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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - The explicit conversion function shouldn't be considered in a model copy-initialization in reference binding"
href="https://bugs.llvm.org/show_bug.cgi?id=51764">51764</a>
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<th>Summary</th>
<td>The explicit conversion function shouldn't be considered in a model copy-initialization in reference binding
</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>All
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>C++2a
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>xmh970252187@gmail.com
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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>
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<pre>struct D{};
D global;
struct A{
explicit operator D(){
return global;
}
};
int main(){
A a;
D const& rf(a);
}
Clang is wrong to accept this example, as per [dcl.init.ref#5.4.1]
<span class="quote">> If T1 or T2 is a class type and T1 is not reference-related to T2, user-defined conversions are considered using the rules for copy-initialization of an object of type “cv1 T1” by user-defined conversion ([dcl.init], [over.match.copy], [over.match.conv]); the program is ill-formed if the corresponding non-reference copy-initialization would be ill-formed. The result of the call to the conversion function, as described for the non-reference copy-initialization, is then used to direct-initialize the reference. For this direct-initialization, user-defined conversions are not considered. </span >
In the copy-initialization of an object, the explicit conversion function is
not a candidate, hence the copy-initialization is ill-formed, hence the
reference binding is also ill-formed.</pre>
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