<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/65843>65843</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Failure to match alias template against template template parameter
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          ecatmur
      </td>
    </tr>
</table>

<pre>
    ```c++
template<template<class T> class> struct A {};
template<class T> struct Q {};
template<class T> using R = Q<T>;
int f(A<R>);
int g(A<Q> a) { return f(a); }
```
gcc accepts (since 4.9.0), clang rejects with:
```
<source>:5:24: error: no matching function for call to 'f'
int g(A<Q> a) { return f(a); }
 ^
<source>:4:5: note: candidate function not viable: no known conversion from 'A<template Q>' to 'A<template R>' for 1st argument
int f(A<R>);
    ^
```
-frelaxed-template-template-args doesn't seem to help in any recent major.
</pre>
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