Implement support in protoc-gen-go for generating messages and enums
that satisfy the v2 protobuf reflection interfaces. Specifically, the following
are added:
* top-level variable representing the file descriptor
* ProtoReflect method on enums (to implement protoV2.Enum)
* ProtoReflect method on messages (to implement protoV2.Message)
The following are not supported yet:
* resolving transitive dependencies for file imports
* Extension descriptors
* Service descriptors
The implementation approach creates a single array for all the message and enum
declarations and references sections of that array to complete dependencies.
Since protobuf declarations can form a graph (a message may depend on itself),
it is difficult to construct a graph as a single literal. One way is to use
placeholder descriptors, but that is not efficient as it requires encoding
the full name of each dependent enum and message and then later resolving it;
thus, both expanding the binary size and also increasing initialization cost.
Instead, we add a prototype.{Enum,Message}.Reference method to obtain a
descriptor reference for the purposes for satisfying dependencies.
As such, nested declarations and dependencies are populated in an init function.
Other changes to support the implementation:
* Added a protoimpl package to expose the MessageType type and also the
MessageTypeOf and EnumTypeOf helper functions.
* Added a protogen.File.GoIdent field to provide a suggested variable name
for the file descriptor.
* Added prototype.{Enum,Message}.Reference that provides a descriptor reference
for the purposes for satisfying cyclic dependencies.
* Added protoreflect.{Syntax,Cardinality,Kind}.GoString to obtain a Go source
identifier that represents the given constant.
Change-Id: I9455764882dee6ad10f251901e7d419091e8bf1d
Reviewed-on: https://go-review.googlesource.com/c/150074
Reviewed-by: Damien Neil <dneil@google.com>
The marshaler, unmarshaler, and sizer functions are unused ever since
the underlying implementation was switched to be table-driven.
Change the function to only return the wrapper structs.
This change:
* enables generated protos to drop dependencies on certain proto types
* reduces the size of generated protos
* simplifies the implementation of oneofs in protoc-gen-go
Updates #708
Change-Id: I845c9009bc0236d1b51d34b014dc3e184303c0f2
Reviewed-on: https://go-review.googlesource.com/c/151357
Reviewed-by: Damien Neil <dneil@google.com>
When the generator parameter 'annotate_code' is provided, generate a .meta
file containing a GeneratedCodeInfo message describing the generated code's
relation to the source .proto file.
Annotations are added with (*protogen.GeneratedFile).Annotate, which takes the
name of a Go identifier (e.g., "SomeMessage" or "SomeMessage.GetField") and an
associated source location. The generator examines the generated AST to
determine source offsets for the symbols.
Change the []int32 "Path" in protogen types to a "Location", which also captures
the source file name.
Change-Id: Icd2340875831f40a1f91d495e3bd7ea381475c77
Reviewed-on: https://go-review.googlesource.com/c/139759
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
