Make number-at-point recognize some hex numbers

* lisp/thingatpt.el (number-at-point): Also return common hex
numbers (bug#37458).

etc/NEWS

@@ -1661,6 +1661,10 @@ backtrace with 'b'.
 A symbol 'uuid' can be passed to 'thing-at-point' and it returns the
 UUID at point.
 
+---
+*** 'number-at-point' will now recognize hex number like 0xAb09 and #xAb09
+and return them as numbers.
+
 ---
 *** 'word-at-point' and 'sentence-at-point' accept NO-PROPERTIES.
 Just like 'thing-at-point' itself.

lisp/thingatpt.el

@@ -632,10 +632,17 @@ Signal an error if the entire string was not used."
     (if thing (intern thing))))
 ;;;###autoload
 (defun number-at-point ()
-  "Return the number at point, or nil if none is found."
-  (when (thing-at-point-looking-at "-?[0-9]+\\.?[0-9]*" 500)
-    (string-to-number
-     (buffer-substring (match-beginning 0) (match-end 0)))))
+  "Return the number at point, or nil if none is found.
+Decimal numbers like \"14\" or \"-14.5\", as well as hex numbers
+like \"0xBEEF09\" or \"#xBEEF09\", are regognized."
+  (when (thing-at-point-looking-at
+         "\\(-?[0-9]+\\.?[0-9]*\\)\\|\\(0x\\|#x\\)\\([a-zA-Z0-9]+\\)" 500)
+    (if (match-beginning 1)
+        (string-to-number
+         (buffer-substring (match-beginning 1) (match-end 1)))
+      (string-to-number
+       (buffer-substring (match-beginning 3) (match-end 3))
+       16))))
 
 (put 'number 'thing-at-point 'number-at-point)
 ;;;###autoload