-;;;###autoload
-(defun time-subtract (t1 t2)
- "Subtract two time values, T1 minus T2.
+;; These autoloads do nothing in Emacs 25, where the functions are builtin.
+;;;###autoload(autoload 'time-add "time-date")
+;;;###autoload(autoload 'time-subtract "time-date")
+;;;###autoload(autoload 'time-less-p "time-date")
+
+(eval-and-compile
+ (when (not (and (fboundp 'time-add) (subrp (symbol-function 'time-add))))
+
+ (defun time-add (t1 t2)
+ "Add two time values T1 and T2. One should represent a time difference."
+ (with-decoded-time-value ((high low micro pico type t1)
+ (high2 low2 micro2 pico2 type2 t2))
+ (setq high (+ high high2)
+ low (+ low low2)
+ micro (+ micro micro2)
+ pico (+ pico pico2)
+ type (max type type2))
+ (when (>= pico 1000000)
+ (setq micro (1+ micro)
+ pico (- pico 1000000)))
+ (when (>= micro 1000000)
+ (setq low (1+ low)
+ micro (- micro 1000000)))
+ (when (>= low 65536)
+ (setq high (1+ high)
+ low (- low 65536)))
+ (encode-time-value high low micro pico type)))
+
+ (defun time-subtract (t1 t2)
+ "Subtract two time values, T1 minus T2.