This gist of the new test case coverage can be summarized as:
- The wire does not distinguish between explicit and implicit fields.
- For implicit presence fields, zeros on the wire can overwrite nonzero values
(i.e. they are treated as a 'clear' operation).
It's TBD whether we want to accept this behaviour going forward.
Right now we are leaning towards keeping this behaviour, because:
- If we receive zeros on the wire for implicit-presence fields, the protobuf
wire format is "wrong" anyway. Well-behaved code should never generate zeros
on the wire for implicit presence fields or serialize the same field multiple
times.
- There might be some value to enforce that "anything on the wire is accepted".
This can make handling of wire format simpler.
There are some drawbacks with this approach:
- It might be somewhat surprising for users that zeros on the wire are always
read, even for implicit-presence fields.
- It might make the transition from implicit-presence to explicit-presence
harder (or more unsafe) if user wants to migrate.
- It leads to an inconsistency between what it means to "Merge".
- Merging from a constructed object, with implicit presence and with field
set to zero, will not overwrite.
- Merging from the wire, with implicit presence and with zero explicitly
present on the wire, WILL overwrite.
I still need to add conformance tests to ensure that this is a consistent
behavior across all languages, but for now let's at least add some coverage in
C++ to ensure that this is a tested behaviour.
PiperOrigin-RevId: 657724599
With the C++ kernel for Rust, we currently need to generate quite a few C++
thunks for operations on map fields. For each message we generate, we generate
these thunks for all possible map types that could have that message as a
value. These operations are for things such as insertion, removal, clearing,
iterating, etc.
The reason we do this is that templated types don't play well with FFI, so we
effectively need separate FFI endpoints for every possible combination of key
and value types used (or even potentially used) as a map field.
This CL fixes the problem by replacing the generated thunks with functions in
the runtime that can operate on `proto2::MessageLite*` without needing to care
about the specific message type.
The way it works is that we implement the operations using either
`UntypedMapBase` (the base class of all map types, which knows nothing about
the key and value types) or `KeyMapBase`, which knows the key type but not the
value type. I roughly followed the example of the table-driven parser, which
has a similar problem of needing to operate generically on maps without having
access to the concrete types.
I removed 54 thunks per message (that's 6 key types times 9 operations per
key), but had to add two new thunks per message:
- The `size_info` thunk looks up the `MapNodeSizeInfoT`, which is stored in a
small constant table. The important thing here is an offset indicating where
to look for the value in each map entry. This offset can be different for
every pair of key and value types, but we can safely assume that the result
does not depend on the signedness of the key. As a result we only need to
store four entries per message: one each for i32, i64, bool, and string.
- The `placement_new` thunk move-constructs a message in place. We need this
to be able to efficiently implement map insertion.
There are two big things that this CL does not address yet but which I plan to
follow up on:
- Enums still generate many map-related C++ thunks that could be replaced with
a common implementation. This should actually be much easier to handle than
messages, because every enum has the same representation as an i32.
- We still generate six `ProxiedInMapValue` implementations for every message,
but it should be possible to replace these with a blanket implementation that
works for all message types.
PiperOrigin-RevId: 657681421
The owned and mut interop traits have the corresponding to/from behaviors on cpp but are defined as empty on upb, while the view interop is implemented for both.
PiperOrigin-RevId: 657617187
The purpose of this trait is that it is declared as a supertrait of the traits that we don't want application code to implement (like "Proxied" and "MessageView"); application code can see those traits but not the supertrait, which enables them to use them but not implement them.
PiperOrigin-RevId: 657555025
I also added a blanket implementation of `IntoProxied<T> for T` so that we
don't have to duplicate this no-op implementation for all our types.
PiperOrigin-RevId: 656465755
Distinct from any clear_submsg(), this clears the message contents and doesn't affect presence on parent (and also allows for clearing owned messages which don't exist as a field to be cleared).
PiperOrigin-RevId: 656453234
Adds a new 'bzl' feature that is used to adjust import paths that need to change
in the Cargo build vs Blaze build.
This protobuf rust crate is a single crate that merges all of our current crates (protobuf, rust/upb, and utf8).
PiperOrigin-RevId: 656405153
Default to collecting unknown fields as data and then create the
`GPBUnknownFieldSet` on demand when requested.
This should reduce the as the extra objects are created until requested
and clears the way to eventually deprecated `GPBUnknownFieldSet` in the
future.
This also fixes the failing conformance test related to keeping the ordering.
PiperOrigin-RevId: 655929316
We have received several reports in #17036 that the addition of this flag
actually broke the use of command argument files with non-ASCII characters in
their names. It looks like #14253 ended up fixing the original issue with a
different solution anyway. Hopefully this change fixes the issue with non-ASCII
characters.
PiperOrigin-RevId: 655660885
- Add overloads that take `absl::Cord` and `std::string&&` as inputs, putting the burden in the implementation instead of users.
- Add overload that returns `absl::Span<char>` for callers that need higher performance requirements where we can avoid copies altogether.
- Hide the APIs that return `std::string*` when the breaking change is enabled (via `-D PROTOBUF_TEMPORARY_ENABLE_STRING_VIEW_RETURN_TYPE`).
PiperOrigin-RevId: 655600399
- We introduce two new view types ProtoStringCow and ProtoBytesCow.
- In UPB, for cord field accessors we always return a Cow::Borrowed.
- In C++, for coed field accessors we check if the underlying absl::Cord is flat (contigous) and if so return a Cow::Borrowed. If it's not flat we copy the data to a ProtoString and return a Cow::Owned.
- We expect the absl::Cord to be flat almost all the time. We have experimentally verified that for small strings (<4 KiB) and less than 6 appends the cord is in fact flat [1].
- This change lifts the requirement of all ViewProxy types to be Copy. Our Cow types cannot be Copy because the owned types aren't copy.
[1] https://source.corp.google.com/piper///depot/google3/experimental/users/buchgr/cords/cords.cc
PiperOrigin-RevId: 655485943
`GPBTextFormatForMessage()` will contain any information for unknown fields.
And it clears the way for `GPBUnknownFieldSet` to eventually be deprecated
also.
PiperOrigin-RevId: 655184316
GenerateByteSize itself remains deeply nested, but by factoring out one part of
the loop, at least we make the part that generates UpdateByteSize a bit more
readable.
Making the callsite of MayEmitIfNonDefaultCheck less nested actually resulted
in slight readability improvements also in the generated code, namely of the
form:
@@ -10563,8 +10559,7 @@ PROTOBUF_NOINLINE void OneStringEdition:
{
// string data = 1;
- cached_has_bits =
- this_._impl_._has_bits_[0];
+ cached_has_bits = this_._impl_._has_bits_[0];
if (cached_has_bits & 0x00000001u) {
total_size += 1 + ::proto2::internal::WireFormatLite::StringSize(
this_._internal_data());
These readability improvements should be kept IMO -- they make the generated
protobuf C++ code slightly easier to read.
PiperOrigin-RevId: 655180880
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