Code:
  (lambda ()
    (c-ts-mode)
    (setq-local indent-tabs-mode nil)
    (newline)
    (indent-for-tab-command))

Point-Char: |

Name: Indents inside #if preproc

=-=
static void
free_glyph_pool (struct glyph_pool *pool)
{
  if (pool)
    {
#if defined GLYPH_DEBUG|
#endif
    }
}
=-=
static void
free_glyph_pool (struct glyph_pool *pool)
{
  if (pool)
    {
#if defined GLYPH_DEBUG
      |
#endif
    }
}
=-=-=

Name: Indents to 0 if #if preproc at root

=-=
#if 0|
/* */
static void
=-=
#if 0
|
/* */
static void
=-=-=

Code:
  (lambda ()
    (c-ts-mode)
    (setq-local indent-tabs-mode nil)
    (setq-local c-ts-mode-indent-offset 2)
    (c-ts-mode-set-style 'gnu)
    (indent-region (point-min) (point-max)))

Name: Prev-Sibling When Prev-Sibling is Preproc

=-=
static void
free_glyph_pool (struct glyph_pool *pool)
{
  if (pool)
    {
#if defined GLYPH_DEBUG
      int c = 1;
#endif
      int check_this = 3;

#ifdef stuff
      int c = 1;
#elif defined stuff
      int e = 5;
#else
      int d = 11;
      int f = 11;
#endif
      int check_this = 3;
    }
}
=-=-=