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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - no_unique_address non-static data member doesn't make class non-POD for the purpose of layout"
href="https://bugs.llvm.org/show_bug.cgi?id=49758">49758</a>
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<th>Summary</th>
<td>no_unique_address non-static data member doesn't make class non-POD for the purpose of layout
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>C++2a
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>leni536@gmail.com
</td>
</tr>
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<th>CC</th>
<td>blitzrakete@gmail.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
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<p>
<div>
<pre>Version: clang version 13.0.0 (<a href="https://github.com/llvm/llvm-project.git">https://github.com/llvm/llvm-project.git</a>
aaab4441796909e1b9cf4279906a56350c8fade7)
Compiler flags: -std=C++20
Consider the following:
```
struct alignas(2) A { char ch1[2]; };
struct Base {
[[no_unique_address]] A a;
char ch2;
};
struct D : Base {
char ch3;
};
int x = sizeof(A);
int y = sizeof(Base);
int z = sizeof(D);
```
<a href="https://godbolt.org/z/Yna9b4535">https://godbolt.org/z/Yna9b4535</a>
Observed behavior:
z is initialized to 6.
Expected behavior:
z is initialized to 4.
Explanation:
Base is not POD for the purpose of layout as it has a potentially-overlapping
non-static data member. As a result `ch3` should be allocated on the
tail-padding of `Base` and `D` should have the same size as `Base`.</pre>
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