Re: Minimum bison and flex versions

Hi,

On 2022-09-02 15:08:01 -0400, Tom Lane wrote:
> As fodder for discussion, here's a scraping of the currently-tested
> versions. (This counts only animals running configure, ie not MSVC.
> Also, my query looked back a few months, so some recently-dead
> animals are still here.)

If we also count older branches, there's a few alive cases of old bison:

REL_10_STABLE | {2,4,1} | 2022-09-01 12:30:05 | {castoroides,frogmouth}
REL_10_STABLE | {2,4,2} | 2022-09-01 08:30:15 | {brolga}

All the other animals using bison < 3.0.2 are dead. There's two live animals
using 3.0.2:
HEAD | {3,0,2} | 2022-09-01 19:23:26 | {chipmunk,topminnow}

So it looks like we could trivialy go to 3.0 as the minimum. The number of
animals using some version of 3.0 is quite large:

chipmunk,topminnow,parula,perch,buri,cotinga,tern,elasmobranch,trilobite,urocryon,vulpes,avocet,wobbegong,ayu,batfish,cavefish,bichir,grison,hippopotamus,hornet,hoverfly,chimaera,jay,chub,clam,blossomcrown,lorikeet,mandrill,mantid,massasauga,cuon,curculio,demoiselle,quokka,rhinoceros,mussurana,dhole,butterflyfish,snakefly,spurfowl,sungazer,tadarida,bonito

So I don't think we could easily go to something newer.

There's nothing in 3.1-3.5 release notes [1] that looks particularly helpful
for us to require on a quick glance. 2.6 would be nice to have as noted
e.g. in
https://postgr.es/m/CAFBsxsEospoUX%3DQYkfC%3DWcJqNB%2BiZtBf%3DBaRwn-zbHa48X0NKQ%40mail.gmail.com
but as noted in Tom's followup, apple still ships 2.3.

2.3 is the last bison version using GPLv2, so it's unlikely that apple will
ever update. Given that I'm not sure how much we should feel beholden to
support that, given that we'll eventually have to bite the bullet.

For flex, the minimum after prariedog's demise seems to be 2.5.35, with a
decent population. Skimming the release notes [2] between 2.5.31 and 2.5.35
doesn't show anything particularly interesting. But given that we don't have
coverage and that 2.5.35 was released in 2008, it seems we could just update
our requirements so that we have test coverage?

Greetings,

Andres Freund

[1] https://savannah.gnu.org/news/?group_id=56
[2] https://github.com/westes/flex/blob/master/NEWS