Debug help - Programming in D - extending tail slice terminates sharing unexpectedly. Page 69, 70

[monkyyy]

On Monday, 20 October 2025 at 14:43:05 UTC, Steven Schveighoffer 
wrote:
> On Sunday, 19 October 2025 at 20:44:39 UTC, Brother Bill wrote:
>
>> Console output:
>> ```
>> slice: [1, 3, 5, 7, 9, 11, 13, 15, 17] length: 9 capacity: 11
>>
>> slice: [1, 3, 5, 7, 9, 11, 13, 15, 17] length: 9 capacity: 11
>> tailSlice: [9, 11, 13, 15, 17] length: 5 capacity: 7 
>> &tailSlice[0]: 26AAAA31040
>> tailSlice after incrementing length by 1: [9, 11, 13, 15, 17, 
>> 0] length: 6 capacity: 11 &tailSlice[0]: 26AAAA31060
>> After tail slice length increase and changing tailSlice[0] to 
>> 888.  length: 6 capacity: 11
>> tailSlice: [888, 11, 13, 15, 17, 0]
>> slice    : [1, 3, 5, 7, 9, 11, 13, 15, 17]
>>
>> ```
>
> This is a bug, introduced in 2.111.0
>
> If you use 2.110.0 you will get the expected behavior.
>
> -Steve

someone swapped the tradeoffs then calling it a bug is misleading
if you disagree pls fix this bug
```d
import std;
bool issubset(T)(T[] a,T[] b){
	T* c=min(&a[0],&b[0]);
	T* d=max(&a[$-1],&b[$-1]);
	return &a[0]==c&& &a[$-1]==d;
}
unittest{
	int[100] foo;
	assert(issubset(foo[10..20],foo[15..19]));
	assert( ! issubset(foo[50..100],foo[15..30]));
}
unittest{
	int[] data=[1,2,3];
	int[] tail=data[1..$];
	assert(issubset(data,tail));
	assert(data.capacity>0);
	assert(tail.capacity>0);
	data.length+=1;
	assert(data[$-1]==int.init);
	data[$-1]=4;
	assert(data[$-1]==4);
	assert(issubset(data,tail));
	assert(tail.capacity>0);
	tail.length+=1;
	assert(tail[$-1]==int.init);
	assert(issubset(data,tail));
}
```