cmd/go: relative replacements in a workspace are not resolved relative to their go.mod files

[jezell]

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

1.18beta2

Does this issue reproduce with the latest release?

What did you do?

Checkout the following repo:

https://github.com/jezell/gosync

run go work sync

What did you expect to see?

expect the command to complete successfully

What did you see instead?

go: conflicting replacements for example.com/test:
	../test
	../../test
use "go work edit -replace example.com/test=[override]" to resolve

Suggested Fix

It appears that when checking for replacement conflicts, go work sync does not resolve relative replacement paths. While this may work for flat workspaces, this causes problems when module replacements are used within sub folders. Perhaps go work sync should resolve relative paths to absolute paths before performing its check for conflicts so that when two replacements point to exactly the same place the command doesn't fail.

[bcmills]

FWIW, I don't think this is specific to go work sync. Investigating.

[gopherbot]

Change https://go.dev/cl/385994 mentions this issue: cmd/go: in workspace mode, resolved replacements relative to their go.mod files

[bcmills]

Marking as release-blocker: I have a fix out for review and passing tests, and the sort of replace that triggers this bug is likely to occur in real multi-module repos.