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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - std::reduce(begin, end, init) does not accept init with only move constructor"
href="https://bugs.llvm.org/show_bug.cgi?id=43013">43013</a>
</td>
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<th>Summary</th>
<td>std::reduce(begin, end, init) does not accept init with only move constructor
</td>
</tr>
<tr>
<th>Product</th>
<td>libc++
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>All Bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>sei_yichen@outlook.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org, mclow.lists@gmail.com
</td>
</tr></table>
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<pre>Created <span class=""><a href="attachment.cgi?id=22380" name="attach_22380" title="repro">attachment 22380</a> <a href="attachment.cgi?id=22380&action=edit" title="repro">[details]</a></span>
repro
Overview: std::reduce(begin, end, init) could not be compiled with init only
have move constructor.
Steps to Reproduce: clang++ -o /dev/null -std=c++17 -c test.cc, test.cc
attched.
Actual Results:
$ clang++ -o /dev/null -std=c++17 -stdlib=libc++ -c test.cc
In file included from test.cc:3:
/home/yiyan/.local/bin/../include/c++/v1/numeric:196:43: error: call to
implicitly-deleted copy constructor of 'T'
return _VSTD::reduce(__first, __last, __init, _VSTD::plus<>());
^~~~~~
test.cc:17:10: note: in instantiation of function template specialization
'std::__1::reduce<T *, T>' requested here
std::reduce(t, t + 1, T(0));
^
test.cc:9:5: note: copy constructor is implicitly deleted because 'T' has a
user-declared move constructor
T(T &&); // MoveConstructible
^
/home/yiyan/.local/bin/../include/c++/v1/numeric:184:59: note: passing argument
to parameter '__init' here
reduce(_InputIterator __first, _InputIterator __last, _Tp __init, _BinaryOp
__b)
^
1 error generated.
Expected Results: Compiled without error.
Build Date & Hardware: Build 2019-08-15 on Linux x86_64
Additional Information: I think std::reduce(begin, end, init) should be same
with std::reduce(begin, end, init, std::plus<>()), the former failed while the
latter passed.</pre>
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