Parameters declared as the alias of a template won't accept the arguments of the same type.

[Loara]

On Monday, 2 May 2022 at 17:21:53 UTC, JG wrote:
> On Monday, 2 May 2022 at 16:29:05 UTC, Loara wrote:
>> On Sunday, 1 May 2022 at 03:57:12 UTC, Elfstone wrote:
>>> [...]
>>
>> Template deduction for aliased function parameter is a very 
>> tricky argument and it's not so simple to handle in certain 
>> cases. Consider for example this code:
>>
>> ```d
>>     template MyAlias(T){
>>       alias MyAlias = int;
>>     }
>>
>>     T simp(T)(MyAlias!T val){
>>       return T.init;
>>     }
>>
>>     int main(){
>>       simp(3);//Impossible to deduce T
>>       simp( cast(MyAlias!string) 4);//Also invalid since 
>> MyAlias!string is exactly int
>>       simp!string(4);//Ok, no parameter deduction
>>     }
>> ```
>
>
> I don't really see what your example is trying to show. This 
> also doesn't work,
> and in my mind should be equivalent:
> ```d
> T simp(T)(int val) {
>     return T.init;
> }
>
> int main() {
>     simp(3);//Impossible to deduce T
> }
> ```

Yeah I know, but I'm trying  to show that allowing aliased 
templated function parameters will bring many bugs in user code, 
especially with aliases that alias another aliased declarations. 
I think using 
[typedefs](https://dlang.org/phobos/std_typecons.html#Typedef) 
and template constraints is simpler and make your code more 
readable too.