[Issue 24233] T[].canFind(Nullable!T()) returns true when it used to return false

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=24233

Jonathan M Davis <issues.dlang at jmdavisProg.com> changed:

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--- Comment #3 from Jonathan M Davis <issues.dlang at jmdavisProg.com> ---
(In reply to Paul Backus from comment #2)
> This is arguably a design flaw in canFind (and find). Having different
> overloads of the same function take inputs with different "shapes" (range
> vs. element) seems like an open invitation for this kind of confusion.
> Perhaps something to think about for Phobos v3.

Agreed. Regardless of the issues with Nullable, there are a variety of places
in Phobos where things were made too liberal in what they accepted (be it
originally or by expanding their functionality later to try to make them more
useful), and it's caused subtle issues and confusion like this. A similar issue
is with put on output ranges accepting both singular values and ranges. It
works in most cases, but in others, it results in the wrong overload being
used.

Of course that doesn't necessarily mean that we shouldn't have any range-based
functions accepting both elements and ranges, but it is definitely something
that we need to carefully consider with each function where we're looking to do
it so that we can hopefully provide the desired functionality without the
subtle issues. We obviously won't catch everything, but we should be able to do
better now that we know more from having used this stuff over time and folks
reporting stuff like this.

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