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<base href="https://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Clang fails to compile (possibly) legal code"
href="https://llvm.org/bugs/show_bug.cgi?id=25266">25266</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Clang fails to compile (possibly) legal code
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>3.7
</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++
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>hyrosen@mail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>dgregor@apple.com, llvm-bugs@lists.llvm.org
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Here's a bit of code which clang 3.7 doesn't compile:
template <class T> struct R { static T& r(); };
struct M {
static char m(M&);
template <class T>
static int m(const T&);
};
template <class T> struct A;
template <class T>
struct B {
struct U { };
struct V { M& operator, (U) const; };
enum { v = sizeof(M::m((R<V>::r(), R<A<T>*>::r()))) };
};
template <class T> struct A { B<T> y; };
int main()
{
// A<int>(); // Works if uncommented.
B<int>();
}
Clang reports
h.cpp:14:36: error: field has incomplete type 'B<int>'
template <class T> struct A { B<T> y; };
^
h.cpp:12:38: note: in instantiation of template class 'A<int>' requested here
enum { v = sizeof(M::m((R<V>::r(), R<A<T>*>::r()))) };
^
h.cpp:18:5: note: in instantiation of template class 'B<int>' requested here
B<int>();
^
h.cpp:9:8: note: definition of 'B<int>' is not complete until the closing '}'
struct B {
^
1 error generated.
If I uncomment the marked line, clang compiles the code. I don't know why the
compiler wants A<T> to be complete when it's just dealing with A<T>*, or why
uncommenting the marked line helps.</pre>
</div>
</p>
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