Duplicated functions not reported?

[Temtaime via Digitalmars-d-learn]

On Sunday, 16 April 2017 at 15:54:16 UTC, Stefan Koch wrote:
> On Sunday, 16 April 2017 at 10:56:37 UTC, Era Scarecrow wrote:
>> On Saturday, 15 April 2017 at 11:10:01 UTC, Stefan Koch wrote:
>>> It would requires an O(n^2) check per declaration.
>>> Even it is never used.
>>> which would make imports that much more expensive.
>>
>>  Seems wrong to me...
>>
>>  If you made a list/array of all the functions (based purely 
>> on signatures) then sorted them, then any duplicates would be 
>> adjacent. Scanning that list would be O(n-1).
>>
>>  This assumes it's done after all functions are scanned and 
>> identified, doing it earlier is a waste of time and energy.
>
>
> sorting has O(n^2) worst case complexity.
> Therefore totaling to O(n^2) worst case again.

Why this difficulty ?
Function[args][name] funcs;

AA lookup is O(1).