RFR JDK-8194667: Regex: Serialization doesn't work with match flags

[Xueming Shen]

Hi,

Please help review the change for JDK-8194667

issue: https://bugs.openjdk.java.net/browse/JDK-8194667
webrev: http://cr.openjdk.java.net/~sherman/8194667/webrev

The bits of "flags" are being updated on and off during the pattern 
compiling by
the possible embedded match flag(s) in old implementation. The proposed 
fix is
to add a temporary field "flags0" for this purpose and save/store 
"flags" for the
purpose of deserialization (same as the field "pattern").

For the compatibility concern I'm leaving the behavior of method flags() 
unchanged
to return the muted "flags". Arguably it might be desired to return the 
original "flags"
instead. We can leave this "issue" for future RFE.

1145     public int flags() {
1146         return flags0;
1147     }


Thanks,
Sherman