tree 8a39190fee5dcd4cb68e5c7b6e852a16779e7888
parent 58d6425be864f904aee3f2e7c7fd66d3ee2288c7
author Michael Stapelberg <stapelberg@golang.org> 1746521180 +0200
committer Michael Stapelberg <stapelberg@golang.org> 1746523778 -0700

internal/impl: clean up usePresenceForField() (no-op)

When looking into presence behavior, I noticed that this function
is rather hard to follow. Specifically:

1. usesPresenceArray was only used in the default case,
   but re-iterated all conditions of the non-default cases.
   usesPresenceArray was a convoluted way to write fd.HasPresence().

2. hasLazyField was a misnomer: the function does not look at entire
   messages (which can have a lazy field), but at an individual field.

3. Only messages can be lazy right now, so the definition and usage
   of isLazy can be moved into the message case.

4. Instead of the wall-of-text comment above the function,
   I have moved the comments to each individual case.

I have verified Google-internally that my new usePresenceForField()
yields exactly the same results as the old one on all our .protos
(see Google-internal CL 753969456 for details).

Change-Id: Ida598fda7f472c71e18802aecabfae3e16de321c
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/670275
Reviewed-by: Lasse Folger <lassefolger@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>