how to get the arenastring.patch for lower protobuf version?

[welsonzhang]

Is it possible to merge the arenastring.patch to lower protobuf version, example for 21.7？Is there anything I need to pay attention to?

[oathdruid]

Possible but need do a careful merge diff check.

• the core new file arenastring_impl.h is same for each version
• check TaggedPtr in arenastring.h, some old version have different implementation, that will make it hard to merge.
• most ugly part is repeated_ptr_field.h, need to be carefully diffed line by line

in fact, we do have a 21.12 version of this patch internal, maybe you could ask @eesly if it can be exported to open source repo

[welsonzhang]

Thanks a lot. I have found it in internal repository.