// run // Copyright 2020 The Go Authors. All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. //go:build cgo package main import ( "runtime/cgo" "unsafe" ) type S struct { _ cgo.Incomplete x int } func main() { var i int p := (*S)(unsafe.Pointer(uintptr(unsafe.Pointer(&i)))) v := uintptr(unsafe.Pointer(p)) // p is a pointer to a not-in-heap type. Like some C libraries, // we stored an integer in that pointer. That integer just happens // to be the address of i. // v is also the address of i. // p has a base type which is marked not-in-heap, so it // should not be adjusted when the stack is copied. recurse(100, p, v) } func recurse(n int, p *S, v uintptr) { if n > 0 { recurse(n-1, p, v) } if uintptr(unsafe.Pointer(p)) != v { panic("adjusted notinheap pointer") } }