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      <base href="https://bugs.llvm.org/">
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    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - Clang rejects braced-init-list as default non-type template parameter"
   href="https://bugs.llvm.org/show_bug.cgi?id=50634">50634</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Clang rejects braced-init-list as default non-type template parameter
          </td>
        </tr>

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

        <tr>
          <th>Version</th>
          <td>12.0
          </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>pilarlatiesa@gmail.com
          </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>Clang rejects this code:

```c++
template<bool = {}>
int f() {}
```

with:
<span class="quote">> error: expected expression</span >

However I believe that the C++ grammar permits that.

[temp.param]:
<span class="quote">> The syntax for template-parameters is:
> template-parameter:
>    type-parameter
>    parameter-declaration</span >

[dcl.fct]:

<span class="quote">> parameter-declaration:
>    attribute-specifier-seq_{opt} decl-specifier-seq declarator
>    attribute-specifier-seq_{opt} decl-specifier-seq declarator = initializer-clause
>    attribute-specifier-seq_{opt} decl-specifier-seq abstract-declarator_{opt} 
>    attribute-specifier-seq_{opt} decl-specifier-seq abstract-declarator</span >
_{opt} = initializer-clause

[dcl.init]:
<span class="quote">> initializer-clause:
>    assignment-expression
>    braced-init-list</span >

My motivating usecase is:

```c++
template<std::true_type = {}>
int f() {}
```

which is accepted by G++.</pre>
        </div>
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