[Bug fortran/68227] ICE on using variable limit in forall header (gfc_do_allocate)

["dominiq at lps dot ens.fr" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68227

--- Comment #3 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
The ICE occurs at

      gcc_assert (INTEGER_CST_P (size));

I don't follow the logic of

gfc_do_allocate (tree bytesize, tree size, tree * pdata, stmtblock_t * pblock,
                 tree elem_type)
{
  tree tmpvar;
  tree type;
  tree tmp;

  if (INTEGER_CST_P (size))
    tmp = fold_build2_loc (input_location, MINUS_EXPR, gfc_array_index_type,
                           size, gfc_index_one_node);
  else
    tmp = NULL_TREE;

  type = build_range_type (gfc_array_index_type, gfc_index_zero_node, tmp);
  type = build_array_type (elem_type, type);
  if (gfc_can_put_var_on_stack (bytesize))
    {
      gcc_assert (INTEGER_CST_P (size));
      tmpvar = gfc_create_var (type, "temp");
      *pdata = NULL_TREE;
    }
  else
...

>From the first 'if' block, I understand that INTEGER_CST_P (size) can be NULL,
why the first branch in the second if block can be taken in this case?

May be related to pr55086.