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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Allow std::vector::insert to compile when elements have a deleted assignment operator"
href="https://bugs.llvm.org/show_bug.cgi?id=48619">48619</a>
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<th>Summary</th>
<td>Allow std::vector::insert to compile when elements have a deleted assignment operator
</td>
</tr>
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<th>Product</th>
<td>libc++
</td>
</tr>
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<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Hardware</th>
<td>All
</td>
</tr>
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<th>OS</th>
<td>All
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>All Bugs
</td>
</tr>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>bstanimirov6@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org, mclow.lists@gmail.com
</td>
</tr></table>
<p>
<div>
<pre>Create a class `X` which is copy-constructible but not copy-assignable
```
struct X {
X();
X(const X&);
X& operator=(const X&) = delete; // !!
X(X&&) noexcept;
X& operator=(X&&) noexcept;
int data = 54;
};
```
Have vectors of X `a` and `b`. Try to add all elements of b at the front of a:
```
void add_to_front(std::vector<X>& a, const std::vector<X>& b) {
a.insert(a.begin(), b.begin(), b.end());
}
```
Live demo: <a href="https://godbolt.org/z/K1WT8n">https://godbolt.org/z/K1WT8n</a>
It doesn't compile. My guess is that code which will never get invoked, still
needs to compile (or, worse yet, copy assignment does get invoked?!)
The only way to achieve the desired behavior efficiently is to use a custom
vector implementation. There is a stackoverflow question which has some *worse*
workarounds:
<a href="https://stackoverflow.com/questions/65489039/how-to-efficiently-insert-multiple-copy-constructible-but-not-copy-assignable-el">https://stackoverflow.com/questions/65489039/how-to-efficiently-insert-multiple-copy-constructible-but-not-copy-assignable-el</a>
This does compile and work on msvc, so a compile-time check for the
copy-assignment code is possible.</pre>
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