<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/96451>96451</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [Clang][Windows] `-Wctad-maybe-unsupported` triggered for `std::equal_to`
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          MagentaTreehouse
      </td>
    </tr>
</table>

<pre>
    The following code, when using MSVC STL, triggers the clang warning enabled by `-Wctad-maybe-unsupported`.
```cpp
#include <functional>
int main() { return std::equal_to{}(-1, 1); }
```
```
.\test.cpp:12:9: warning: 'equal_to' may not intend to support class template argument deduction      [-Wctad-maybe-unsupported]
   12 |         return std::equal_to{}(-1, 1);
      |                ^
C:\Program Files (x86)\Microsoft Visual Studio\2022\BuildTools\VC\Tools\MSVC\14.40.33807\include\xutility:510:8: note:
      add a deduction guide to suppress this warning
  510 | struct equal_to {
      |        ^
1 warning generated.
```
This use of CTAD doesn't look harmful. The warning seems not triggered when using libc++.
</pre>
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