<html>
    <head>
      <base href="https://bugs.llvm.org/">
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - DenseMap and StringMap can't be used in range for under c++20"
   href="https://bugs.llvm.org/show_bug.cgi?id=47624">47624</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>DenseMap and StringMap can't be used in range for under c++20
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>libraries
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>trunk
          </td>
        </tr>

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

        <tr>
          <th>OS</th>
          <td>Linux
          </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>Core LLVM classes
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>N.James93@hotmail.co.uk
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Using llvm::DenseMap and llvm::StringMap in external projects compiled with
c++20 results in error when comparing their iterators

Iterating over a `const DenseMap&` causes no issues. However There are issues
with iterating over a non const DenseMap. With StringMap there are issues no
matter what kind of reference the StringMap is.

using clang-10 as the host compiler, warnings for StringMap can be supressed
with `-Wno-ambiguous-reversed-operator` however this has no effect on
supressing the DenseMap warnings. That has been addressed in clang-11 which
will suppress all these warnings

See example here
<a href="https://godbolt.org/z/Keqa1n">https://godbolt.org/z/Keqa1n</a>
Note this is compiling with a trunk build of clang so some of these warnings
could change down the line, the warnings emitted for clang-10.0.1 will stay
consistent though</pre>
        </div>
      </p>


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