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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 - Constexpr variable template constructor initializing flexible array member crashes compiler"
   href="https://bugs.llvm.org/show_bug.cgi?id=49742">49742</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Constexpr variable template constructor initializing flexible array member crashes compiler
          </td>
        </tr>

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

        <tr>
          <th>Version</th>
          <td>unspecified
          </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>Frontend
          </td>
        </tr>

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

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

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org, neeilans@live.com, richard-llvm@metafoo.co.uk
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Created <span class=""><a href="attachment.cgi?id=24699" name="attach_24699" title="Compiler crash backtrace">attachment 24699</a> <a href="attachment.cgi?id=24699&action=edit" title="Compiler crash backtrace">[details]</a></span>
Compiler crash backtrace

See attachment for compiler backtrace.

Affected versions:
Note: The issue seems to have been fixed in trunk already.
 - 11.0.1
 - 11.0.0
 - 10.0.1
 - 10.0.0
 - 9.0.1
 - 9.0.0
 - 8.0.1
 - 8.0.0
 - 7.1.0
 - 7.0.0

Driver cmdline:
Note: For versions that do not support -std=c++20, -std=c++2a was used.

clang++ -Xclang -disable-llvm-passes -std=c++20

Note: The original code has been reduced with creduce.
Reduced code:

struct a {
  int b[];
  template <typename... c> constexpr a(c... e) : b{e...} {}
};
int main() { constexpr a d{4}; }


Original code:

template<typename T>
struct S {
 T t[];

 template<typename... Args>
 constexpr S(Args... args) noexcept :
  t{args...}
 {}
};

int main() {
 constexpr const S<int> s{1, 2, 3, 4};
}</pre>
        </div>
      </p>


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