This test checks that gopls works with multiple ad-hoc packages, which lack
a go.mod file.

We should be able to import standard library packages, get diagnostics, and
reference symbols defined in the same directory.

-- main.go --
package main

import "fmt"

func main() {
	fmt.Println(mainMsg) //@def("mainMsg", mainMsg)
	fmt.Println(undef) //@diag("undef", re"undefined|undeclared")
}
-- main2.go --
package main

const mainMsg = "main" //@loc(mainMsg, "mainMsg")

-- a/a.go --
package a

import "fmt"

func _() {
	fmt.Println(aMsg) //@def("aMsg", aMsg)
	fmt.Println(undef) //@diag("undef", re"undefined|undeclared")
}

-- a/a2.go --
package a

const aMsg = "a" //@loc(aMsg, "aMsg")

-- b/b.go --
package b

import "fmt"

func _() {
	fmt.Println(bMsg) //@def("bMsg", bMsg)
	fmt.Println(undef) //@diag("undef", re"undefined|undeclared")
}

-- b/b2.go --
package b

const bMsg = "b" //@loc(bMsg, "bMsg")