为什么此版本标签会导致错误？

Question

In my go.mod file, I have:

require (
    // ... editted for brevity
    github.com/Liquid-Labs/catalyst-firewrap v2.0.0-prototype.3
    // ... 
)

When I tried to build another package dependent on this package, I get: invalid module: github.com/Liquid-Labs/catalyst-firewrap should be v0 or v1, not v2 (v2.0.0-prototype.3).

There was a rewrite back before go went modular, and I wasn't tagging stuff back then, so there is no v1... is that the problem? I'm not having any luck finding an explanation of the underlying problem here.

Answer 1

Per the Go modules wiki:

If the module is version v2 or higher, the major version of the module must be included as a /vN at the end of the module paths used in go.mod files (e.g., module github.com/my/mod/v2, require github.com/my/mod/v2 v2.0.0) and in the package import path (e.g., import "github.com/my/mod/v2/mypkg").

The same document quotes the rationale from the official Go FAQ:

Packages intended for public use should try to maintain backwards compatibility as they evolve. The Go 1 compatibility guidelines are a good reference here: don't remove exported names, encourage tagged composite literals, and so on. If different functionality is required, add a new name instead of changing an old one. If a complete break is required, create a new package with a new import path.

and:

If an old package and a new package have the same import path, the new package must be backwards compatible with the old package.