Add line_count field to rb_ast_body_t

This patch adds `int line_count` field to `rb_ast_body_t` structure.
Instead, we no longer cast `script_lines` to Fixnum.

## Background

Ref https://github.com/ruby/ruby/pull/10618

In the PR above, we have decoupled IMEMO from `rb_ast_t`.
This means we could lift the five-words-restriction of the structure
that forced us to unionize `rb_ast_t *` and `FIXNUM` in one field.

## Relating refactor

- Remove the second parameter of `rb_ruby_ast_new()` function

## Attention

I will remove a code that assigns -1 to line_count, in `rb_binding_add_dynavars()`
of vm.c, because I don't think it is necessary.
But I will make another PR for this so that we can atomically revert
in case I was wrong (See the comment on the code)

1 files changed, 11 insertions, 1 deletions

diff --git a/vm.c b/vm.c
index 4bd95034cc..e2813c9cc0 100644
--- a/vm.c
+++ b/vm.c
@@ -1480,7 +1480,17 @@ rb_binding_add_dynavars(VALUE bindval, rb_binding_t *bind, int dyncount, const I
     tmp_node.nd_body = 0;
     tmp_node.nd_args = 0;
 
-    VALUE vast = rb_ruby_ast_new(RNODE(&tmp_node), (rb_parser_ary_t *)INT2FIX(-1));
+    VALUE vast = rb_ruby_ast_new(RNODE(&tmp_node));
+    {   /*
+         * TODO:
+         * Assigning -1 to line_count is to maintain the previous code.
+         * However, the author of this patch guesses this code is no longer necessary.
+         * We will try to remove this code in the next commit which is atomically
+         * revertable if the author is wrong.
+         */
+        rb_ast_t *ast = (rb_ast_t *)DATA_PTR(vast);
+        ast->body.line_count = -1;
+    }
 
     if (base_iseq) {
         iseq = rb_iseq_new(vast, ISEQ_BODY(base_iseq)->location.label, path, realpath, base_iseq, ISEQ_TYPE_EVAL);