<html>
    <head>
      <base href="https://llvm.org/bugs/" />
    </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 --- - Invalid C accepted: flexible array member in struct with only unnamed member"
   href="https://llvm.org/bugs/show_bug.cgi?id=28407">28407</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Invalid C accepted: flexible array member in struct with only unnamed member
          </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>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>-New Bugs
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>ch3root@openwall.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr></table>
      <p>
        <div>
        <pre>A flexible array member is only permitted in a struct when the struct contains
another _named_ member:

C11, 6.7.2.1p3: "A structure or union shall not contain a member with
incomplete or function type [...], except that the last member of a structure
with more than one named member may have incomplete array type"

This is a constraint violation and must be diagnosed.

Source code:

----------------------------------------------------------------------
int main()
{
  struct s {
    int :1;
    int a[];
  };
}
----------------------------------------------------------------------

Results:

----------------------------------------------------------------------
$ clang -std=c11 -Weverything -O3 test.c && ./a.out
----------------------------------------------------------------------

clang version: clang version 3.9.0 (trunk 271312)</pre>
        </div>
      </p>
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