Re: [ros-dev] [ros-diffs] [cwittich] 32018: compilerflags can be set for compiler {ALL|CC|CPP} now (ALL is default)

Alex wrote:

>  On 26-Jan-08, at 2:34 PM, Marc Piulachs wrote:
>
> >   Hi,
> >
> >  I'm not very sure about r32018-r32022.
> >
> >  Some compiler warnings are stupid and useless, some others not. 
> This one is stupid. 
Actually, I'd say the stupidity is in using a runtime assert, when a 
compile-time assert will do the trick (not using CPU at runtime, while 
enforcing the condition).

Unless memory fails me, in C++ you can implement ct_assert(x) like:

typedef char[x!=0] foo;

as an array of size zero is an error.

How does current C compilers react to typedefs of zero-sized arrays? 
Sure, one can't use it exactly as in C++, but it could still be useful 
to at least know about this idiom.

Problems should be trapped as early as possible.

-- 
Mike

[Timo Kreuzer]

arrays of size 0 are no problem for gcc both in C and C++, so you should 
use something like

#define ct_assert(x) typedef char _ct_assert__[(x)? 1 : -1];

tamlin(a)algonet.se schrieb:
>   Actually, I'd say the stupidity is in using a
> runtime assert, when a
>  compile-time assert will do the trick (not using CPU at runtime, while 
>  enforcing the condition).
>
>  Unless memory fails me, in C++ you can implement ct_assert(x) like:
>
>  typedef char[x!=0] foo;
>
>  as an array of size zero is an error.
>
>  How does current C compilers react to typedefs of zero-sized arrays? 
>  Sure, one can't use it exactly as in C++, but it could still be useful 
>  to at least know about this idiom.
>
>  Problems should be trapped as early as possible.
>
>