8233435: (dc) DatagramChannel should allow IPv6 socket join IPv4 multicast groups (macOS, win)

[Alan Bateman]

On 08/11/2019 20:21, Daniel Fuchs wrote:
> :
>
> Your changes mean that Net.canIPv6SocketJoinIPv4Group() will now
> return false for *all* platforms but __linux__ __APPLE__ and
> __solaris__ - whereas it previously returned false only
> for __APPLE__ and __AIX__. This means that the opt-out has
> now become an opt-in - and potentially affects any other
> downstream platform. I agree that opt-in is probably a better
> strategy than opt-out though, so that looks good to me
> nonetheless.
Thanks for looking at this change. The change to 
canIPv6SocketJoinIPv4Group is intentional. It should have no impact on 
the ports that are maintained in OpenJDK. Anyone porting the code to 
another operating system will need to know if IPv6 sockets can join IPv4 
multicast groups, the previous default for unknown platforms was 
surprising. The alternative is to have the #error for unknown platforms 
but I didn't want to go there.

-Alan