x/tools/gopls: expands workspace to the wrong root when go.mod file is above go.work.

[findleyr]

The following bug was discovered in golang/vscode-go#2884:

output.txt:

go/packages.Load #1
	snapshot=0
	directory=file:///C:/Users/Kindred87/OneDrive%20-%20Company/Projects/Project%20Name/code
	query=[C:\Users\Kindred87\OneDrive - Company\Projects\Project Name\code\TGB\... C:\Users\Kindred87\OneDrive - Company\Projects\Project Name\code\cwb\... builtin]
	packages=3

happy_output.txt:

go/packages.Load #1
	snapshot=0
	directory=file:///C:/Users/Kindred87/OneDrive%20-%20Company/Projects/Project%20Name/code
	query=[C:\Users\Kindred87\OneDrive - Company\Projects\Project Name\code\TGB\... C:\Users\Kindred87\OneDrive - Company\Projects\Project Name\code\cwb\... builtin]
	packages=12

In other words, it looks like the same query, from the same workspace, is returning different results.

Digging deeper, I found it:

output.txt:

Params: {"type":3,"message":"2023/11/02 11:27:46 go info for C:\\Users\\Kindred87\\OneDrive - Company\\Projects\\Project Name\\code\n(go dir C:\\Users\\Kindred87\\OneDrive - Company\\Projects\\Project Name)\n(go version go version go1.21.3 windows/amd64)\n(valid build configuration = true)\n(build flags: [])\n(selected go env: [GO111MODULE=, GOCACHE=C:\\Users\\Kindred87\\AppData\\Local\\go-build, GOFLAGS=, GOMODCACHE=C:\\Users\\Kindred87\\go\\pkg\\mod, GOPATH=C:\\Users\\Kindred87\\go, GOPRIVATE=, GOROOT=C:\\Program Files\\Go, GOWORK=C:\\Users\\Kindred87\\OneDrive - Company\\Projects\\Project Name\\code\\go.work])\n\n"}

happy_output.txt:

Params: {"type":3,"message":"2023/11/02 11:42:45 go info for C:\\Users\\Kindred87\\OneDrive - Company\\Projects\\Project Name\\code\n(go dir C:\\Users\\Kindred87\\OneDrive - Company\\Projects\\Project Name\\code)\n(go version go version go1.21.3 windows/amd64)\n(valid build configuration = true)\n(build flags: [])\n(selected go env: [GO111MODULE=, GOCACHE=C:\\Users\\Kindred87\\AppData\\Local\\go-build, GOFLAGS=, GOMODCACHE=C:\\Users\\Kindred87\\go\\pkg\\mod, GOPATH=C:\\Users\\Kindred87\\go, GOPRIVATE=, GOROOT=C:\\Program Files\\Go, GOWORK=C:\\Users\\Kindred87\\OneDrive - Company\\Projects\\Project Name\\code\\go.work])\n\n"}

The "go dir" is being computed incorrectly. That logic is here:
https://cs.opensource.google/go/x/tools/+/master:gopls/internal/lsp/cache/view.go;l=1005;drc=cf5aad9d898a74d0f6cd041af86762f1122b926a

So @Kindred87 can you please confirm that you have a go.mod file in C:\\Users\\Kindred87\\OneDrive - Company\\Projects\\Project Name? If that is the case, then gopls is expanding the workspace to the wrong directory. Adding another go.mod file truncates the search, as you discovered.

Gopls should instead be truncating that expansion at a go.work file, if present. This is just a bug, though we probably don't hit it that often as go.mod > go.work is relatively unlikely. All of this is being rewritten right now in https://go.dev/issue/57979, so I'm not sure if it is worth fixing this bug, which has been present for a long time. Soon gopls will "do the right thing always"...

Originally posted by @findleyr in golang/vscode-go#2884 (comment)

[gopherbot]

Change https://go.dev/cl/562015 mentions this issue: gopls/internal/test/integration: add a test for an inner go.work file