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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Incorrect overload resolution dependent on instantiation order"
href="https://bugs.llvm.org/show_bug.cgi?id=35077">35077</a>
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<th>Summary</th>
<td>Incorrect overload resolution dependent on instantiation order
</td>
</tr>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>trunk
</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>C++
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>kaballo86@hotmail.com
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</tr>
<tr>
<th>CC</th>
<td>dgregor@apple.com, llvm-bugs@lists.llvm.org
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<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=19340" name="attach_19340" title="include-less test case">attachment 19340</a> <a href="attachment.cgi?id=19340&action=edit" title="include-less test case">[details]</a></span>
include-less test case
In the following snippet, the result of overload resolution changes depending
on whether the template argument has been previously instantiated:
#include <cstdio>
#include <type_traits>
using namespace std;
template <typename ...Ts> struct foo {};
template <typename T> struct is_foo : std::false_type {};
template <typename ...Ts> struct is_foo<foo<Ts...>> : std::true_type {};
///
template <typename ...Ts>
void any_of(...) {
puts("true");
}
template <typename ...Ts>
auto any_of(int) -> void_t<enable_if_t<!Ts::value>...> {
puts("false");
}
// sizeof(is_foo<foo<>>); // uncomment-me
any_of<is_foo<foo<>>>(0); // prints "false"
The result is "false", unless `is_foo<foo<>>` has been instantiated before in
the TU in which case the result is "true".</pre>
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