Improve C standard compliance.

- Don't cast between object and function pointers.
- Use standard compliant `__VA_ARGS__` in macros.
- Add explicit `__extension__` on unnamed union in struct (it's a GNU
  extension).
- Remove ; after function definitions.
- Replace `const T foo = 3;` for integral types `T` with `enum { foo = 3 };`.
  Folding integral constants like that as compile time constants is a GNU
  extension. Arrays allocated with `foo` as dimension are VLAs on strictly
  compliant C99 compilers.
- Replace empty initialiser list `{}` with zero-initialiser-list `{0}`.
  The former is a GNU extension meaning the latter.
- Cast `T*` (where `T != void`) to `void *` in format arguments. While any
  object pointer can be implicitly converted to and from `void *`, this
  conversion does not happen in variadic function calls.
- Replace arithmetic on `void *` with arithmetic on `char *`. The former
  is non-compliant.
- Replace non-`int`-derived types (like `uint16_t`, which is
  `short`-derived) in bit fields with `int`-derived types. Using any type
  other than `int` or `unsigned int` (or any of their aliases) in bit
  fields is a GNU extension.

1 files changed, 1 insertions, 1 deletions

diff --git a/toxcore/network.h b/toxcore/network.h
index 5cc16523..6d24caac 100644
--- a/toxcore/network.h
+++ b/toxcore/network.h
@@ -155,7 +155,7 @@ IP6;
 
 typedef struct {
     uint8_t family;
-    union {
+    __extension__ union {
         IP4 ip4;
         IP6 ip6;
     };