<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 - Failure to deduce template arguments for std::initializer_list aliases"
   href="https://bugs.llvm.org/show_bug.cgi?id=40366">40366</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Failure to deduce template arguments for std::initializer_list aliases
          </td>
        </tr>

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

        <tr>
          <th>Version</th>
          <td>7.0
          </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>normal
          </td>
        </tr>

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

        <tr>
          <th>Component</th>
          <td>C++'17
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>davorin.ucakar@gmail.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>Using an alias for std::initializer_list results in a failure to deduce
template arguments as in the following example (it compiles fine with GCC 8.2):

#include <initializer_list>

template <typename T>
using IL = std::initializer_list<T>;

template <typename T>
struct Foo {
  Foo(IL<T> list) {}
};

int main() {
  Foo foo{42}; // Error: no viable constructor or deduction guide
               // for deduction of template arguments of 'Foo'
  return 0;
}

However, the next deduction guide fixes the error:

template <typename T>
Foo(std::initializer_list<T>) -> Foo<T>;

The deduction guide doesn't work if we use IL<T> instead of
std::initializer<T>.</pre>
        </div>
      </p>


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