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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 - Clang (front end) errors on variadic template operator="
href="https://bugs.llvm.org/show_bug.cgi?id=43944">43944</a>
</td>
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<th>Summary</th>
<td>Clang (front end) errors on variadic template operator=
</td>
</tr>
<tr>
<th>Product</th>
<td>new-bugs
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</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>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>new bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>davidfink314@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>htmldeveloper@gmail.com, llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>Clang determines a variadic template operator= as taking 0 arguments (which it
then errors on, since it requires 1), no matter what arguments are actually
passed.
See godbolt, or the same code below:
<a href="https://godbolt.org/z/cqqnCb">https://godbolt.org/z/cqqnCb</a>
<source>:21:20: error: overloaded 'operator=' must be a binary operator (has 1
parameter)
decltype(auto) operator=(Args&&... args) {
^
<source>:40:7: note: in instantiation of function template specialization
'mynamespace::vector<C, std::allocator<C> >::operator=<>' requested here
c.operator=({getc()});
#include <vector>
namespace mynamespace {
template <class T, class Alloc = std::allocator<T>>
class vector : public std::vector<T, Alloc> {
private:
using Base = std::vector<T, Alloc>;
public:
template <class... Args>
vector(Args&&... args)
: Base(std::forward<Args>(args)...) {
}
vector(std::initializer_list<T> il)
: Base(il) {
}
template<class... Args>
decltype(auto) operator=(Args&&... args) {
Base::operator=(std::forward<Args>(args)...);
return *this;
}
};
} /* namespace mynamespace */
struct C {
int x;
};
C getc();
int main() {
mynamespace::vector<C> c;
// works
c.operator=(mynamespace::vector<C>{getc()});
// doesn't work (= template errors on 0 params)
c.operator=({getc()});
// also doesn't work
c = {getc()};
// also doesn't work
c = {getc(), getc()};
}</pre>
</div>
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