[Issue 3720] Taking address of member functions possible without an instance

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=3720

ZombineDev <petar.p.kirov at gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
                 CC|                            |petar.p.kirov at gmail.com
         Resolution|INVALID                     |---

--- Comment #18 from ZombineDev <petar.p.kirov at gmail.com> ---
Reopening as this issue is a too ugly issue to be left unaddressed.

I suggest the following plan going forward:
1. Deprecate the expression &<AggregateType>.<memberFunction> even in @system
code, but allow the equivalent:
  &__traits(getMember, <AggregateType>, "<memberFunction>")

as we need to have migration path for the small amount of code that is able to
correctly use &<AggregateType>.<memberFunction>

2. After deprecation period is finished, reintroduce the
&<AggregateType>.<memberFunction> but with different semantics: retunring a
delegate with context pointer set to null.

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