<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 --- - Clang 3.6 cannot compile program with -std=c++14"
   href="https://llvm.org/bugs/show_bug.cgi?id=30277">30277</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Clang 3.6 cannot compile program with -std=c++14
          </td>
        </tr>

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

        <tr>
          <th>Version</th>
          <td>3.6
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>PC
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>All
          </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++14
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>noloader@gmail.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>I'm working on Ubuntu 14.0.5 LTS. Ubuntu provides GCC 4.8 and Clang 3.6.

Clang 3.6 provided by Ubuntu claims to support C++14. -std=c++14 is not
rejected by the compiler during feature testing. The feature test program
includes the C++ header <iosfwd>.

Attempting to compile a test program:

$ cat test.cxx
#include <string>
int main(int argc, char* argv[])
{
  return 0;
}

Results in the following:

$ clang++ -std=c++14 test.cxx -o test.exe
In file included from test.cxx:1:
In file included from
/usr/bin/../lib/gcc/x86_64-linux-gnu/4.8/../../../../include/c++/4.8/string:52:
In file included from
/usr/bin/../lib/gcc/x86_64-linux-gnu/4.8/../../../../include/c++/4.8/bits/basic_string.h:2815:
In file included from
/usr/bin/../lib/gcc/x86_64-linux-gnu/4.8/../../../../include/c++/4.8/ext/string_conversions.h:43:
/usr/bin/../lib/gcc/x86_64-linux-gnu/4.8/../../../../include/c++/4.8/cstdio:120:11:
error:
      no member named 'gets' in the global namespace
  using ::gets;
        ~~^
1 error generated.

**********

Ubuntu Issue at "Clang 3.6 cannot compile program with -std=c++14",
<a href="http://bugs.launchpad.net/ubuntu/+bug/1620181">http://bugs.launchpad.net/ubuntu/+bug/1620181</a> .

According to <a href="http://stackoverflow.com/q/17775390/608639">http://stackoverflow.com/q/17775390/608639</a>, this issue is present
as early as Clang 3.3.

An interesting answer from a similar error report on Stack Overflow reveals
this (<a href="http://stackoverflow.com/a/17776548/608639">http://stackoverflow.com/a/17776548/608639</a>):

<BEGIN SNIP>

This note in the gets manpage looks relevant:

    ISO C11 removes the specification of gets() from the C language, and since
version 2.16, glibc header files don't expose the function declaration if the
_ISOC11_SOURCE feature test macro is defined.

Probably should be:

#if !_ISOC11_SOURCE
using ::gets;
#endif

<END SNIP>

**********

$ clang++ -v
Ubuntu clang version 3.6.0-2ubuntu1~trusty1 (tags/RELEASE_360/final) (based on
LLVM 3.6.0)
Target: x86_64-pc-linux-gnu
Thread model: posix

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 14.04.5 LTS
Release: 14.04
Codename: trusty</pre>
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