cmd/go: go generate fails silently when run on a package in a nested workspace module

[findleyr]

I noticed the following while working on https://go.dev/cl/440181. I have a go.work file using both x/tools and x/tools/gopls. When running go generate on a package in x/tools/gopls, the command exits with status 0 without doing anything.

When run from the gopls module, the go generate command works as expected. This can be seen from the following shell history, where I start from a clean workspace (at patchset 2 of the above CL), make an arbitrary edit in one of the generated files, and run go generate expecting it to revert the diff.

$ git status
On branch accessdenied
Your branch is ahead of 'origin/master' by 1 commit.

nothing to commit, working tree clean
$ echo "// arbitrary edit" >> gopls/internal/robustio/robustio.go
$ git status
On branch accessdenied
Your branch is ahead of 'origin/master' by 1 commit.

Changes not staged for commit:
        modified:   gopls/internal/robustio/robustio.go

no changes added to commit
$ go generate ./gopls/internal/robustio
$ echo $?
0
$ git status
On branch accessdenied
Your branch is ahead of 'origin/master' by 1 commit.

Changes not staged for commit:
        modified:   gopls/internal/robustio/robustio.go

no changes added to commit
$ cd gopls && go generate ./internal/robustio
$ git status
On branch accessdenied
Your branch is ahead of 'origin/master' by 1 commit.

nothing to commit, working tree clean

[bcmills]

Duplicate of #29751

[bcmills]

Hmm, not quite a duplicate (because of workspace mode). But #29751 is definitely closely related.

[gopherbot]

Change https://go.dev/cl/559195 mentions this issue: cmd/go/internal/generate: call modload.InitWorkFile

[matloob]

@gopherbot please backport to 1.21 and 1.22. go generate doesn't work in workspace mode and it's a one-line fix

[gopherbot]

Backport issue(s) opened: #65351 (for 1.21), #65352 (for 1.22).

Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://go.dev/wiki/MinorReleases.

[gopherbot]

Change https://go.dev/cl/559235 mentions this issue: cmd/go/internal/generate: call modload.InitWorkFile

[gopherbot]

Change https://go.dev/cl/559236 mentions this issue: cmd/go/internal/generate: call modload.InitWorkFile