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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - no zero initialization in value initialization"
href="http://llvm.org/bugs/show_bug.cgi?id=19779">19779</a>
</td>
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<tr>
<th>Summary</th>
<td>no zero initialization in value initialization
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>3.4
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Linux
</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>
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<th>Component</th>
<td>C++11
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>kezhuw@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>dgregor@apple.com, llvmbugs@cs.uiuc.edu
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>struct A {
int i;
A() {}
};
struct B {
// no user-provided constructor,
// implicitly-declared default constructor is generated by compiler.
A a;
};
char mem[1024];
memset(mem, 0xcc, sizeof mem);
new (mem) B{};
B& b = *(reinterpret_cast<B*>(mem));
Compiles it with `clang++ -std=c++11`, `b.a.i` is 0xcccccccc.
This conflicts with what C++11 says about value initialization:
— if T is a (possibly cv-qualified) non-union class type without a
user-provided constructor, then the object is zero-initialized and, if T’s
implicitly-declared default constructor is non-trivial, that constructor is
called.
Or my understanding of value initialization in C++11 is wrong ?
The example comes from
<a href="http://en.cppreference.com/w/cpp/language/value_initialization">http://en.cppreference.com/w/cpp/language/value_initialization</a> .</pre>
</div>
</p>
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