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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - MS ABI: dllexport default closure constructor"
href="http://llvm.org/bugs/show_bug.cgi?id=22840">22840</a>
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<th>Summary</th>
<td>MS ABI: dllexport default closure constructor
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>unspecified
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>C++
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>david.majnemer@gmail.com
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<th>CC</th>
<td>dgregor@apple.com, llvmbugs@cs.uiuc.edu
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<th>Classification</th>
<td>Unclassified
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<p>
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<pre>consider:
struct __declspec(dllimport) S { S(int = 3) {} };
void f() {
S s[5];
}
compiling with MSVC 2013 or 2015 yields a reference to __imp_??_FS@@QEAAXXZ
which is the default constructor closure. The default constructor closure
evaluates all the default arguments and then calls the default constructor.
Wrapping it this way makes it possible to call the "vector constructor
iterator" which MSVC employs as a code-size optimization.
If you change the dllimport to dllexport and compile with clang, no default
constructor is emitted and thus our program will not link.</pre>
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