<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 - Non-type template argument parse error"
   href="https://bugs.llvm.org/show_bug.cgi?id=48090">48090</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Non-type template argument parse error
          </td>
        </tr>

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

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

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

        <tr>
          <th>OS</th>
          <td>Windows XP
          </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++
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>oleg-derevenetz@yandex.ru
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>blitzrakete@gmail.com, dgregor@apple.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Consider the following code:

namespace BitOp
{
enum Op
{
    Copy
};
};

template<typename T>
class Bits
{
public:
    template <BitOp::Op op = BitOp::Copy>
    static T& bitop(T& dst, T src) {
        if (op == BitOp::Copy)
            dst = src;
        return dst;
    };
};

template<typename T>
struct Bitmap3D
{
    template <BitOp::Op op = BitOp::Copy>
    void exportBits(T* bits) const
    {
        Bits<T>::bitop<op>(bits[0], bits[0]);
    };
};

int main(int, char *[])
{
    Bitmap3D<int> bm3d;
    int *bits;

    bm3d.exportBits(bits);
}

It fails to compile with the following error:

<source>:27:18: error: reference to overloaded function could not be resolved;
did you mean to call it?

        Bits<T>::bitop<op>(bits[0], bits[0]);

        ~~~~~~~~~^~~~~

<source>:36:10: note: in instantiation of function template specialization
'Bitmap3D<int>::exportBits<BitOp::Copy>' requested here

    bm3d.exportBits(bits);

         ^

<source>:14:15: note: possible target for call

    static T& bitop(T& dst, T src) {

              ^

1 error generated.

This code compiles just fine with MSVC 19.27 though:

<a href="https://godbolt.org/z/KqMKnv">https://godbolt.org/z/KqMKnv</a>

It seems that clang parser interprets "Bits<T>::bitop<op" part like call of
operator<(Bits<T>::bitop, op), but it's just a guess.</pre>
        </div>
      </p>


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