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_5@67758 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 4 insertions, 0 deletions

diff --git a/symbol.h b/symbol.h
index 1f0b139811..cc7f156997 100644
--- a/symbol.h
+++ b/symbol.h
@@ -53,6 +53,10 @@ id_type(ID id)
 }
 
 typedef uint32_t rb_id_serial_t;
+static const uint32_t RB_ID_SERIAL_MAX = /* 256M on LP32 */
+    UINT32_MAX >>
+    ((sizeof(ID)-sizeof(rb_id_serial_t))*CHAR_BIT < RUBY_ID_SCOPE_SHIFT ?
+     RUBY_ID_SCOPE_SHIFT : 0);
 
 static inline rb_id_serial_t
 rb_id_to_serial(ID id)