[php-src] Issue #7949: FFI struct with flexible array member

Issue: https://github.com/php/php-src/issues/7949 Comment Author: userqq > but the programmer is responsible to allocate a proper struct I finally got it. Such struct could be allocated in foreign function, like: ```php $lib = FFI::cdef(" typedef struct Data { int32_t size; char data[]; } Data; Data createData(); ", 'lib.so'); ``` > FFI::new() can't do that > The fact that FFI::memcpy() does not work, looks like a bug to me. So it still could be possible allocate such structs in PHP? In some cases passing PHP string to FFI function (and receiving it as C string) will not work properly. If there is a possibility string contains \0 it will be truncated at first NULL-byte, so to handle such cases length should be passed explicitly. It would be very handy to have possibility use structs with flexible array member instead of additional length argument in foreign function. ```php $lib = FFI::cdef(" typedef struct Data { int32_t size; char data[]; } Data; void handleData(Data data); ", 'lib.so'); ```