Test of references applied to concrete and interface types that are
related by assignability. The result includes references to both.

-- go.mod --
module example.com
go 1.12

-- a/a.go --
package a

type first interface {
	common() //@loc(firCommon, "common"), refs("common", firCommon, xCommon, zCommon)
	firstMethod() //@loc(firMethod, "firstMethod"), refs("firstMethod", firMethod, xfMethod, zfMethod)
}

type second interface {
	common() //@loc(secCommon, "common"), refs("common", secCommon, yCommon, zCommon)
	secondMethod() //@loc(secMethod, "secondMethod"), refs("secondMethod", secMethod, ysMethod, zsMethod)
}

type s struct {}

func (*s) common() {} //@loc(sCommon, "common"), refs("common", sCommon, xCommon, yCommon, zCommon)

func (*s) firstMethod() {} //@loc(sfMethod, "firstMethod"), refs("firstMethod", sfMethod, xfMethod, zfMethod)

func (*s) secondMethod() {} //@loc(ssMethod, "secondMethod"), refs("secondMethod", ssMethod, ysMethod, zsMethod)

func main() {
	var x first = &s{}
	var y second = &s{}

	x.common() //@loc(xCommon, "common"), refs("common", firCommon, xCommon, zCommon)
	x.firstMethod() //@loc(xfMethod, "firstMethod"), refs("firstMethod", firMethod, xfMethod, zfMethod)
	y.common() //@loc(yCommon, "common"), refs("common", secCommon, yCommon, zCommon)
	y.secondMethod() //@loc(ysMethod, "secondMethod"), refs("secondMethod", secMethod, ysMethod, zsMethod)

	var z *s = &s{}
	z.firstMethod() //@loc(zfMethod, "firstMethod"), refs("firstMethod", sfMethod, xfMethod, zfMethod)
	z.secondMethod() //@loc(zsMethod, "secondMethod"), refs("secondMethod", ssMethod, ysMethod, zsMethod)
	z.common() //@loc(zCommon, "common"), refs("common", sCommon, xCommon, yCommon, zCommon)
}