<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 - `final` does not cause devirtualization of nested calls"
   href="https://bugs.llvm.org/show_bug.cgi?id=43640">43640</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>`final` does not cause devirtualization of nested calls
          </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>C++
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>antoshkka@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>Consider the example:

struct A {
    virtual int f() { return 0; }
    virtual int g() { return f() + 40; } 
};

struct B2 final : A {
    int g() override;
};
int B2::g() { return A::g(); }


`B2` is final, so any call to the virtual functions of `A` end up with a call
to the same function in `B2`. So `B2::g()` should inline the `A::g()` and get
optimized to:

int B2::g() { return B2::f() + 40; }

Which is just 40, because `B2::f()` always returns 0.


Godbolt playground: <a href="https://godbolt.org/z/skqgH8">https://godbolt.org/z/skqgH8</a></pre>
        </div>
      </p>


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