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Currently, implementations of InputIterator are required to silently enter
an invalid state after being copied from, and so is prone to the same kind
of programmer mistakes that auto_ptr is.

It would be better if InputIterator was excepted from the requirement that
all Iterators must satisfy CopyConstructible and CopyAssignable (From
n3337, it is 24.2.2/2).

This can be done without breaking backward compatibility:
1. Existing implementations of standard library algorithms that accept
InputIterators are rewritten to work with move-only.
2. Existing standard library implementations iterators are NOT rewritten,
however the copy ctors are deprecated.
3.  Implementations could provide a technique to completely remove
deprecated things, but it's may be a bad idea to make anything in headers
conditional as this plays poorly with modules.

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<div>Currently, implementations of InputIterator&nbsp;are required to silen=
tly enter an invalid state after being copied from, and so is prone to the =
same kind of programmer mistakes that auto_ptr is.</div><div><br></div><div=
>It would be better if InputIterator was excepted from the requirement that=
 all Iterators must satisfy CopyConstructible and CopyAssignable (From n333=
7, it is 24.2.2/2).</div><div><br></div><div>This can be done without break=
ing backward compatibility:</div><div>1. Existing implementations of standa=
rd library algorithms that accept InputIterators are rewritten to work with=
 move-only.</div><div>2. Existing standard library implementations iterator=
s are NOT rewritten, however the copy ctors are deprecated.</div><div>3.&nb=
sp; Implementations could provide a technique to completely remove deprecat=
ed things, but it's may be a bad idea to make anything in headers condition=
al as this plays poorly with modules.</div>

<p></p>

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