[PATCH 2/5] CodingGuidelines: mention dynamic C99 initializer elements
- From
Ævar Arnfjörð Bjarmason <avarab@gmail.com>
- Date
- Oct 7, 2022, 09:30 UTC
- Message-ID
- <patch-2.5-343ec223dff-20221007T092505Z-avarab@gmail.com>
- In-Reply-To
- <cover-0.5-00000000000-20221007T092505Z-avarab@gmail.com>
The first use of variables in initializer elements appears to have been 2b6854c863a (Cleanup variables in cat-file, 2007-04-21) released with v1.5.2.
Some of those caused portability issues, and e.g. that "cat-file" use was changed in 66dbfd55e38 (Rewrite dynamic structure initializations to runtime assignment, 2010-05-14) which went out with v1.7.2.
But curiously 66dbfd55e38 missed some of them, e.g. an archive.c use added in d5f53d6d6f2 (archive: complain about path specs that don't match anything, 2009-12-12), and another one in merge-index.c (later builtin/merge-index.c) in 0077138cd9d (Simplify some instances of run_command() by using run_command_v_opt()., 2009-06-08).
As far as I can tell there's been no point since 2b6854c863a in 2007 where a compiler that didn't support this has been able to compile git. Presumably 66dbfd55e38 was an attempt to make headway with wider portability that ultimately wasn't completed.
In any case, we are thoroughly reliant on this syntax at this point, so let's update the guidelines, see https://lore.kernel.org/git/xmqqy1tunjgp.fsf@gitster.g/ for the initial discussion.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> --- Documentation/CodingGuidelines | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/Documentation/CodingGuidelines b/Documentation/CodingGuidelines index 386ca0a0d22..8afda28cfce 100644 --- a/Documentation/CodingGuidelines +++ b/Documentation/CodingGuidelines @@ -213,6 +213,11 @@ For C programs: compilers we target have only partial support for it. These are considered safe to use: + . since around 2007 with 2b6854c863a, we have been using + initializer elements which are not computable at load time. E.g.: + + const char *args[] = {"constant", variable, NULL}; + . since early 2012 with e1327023ea, we have been using an enum definition whose last element is followed by a comma. This, like an array initializer that ends with a trailing comma, can be used
-- 2.38.0.971.ge79ff6d20e7