merge revision(s) d0ba4abf1a00339ebbb5d405db3240a8bdb7b68b,54eac83b2ad77ddea84fa6d66c09e0bb014cf61e: [Backport #15786]

	Add RB_ID_SERIAL_MAX


	Hide internal IDs

	* parse.y (internal_id): number the ID serial for internal use by
	  counting down from the neary maximum value, not to accidentally
	  match permanent IDs.

	[Bug #15768]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_6@67718 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 2 insertions, 1 deletions

diff --git a/parse.y b/parse.y
index 8e7dfecf0e..aa067f6fa3 100644
--- a/parse.y
+++ b/parse.y
@@ -10810,8 +10810,9 @@ rb_init_parse(void)
 static ID
 internal_id(struct parser_params *p)
 {
+    const ID max_id = RB_ID_SERIAL_MAX & ~0xffff;
     ID id = (ID)vtable_size(p->lvtbl->args) + (ID)vtable_size(p->lvtbl->vars);
-    id += ((tLAST_TOKEN - ID_INTERNAL) >> ID_SCOPE_SHIFT) + 1;
+    id = max_id - id;
     return ID_STATIC_SYM | ID_INTERNAL | (id << ID_SCOPE_SHIFT);
 }