c++ - Overwriting a repeated field in protobuf MergeFrom vs. MergeFromString -

suppose have proto defined as:

myproto {     optional mywrapper wrapper = 1; } 

where:

mywrapper {     repeated int32 data = 1; } 

when call mergefromstring on 2 text specifications of myproto, 2 versions of repeated field inside wrapper concatenated (one appended other.) want them overwritten instead. docs mergefromstring say:

when find field in |serialized| present in message:

• if it's "repeated" field, append end of our list.
• else, if it's scalar, overwrite our field.
• else, (it's nonrepeated composite), recursively merge existing composite.

clearly, wrapper, we're talking third case. recursively merge, , on next go-around see repeated field , values appended target. see why happened.

compare specification mergefrom:

this method merges contents of specified message current message. singular fields set in specified message overwrite corresponding fields in current message. repeated fields appended. singular sub-messages , groups recursively merged.

in case, isn't wrapper field singular field, , wouldn't wrapper overridden?

so question two-fold,

1) inconsistent, or have misunderstood something?

2) how can desired behavior of overwriting instead of merging repeated field when call mergefromstring?

for first part of question, mergefrom specification quoted technically correct although worded bit confusingly. says "singular fields" overwritten "singular sub-messages" recursively merged, , wrapper considered singular sub- message.

to behavior want, should able use fieldmaskutil. in particular can call fieldmaskutil::mergemessageto(...) , pass mergeoptions configured replace repeated fields instead of concatenating them. first have parse 2 messages text format representation.