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    <body><span class="vcard"><a class="email" href="mailto:dane@mapbox.com" title="Dane Springmeyer <dane@mapbox.com>"> <span class="fn">Dane Springmeyer</span></a>

</span> changed

              <a class="bz_bug_link 

          bz_status_RESOLVED  bz_closed"

   title="RESOLVED FIXED - Invalid code generation / optimization of C++ with -O3"

   href="http://llvm.org/bugs/show_bug.cgi?id=19824">bug 19824</a>

        <br>

             <table border="1" cellspacing="0" cellpadding="8">

          <tr>

            <th>What</th>

            <th>Removed</th>

            <th>Added</th>

          </tr>

         <tr>

           <td style="text-align:right;">Status</td>

           <td>NEW

           </td>

           <td>RESOLVED

           </td>

         </tr>

         <tr>

           <td style="text-align:right;">Resolution</td>

           <td>---

           </td>

           <td>FIXED

           </td>

         </tr></table>

      <p>

        <div>

            <b><a class="bz_bug_link 

          bz_status_RESOLVED  bz_closed"

   title="RESOLVED FIXED - Invalid code generation / optimization of C++ with -O3"

   href="http://llvm.org/bugs/show_bug.cgi?id=19824#c3">Comment # 3</a>

              on <a class="bz_bug_link 

          bz_status_RESOLVED  bz_closed"

   title="RESOLVED FIXED - Invalid code generation / optimization of C++ with -O3"

   href="http://llvm.org/bugs/show_bug.cgi?id=19824">bug 19824</a>

              from <span class="vcard"><a class="email" href="mailto:dane@mapbox.com" title="Dane Springmeyer <dane@mapbox.com>"> <span class="fn">Dane Springmeyer</span></a>

</span></b>

        <pre>Good news. This turns out to be a bug in our usage of c++11 lambdas and is not

a problem in clang/llvm. We were passing references to objects into the lambdas

that were not designed to be copied or moved, which was perhaps creating

undefined behavior. Our guess is that its the -argpromotion optimization that

was triggering this problem - without it we were getting away with dodgy code.

Our fix was to do some deep refactoring in our code to not rely on lambdas in

the same way:

<a href="https://github.com/mapnik/mapnik/commit/a49e1d075e75ac5ddc6101e7d85c15c8688b5a32">https://github.com/mapnik/mapnik/commit/a49e1d075e75ac5ddc6101e7d85c15c8688b5a32</a>.

Sorry for the noise and thanks for helping discuss this issue until it became

clearer.</pre>

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