Help ! Frozen by a comment in gcc/c-common.h!

["Alexei I. Adamovich" <lexa at adam dot botik dot ru>]

Hi All!

While modifying the C lexer to accommodate it for experimental
C-derived language front-end, I've stumbled across the following
comment in gcc/c-common.h before the "enum rid" definition (still
there in gcc-4.5-20090820 snapshot):

42 /* Reserved identifiers.  This is the union of all the keywords for C,
43    C++, and Objective-C.  All the type modifiers have to be in one
44    block at the beginning, because they are used as mask bits.  There
45    are 27 type modifiers; if we add many more we will have to redesign
46    the mask mechanism.  */
47 
48 enum rid
49 {
50   /* Modifiers: */
51   /* C, in empirical order of frequency.  */
52   RID_STATIC = 0,
53   RID_UNSIGNED, RID_LONG,    RID_CONST, RID_EXTERN
...

Could you please enlighten me -- is the comment still relevant? If so,
where the usage of type modifiers entries in enum rid as mask bits can
be seen in gcc code (or documentation, if applicable)?

I'd like to be aware, since I've defined several (four) additional type
modifiers.

Thanks in advance,

Alexei I. Adamovich