[Issue 14125] @trusted nested helper functions in std.file

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=14125

--- Comment #46 from Walter Bright <bugzilla at digitalmars.com> ---
I was a bit curious where these misunderstandings came from. Turns out, 
example code for C# 'unsafe' code presents not only unsafe code, but an unsafe
interface:

https://msdn.microsoft.com/en-us/library/aa288474(v=vs.71).aspx#vcwlkunsafecode_readfileexample

      public unsafe int Read(byte[] buffer, int index, int count) 
      {
            int n = 0;
            fixed (byte* p = buffer) 
            {
                  if (!ReadFile(handle, p + index, count, &n, 0))
                        return 0;
            }
            return n;
      }

Note that there's no guarantee that index is within the length of buffer[]. The
poor sot cannot simply review Read(), he's got to review EVERY SINGLE CALLER of
read(). Since this is taught as correct usage of 'unsafe', it's something we're
going to have to regularly auger against.

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