How to import two versions of the same go module?

Question

I have this problem:

• Module A imports module X v0.1.0
• Module B imports module X v0.2.0
• I import both A and B in my project.

Golang picks out X v0.2.0 and calls it good. But it is not good. v0.1 and v0.2 are different enough that A breaks and my project doesn't compile.

What options do I have to fix this?

The offical go stance seems to be "developers of X were doing it wrong and should've released a major version after breaking changes". But that doesn't help the current situation.

I can't find discussions of practical solutions.

---

Further information

• The above is a simplification, A and B have a couple more dependencies that also depend on X.
• This project needs to be maintainable by a group of people. So updating A and B to new versions is ideally straightforwards.
• This is security-critical code so subtle bugs from mismatched dependencies are a concern.

Things I've tried:

• Forking A and X, changing the import paths throughout, and updating A's go.mod. It works but makes updates to those modules slow and error prone.
• Copy and pasting the required code out of A and X to avoid importing it. Also slow and error prone.
• Did a deep dive into creative applications of go mod vendor, but couldn't find a solution.

Answer 1

You can, for example, create local copies of the both modules and use replace directives along with a pseudo major versions to import multiple versions of the same repo using different tags:

replace moduleX/v1010 => ./src/moduleX/0.1.0

replace moduleX/v1020 => ./src/moduleX/0.2.0

Then in your project would use either of the versions as needed:

import (
  moduleX_010 "moduleX/v1010"
  moduleX_020 "moduleX/v1020"
)