Bug 11561 – Built-in array .capacity returns 0 if array length is decreased

Consider the following code: int[] arr; arr.length = 10; writeln(arr.length, "\t", arr.capacity); arr.length = 5; writeln(arr.length, "\t", arr.capacity); Expected output: 10 15 5 n ... where n >= 5. Actual output: 10 15 5 0 Since clearly the capacity of the array of length 5 _isn't_ 0, there is something wrong in how the .capacity property is calculating its value after the array length is reduced.

No, this is correct. A capacity of zero simply means the slice cannot be appended to. http://dlang.org/phobos/object.html#.capacity If an append must reallocate a slice with no possibility of extension, then 0 is returned. This happens when the slice references a static array, or if another slice references elements past the end of the current slice.

Fair enough. Apologies for the misunderstanding.