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<base href="http://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Deleted copy constructor, value parameter & move cause incorrect results"
href="http://llvm.org/bugs/show_bug.cgi?id=20799">20799</a>
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<tr>
<th>Summary</th>
<td>Deleted copy constructor, value parameter & move cause incorrect results
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
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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>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>mrintala43+llvmbugs@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>dgregor@apple.com, llvmbugs@cs.uiuc.edu
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</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=12951" name="attach_12951" title="Code demonstrating the bug">attachment 12951</a> <a href="attachment.cgi?id=12951&action=edit" title="Code demonstrating the bug">[details]</a></span>
Code demonstrating the bug
The attached source code declares a class with a deleted copy constructor and a
move constructor. Such object is passed using std::move() to a function taking
a normal value parameter.
When the program is run, it's clear that the address of the parameter in f and
the address of the object created by the move constructor are not the same (the
object is probably bitwise copied somewhere?):
<span class="quote">> clang++ --version</span >
clang version 3.4.2 (tags/RELEASE_342/final 213642)
Target: x86_64-suse-linux
Thread model: posix
<span class="quote">> clang++ -std=c++11 clangbug.cc
> ./a.out </span >
z in main: 0x7ffff7298368
Move: 0x7ffff7298360<-0x7ffff7298368
x in f: 0x7ffff7298338
However, if we use the pre-C++11 way to disable copy constructor (<a href="show_bug.cgi?id=20799#c2">comment 2</a>),
then everything works as I expedted:
<span class="quote">> ./a.out </span >
z in main: 0x7fff49f609d8
Move: 0x7fff49f609d0<-0x7fff49f609d8
x in f: 0x7fff49f609d0
Gcc 4.9.1 seems to produce expected results in both cases.
I'm not sure, but when I searched for this bug, I found #18185, which might or
might not have something to do with the case. I ran into this bug when I
debugged a strange behaviour in std::push_heap(), so there's real code
suffering from the problem.</pre>
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