[Issue 21891] Cannot alias every kind that can be passed via variadic templates

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=21891

hsteoh at quickfur.ath.cx changed:

           What    |Removed                     |Added
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                 CC|                            |hsteoh at quickfur.ath.cx

--- Comment #1 from hsteoh at quickfur.ath.cx ---
This makes me wonder why alias parameters were introduced in the first place.
Phobos makes extensive use of alias parameters for binding to lambdas, for
example, so it appears that it was a deliberate decision to distinguish between
unmarked template parameters receiving types vs alias parameters receiving
things that might not be types.  But yeah, this subtle and mostly-arbitrary
distinction is the source of a number of weird corner cases and inhomogeneities
in Phobos and also in the language in general.

My inclination is to get rid of this arbitrary distinction so that the language
has less special cases.

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