<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 --- - alignas and packed attribute not obeyed"
   href="https://llvm.org/bugs/show_bug.cgi?id=30479">30479</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>alignas and packed attribute not obeyed
          </td>
        </tr>

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

        <tr>
          <th>Version</th>
          <td>3.9
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>Other
          </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>C++11
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>david.jobet@free.fr
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>dgregor@apple.com, llvm-bugs@lists.llvm.org
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Here's the test case :
-----------------
#include <cstdint>
#include <cstddef>

struct alignas(128) test
{
  uint8_t  v;
  uint64_t s;
} __attribute__((__packed__));

int main(int argc, char** argv)
{
  struct test t;
  static_assert(offsetof(test, s) == 1, "Bug on!");
  return 0;
}
-----------------
And here's the output :
$ clang++  -std=c++11 test.cpp 
test.cpp:13:3: error: static_assert failed "Bug on!"
  static_assert(offsetof(test, s) == 1, "Bug on!");
  ^             ~~~~~~~~~~~~~~~~~~~~~~
1 error generated.
$ clang++ --version
TPM built 20160902 clang version 3.9.0 (tags/RELEASE_390/final) (based on LLVM
3.9.0)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: [redacted]
-----------------
While it compiles fine with gcc and icc :
$ g++  -std=c++11 test.cpp
$ g++ --version
g++ (TPM built 20160719) 5.4.0</pre>
        </div>
      </p>
      <hr>
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