Hi Junio, On Fri, Nov 08, 2019 at 09:49:02PM +0900, Junio C Hamano wrote: > Denton Liu <liu.denton@xxxxxxxxx> writes: > > >> > local r1 r2 > >> > r1=$(git rev-parse --verify "$1") && > >> > r2=$(git rev-parse --verify "$2") && > >> > >> If either of the calls fail, the assignment itself would fail, and > >> the &&-cascade would stop without executing the if statment below. > >> > >> I see the "!" feature, but where is the promised "fix" for > >> segfaulting rev-parse? > >> > >> Puzzled. > > > > I suppose your puzzlement comes from my badly worded commit message > > above. I meant to say that in the _hypothetical_ case that > > `git rev-parse` segfaults, it wouldn't be caught because we're > > blanket-ignoring failures if we do `! test_cmp_rev`. > > > > But I suppose I focused too much on segfaults. I guess I didn't realise > > that the problem is more general than that; any failure of > > `git rev-parse` should be reported. > > But if that is the case, shouldn't the part that runs two rev-parse > read more like this? > > r1=$(git rev-parse --verify "$1") || > error "'$1' does not name a valid object" > r2=$(git rev-parse --verify "$2") || > error "'$2' does not name a valid object" > if ! test "$r1" $op "$r2" > then > ... they do not compare the same ... > fi With your suggestion, we actually introduce subtle undesired behaviour. The `error` calls don't actually exit the function early. To make it work, we need to add && to the end of the `error` calls. I'm wondering why we want to do this, though. rev-parse should already output an error message on stderr in the case where the rev-parse fails. I guess the error message of "fatal: Needed a single revision" could probably be improved but that feels like an improvement that should be targeted to rev-parse. > > Offhand I do not know if the current callers depend on being able to > pass a string that is not an object name in either $1 or $2 and a > valid object name in the other one, and relying on the helper > function to say "$1 and $2 are different!" If such callers exist, a > defensive change like the above that requires the caller to always > pass valid object names would need to be accompanied with changes to > these callers, too. Overall, I think that would give us a better > end result, but it might be a bit more work. This patch changes all instances of `! test_cmp_rev` to `test_cmp_rev !`. Since nothing failed after applying the patch, I believe that all callers already pass in valid object names. Thanks, Denton > > Thanks.
