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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - is_default_constructible and DRs 1354, 1424"
href="http://llvm.org/bugs/show_bug.cgi?id=18876">18876</a>
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<th>Summary</th>
<td>is_default_constructible and DRs 1354, 1424
</td>
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<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>3.4
</td>
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<tr>
<th>Hardware</th>
<td>Other
</td>
</tr>
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<th>OS</th>
<td>Linux
</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>
</tr>
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<th>Component</th>
<td>C++
</td>
</tr>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>hstong@ca.ibm.com
</td>
</tr>
<tr>
<th>CC</th>
<td>dgregor@apple.com, llvmbugs@cs.uiuc.edu
</td>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>The implementation of is_default_constructible in libstdc++ is based on the
validity of a decltype-specifier whose expression is a function-style cast for
the type being queried with no arguments.
Using that implementation, Clang 3.4 (tags/RELEASE_34/final) does not produce
the expected result for struct A below. It seems that one or both of DR 1354
and 1424 is not yet implemented by Clang.
SOURCE:
struct A { ~A() = delete; };
template <typename T> struct TypeSink;
TypeSink<decltype(A())> *typeSink;
/*
#include <type_traits>
extern char x[std::is_default_constructible<A>::value ? 42 : -1];
extern char x[42];
*/
EXPECTED OUTPUT:
(errors)
ACTUAL OUTPUT:
(successful compile)</pre>
</div>
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