cmd/go: inconsistent handling of package main importing another package main #5198
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The go tool assumes that a package main is an executable, and this is by design. The use
of "package main" is a signal to the go tool that you want to compile a command, not a
package object.
The spec allows importing another package main to allow for testing of package main. For
instance:
$ cat main.go
package main
import "fmt"
func Hello() string {
return "Hi"
}
func main() {
fmt.Println(Hello())
}
$ cat main_test.go
package main
import "testing"
func TestHello(t *testing.T) {
want := "Hi"
if got := Hello(); got != want {
t.Errorf("Hello() = %q, want %q", got, want)
}
}
Behind the scenes, when you run "go test", a new main package is constructed that
imports the package main that is under test.
Status changed to WorkingAsIntended. |
Okay, so maybe at the very least the go tool should reject such programs consistently. This scenario: % go install ./a % touch a/a.go % go install ./a # foo/a a/a.go:3: can't find import: "foo/b" % is surprising. The go tool should have either errored out on the first run, or succeed on both; it should do something consistent. It feels buggy that a mere touch breaks the build. |
I believe this is related to this issue, https://golang.org/issue/3417. |
|
Status changed to Duplicate. Merged into issue #4210. |
This issue was closed.
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The spec seems to allow package main to import another package main under another name. However, the experience with the go tool is inconsistent: % cd $GOPATH/src/foo % cat a/a.go package main import _ "foo/b" func init() { println("init: a") } func main() {} % cat b/b.go package main func init() { println("init: b") } func main() {} % rm -f $GOPATH/bin/a % rm -f $GOPATH/bin/b % go install ./a % touch a/a.go % go install ./a # foo/a a/a.go:3: can't find import: "foo/b" % My setup: % go env GOARCH="amd64" GOBIN="" GOCHAR="6" GOEXE="" GOGCCFLAGS="-g -O2 -fPIC -m64 -pthread -fno-common" GOHOSTARCH="amd64" GOHOSTOS="darwin" GOOS="darwin" GOPATH="/p/go" GOROOT="/usr/local/Cellar/go/1.0.3" GOTOOLDIR="/usr/local/Cellar/go/1.0.3/pkg/tool/darwin_amd64" CGO_ENABLED="1" %The text was updated successfully, but these errors were encountered: