go-autorest ambiguous module #3137
Description
If you are building a project with a dependency on distribution/distribution and another dependency which uses a go-autorest version after go-autorest was broken into sub modules, there will be a ambiguous import found which causes go mod to fail.
Here's an example where the project has a dependency on this project and we try to add a dependency on sigs.k8s.io/cluster-api-provider-azure.
davidjustice at extremis in ~/code/devigned/go-autorest-mods-test on master [+!?]
$ go get github.com/docker/distribution@v0.0.0-20191216044856-a8371794149d
go: downloading github.com/docker/distribution v0.0.0-20191216044856-a8371794149d
go: downloading github.com/opencontainers/go-digest v0.0.0-20170106003457-a6d0ee40d420
go: downloading github.com/opencontainers/image-spec v1.0.0
davidjustice at extremis in ~/code/devigned/go-autorest-mods-test on master [+!?]
$ go get sigs.k8s.io/cluster-api-provider-azure
go: downloading sigs.k8s.io/cluster-api-provider-azure v0.4.0
go: sigs.k8s.io/cluster-api-provider-azure upgrade => v0.4.0
go: downloading sigs.k8s.io/cluster-api v0.3.0
go: downloading sigs.k8s.io/controller-runtime v0.5.0
go: downloading github.com/Azure/go-autorest v10.8.1+incompatible
../../../go/pkg/mod/sigs.k8s.io/cluster-api-provider-azure@v0.4.0/cloud/errors.go:20:2: ambiguous import: found package github.com/Azure/go-autorest/autorest in multiple modules:
github.com/Azure/go-autorest v10.8.1+incompatible (/Users/davidjustice/go/pkg/mod/github.com/!azure/go-autorest@v10.8.1+incompatible/autorest)
github.com/Azure/go-autorest/autorest v0.10.0 (/Users/davidjustice/go/pkg/mod/github.com/!azure/go-autorest/autorest@v0.10.0)
../../../go/pkg/mod/github.com/!azure/azure-sdk-for-go@v40.4.0+incompatible/services/compute/mgmt/2019-12-01/compute/availabilitysets.go:23:2: ambiguous import: found package github.com/Azure/go-autorest/autorest/azure in multiple modules:
github.com/Azure/go-autorest v10.8.1+incompatible (/Users/davidjustice/go/pkg/mod/github.com/!azure/go-autorest@v10.8.1+incompatible/autorest/azure)
github.com/Azure/go-autorest/autorest v0.10.0 (/Users/davidjustice/go/pkg/mod/github.com/!azure/go-autorest/autorest@v0.10.0/azure)
../../../go/pkg/mod/sigs.k8s.io/cluster-api-provider-azure@v0.4.0/cloud/scope/clients.go:23:2: ambiguous import: found package github.com/Azure/go-autorest/autorest/azure/auth in multiple modules:
github.com/Azure/go-autorest v10.8.1+incompatible (/Users/davidjustice/go/pkg/mod/github.com/!azure/go-autorest@v10.8.1+incompatible/autorest/azure/auth)
github.com/Azure/go-autorest/autorest/azure/auth v0.4.2 (/Users/davidjustice/go/pkg/mod/github.com/!azure/go-autorest/autorest/azure/auth@v0.4.2)
../../../go/pkg/mod/github.com/!azure/azure-sdk-for-go@v40.4.0+incompatible/services/compute/mgmt/2019-12-01/compute/models.go:25:2: ambiguous import: found package github.com/Azure/go-autorest/autorest/date in multiple modules:
github.com/Azure/go-autorest v10.8.1+incompatible (/Users/davidjustice/go/pkg/mod/github.com/!azure/go-autorest@v10.8.1+incompatible/autorest/date)
github.com/Azure/go-autorest/autorest/date v0.2.0 (/Users/davidjustice/go/pkg/mod/github.com/!azure/go-autorest/autorest/date@v0.2.0)
../../../go/pkg/mod/sigs.k8s.io/cluster-api-provider-azure@v0.4.0/controllers/azuremachine_reconciler.go:23:2: ambiguous import: found package github.com/Azure/go-autorest/autorest/to in multiple modules:
github.com/Azure/go-autorest v10.8.1+incompatible (/Users/davidjustice/go/pkg/mod/github.com/!azure/go-autorest@v10.8.1+incompatible/autorest/to)
github.com/Azure/go-autorest/autorest/to v0.3.0 (/Users/davidjustice/go/pkg/mod/github.com/!azure/go-autorest/autorest/to@v0.3.0)
../../../go/pkg/mod/github.com/!azure/azure-sdk-for-go@v40.4.0+incompatible/services/compute/mgmt/2019-12-01/compute/containerservices.go:24:2: ambiguous import: found package github.com/Azure/go-autorest/autorest/validation in multiple modules:
github.com/Azure/go-autorest v10.8.1+incompatible (/Users/davidjustice/go/pkg/mod/github.com/!azure/go-autorest@v10.8.1+incompatible/autorest/validation)
github.com/Azure/go-autorest/autorest/validation v0.2.0 (/Users/davidjustice/go/pkg/mod/github.com/!azure/go-autorest/autorest/validation@v0.2.0)
This is an issue folks are running into as evidenced by this thread https://twitter.com/ibuildthecloud/status/1245061326629556226