<html>
    <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 - Thread Sanitizer causes false positive on a static array"
   href="https://bugs.llvm.org/show_bug.cgi?id=41769">41769</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Thread Sanitizer causes false positive on a static array
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>compiler-rt
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>unspecified
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>Macintosh
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>MacOS X
          </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>compiler-rt
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>vincent.lebourlot@starqube.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>The following code causes a false data race detection.
~~~
#include <array>
#include <thread>
#include <vector>

class String{
public:
        std::array<unsigned char,16>value;
        String(const
char(&s)[2])noexcept:value(){std::memcpy(value.data(),s,1);}
};

void createStaticAndFind(){
        static const std::array<String,3>a={"1","2","3"};
        if(a[2].value==String("3").value){}}

int main(){
        std::vector<std::thread>threads;
        for(size_t i=0;i<100;++i){
                threads.emplace_back(createStaticAndFind);}
        return 0;}
~~~

Compiled and linked with -L/usr/local/lib and -fsanitize=thread.</pre>
        </div>
      </p>


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