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<head>
<base href="http://llvm.org/bugs/" />
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<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - code compiles with g++-4.9.0, but not clang-3.4.2"
href="http://llvm.org/bugs/show_bug.cgi?id=20195">20195</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>code compiles with g++-4.9.0, but not clang-3.4.2
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>C++11
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>janezz55@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>dgregor@apple.com, llvmbugs@cs.uiuc.edu
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>clang fails to compile this code with the error:
t.cpp:24:13: error: a lambda expression may not appear inside of a constant
expression
address([](C* const object) noexcept {
#include <iostream>
#include <type_traits>
#include <utility>
#ifndef MEMBER
# define MEMBER(f) decltype(&f),&f
#endif // MEMBER
namespace detail
{
template <typename T>
auto address(T&& t) -> typename ::std::remove_reference<T>::type*
{
return &t;
}
template <typename FP, FP fp, class C, typename ...A>
struct S
{
static constexpr auto* l = false ?
address([](C* const object) noexcept {
return [object](A&& ...args) {
return (object->*fp)(::std::forward<A>(args)...);
};
}) :
nullptr;
};
template <typename FP, FP fp, typename R, class C, typename ...A>
auto make_delegate(C* const object, R (C::* const)(A...)) ->
decltype((*decltype(S<FP, fp, C, A...>::l)(nullptr))(object))
{
return (*decltype(S<FP, fp, C, A...>::l)(nullptr))(object);
}
}
template <typename FP, FP fp, class C>
auto make_delegate(C* const object) ->
decltype(detail::make_delegate<FP, fp>(object, fp))
{
return detail::make_delegate<FP, fp>(object, fp);
}
struct A
{
void operator()()
{
::std::cout << "hello world" << ::std::endl;
}
};
int main()
{
A a;
auto d(make_delegate<MEMBER(A::operator())>(&a));
d();
return 0;
}</pre>
</div>
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