On Mon, Apr 12 2021, Junio C Hamano wrote:

Ævar Arnfjörð Bjarmason [off-list ref] writes:

quoted

But we can use some subset of C99 features, and happily designated
initializers is one of those, see cbc0f81d96f (strbuf: use designated
initializers in STRBUF_INIT, 2017-07-10). It's been used all over the
place since then.

Good advice to cite a commit that on purpose used a feature and
documented that it is allowed.

Also see Documentation/CodingGuidelines ;-)  The document should
give the authoritative blessing for features allowed to be used (add
any missing with a proposed patch).

Our E-Mails probably crossed, my initial motivation for just-submitted
http://lore.kernel.org/git/cover-0.2-00000000000-20210412T105422Z-avarab@gmail.com (local)
was going to CodingGuidelines, and vaguely remembering that there was
some other C99 thing that wasn't listed there, and then (re-)discovering
the recent variadic macro commit from Jeff King.

As noted there maybe 2/2 of that is too aggressive, but in that case it
would make sense to have a V2 of that which just carved off the
CodingGuidelines change.