Re: SWIG: Bug with 'C' arrays of zero size ?

On 27/06/2020 09:58, William S Fulton wrote:
>
>
> On Fri, 12 Jun 2020 at 09:37, Terry Barnaby <[email protected] 
> <mailto:[email protected]>> wrote:
>
>     Hi,
>
>     If you have a data structure like the following all is well:
>
>     struct DataBlock {
>          Header    header;
>          char        data[4];    ///< The packet data
>     };
>
>     However if you have a data structure that has a zero length array
>     like
>     the following, SWIG considers the "char data[]" as a pointed to
>     data and
>     tries to delete[] and allocate memory for it.
>
>     struct DataBlock {
>         Header    header;
>          char        data[];    ///< The packet data
>     };
>
>     I think this is a bug ?
>
>
> Hi Terry
>
> This is a pointer to an undetermined array of char characters. By 
> default SWIG chooses to wrap this a pointer to a NULL terminated array 
> of characters, that is, a string. There is no bug here!
>
> You can use typemaps to change the behaviour to whatever you want.
>
> William
>
But actually the data member is not a pointer to an array of characters, 
the actual array is contained within the structures memory area as part 
of the data structure (although 0 length!). So I would have though that 
SWIG should handle this just as if you had a size to this. Admittedly 
this is probably mute as you may not be able to wrap that member 
correctly in SWIG anyway :)

Terry

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