How to correctly fix “zero-sized array in struct/union” warning (C4200) without breaking the code?

Question

I\'m integrating some code into my library. It is a complex data structure well optimized for speed, so i\'m trying not to modify it too much. The integration process goes well

Answer 1

If this is a MSVC compiler (which is what the warning message tells me), then you can disable this warning using #pragma warning, ie.:

#pragma warning( push )
#pragma warning( disable : 4200 )
struct _TREEDATSTR
{
    BYTE btLen;
    DWORD dwModOff;
    BYTE btPat[0];
};
#pragma warning( pop )

BTW, the message about the copy-constructor is not creepy, but a good thing because it means, that you can't copy instances of _TREEDATSTR without the unknown bytes in btPat: The compiler has no idea how big _TREEDATSTR really is (because of the 0-size array) and therefore refuses to generate a copy constructor. This means, that you can't do this:

_TREEDATSTR x=y;

which shouldn't work anyway.