<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/133734>133734</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [clang-tidy] Check for uncessary copies as return value for getter functions
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang-tidy
      </td>
    </tr>

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

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

<pre>
    The following code:
```
std::string GetValue() const { return mValue; }
```
(with `mValue` being a `std::string` member)

is not optimal since it might perform an unnecessary copy of the string object, which might not be needed.

The following code would be best:
```
const std::string& GetValue() const { return mValue; }
```

Similar to performance-unnecessary-value-param[¶](https://clang.llvm.org/extra/clang-tidy/checks/performance/unnecessary-value-param.html#performance-unnecessary-value-param) I think it would be nice to have a check for this.

What do you think?

Probably only if the method is not virtual, since I can imagine cases where children classes might not always be able to return a const reference.

I guess some people might still prefer to return a copy, to avoid callers to potentially mess up things using `const_cast`, but for most users, I think it would be nice to have this check.
</pre>
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