$ cat a.go
package a

func F(x, y int) int { return x << y }

$ cat b.go
package b

import "./a"

func f() { a.F(0, 0) }

$ go tool compile -lang=go1.13 a.go
$ go tool compile -lang=go1.12 b.go
/tmp/a.go:3:33: invalid operation: a.x << a.y (signed shift count type int) requires go1.13 or later (-lang was set to go1.12; check go.mod)