Without objection, I will add this to the Util/ directory in the
distribution.  It does require the named references patches and the
zsh/param/private module.

This script takes as arguments a name representing one of the sets of
bitflag (or similar) values that are #defined in Src/zsh.h, followed
by an integer or a pattern, and prints out the corresponding
definition if it can.  This has been really helpful for me when using
gdb to examine structures that contain bitflags.  I extended it beyond
the two or three that I regularly found myself using and tried to make
the output as useful as possible, i.e., to match the format used in
the #define.  For flags defined by bit-shifting it also displays the
integer value.

Example:

% Util/printdefines paramflags 50331648
50331648 PM_UNSET|PM_REMOVABLE
% Util/printdefines scanparamflags '*MATCH*'
SCANPM_MATCHKEY     1<<3        8
SCANPM_MATCHVAL     1<<4        16
SCANPM_MATCHMANY    1<<5        32
SCANPM_KEYMATCH     1<<7        128

If the only argument is a name, all the flags for that name are displayed.

% Util/printdefines lexflags
LEXFLAGS_ACTIVE          16#01
LEXFLAGS_ZLE             16#02
LEXFLAGS_COMMENTS_KEEP   16#04
LEXFLAGS_COMMENTS_STRIP  16#08
LEXFLAGS_NEWLINE         16#10

If the only argument is a pattern, every set of flags available is
searched for a match.

% Util/printdefines '(#i)S*G'
--- scanparamflags  ---
SCANPM_ASSIGNING    1<<6    64
SCANPM_CHECKING     1<<10    1024
--- chartokens  ---
String          85
--- substmodifiers  ---
SUB_LONG            16#2

(This doesn't work for numbers.)

With no arguments, displays a usage message including the names of all
the sets of #defines that can be used as the first argument.

Although I initially generated the tables mostly programmatically, I
haven't come up with any way to keep them up to date if zsh.h changes.

Bug reports welcome, I've used it for a while with some of the tables
but not all.