Strange behavior on shrinking a Dynamic Array -- Capacity reduces to 0

[d coder]

Hello List

As per TDPL and D documentation, shrinking a dynamic array should not
relocate it. But that is exactly what is happening.
On shrinking an array, its capacity is getting reduced to 0. Surprisingly
the capacity after a shrink is even less than the length
of the array. As a result the array gets relocated as soon as another
element is added to it.

I have to call reserve again after shrinking it to make sure that the array
is not relocated.

Is this the expected behavior?

Regards
- Puneet

P.S. Please compile the following code to see yourself.

import std.stdio;

void main() {
  uint [] arr;
  reserve(arr, 2048);
  writeln("After reservation:");
  writefln("arr is at: %10s, length: %6s, capacity %6s",
   arr.ptr, arr.length, capacity(arr));
  // Grow the array
  for (size_t i = 0; i < 64; ++i) arr ~= i;

  writeln("After appending:");
  writefln("arr is at: %10s, length: %6s, capacity %6s",
   arr.ptr, arr.length, capacity(arr));

  arr.length = 32;
  // reserve(arr, 2048); // does not relocate if uncommented

  writeln("After setting length:");
  writefln("arr is at: %10s, length: %6s, capacity %6s",
   arr.ptr, arr.length, capacity(arr));

  // grow the array again
  for (size_t i = 0; i < 32; ++i) arr ~= i;
  writeln("After appending again:");
  writefln("arr is at: %10s, length: %6s, capacity %6s",
   arr.ptr, arr.length, capacity(arr));
}
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