Suboptimal golang escape analysis test

escape.go

// Package escape allows you to observe suboptimal compiler escape analysis as
// seen in go1.3.3. Try with: `go build -gcflags -m escape.go'
package escape
 
// Compiler figures out that num does not escape.
func NoEscape() {
  for i := 0; i < 2; i++ {
    num := new(int)
    _ = num
  }
}
 
// Compiler figures out that num2 does not escape.
func NoEscape2() {
  var num int
  var num2 *int
  for i := 0; i < 2; i++ {
    num2 = &num
    _ = num2
  }
}
 
// However, here the compiler can't figure out that num doesn't escsape.
func ShouldntEscape() {
  var num *int
  for i := 0; i < 2; i++ {
    num = new(int)
    _ = num
  }
}