Synchronized classes have no public members

[Andrei Alexandrescu via Digitalmars-d]

https://github.com/D-Programming-Language/dmd/pull/5188 implements a 
rule defined in TDPL: synchronized classes shall have no public members.

The motivation behind this limitation is that member accesses in 
synchronized objects should not occur without some handshake occurring. 
Public members would make that possible and easy.

Walter and I are on board with this change. However, it is a breaking 
change so we want to gather a level of community support before we push 
the button.


Thanks,

Andrei