Fix TAB display when the line-number face uses a smaller/larger font

* src/dispextern.h (struct it): New member lnum_pixel_width.
* src/xdisp.c (maybe_produce_line_number): Compute the width of
the line-number display in pixels.
(x_produce_glyphs): Use it->lnum_pixel_width instead of a kludge
that used it->lnum_width and made assumptions about pixel width.

1 files changed, 3 insertions, 2 deletions

diff --git a/src/dispextern.h b/src/dispextern.h
index 08e5caa893b..84a27169ea1 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -2667,9 +2667,10 @@ struct it
   /* The byte position corresponding to lnum.  */
   ptrdiff_t lnum_bytepos;
 
-  /* The width in columns needed for display of the line numbers, or
-     zero if not computed.  */
+  /* The width, in columns and in pixels, needed for display of the
+     line numbers, or zero if not computed.  */
   int lnum_width;
+  int lnum_pixel_width;
 
   /* The line number of point's line, or zero if not computed yet.  */
   ptrdiff_t pt_lnum;