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    <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 - Incorrect arguments matching in a template class constructor"
   href="https://bugs.llvm.org/show_bug.cgi?id=33195">33195</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Incorrect arguments matching in a template class constructor
          </td>
        </tr>

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

        <tr>
          <th>Version</th>
          <td>4.0
          </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>C++
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>dvtikhomirov@gmail.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>dgregor@apple.com, llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Created <span class=""><a href="attachment.cgi?id=18524" name="attach_18524" title="Compilation error">attachment 18524</a> <a href="attachment.cgi?id=18524&action=edit" title="Compilation error">[details]</a></span>
Compilation error

The following program causes compilation error in the Outer class constructor
while the Function is compiled without any problems:

#include <tuple>

struct Inner {
  Inner(const char *) {}
};

template <typename T> struct Middle {
  Middle(const int &, const T & = {}) {}
};

template <typename... Ts> struct Outer {
  Outer(const std::tuple<Middle<Ts>...> &, void * = nullptr) {}
};

template <typename... Ts>
void Function(const std::tuple<Middle<Ts>...> &, void * = nullptr) {}

int main() {
  // Compiles ok
  Function<Inner, Inner>({{1, "a"}, {2, "b"}});
  // Compilation error
  Outer<Inner, Inner>({{1, "a"}, {2, "b"}});
  return 0;
}

Looks like for some reason clang thinks that tuple's argument is {1, "a"}, not
{{1, "a"}, {2, "b"}}.
If you remove the void* argument from the Outer's constructor, or remove the
default value of T from Middle's constructor, the compilation succeeds.
GCC compiles this without any errors.

clang version 4.0.0 (tags/RELEASE_400/final)
Target: x86_64-unknown-linux-gnu
System: Arch linux</pre>
        </div>
      </p>


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