Is there any import path limitation when using go:linkname localname importpath.name?

[Cholerae Hu]

I'm trying to play with go:linkname, and I wrote a demo for this.

directory structure:

[test]$ tree

.

├── main.go

├── pri

│   └── a.go

└── pub

    ├── issue15006.s

    └── b.go

a.go:

package pri


import (
    "fmt"
)
func rua() int64 {
    fmt.Println("rua in pri")
    return 1
}

b.go:

package pub


import (
    "unsafe"
)


var _ = unsafe.Sizeof(0)


//go:noescape
//go:linkname rua test/pri.rua
func rua() int64


func Rua() int64 {
    return rua()
}

main.go:

package main


import (
    "test/pub"
)


func main() {
    println(pub.Rua())
}

issue15006.s is a workaround for issue 15006 and it's totally empty.

Than I ran `go run main.go` and got an error:

# command-line-arguments
test/pub.Rua: test/pri.rua: not defined
test/pub.Rua: undefined: test/pri.rua

So what's wrong with this demo?

[Ian Lance Taylor]

Nothing in your program imports test/pri. go:linkname only changes
the name used for a symbol. It doesn't cause a package to be
imported.

Ian

[Cholerae Hu]

I edited my code to import test/pri in test/pub:

pri/a.go:

package pri


import (
    "fmt"
)

const (
    Dummy = 1

)
func rua() int64 {
    fmt.Println("rua in pri")

    return int64(1)
}

pub/b.go:

package pub


import (
    "unsafe"

    pri "test/pri"

)


var _ = unsafe.Sizeof(0)

var _ = pri.Dummy


//go:noescape
//go:linkname rua pri.rua

func rua() int64


func Rua() int64 {
    return rua()
}

But this still don't work.  

# command-line-arguments

test/pub.Rua: pri.rua: not defined

test/pub.Rua: undefined: pri.rua

Besides, this package doesn't import "runtime" at all, but it can use "runtime.nanotime" in go:linkname.

在 2017年1月20日星期五 UTC+8下午1:34:43，Ian Lance Taylor写道：

[Cholerae Hu]

I removed the alias "pri", and it works, thanks!

By the way, when go:linkname with runtime, why don't I need to import "runtime" package explicitly?

在 2017年1月20日星期五 UTC+8下午1:34:43，Ian Lance Taylor写道：

On Wed, Jan 18, 2017 at 6:55 PM, Cholerae Hu <chole...@gmail.com> wrote:

[Ian Lance Taylor]

On Fri, Jan 20, 2017 at 12:16 AM, Cholerae Hu <chole...@gmail.com> wrote:
> I removed the alias "pri", and it works, thanks!
> By the way, when go:linkname with runtime, why don't I need to import
> "runtime" package explicitly?

The runtime package is always imported implicitly by every Go package
(other than runtime and runtime/internal/*).

Ian