GNU bug report logs - #30226
Fixing it->pixel_width / it->current_x when tabs and line numbers.

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Package: emacs;

Reported by: Keith David Bershatsky <esq <at> lawlist.com>

Date: Tue, 23 Jan 2018 07:33:02 UTC

Severity: minor

Tags: wontfix

Done: Stefan Kangas <stefankangas <at> gmail.com>

Bug is archived. No further changes may be made.

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From: Keith David Bershatsky <esq <at> lawlist.com>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 30226 <at> debbugs.gnu.org
Subject: bug#30226: Fixing it->pixel_width / it->current_x when tabs and line numbers.
Date: Sun, 18 Feb 2018 18:17:26 -0800

A major break-through in the tracing of bug 30226 ....  it->current_x differs between the real thing (when display_line calls PRODUCE_GLYPHS), versus the simulation (when move_it_in_display_line_to calls PRODUCE_GLYPHS), _because_ maybe_produce_line_number advances it->current_x in the former but _not_ the latter.

In the revised fact pattern described in Message #26 of this thread (i.e., TAB TAB Hello-world, and w->hscroll >= 2):

https://debbugs.gnu.org/cgi/bugreport.cgi?bug=30226#26

it->current_x stops at 7 when w->hscroll == 2.

In the simulation (move_it_in_display_line_to that does _not_ produce glyphs), it is impossible to reach an X of 35 because that would be in the middle of the STRETCH.  maybe_produce_line_number does _not_ advance it->current_x in the simulation.

In the real thing (display_line actually produces glyphs), maybe_produce_line_number advances it->current_x from 7 to 35.

SOLUTION (suggested):  Revise move_it_in_display_line_to advance X by simulating a call to maybe_produce_line_number and permitting that function to advance X.
This bug report was last modified 126 days ago.

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