<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 - -Wunused-lambda-capture too strict with 'this'"
   href="https://bugs.llvm.org/show_bug.cgi?id=42958">42958</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>-Wunused-lambda-capture too strict with 'this'
          </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>Windows NT
          </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>C++
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>rogero@howzatt.demon.co.uk
          </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>Compiler Explorer <a href="https://godbolt.org/z/57PJFq">https://godbolt.org/z/57PJFq</a>

When compiled with -Wunused-lambda-capture clang gives:
warning: lambda capture 'this' is not used

However, it is used *implicitly* by the call to impl() and removal causes an
error.

--- example.cpp ---
#include <functional>

void doit(std::function<void(int)>){}

struct S
{
  template <typename T>
  void impl(T, int) {}

  template <typename T>
  void run(T t)
  {
    doit([t, this](auto r) {
      impl(t, r);
    });
  }
};

int main()
{
  S s;
  s.run(1);
}
--- ends ---</pre>
        </div>
      </p>


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