x/tools/cmd/goimports: Unexpected goimports behaviour depending on prior imports

[rileykarson]

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

go version go1.11 darwin/amd64

Does this issue reproduce with the latest release?

yes

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

darwin (MacOs), amd64

What did you do?

I work on a code generator that generates a Terraform provider for Google Cloud Platform; we generate code without imports and use goimports to add them.

I updated my local copy of goimports today, and ran into some very unexpected changes. There was a large diff, but most importantly goimports isn't generating correct imports for at least 1 file anymore.

These examples aren't runnable; they're variants of this file, the correct output: https://github.com/terraform-providers/terraform-provider-google/blob/2.0.0/google/resource_compute_subnetwork.go

Given this file: https://play.golang.org/p/Ku1KKO3urCd

when I run goimports -v -w google/resource_compute_subnetwork.go

What did you expect to see?

I expect to see https://github.com/terraform-providers/terraform-provider-google/blob/2.0.0/google/resource_compute_subnetwork.go

If I run goimports in a separate directory with no other files, I see the correct import path. When I run it on an unformatted copy of the file in the provider repo, I get an incorrect output with the bad import path.

What did you see instead?

-compute "google.golang.org/api/compute/v1"
+computeBeta "google.golang.org/api/compute/v0.beta"

Full file: https://play.golang.org/p/wKgEyMWdZto

[rileykarson]

Possibly related to #23001

[heschi]

This is probably related to my recent changes. I'll take a look tomorrow.

[chrisst]

Adding a few more details:
I removed the entire imports block and ran goimports and found the output was as @rileykarson posted above with the reference to the compute beta. Running goimports a second time on the same file (without any other changes) resulted in something more correct looking:

 -   compute "google.golang.org/api/compute/v1"
 +   "google.golang.org/api/compute/v1"

The reference to computeBeta doesn't build, but after running goimports a second time it does result in compilable code.

The behavior appears to have changed as of https://go.googlesource.com/tools/+/ee45598d2ff288037f53f9e13ae0b1a6e2165ad5

[heschi]

This is a variant of a bug I failed to fix correctly in https://golang.org/cl/153440. CL shortly.

[gopherbot]

Change https://golang.org/cl/153859 mentions this issue: imports: fix renamed sibling imports more

[rileykarson]

For completeness, I wanted to confirm that this is working again. Thanks for the quick turnaround!

[heschi]

Quite welcome, sorry for the glitch.