[Issue 21780] deprecation warning for considered but unused alias this

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=21780

moonlightsentinel at disroot.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |moonlightsentinel at disroot.o
                   |                            |rg
           Hardware|x86_64                      |All
            Summary|alias this preferred over   |deprecation warning for
                   |immutable conversion even   |considered but unused alias
                   |if alias this is deprecated |this
                   |and de is on                |
                 OS|Linux                       |All
           Severity|trivial                     |regression

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