gcc/testsuite/go.test/test/nilptr/arrayindex.go

   1 // [ $GOOS != nacl ] || exit 0  # do not bother on NaCl
   2 // $G $D/$F.go && $L $F.$A &&
   3 //      ((! sh -c ./$A.out) >/dev/null 2>&1 || echo BUG: should fail)
   4
   5 // Copyright 2009 The Go Authors. All rights reserved.
   6 // Use of this source code is governed by a BSD-style
   7 // license that can be found in the LICENSE file.
   8
   9 package main
  10
  11 import "unsafe"
  12
  13 var x byte
  14
  15 func main() {
  16         var p *[1<<30]byte = nil
  17         x = 123
  18
  19         // The problem here is not the use of unsafe:
  20         // it is that indexing into p[] with a large
  21         // enough index jumps out of the unmapped section
  22         // at the beginning of memory and into valid memory.
  23         // Pointer offsets and array indices, if they are
  24         // very large, need to dereference the base pointer
  25         // to trigger a trap.
  26         println(p[uintptr(unsafe.Pointer(&x))]) // should crash
  27 }