emacs-27 101a049: Improve doc string of 'tab-width'.

[Eli Zaretskii]

branch: emacs-27
commit 101a049f551b4013e54fdef0d87a74ec5dfd05e0
Author: Eli Zaretskii <eliz@gnu.org>
Commit: Eli Zaretskii <eliz@gnu.org>

    Improve doc string of 'tab-width'.
    
    * src/buffer.c (syms_of_buffer) <tab-width>: Clarify doc string.
    (Bug#48058)
---
 src/buffer.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/buffer.c b/src/buffer.c
index a60327b..60a4573 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -5639,9 +5639,12 @@ Linefeed indents to this column in Fundamental mode.  
*/);
   DEFVAR_PER_BUFFER ("tab-width", &BVAR (current_buffer, tab_width),
                     Qintegerp,
                     doc: /* Distance between tab stops (for display of tab 
characters), in columns.
-NOTE: This controls the display width of a TAB character, and not
-the size of an indentation step.
-This should be an integer greater than zero.  */);
+This controls the width of a TAB character on display.
+The value should be a positive integer.
+Note that this variable doesn't necessarily affect the size of the
+indentation step.  However, if the major mode's indentation facility
+inserts one or more TAB characters, this variable will affect the
+indentation step as well, even if `indent-tabs-mode' is non-nil.  */);
 
   DEFVAR_PER_BUFFER ("ctl-arrow", &BVAR (current_buffer, ctl_arrow), Qnil,
                     doc: /* Non-nil means display control chars with uparrow.