From: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
Date: Tue, 6 Jul 2021 11:44:51 +0000 (+0200)
Subject: CODING_STYLE: allow joined variable declarations and function calls
X-Git-Tag: v250-rc1~353^2~5
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9214f2999b85533ad184e6508f0a0a078d9d3b8f;p=thirdparty%2Fsystemd.git

CODING_STYLE: allow joined variable declarations and function calls

… but only for a single variable.

The guidelines already allowed declaring variables at the point of
initialization. But not making a function call to do that. Let's allow that
now.  The existing style of declaring and initializing seperate is still
allowed, and whatever makes most sense should be used.
---

diff --git a/docs/CODING_STYLE.md b/docs/CODING_STYLE.md
index f2c877ccebf..4792f270c59 100644
--- a/docs/CODING_STYLE.md
+++ b/docs/CODING_STYLE.md
@@ -153,25 +153,34 @@ SPDX-License-Identifier: LGPL-2.1-or-later
 ## Using C Constructs
 
 - Allocate local variables where it makes sense: at the top of the block, or at
-  the point where they can be initialized. `r` is typically used for a local
-  state variable, but should almost always be declared at the top of the
-  function.
+  the point where they can be initialized. Avoid huge variable declaration
+  lists at the top of the function.
+
+  As an exception, `r` is typically used for a local state variable, but should
+  almost always be declared as the last variable at the top of the function.
 
   ```c
   {
-          uint64_t a, b;
+          uint64_t a;
           int r;
 
-          a = frobnicate();
-          b = a + 5;
+          r = frobnicate(&a);
+          if (r < 0)
+                  …
+
+          uint64_t b = a + 1, c;
 
-          r = do_something();
+          r = foobarify(a, b, &c);
           if (r < 0)
                   …
+
+          const char *pretty = prettify(a, b, c);
+          …
   }
   ```
 
-- Do not mix function invocations with variable definitions in one line.
+- Do not mix multiple variable definitions with function invocations or
+  complicated expressions:
 
   ```c
   {
@@ -225,7 +234,7 @@ SPDX-License-Identifier: LGPL-2.1-or-later
 - To determine the length of a constant string `"foo"`, don't bother with
   `sizeof("foo")-1`, please use `strlen()` instead (both gcc and clang optimize
   the call away for fixed strings). The only exception is when declaring an
-  array. In that case use STRLEN, which evaluates to a static constant and
+  array. In that case use `STRLEN()`, which evaluates to a static constant and
   doesn't force the compiler to create a VLA.
 
 - Please use C's downgrade-to-bool feature only for expressions that are