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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 - SIGSEGV at DeduceTemplateArgumentsByTypeMatch"
   href="https://bugs.llvm.org/show_bug.cgi?id=51171">51171</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>SIGSEGV at  DeduceTemplateArgumentsByTypeMatch
          </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>All
          </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>Frontend
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>ivan.murashko@gmail.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org, neeilans@live.com, richard-llvm@metafoo.co.uk
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Created <span class=""><a href="attachment.cgi?id=25049" name="attach_25049" title="The crash reproducer">attachment 25049</a> <a href="attachment.cgi?id=25049&action=edit" title="The crash reproducer">[details]</a></span>
The crash reproducer

There is a SIGSEGV (NULL dereference) at DeduceTemplateArgumentsByTypeMatch as
soon as FunctionType parameter passed into the function is NULL. See reproducer
at the attachment

The possible fix for the problem is

--- a/clang/lib/Sema/SemaTemplateDeduction.cpp
+++ b/clang/lib/Sema/SemaTemplateDeduction.cpp
@@ -4346,7 +4346,7 @@ Sema::TemplateDeductionResult
Sema::DeduceTemplateArguments(
     HasDeducedReturnType = true;
   }

-  if (!ArgFunctionType.isNull()) {
+  if (!ArgFunctionType.isNull() && !FunctionType.isNull()) {
     unsigned TDF =
         TDF_TopLevelParameterTypeList | TDF_AllowCompatibleFunctionType;
     // Deduce template arguments from the function type.</pre>
        </div>
      </p>


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