On Tue, Oct 01, 2024 at 11:55:48AM -0700, Masahiko Sawada wrote: > On Mon, Sep 30, 2024 at 11:49 AM Noah Misch <n...@leadboat.com> wrote: > > This has initdb set the field to the current C implementation's signedness. > > I > > wonder if, instead, initdb should set signedness=true unconditionally. Then > > the only source of signedness=false will be pg_upgrade. > > > > Advantage: signedness=false will get rarer over time. If we had known about > > this problem during the last development cycle that forced initdb (v8.3), we > > would have made all clusters signed or all clusters unsigned. Making > > pg_upgrade the only source of signedness=false will cause the population of > > database clusters to converge toward that retrospective ideal. > > I think it's a good idea. Being able to treat one case as a rarer one > rather than treating both cases equally may have various advantages in > the future, for example when developing or investigating a problem. > > > Disadvantage: testing signedness=false will require more planning. > > If testing signedness=false always requires pg_upgrade, there might be > some cumbersomeness. Inventing a testing-purpose-only tool (e.g., a > CLI program) that changes the signedness might make tests easier. > > > What other merits should we consider as part of deciding? > > Considering that the population of database cluster signedness will > converge to signedness=true in the future, we can consider using > -fsigned-char to prevent similar problems for the future. We need to > think about possible side-effects as well, though.
It's good to think about -fsigned-char. While I find it tempting, several things would need to hold for us to benefit from it: - Every supported compiler has to offer it or an equivalent. - The non-compiler parts of every supported C implementation need to cooperate. For example, CHAR_MIN must change in response to the flag. See the first comment in cash_in(). - Libraries we depend on can't do anything incompatible with it. Given that, I would lean toward not using -fsigned-char. It's unlikely all three things will hold. Even if they do, the benefit is not large.
