混合和匹配 protoc 和 protoc-gen-go 版本

Question

go protobuf generated code reports (elided):

// protoc-gen-go v1.25.0
// protoc.       v3.5.1

import "github.com/golang/protobuf/..."
import "google.golang.org/protobuf/..."

resulting in a go.mod which references two protobuf's:

require(
    github.com/golang/protobuf v1.4.3
    google.golang.org/protobuf v1.25.0
)

Is that kosher? I mean it seems to work but it's like twice the code.

The root cause, I believe, of this gunk is sysadmin issues (incomplete and incompatible install of protobuf generator utils) plus the fact Google couldn't just stay on one URL.

Answer 1

github.com/golang/protobuf is imported in the generated code to allow the following to be included:

// This is a compile-time assertion that a sufficiently up-to-date version
// of the legacy proto package is being used.
const _ = proto.ProtoPackageIsVersion4

There are further details in this issue - quoting dsnet:

The only reason the newly generated.pb.go files depend on the deprecated proto package is to enforce a weak dependency on a sufficiently new version of the legacy package. This is necessary because not everyone is using Go modules such that the Go toolchain would enforce this dependency constraint. I wasn't fond of adding it, but I think it's probably necessary to keep at least for a few months.

As per the comments on this issue the dependency should be removed in version 1.26 (when released).

(found this duplicate question after answering but as I have included more detail in this answer than I did in the previous one I will leave it up)