cmd/go: tool should explicitely reject an empty tool name

[dolmen]

Go version

go version go1.24.5 darwin/arm64

Output of go env in your module/workspace:

GOROOT='/opt/homebrew/Cellar/go/1.24.5/libexec'

What did you do?

$ go tool !
go: no such tool "!"
$ go tool ""
go tool : fork/exec /opt/homebrew/Cellar/go/1.24.5/libexec/pkg/tool/darwin_arm64: permission denied

What did you see happen?

The error message shows that the tool execution failure is caught by the OS which was given a directory path instead of a executable file path.

What did you expect to see?

go tool should reject much earlier such an invalid tool name and immediately fail with an error message.

$ go tool ""
go: no such tool ""

[dolmen]

The implementation of tool lookup is in cmd/go/internal/base.Tool and ToolPath.

[dolmen]

Patch in progress...

[gopherbot]

Change https://go.dev/cl/690435 mentions this issue: cmd/go/internal/base: reject an empty tool name

[gabyhelp]

Related Issues

• cmd/go: `go tool -n` can point to a file that doesn't exist #72824 (closed)
• cmd/go get doesn't validate module arguments #71437 (closed)

Related Code Changes

• cmd/go/internal/base: reject an empty tool name

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[mknyszek]

CC @golang/command-line