Boxing In Hot Path (ARCH5087)

Key go.performance.boxing-in-hot-path · Severity info · Category performance

Wrapping values in interface{} (any) inside a tight loop forces a heap allocation on every iteration. Keep concrete types on hot paths.

Incorrect

func sum(nums []int) int {
  var total int
  for _, n := range nums {
    var boxed any = n
    total += boxed.(int)
  }
  return total
}

Correct

func sum(nums []int) int {
  var total int
  for _, n := range nums {
    total += n
  }
  return total
}

Fix

Remove interface{}/any wrapping in hot loops and use the concrete type directly.