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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Parameter pack not expanded in typedef for function type"
href="https://bugs.llvm.org/show_bug.cgi?id=46377">46377</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Parameter pack not expanded in typedef for function type
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>All
</td>
</tr>
<tr>
<th>OS</th>
<td>All
</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++
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>zilla@kayari.org
</td>
</tr>
<tr>
<th>CC</th>
<td>blitzrakete@gmail.com, dgregor@apple.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
</td>
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<p>
<div>
<pre>template<typename T, typename U>
struct require_same;
template<typename T> struct require_same<T,T>
{ };
template<typename T> using int_t = int;
void (*f)();
template<typename ...Ts>
void g(Ts... args) {
// This works
((void (*)(int_t<Ts>...)) f)(args...);
// This works
using funcptr = void (*)(decltype((void)args, 0)...);
((funcptr) f)(args...);
// This is wrong
using funcptr2 = void (*)(int_t<Ts>...);
// The type funcptr2 only has a single parameter, pack not expanded
require_same<funcptr, funcptr2> chk;
// So this fails
((funcptr2) f)(args...);
}
void h(int x, int y) { g(x, y); }
This works with Clang 3.0 but fails with anything later. This prevents building
GCC master with Clang.
var.cc:24:35: error: implicit instantiation of undefined template
'require_same<void (*)(int, int), void (*)(int)>'
require_same<funcptr, funcptr2> chk;
^
var.cc:30:24: note: in instantiation of function template specialization
'g<int, int>' requested here
void h(int x, int y) { g(x, y); }
^
var.cc:2:8: note: template is declared here
struct require_same;
^
var.cc:27:18: error: too many arguments to function call, expected 1, have 2
((funcptr2) f)(args...);
~~~~~~~~~~~~~~ ^~~~
2 errors generated.</pre>
</div>
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