Re: gen_guc_tables improvements

On Sun, Mar 15, 2026 at 12:18:53PM +0000, Zsolt Parragi wrote:
> While reviewing a patch, I noticed a typo in guc_params.dat. The code
> compiled and seemingly worked, and I was very surprised that the
> generator script didn't catch the mistake.

Nice.

> I was also thinking about adding validations for the enum/define
> values (config group, flags, guc context), but that requires a
> somewhat fragile extraction code, and I decided to leave that out for
> now.

I'd say no on this one, which would mean going back-and-forth with the
input.  If these fail due to a compilation failure, it's not that bad
either, it would be easy to pin-point that the failures are related to
the values of the GUC, not the overall shape of the data in the input
file.  Saying that, it would depend on how much complexity this adds
and what kind of validation we'd get out of it.  If the additions to
the script are simple like the ones you are proposing here, that would
be probably OK if these improvements catch a bunch of ground-breaking
inconsistencies.  If the whole script would need to be refactored,
probably not.

> What do you think about these changes?

Such sanity checks can save from stupid mistakes, for new or even
seasoned developers of the tree.  When I worked on the wait event
parsing scripts or even the query jumbling for DDLs, I have noticed
that checking ahead the shape of the input files to make sure that
correct C code is produced may not catch all the mistakes, but
catching most of them is more productive than catching none of them.
The GUC script is new as of HEAD, so it seems more useful to do such
adjustments now.
--
Michael