon Sep 17 00:00:00 2001
From: Juri Linkov <juri@linkov.net>
Date: Wed, 10 Dec 2025 19:37:33 +0200
Subject: [PATCH] Evaluate result on first call to throttled func in timeout.el

* lisp/emacs-lisp/timeout.el (timeout--throttle-advice)
(timeout-throttled-func): Replace 'prog1' with 'progn'
to return the evaluated value of 'result' (bug#79979).
This will capture the correct return value the first time
a throttled function is called.  Previously, it would return nil
on the very first call.
(timeout-debounce, timeout-throttle, timeout-throttled-func)
(timeout-debounced-func): Add the autoload cookie.
---
 lisp/emacs-lisp/timeout.el | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/lisp/emacs-lisp/timeout.el b/lisp/emacs-lisp/timeout.el
index 2b90650f02a..7529d4bc0a4 100644
--- a/lisp/emacs-lisp/timeout.el
+++ b/lisp/emacs-lisp/timeout.el
@@ -82,7 +82,7 @@ This is intended for use as function advice."
         (result))
     (lambda (orig-fn &rest args)
       "Throttle calls to this function."
-      (prog1 result
+      (progn
         (unless (and throttle-timer (timerp throttle-timer))
           (setq result (apply orig-fn args))
           (setq throttle-timer
@@ -90,7 +90,8 @@ This is intended for use as function advice."
                  (timeout--eval-value timeout-value) nil
                  (lambda ()
                    (cancel-timer throttle-timer)
-                   (setq throttle-timer nil)))))))))
+                   (setq throttle-timer nil)))))
+        result))))
 
 (defun timeout--debounce-advice (&optional delay default)
   "Return a function that debounces its argument function.
@@ -122,6 +123,7 @@ This is intended for use as function advice."
                            (apply orig-fn args))))
                  (current-buffer))))))))
 
+;;;###autoload
 (defun timeout-debounce (func &optional delay default)
   "Debounce FUNC by making it run DELAY seconds after it is called.
 
@@ -143,6 +145,7 @@ returned."
                 '((name . debounce)
                   (depth . -99)))))
 
+;;;###autoload
 (defun timeout-throttle (func &optional throttle)
   "Make FUNC run no more frequently than once every THROTTLE seconds.
 
@@ -159,6 +162,7 @@ previous successful call is returned."
                 '((name . throttle)
                   (depth . -98)))))
 
+;;;###autoload
 (defun timeout-throttled-func (func &optional throttle)
   "Return a throttled version of function FUNC.
 
@@ -182,7 +186,7 @@ previous successful call is returned."
             "\n\nThrottle calls to this function"))
           (interactive (advice-eval-interactive-spec
                         (cadr (interactive-form func))))
-          (prog1 result
+          (progn
             (unless (and throttle-timer (timerp throttle-timer))
               (setq result (apply func args))
               (setq throttle-timer
@@ -190,14 +194,15 @@ previous successful call is returned."
                      (timeout--eval-value throttle-value) nil
                      (lambda ()
                        (cancel-timer throttle-timer)
-                       (setq throttle-timer nil)))))))
+                       (setq throttle-timer nil)))))
+            result))
       ;; NON-INTERACTIVE version
       (lambda (&rest args)
         (:documentation
          (concat
           (documentation func)
           "\n\nThrottle calls to this function"))
-        (prog1 result
+        (progn
           (unless (and throttle-timer (timerp throttle-timer))
             (setq result (apply func args))
             (setq throttle-timer
@@ -205,8 +210,10 @@ previous successful call is returned."
                    (timeout--eval-value throttle-value) nil
                    (lambda ()
                      (cancel-timer throttle-timer)
-                     (setq throttle-timer nil))))))))))
+                     (setq throttle-timer nil)))))
+          result)))))
 
+;;;###autoload
 (defun timeout-debounced-func (func &optional delay default)
   "Return a debounced version of function FUNC.