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      <base href="https://bugs.llvm.org/">
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    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - clang++ prints bogus error: use of overloaded operator '!=' is ambiguous"
   href="https://bugs.llvm.org/show_bug.cgi?id=50366">50366</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>clang++ prints bogus error: use of overloaded operator '!=' is ambiguous
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>clang
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>10.0
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>PC
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>FreeBSD
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>enhancement
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>C++2a
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>unassignedclangbugs@nondot.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>yuri@tsoft.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>blitzrakete@gmail.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
          </td>
        </tr></table>
      <p>
        <div>
        <pre>The Gecode project <a href="https://github.com/Gecode/gecode">https://github.com/Gecode/gecode</a> (release/6.3.0 branch
rev.ad52315) fails with -std=c++2a:

<span class="quote">> In file included from gecode/float/var-imp/float.cpp:41:
> In file included from ./gecode/float.hh:833:
> ./gecode/float/val.hpp:319:18: error: use of overloaded operator '!=' is ambiguous (with operand types 'const Gecode::FloatVal::FloatValImpType' (aka 'const interval<double,
>       policies<save_state<Float::Rounding>, checking_strict<double> > >') and 'const Gecode::FloatVal::FloatValImpType')
>       return x.x != y.x;
>              ~~~ ^  ~~~
> ./gecode/third-party/boost/numeric/interval/interval.hpp:85:8: note: candidate function
>   bool operator!= (const interval_holder& r) const;
>        ^
> ./gecode/third-party/boost/numeric/interval/interval.hpp:84:8: note: candidate function
>   bool operator== (const interval_holder& r) const;
>        ^
> ./gecode/third-party/boost/numeric/interval/interval.hpp:84:8: note: candidate function (with reversed parameter order)
> In file included from gecode/float/rel.cpp:36:
> In file included from ./gecode/float/rel.hh:46:
> In file included from ./gecode/float.hh:833:
> ./gecode/float/val.hpp:296:18: warning: ISO C++20 considers use of overloaded operator '==' (with operand types 'const Gecode::FloatVal::FloatValImpType' (aka 'const interval<double,
>       policies<save_state<Float::Rounding>, checking_strict<double> > >') and 'const Gecode::FloatVal::FloatValImpType') to be ambiguous despite there being a unique best viable function
>       [-Wambiguous-reversed-operator]
>       return x.x == y.x;
>              ~~~ ^  ~~~
> ./gecode/third-party/boost/numeric/interval/interval.hpp:84:8: note: ambiguity is between a regular call to this operator and a call with the argument order reversed
>   bool operator== (const interval_holder& r) const;
>        ^</span >

Both operand types in the error message are same: 'const
Gecode::FloatVal::FloatValImpType'
It doesn't make sense that type order reversal can cause ambiguity.

Additionally, when compiled with -Wno-ambiguous-reversed-operator this error
message is still printed.</pre>
        </div>
      </p>


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