From cc0c42975a2d9159fea5fdd053425492333c1aba Mon Sep 17 00:00:00 2001 From: Junio C Hamano Date: Tue, 16 Jul 2019 10:21:20 -0700 Subject: CodingGuidelines: spell out post-C89 rules Even though we have been sticking to C89, there are a few handy features we borrow from more recent C language in our codebase after trying them in weather balloons and saw that nobody screamed. Spell them out. While at it, extend the existing variable declaration rule a bit to read better with the newly spelled out rule for the for loop. Signed-off-by: Junio C Hamano diff --git a/Documentation/CodingGuidelines b/Documentation/CodingGuidelines index 32210a4..3770554 100644 --- a/Documentation/CodingGuidelines +++ b/Documentation/CodingGuidelines @@ -195,10 +195,30 @@ For C programs: by e.g. "echo DEVELOPER=1 >>config.mak". - We try to support a wide range of C compilers to compile Git with, - including old ones. That means that you should not use C99 - initializers, even if a lot of compilers grok it. + including old ones. You should not use features from newer C + standard, even if your compiler groks them. - - Variables have to be declared at the beginning of the block. + There are a few exceptions to this guideline: + + . 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 + to reduce the patch noise when adding a new identifer at the end. + + . since mid 2017 with cbc0f81d, we have been using designated + initializers for struct (e.g. "struct t v = { .val = 'a' };"). + + . since mid 2017 with 512f41cf, we have been using designated + initializers for array (e.g. "int array[10] = { [5] = 2 }"). + + These used to be forbidden, but we have not heard any breakage + report, and they are assumed to be safe. + + - Variables have to be declared at the beginning of the block, before + the first statement (i.e. -Wdeclaration-after-statement). + + - Declaring a variable in the for loop "for (int i = 0; i < 10; i++)" + is still not allowed in this codebase. - NULL pointers shall be written as NULL, not as 0. -- cgit v0.10.2-6-g49f6