From 0891ee111217101bce683e30ed9f08cf0cfcffd7 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Wed, 16 Nov 2016 14:39:21 +0000 Subject: [PATCH] HACKING: document #include order It was not obvious to me why "qemu/osdep.h" must be the first #include. This documents the rationale and the overall #include order. Cc: Fam Zheng Cc: Markus Armbruster Cc: Eric Blake Signed-off-by: Stefan Hajnoczi Reviewed-by: Eric Blake Reviewed-by: Markus Armbruster Message-id: 1479307161-24658-1-git-send-email-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi --- HACKING | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/HACKING b/HACKING index 20a910168d..4125c97d8d 100644 --- a/HACKING +++ b/HACKING @@ -1,10 +1,28 @@ 1. Preprocessor +1.1. Variadic macros + For variadic macros, stick with this C99-like syntax: #define DPRINTF(fmt, ...) \ do { printf("IRQ: " fmt, ## __VA_ARGS__); } while (0) +1.2. Include directives + +Order include directives as follows: + +#include "qemu/osdep.h" /* Always first... */ +#include <...> /* then system headers... */ +#include "..." /* and finally QEMU headers. */ + +The "qemu/osdep.h" header contains preprocessor macros that affect the behavior +of core system headers like . It must be the first include so that +core system headers included by external libraries get the preprocessor macros +that QEMU depends on. + +Do not include "qemu/osdep.h" from header files since the .c file will have +already included it. + 2. C types It should be common sense to use the right type, but we have collected