无法使用通过“ Go build”从Go代码编译的C库

I am trying to get a minimal example of using Go code in C to work, such as this. I am struggling with the following compilation error message:

ld: warning: ignoring file /Users/username/gocode/src/example/example.dylib, file was built for archive which is not the architecture being linked (x86_64): /Users/username/gocode/src/example/example.dylib

My attempt is the following. I have a simple Go package in a file main.go:

package example

import "C"

//export GoEcho
func GoEcho(s *C.char) string {
    return C.GoString(s)
}

func main() {}

which I then compile using either

go build -buildmode=c-archive -o example.dylib main.go

go build -buildmode=c-shared -o example.dylib main.go

GOARCH=amd64 go build -buildmode=c-shared -o LibraryLinkExamples.dylib main.go

The operating system is OS X 10.11 and the the Go version is, as go version puts it, go1.9 darwin/amd64.

The C code I'm using is the following:

#include "example.h"
#include <stdio.h>

int main(int argc, char const *argv[])
{
    GoString res = GoEcho("test");
    printf("%.*s
", (int)res.n, res.p);
    return 0;
}

I don't understand why I am getting the "which is not the architecture being linked (x86_64)" error message when I am building the library and using it on the same operating system, even the computer? What can explain this?

Update In the official documentation here it says: