<html>
    <head>
      <base href="https://llvm.org/bugs/" />
    </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 --- - is_same<const const char*, const char*>::value == false"
   href="https://llvm.org/bugs/show_bug.cgi?id=26109">26109</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>is_same<const const char*, const char*>::value == false
          </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>

        <tr>
          <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>dan.eloff@gmail.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org, mclow.lists@gmail.com
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr></table>
      <p>
        <div>
        <pre>I'm using libc++ from the trusty/universe repo:
libc++1_1.0~svn199600-1_amd64.deb

is_same is used by unordered_map in a static assert to check that the
allocator::value_type is the same as the map value_type. The problem is the map
defines value_type as pair<const Key, Value>. If Key was already a const type
(const char *) in this case, somehow it gets double const qualified and is_same
fails. If however, I make a typedef of const char* as CString and then define
the allocator type as pair<const CString, Value> the is_same check passes.

This seems like a bug to me, double const qualifiers should be ignored by
is_same, right? I'm not sure what other compilers do.

I hope I reported the bug in the right place, it could well be clang issue.</pre>
        </div>
      </p>
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