<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/65282>65282</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Lifetime of temporaries within default member initializers of aggregates
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

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

    <tr>
      <th>Reporter</th>
      <td>
          leni536
      </td>
    </tr>
</table>

<pre>
    version: clang 16.0.0
flags: `-std=c++20 -O2 -pedantic-errors`

Consider the following code:

```cpp
struct X {
    X() noexcept;
    ~X();
};

struct A1 {
    int i = (X(), 42);
};

struct A2 {
    int i = (X(), 42);
    int j = (X(), 42);
};

void foo() {
    // The two objects of type X should have nested lifetimes
    (A1{}, A1{});
}

void bar() {
    // The two objects of type X should have nested lifetimes
 A2{};
}
```

https://godbolt.org/z/f1YTdno83

### Observed behavior

In each of `foo` and `bar` two temporary objects of type `X` are created and destroyed. From the generated code it can be observed that the first object is created and destroyed before the second object is created and destroyed.

### Expected behavior

According to https://timsong-cpp.github.io/cppwp/n4868/intro.execution#5.6 and https://timsong-cpp.github.io/cppwp/n4868/intro.execution#5.sentence-4 the default member initializers are subexpressions of the full expressions `(A1{}, A1{})` and `A2{}`.

The temporaries that materialize within these subexpressions should live to the end of the full-expressions.

This means that in both cases that two objects of type `X` should have overlapping lifetimes.
</pre>
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