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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 - __STDC_IEC_559__ depends on #include <stdio.h>: confused"
   href="https://bugs.llvm.org/show_bug.cgi?id=52533">52533</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>__STDC_IEC_559__ depends on #include <stdio.h>: confused
          </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>C
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>pavel.morozkin@gmail.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>blitzrakete@gmail.com, dgregor@apple.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Note: this may not be a bug. However, it is expected that __STDC_IEC_559__ does
not depend on any #include and stays constant during the translation.

This code:
#include FNAME
#if __STDC_IEC_559__ == 1
#pragma message "__STDC_IEC_559__ is 1"
#else
#pragma message "__STDC_IEC_559__ is not 1"
#endif

compiled with:
$ clang t0.c -std=c11 -pedantic -Wall -Wextra -DFNAME="<stdio.h>"

leads to:
t0.c:3:9: warning: __STDC_IEC_559__ is 1 [-W#pragma-messages]

while compiled with:
$ clang t0.c -std=c11 -pedantic -Wall -Wextra -DFNAME="<float.h>"

leads to:
t0.c:3:9: warning: __STDC_IEC_559__ is not 1 [-W#pragma-messages]

Here we see that the value of __STDC_IEC_559__ depends on #include. Which is
confusing. Please explain / investigate.

Version: clang 13.0.0 on Linux on x86_64</pre>
        </div>
      </p>


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