<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/152026>152026</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            `bugprone-exception-escape` for `std::string` member in default copy constructor invocation reported with libc++
        </td>
    </tr>

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

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

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

<pre>
    ```cpp
#include <string>

struct CallBase {
    std::string callId;
};

void f() noexcept
{
    CallBase cb;
    CallBase cb1 = cb;
}
```

```
<source>:7:6: warning: an exception may be thrown in function 'f' which should not throw exceptions [bugprone-exception-escape]
 7 | void f() noexcept
      | ^
/opt/compiler-explorer/clang-trunk-20250804/bin/../include/c++/v1/stdexcept:243:3: note: frame #0: unhandled exception of type 'std::length_error' may be thrown in function '__throw_length_error' here
  243 |   throw length_error(__msg);
      | ^
/opt/compiler-explorer/clang-trunk-20250804/bin/../include/c++/v1/string:2477:5: note: frame #1: function '__throw_length_error' calls function '__throw_length_error' here
 2477 | std::__throw_length_error("basic_string");
      | ^
/opt/compiler-explorer/clang-trunk-20250804/bin/../include/c++/v1/string:2583:7: note: frame #2: function '__init_copy_ctor_external' calls function '__throw_length_error' here
 2583 |       this->__throw_length_error();
 | ^
/opt/compiler-explorer/clang-trunk-20250804/bin/../include/c++/v1/string:997:7: note: frame #3: function 'basic_string' calls function '__init_copy_ctor_external' here
  997 | __init_copy_ctor_external(std::__to_address(__str.__get_long_pointer()), __str.__get_long_size());
      |       ^
<source>:3:8: note: frame #4: function 'CallBase' calls function 'basic_string' here
    3 | struct CallBase {
      |        ^
<source>:10:20: note: frame #5: function 'f' calls function 'CallBase' here
   10 |     CallBase cb1 = cb;
      | ^
```

https://godbolt.org/z/G75sj5fYz

This is only reported with libc++.

Somewhat related to #109587.
</pre>
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