Re: Merging the underline attribute at EOL

[Eli Zaretskii <eliz@gnu.org>]

> Date: Mon, 16 Dec 2019 04:12:24 +0100
> From: Ergus <spacibba@aol.com>
> Cc: emacs-devel@gnu.org
> 
> I just saw your message. Actually the problem should be somewhere else a
> bit latter in the same function. Because in terminal your code underlies
> the entire line.

On a text terminal there's no problem because of this:

   if (FRAME_WINDOW_P (f)  <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
       && MATRIX_ROW_DISPLAYS_TEXT_P (it->glyph_row)
       && face->box == FACE_NO_BOX
       && FACE_COLOR_TO_PIXEL (face->background, f) == FRAME_BACKGROUND_PIXEL (f)
  #ifdef HAVE_WINDOW_SYSTEM
       && !face->stipple
  #endif
       && !it->glyph_row->reversed_p
       && !Vdisplay_fill_column_indicator)
     return;

IOW, if we are on a TTY frame, we never return early here, we always
continue to extending the face.

The problem with the early return is only on GUI frames.