proto: Add structured error types for UserSquash RPC

We're about to introduce support for structured errors in the UserSquash
RPC. We cannot roll out this change even with a feature flag though
because some of our testing infrastructure will always test code with
all feature flags enabled. We thus have to land the protobuf changes
independently such that we can adjust downstream callers.

This commit introduces these changes by creating a new UserSquashError
Protobuf message which contains all potential structured errors we want
to return from the UserSquash RPC.

Changelog: added

1 files changed, 10 insertions, 2 deletions

diff --git a/proto/go/gitalypb/operations_grpc.pb.go b/proto/go/gitalypb/operations_grpc.pb.go
index 4be478c25..45c083841 100644
--- a/proto/go/gitalypb/operations_grpc.pb.go
+++ b/proto/go/gitalypb/operations_grpc.pb.go
@@ -63,7 +63,11 @@ type OperationServiceClient interface {
 	UserRebaseConfirmable(ctx context.Context, opts ...grpc.CallOption) (OperationService_UserRebaseConfirmableClient, error)
 	// UserRevert tries to perform a revert of a given commit onto a branch.
 	UserRevert(ctx context.Context, in *UserRevertRequest, opts ...grpc.CallOption) (*UserRevertResponse, error)
-	// UserSquash squashes a range of commits into a single commit.
+	// UserSquash squashes a range of commits into a single commit. If
+	// successful, it returns the object ID of the newly created squash commit.
+	// On error, it returns a gRPC error. Some specific errors will have an
+	// embedded UserSquashError such that clients can deduce what exactly has
+	// failed.
 	UserSquash(ctx context.Context, in *UserSquashRequest, opts ...grpc.CallOption) (*UserSquashResponse, error)
 	// UserApplyPatch applies patches to a given branch.
 	UserApplyPatch(ctx context.Context, opts ...grpc.CallOption) (OperationService_UserApplyPatchClient, error)
@@ -357,7 +361,11 @@ type OperationServiceServer interface {
 	UserRebaseConfirmable(OperationService_UserRebaseConfirmableServer) error
 	// UserRevert tries to perform a revert of a given commit onto a branch.
 	UserRevert(context.Context, *UserRevertRequest) (*UserRevertResponse, error)
-	// UserSquash squashes a range of commits into a single commit.
+	// UserSquash squashes a range of commits into a single commit. If
+	// successful, it returns the object ID of the newly created squash commit.
+	// On error, it returns a gRPC error. Some specific errors will have an
+	// embedded UserSquashError such that clients can deduce what exactly has
+	// failed.
 	UserSquash(context.Context, *UserSquashRequest) (*UserSquashResponse, error)
 	// UserApplyPatch applies patches to a given branch.
 	UserApplyPatch(OperationService_UserApplyPatchServer) error