<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/109327>109327</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [clang-tidy][readability-container-contains] Also match when comparing find() to string::npos.
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang-tools-extra,
            clang-tidy,
            false-negative
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          nicovank
      </td>
    </tr>
</table>

<pre>
    Opening this issue for tracking.

For `std::string` and `std::string_view`, an element is (not) found when comparing `find()` against `std::string::npos` or `std::string_view::npos`, not `end()`. This is not causing false positives since comparing a `find()` result to `end()` doesn't make sense to begin with in those classes, so in fact the check would probably be fixing bugs. (Is there a `bugprone-string-find-end` check?)

As of C++23 the following transformations and derivatives can be added to the check:
```
string.find(...) != std::string::npos; // -> string.contains(...)
string.find(...) != string.npos; // -> string.contains(...)

// Ideally, make this work for any npos, e.g. llvm::StringRef::npos.
```
</pre>
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