Which language constructs could be done as a library if we accept some breaking changes?

[user1234]

On Monday, 29 November 2021 at 13:11:12 UTC, user1234 wrote:
> On Monday, 29 November 2021 at 12:51:47 UTC, Ola Fosheim 
> Grøstad wrote:
>> On Monday, 29 November 2021 at 12:30:42 UTC, user1234 wrote:
>>> static casts, devirtualization, are reasons for built-in
>> Also, since it would be a standard library construct a good 
>> compiler could have a special path for those. So it should 
>> remain the same.
>
> If there must be a special path then it's already a failed 
> library solution, not to say a lie. You make think to the user 
> that classes is a library thing but it's not.

BTW, to be clear: yes I know that AliasSeq borrows such a special 
path in the compiler...but that rather tendd to show that the 
opposite is required: from library to builtin feature.