Why is Go trying to upgrade my
go.mod to Go 1.21?
On oapi-codegen we recently had a report that Go 1.21 results in
go test being unable to run without having
go mod tidy'd the project.
If you're running Go 1.21:
$ go version go version go1.21.0 linux/amd64
Then checking out the project (as of the latest commit and running
make tidy shows the following diff:
diff --git go.mod go.mod index dd8b906..2122b0e 100644 --- go.mod +++ go.mod @@ -1,6 +1,8 @@ module github.com/deepmap/oapi-codegen -go 1.20 +go 1.21 + +toolchain go1.21.0
Through discussion in the Go community (Gopher) Slack, it appears that this is due to one of the modules in my dependency tree using Go 1.21, and therefore Go is upgrading the whole project to Go 1.21.
As noted in the Go 1.21 release notes, the
go directive now defines an explicit minimum, whereas before it could be possible to try and build a future version of Go code, and maybe it would just work, or fail.
I've blogumented that process to determine the versions in a separate blog post.
But if you're seeing this issue, your best course of action is to take the changes and upgrade the whole project to 1.21.