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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - vtable layout of __func in <functional> is sensitive to RTTI settings"
href="http://llvm.org/bugs/show_bug.cgi?id=20187">20187</a>
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<th>Summary</th>
<td>vtable layout of __func in <functional> is sensitive to RTTI settings
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<th>Product</th>
<td>libc++
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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>Windows NT
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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>All Bugs
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>rnk@google.com
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<th>CC</th>
<td>chandlerc@gmail.com, llvmbugs@cs.uiuc.edu, mclow.lists@gmail.com
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<th>Classification</th>
<td>Unclassified
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<p>
<div>
<pre>This segment of <funcitonal> is worrying:
virtual void destroy_deallocate() _NOEXCEPT;
virtual _Rp operator()(_ArgTypes&& ... __arg);
#ifndef _LIBCPP_NO_RTTI
virtual const void* target(const type_info&) const _NOEXCEPT;
virtual const std::type_info& target_type() const _NOEXCEPT;
#endif // _LIBCPP_NO_RTTI
};
What happens if an -frtti and -fno-rtti library both instantiate
std::function<void()> and then link together?
Chandler had some ideas about splitting __func in to __func and __func_rtti
which extends __func. If RTTI is enabled, we get an always inline
std::function ctor that builds a __func_rtti. If it is disabled, we get
__func. Only if we call std::function::target* do we static_cast the __func to
__func_rtti and call the virtual methods.</pre>
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