Re: [PATCH] CodingGuidelines: document test balloons in flight

> Patrick Steinhardt <ps@pks.im> writes:
>
>> On Wed, Jul 23, 2025 at 12:31:26PM -0700, Junio C Hamano wrote:
>>> diff --git a/Documentation/CodingGuidelines b/Documentation/CodingGuidelines
>>> index c1046abfb7..0776d15a95 100644
>>> --- a/Documentation/CodingGuidelines
>>> +++ b/Documentation/CodingGuidelines
>>> @@ -298,6 +298,14 @@ For C programs:
>>>     . since late 2021 with 44ba10d6, we have had variables declared in
>>>       the for loop "for (int i = 0; i < 10; i++)".
>>>  
>>> +   C99 features we have test balloons for:
>>> +
>>> +   . since late 2024 with v2.48.0-rc0~20, we have test balloons for
>>> +     compound literal syntax, e.g., (struct foo){ .member = value };
>>> +     our hope is that no platforms we care about have trouble using
>>> +     them, and officially adopt its wider use in mid 2026.  Do not add
>>> +     more use of the syntax until that happens.
>>
>> Nice. I like that we now have an explicit deadline for people to
>> complain about this feature not being supported on their platform.
>
> I do not think the firm deadline has much practical effect.  Test
> balloons are designed to be placed in a stable and non-optional part
> of the codebase that is exercised by everybody, so even if your
> update cycle from your upstream is once a year, you'd have four or
> five major releases to try building and noticing that your platform
> is unhappy about them.
>
> So the only effect it would have is to smoke out truly slow platform
> maintainers; if their users are happy enough with such slow upgrade,
> they have lived and they can live with versions of Git that are
> years stale that we no longer care about.