os/exec: Cmd changes absolute path to relative when using go

[WillDrug]

Using go version go1.11.1 linux/amd64 with default env I run the following code (simplified for the ticket, added extra fmt.Print*)

cmdArgs = <-stdin
log.Printf("Got %v to run", cmdArgs)
cmd := exec.Command(cmdArgs[0], cmdArgs[1:]...)
ret, err = cmd.CombinedOutput()
fmt.Println(ret)

Expected result --

Got [go build -o=/abs/path/to/output/HelloWorld -a /abs/path/to/code/HelloWorld/] to run

Actual result --

Got [go build -o=/abs/path/to/output/HelloWorld -a /abs/path/to/code/HelloWorld/] to run
go: directory ../HelloWorld/ outside available modules

Somehow, exec.Command transforms an absolute build path to relative (specifically, relative to current software working dir), making me think that when the program runs, additional go execs have the same execution environment.

Appending cmd.Dir = "/abs/path/to/code/HelloWorld/" fixes the issue, but I would like to get around this.

P.S. Since build path is absolute, obviously, I'm using go mod.

[ianlancetaylor]

The go tool prints a path as relative if that is shorter. See https://golang.org/src/cmd/go/internal/base/path.go#L23 . This isn't a bug in os/exec. I don't think it's a bug at all. Closing. Please comment if you disagree. If you do disagree, please provide a complete program that shows the problem, not a fragment; thanks.