[Issue 23726] Array append in CTFE no longer works without _d_arrayappendT

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=23726

--- Comment #2 from zach-dmd at cs.stanford.edu ---
I see, thanks for the explanation. I guess this is not a bug then. However,
lack of stability between DMD and D-runtime makes it difficult to make a case
for bare-metal D (with a custom runtime), since we will have to maintain the
custom D-runtime in unison with compiler updates, and the application will
probably only be usable with the most recent version of D (unless we start
maintaining the custom D-runtime for all compiler versions since the start of
the project). I suppose if we keep the number of language features used to a
minimum (e.g., disallow `~=`, even in CTFE), then hopefully there won't be
much/any breakage across D versions, but there is no guarantee.

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