[Issue 14478] isInputRange failed to recognize some ranges

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=14478

--- Comment #7 from Jonathan M Davis <issues.dlang at jmdavisProg.com> ---
> Most containers in C++ only require movability, otherwise you couldn't have containers of std::unique_ptr<T>

Then that's a change with C++11.

Regardless, while it might be nice to support non-copyable elements with
ranges, I really don't think that it's worth it - particularly when
isInputRange has always required copyability. We'd be forced to either create a
separate set of basic range traits - e.g. isInputRangeWithNonCopyableElements -
or add something like hasCopyableElements and change isInputRange to no longer
require copyable elements, which would then mean that a large portion of the
range-based code out there would be wrong, since a lot of it is going to be
copying elements, and unless folks regularly test their range-based code with
ranges with non-copyable elements, they're not likely to catch the bugs where
they accidentally require it, and they could be in for some rude surprises
later when someone tries to use non-copyable elements. We already have enough
problems with code assuming forward ranges or assuming that ranges aren't full
reference types, which cause all kinds of fun bugs - including in Phobos.

--