invalid offsetof from non-POD type

[John Quigley]

While it is not standards compliant code, gcc still provides the correct 
result.  My question is: will gcc continue to provide the correct result in 
all cases for the foreseeable future? If so, why not add a flag to disable 
this warning and treat this as a "vendor extension" in gcc?  

It would make porting to gcc easier.  In my case I'm porting a large 
application that uses this construct throughout.  It will be quite difficult 
to make this change and will potentially introduce a lot of bugs.  So I would 
prefer to avoid it if possible.

On Monday 21 April 2003 6:39 am, Gabriel Dos Reis wrote:
> John Quigley <johnw@lowestplane.org> writes:
> | The code below triggers an "invalid offsetof from non-POD type" warning:
>
> The compiler is right.
>
> | In this case, and in every case I've seen, the warning is a false alarm
> | and
>
> No, that is not false alarm.  Your class Foo is *not* a POD, and as
> such your program, technically, invokes undefined behaviour.
>
> [...]
>
> | class Foo
> | {
> |    public:
> |       int x;
> |       char fillerdata[256];
> |       int y;
> |
> |       Foo()
>
>         ^^^^^
>
> Your class has a user-defined constructor, therefore it certainly
> cannot not be a POD.  Hence the warning.
>
>
> (if it were only me, I would issue a hard error and halt translation.)
>
> -- Gaby