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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - __is_transparent check requires too much"
href="https://bugs.llvm.org/show_bug.cgi?id=33389">33389</a>
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<th>Summary</th>
<td>__is_transparent check requires too much
</td>
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<th>Product</th>
<td>libc++
</td>
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<th>Version</th>
<td>4.0
</td>
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<th>Hardware</th>
<td>All
</td>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
</td>
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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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</tr>
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<th>Reporter</th>
<td>rs2740@gmail.com
</td>
</tr>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org, mclow.lists@gmail.com
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<p>
<div>
<pre>__is_transparent checks for the nested is_transparent typedef by attempting to
form a pointer to it. That means it gives the wrong answer in cases where
key_compare::is_transparent "is valid and denotes a type" to which a
pointer cannot be formed (such as reference types and abominable function
types).
#include <functional>
#include <set>
enum class Test {};
bool operator<(int, Test) { return true; }
bool operator<(Test, int) { return false; }
struct evil_less : std::less<> {
using is_transparent = void() const &; //int& breaks, too.
};
int main() {
std::set<int, evil_less> s;
s.find(Test{});
}</pre>
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