How Can Go Return a Pointer to a Local Struct?

Understanding the Semantics of Returning Pointers to Local Structs in Go

In Go, a construct such as the following is often encountered:

type point struct {
  x, y int
}

func newPoint() *point {
  return &point{10, 20}
}

This code snippet may raise concerns for developers coming from a C background. The question is: given that the point struct is a local variable within the newPoint function, how can a pointer to it be returned?

The key here lies in Go's memory management mechanism known as pointer escape analysis. Pointer escape analysis examines the flow of pointers and identifies those that escape the local stack frame. If a pointer escapes, as in this case where the pointer is returned from the function, the object it points to will be allocated on the heap.

In the absence of pointer escape, Go is at liberty to allocate the object on the stack. However, it's important to note that the compiler provides no guarantees in this regard. Allocation on the heap or stack is subject to the compiler's ability to determine if the pointer remains local to the function.

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