On 31/03/2022 11:10, Ævar Arnfjörð Bjarmason wrote:
On Wed, Mar 30 2022, Junio C Hamano wrote:
We raised the weather balloon to see if we can allow the construct
in 44ba10d6 (revision: use C99 declaration of variable in for()
loop, 2021-11-14), which was shipped as a part of Git v2.35.
Document that fact in the coding guidelines, and more importantly,
give ourselves a deadline to revisit and update.
Let's declare that we will officially adopt the variable declaration
in the initializaiton [...]
Typo: initialization.
part of "for ()" statement this winter, unless we find that a platform
we care about does not grok it.
I'd think that waiting a couple of releases would be sufficient for this
sort of thing. I.e. contributors to this project already have
access/knowledge about a wide variety of compilers, especially the
"usual suspects" (mainly MSVC) that have been blockers for using new
language features in the past.
So I'm in no rush to use this, and the winter deadline sounds fine to
me in that regard.
Agreed, I think it is worth waiting so we don't get into a situation
where we end up having to revert changes that are using the new features
because we discover they are not supported by a platform we care about.
But on the other hand I think the likelihood that waiting until November
v.s. May revealing that a hitherto unknown compiler or platform has
issues with a new language feature is vanishingly small.
A separate weather balloon for C99 as a whole was raised separately
in 7bc341e2 (git-compat-util: add a test balloon for C99 support,
2021-12-01). Hopefully, as we find out that all C99 features are OK
on all platforms we care about, we can stop probing the features we
want one-by-one like this
Unfortunately this really isn't the case at all, the norm is for
compilers to advertise that they support verison X of the standard via
these macros when they consider the support "good enough", but while
there's still a long list of unimplemented features before they're at
100% support (and most never fully get to 100%).
We also need to worry about the stdlib implementation, and not just the
compiler, see e.g. the %zu format and MinGW in the exchange at
https://lore.kernel.org/git/220318.86bky3cr8j.gmgdl@xxxxxxxxxxxxxxxxxxx/
and
https://lore.kernel.org/git/a67e0fd8-4a14-16c9-9b57-3430440ef93c@xxxxxxxxx/;
That's a good point, it was a surprise to me that the problem is with
MinGW rather than MSVC.
Best Wishes
Phillip
But I think we're thoroughly past needing to worry about basic language
features in C99 such as these inline variable declarations.
(it does not necessarily mean that we would automatically start using
any and all C99 language features, though).
Yes, particularly those that the standards committee backed out of or
made optional after C99 would be good candidates for avoiding
permanently.
