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    <head>
      <base href="https://bugs.llvm.org/">
    </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-analyzer-valist.Uninitialized warning on use of a copied valist"
   href="https://bugs.llvm.org/show_bug.cgi?id=41311">41311</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>clang-analyzer-valist.Uninitialized warning on use of a copied valist
          </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>enhancement
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>Static Analyzer
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>dcoughlin@apple.com
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>juliehockett@google.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>dcoughlin@apple.com, llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>When running the clang-analyzer checks under clang-tidy, the
clang-analyzer-valist.Uninitialized warning is firing on a valist copied using
va_copy().

Command: clang-tidy --checks="-*,clang-analyzer-*" example.cpp

Minimal example.cpp:

#include <stdarg.h>
#include <stdio.h>

void StringVPrintf(const char* format, va_list ap) {
    char stack_buf[1024u];
    va_list ap_copy;
    va_copy(ap_copy, ap);
    vsnprintf(stack_buf, 1024u, format, ap_copy);
    va_end(ap_copy);
}

Clang-tidy warning:

example.cpp:8:5: warning: Function 'vsnprintf' is called with an uninitialized
va_list argument [clang-analyzer-valist.Uninitialized]
    vsnprintf(stack_buf, 1024u, format, ap_copy);
    ^
example.cpp:8:5: note: Function 'vsnprintf' is called with an uninitialized
va_list argument</pre>
        </div>
      </p>


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