C Compiler Bug

[keenan at inmet.UUCP]

Here is a small program that demonstrates what I think is a bug in the
BSD2.9 C compiler. I guess its not appropriate to use a long as the
index to an array, but it should just be cast to an integer, and not
affect the postdecrement. Instead the decrement treats the variable as
an integer.  The results are also presented. Is this a bug, or is my
code just incorrect?

#include <stdio.h>
int arr[100];
int x;
long p_end;
main()
{
  printf("Autodecrement inside array reference\n");
  p_end = 0l;
  printf("before %ld\n", p_end);
  x = arr[p_end--];
  printf("after %ld\n", p_end);
}

++++++++++++++++++++++++++ OUTPUT +++++++++++++++++++++++++
Autodecrement inside array reference
before 0
after 65535

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