remove server silliniess

[Martin Fuchs]

> Well, there seem to be some reasonable tricks for that:
> http://www.jaggersoft.com/pubs/CVu11_3.html
> http://www.panelsoft.com/murphyslaw/apr01.htm
> 
> This is for C++ but maybe also adaptable for C:
> http://www.boost.org/libs/static_assert/static_assert.htm


Here is my version, which has some advantages over the mentioned compile time asserts.
It uses the constraint, that a typedef'd array can't have zero length.
-> It doesn't generate any code in the compiled binary. (no use of switch or other constructs)
-> It doesn't use any memory in the running program. (no declaration of variables)

It generates a unique name for the typedef.
-> You can use any number of assertions, if you put any other in its own source code line.
You don't have to put the assert into a function. You can put it anywhere at global scope


#define	MAKE_UNIQUE_(x,y)	__unique_name_##x##y
#define	MAKE_UNIQUE(x,y)	MAKE_UNIQUE_(x,y)
#define	UNIQUE_NAME(name)	MAKE_UNIQUE(name, __LINE__)

 /* compile time assertions; An assertion failure results in error C2466: cannot allocate an array of constant size 0 */
#define	CASSERT(expr)		typedef char UNIQUE_NAME(cassert_type)[(expr)? 1: 0];

/* Examples */
CASSERT(sizeof(char)>=1);
CASSERT(sizeof(int)>=2);
CASSERT(sizeof(long)=4);
CASSERT(sizeof(__int64)=8);


Using the CASSERT macro you can define some more convenient macros for checking type sizes:

#include <limits.h>

#define	ASSERT_MIN_BITSIZE(type, size) CASSERT(sizeof(type)*CHAR_BIT >#define	ASSERT_EXACT_BITSIZE(type, size) CASSERT(sizeof(type)*CHAR_BIT = (size));

/* Examples */
ASSERT_MIN_BITSIZE(char, 8);
ASSERT_MIN_BITSIZE(int, 16);
ASSERT_EXACT_BITSIZE(long, 32);
ASSERT_EXACT_BITSIZE(__int64, 64);


--
Martin Fuchs
martin-fuchs at gmx.net