Re: Missing features in c-ts-mode

[Eli Zaretskii <eliz@gnu.org>]

> From: Theodor Thornhill <theo@thornhill.no>
> Cc: casouri@gmail.com, emacs-devel@gnu.org
> Date: Wed, 15 Feb 2023 20:18:32 +0100
> 
> >> Isn't M-a and M-e available on master?
> >
> > Maybe, I didn't look there, sorry.  If they work there, then this one
> > is fine.
> >
> 
> They should be there, but they may need tweaking.  Let me know if they
> behave unexpectedly.

Hmm... they behave...strangely.

Visit dispnew.c, turn on c-ts-mode, then go to line 174.  Type M-a and
watch in disbelief where it goes.  Same surprise if you type M-e.
Conclusion: preprocessor directives seem to drive this feature crazy.

OK, so let's find a place without cpp directives.  Go to line 368:

static void
adjust_glyph_matrix (struct window *w, struct glyph_matrix *matrix, int x, int y, struct dim dim)
{
  int i;
  int new_rows;
  bool marginal_areas_changed_p = 0;
  bool tab_line_changed_p = 0;  <<<<<<<<<<<<<<<<<<<<
  bool tab_line_p = 0;

Position point in the middle of the line and press M-a -- point goes
to the first non-blank character of the line: good.  Now type M-a
again -- point goes to the first non-blank character of the _previous_
line: why?

Now go to line 382:

  if (w)
    {
      window_box (w, ANY_AREA, 0, 0, &window_width, &window_height);

      tab_line_p = window_wants_tab_line (w);
      tab_line_changed_p = tab_line_p != matrix->tab_line_p; <<<<<<<<<<<<<<<

      header_line_p = window_wants_header_line (w);
      header_line_changed_p = header_line_p != matrix->header_line_p;
    }
  matrix->tab_line_p = tab_line_p;

Position point anywhere inside that line and press M-a -- point goes
to the "if" that encloses this block: why?  Moreover, if you go to the
first line _after_ the braces, the one which begins with "matrix->",
and press M-a, point still goes to that "if": why?

C-M-f also appears broken: I cannot get it to move from an opening
brace to the matching closing brace -- instead, it goes to the closing
parenthesis of some inner expression.  For example, try C-M-f here:

  else
    {
      /* If MATRIX->pool is null, MATRIX is responsible for managing
	 its own memory.  It is a window matrix for window-based redisplay.
	 Allocate glyph memory from the heap.  */
      if (dim.width > matrix->matrix_w
	  || new_rows
	  || tab_line_changed_p
	  || header_line_changed_p
	  || marginal_areas_changed_p)
	{
	  struct glyph_row *row = matrix->rows;

Place point at the opening brace after "else" and type "C-M-f" --
point goes to the closing paren after "marginal_areas_changed_p".

So this "needs work", I'd say ;-)