This updates all our text parsers and serializers to better handle tag-delimited fields under editions. Under proto2, groups were the only tag-delimited fields possible, and the group name (i.e. the message type) was guaranteed to be unique. Text-format and various generators used this instead of the synthetic field name (lower-cased group name) to represent these fields.
Under editions, we've removed group syntax and allowed any message field to be tag-delimited. This breaks those cases when adding new tag-delimited fields where the message type might not be unique or correspond to the field name. Code generators have already been fixed to treat "group-like" fields using the old behavior, and treat new fields like any other sub-message.
This change addresses the text-format issue. Text parsers will accept *either* the type or field name for "group-like" fields, and only the field name for every other message field. Text serializers will continue to emit the message name for "group-like" fields, but also use the field name for everything else.
This creates some awkward capitalization behavior for fields that happen to *look* like proto2 groups, but it won't lead to any conflicts or invalid encodings. A feature will likely be added to edition 2024 to allow for migration off this legacy behavior.
PiperOrigin-RevId: 622260327
Mike Kruskal
29c69ff00b