What version of Go are you using (go version)?

1.11

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

linux/amd64

What did you do?

Tried importing and using the package github.com/go-gl/mathgl/mgl64 in a project.

What did you expect to see?

Go downloading the package, adding the repository to go.mod and building the executable.

What did you see instead?

$ go run .
go: finding github.com/go-gl/mathgl/mgl64 latest
go: finding github.com/go-gl/mathgl/mgl32 latest
go: finding github.com/go-gl/mathgl latest
phys/phys.go:4:2: unknown import path "github.com/go-gl/mathgl/mgl64": cannot find module providing package github.com/go-gl/mathgl/mgl64

Go does add the repository to go.mod as:

require (
	github.com/go-gl/mathgl v0.0.0-20180804195959-cdf14b6b8f8a
)

but it is not found when building.