<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 --- - C++ language feature macros are also set for clang.exe/clang-cl.exe (but not in MSVC2015's cl.exe)"
   href="https://llvm.org/bugs/show_bug.cgi?id=27217">27217</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>C++ language feature macros are also set for clang.exe/clang-cl.exe (but not in MSVC2015's cl.exe)
          </td>
        </tr>

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

        <tr>
          <th>Version</th>
          <td>3.8
          </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>nikolai.kosjar@theqtcompany.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>Consider

---8<--- D:\work\cppfeaturetest.cpp ---8<---
#ifdef __cpp_constexpr
 #error "HAS __cpp_constexpr"
#else
 #error "NO __cpp_constexpr defined"
#endif
---8<---------------------------------------

...and feeding that to clang.exe:


  D:\work>D:\usr\llvm-3.8.0\bin\clang.exe D:\work\cppfeaturetest.cpp
  D:\work\cppfeaturetest.cpp:2:3: error: "HAS __cpp_constexpr"
   #error "HAS __cpp_constexpr"
    ^
  1 error generated.

and cl.exe (MSVC2015):

  D:\work>cl.exe D:\work\cppfeaturetest.cpp
  Microsoft (R) C/C++ Optimizing Compiler Version 19.00.23506 for x86
  Copyright (C) Microsoft Corporation.  All rights reserved.

  cppfeaturetest.cpp
  D:\work\cppfeaturetest.cpp(4): fatal error C1189: #error:  "NO
__cpp_constexpr defined"

Client code checking for these macros causes trouble with
clang.exe/clang-cl.exe.</pre>
        </div>
      </p>
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