Add absolute optional parameter to line-number-at-pos (Bug#26417)

* lisp/simple.el (line-number-at-pos): Add a second optional
  argument 'absolute'.
* test/list/simple-tests.el: Add tests for 'line-number-at-pos'.

1 files changed, 18 insertions, 11 deletions

diff --git a/lisp/simple.el b/lisp/simple.el
index a5565ab6e73..1db14a859d6 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -1270,18 +1270,25 @@ and the greater of them is not at the start of a line."
 		done)))
 	(- (buffer-size) (forward-line (buffer-size)))))))
 
-(defun line-number-at-pos (&optional pos)
-  "Return (narrowed) buffer line number at position POS.
+(defun line-number-at-pos (&optional pos absolute)
+  "Return buffer line number at position POS.
 If POS is nil, use current buffer location.
-Counting starts at (point-min), so the value refers
-to the contents of the accessible portion of the buffer."
-  (let ((opoint (or pos (point))) start)
-    (save-excursion
-      (goto-char (point-min))
-      (setq start (point))
-      (goto-char opoint)
-      (forward-line 0)
-      (1+ (count-lines start (point))))))
+
+If ABSOLUTE is nil, the default, counting starts
+at (point-min), so the value refers to the contents of the
+accessible portion of the (potentially narrowed) buffer.  If
+ABSOLUTE is non-nil, ignore any narrowing and return the
+absolute line number."
+  (save-restriction
+    (when absolute
+      (widen))
+    (let ((opoint (or pos (point))) start)
+      (save-excursion
+        (goto-char (point-min))
+        (setq start (point))
+        (goto-char opoint)
+        (forward-line 0)
+        (1+ (count-lines start (point)))))))
 
 (defun what-cursor-position (&optional detail)
   "Print info on cursor position (on screen and within buffer).