v2 go mod incompatibility

[rocketbitz]

The RPC v2 module is never downloaded, I believe because of the v2 in the path, go mod believes it is a v2 of gorilla/rpc, not a separate package.

$ go mod vendor
go: finding github.com/gorilla/rpc/v2/json2 latest
go: finding github.com/gorilla/rpc/v2 latest
go: downloading github.com/gorilla/rpc/v2 v2.0.0-20180618141230-5c1378103183

$ go vet ./...
cannot find module for path github.com/gorilla/rpc/v2

hit this today also.

[elithrar]

Noted. This won't be straightforward to rectify - because we have to change the path, which will break existing users (or both!)

• We "break" the v2 path in a new tagged release, removing the existing "v1" code. This will break those without a module-aware Go toolchain still relying on those paths.
• Move to a v3 (tagged) and duplicate v2 in both the root and /v2 (duplicate, hugely error prone, maintenance burden)
• ???

I'm not aware of other great options here, and am open to suggestions.

[dangerousvasil]

hit this also.

[elithrar]

(Deleted a comment that wasn’t constructive)

[stek29]

Workaround: Add +incompatible to version tag in go.mod manually.

[jbrukh]

Thanks @stek29, can you please post an example of how to define +incompatible require clause here?

Edit:

I was able to do it as follows:

require (
  github.com/gorilla/rpc v1.2.0+incompatible // indirect
  github.com/alpacahq/marketstore v3.2.6+incompatible
)

[stek29]

@jbrukh yup, that's what i've meant.

[kisielk]

Honestly we could just move it all to an entirely new repo path and close this one. eg: github.com/gorilla/rpc2.

[stek29]

@kisielk Agreed. I was quite confused when I realized that rpc/v2/json is in fact JSON RPC 1, not 2, and v2 refers to library itself.

[bcmills]

@rocketbitz, what did you run before go mod vendor? I don't see any incompatibility here.

example.com$ go1.13beta1 mod init example.com
go: creating new go.mod: module example.com

example.com$ go1.13beta1 get -d github.com/gorilla/rpc/v2/json2
go: finding github.com/gorilla/rpc/v2/json2 latest
go: finding github.com/gorilla/rpc/v2 latest
go: finding github.com/gorilla/rpc v1.2.0+incompatible
go: downloading github.com/gorilla/rpc v1.2.0+incompatible
go: extracting github.com/gorilla/rpc v1.2.0+incompatible

example.com$ go1.13beta1 list github.com/gorilla/rpc/v2/...
github.com/gorilla/rpc/v2
github.com/gorilla/rpc/v2/json
github.com/gorilla/rpc/v2/json2
github.com/gorilla/rpc/v2/json2/testapp
github.com/gorilla/rpc/v2/protorpc

example.com$ go1.13beta1 test github.com/gorilla/rpc/v2/...
ok      github.com/gorilla/rpc/v2       0.038s
ok      github.com/gorilla/rpc/v2/json  0.084s
ok      github.com/gorilla/rpc/v2/json2 0.053s
?       github.com/gorilla/rpc/v2/json2/testapp [no test files]
ok      github.com/gorilla/rpc/v2/protorpc      0.047s

example.com$

[bcmills]

Ah, now I see it. This triggered golang/go#33099 (and was masked by golang/go#32805) using go1.13beta1, but is fixed at head.

example.com$ GOPROXY=direct go1.13beta1 get -d github.com/gorilla/rpc/v2/json2
go: finding github.com/gorilla/rpc/v2/json2 latest
go: finding github.com/gorilla/rpc v1.2.0
go: finding github.com/gorilla/rpc/v2 latest
go: downloading github.com/gorilla/rpc v1.2.0
go: downloading github.com/gorilla/rpc/v2 v2.0.0-20190627040322-27d3316e212c
go: extracting github.com/gorilla/rpc v1.2.0
go get github.com/gorilla/rpc/v2/json2: missing github.com/gorilla/rpc/go.mod and .../v2/go.mod at revision 27d3316e212c

example.com$ GOPROXY=direct gotip get -d github.com/gorilla/rpc/v2/json2
go: finding github.com/gorilla/rpc/v2/json2 latest
go: finding github.com/gorilla/rpc/v2 latest

example.com$ go list -m all
example.com
github.com/gorilla/rpc v1.2.0