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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Rejects-valid for overloaded hidden non-template friend functions with mutually exclusive requires-clauses"
href="https://bugs.llvm.org/show_bug.cgi?id=48872">48872</a>
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<th>Summary</th>
<td>Rejects-valid for overloaded hidden non-template friend functions with mutually exclusive requires-clauses
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<th>Product</th>
<td>clang
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</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
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<th>Component</th>
<td>C++2a
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>davveston@gmail.com
</td>
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<th>CC</th>
<td>blitzrakete@gmail.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
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<p>
<div>
<pre>As per [defns.signature.friend] in N4861, the signature of a non-template
friend function includes a trailing requires-clause, if it is present.
Moreover, [over.dcl]/1 states that two function declarations declare different
functions if they have different trailing requires-clauses.
The following example fails to compile for Clang (-std=c++2b, 12.0.0 trunk):
#include <iostream>
template<int N>
struct S {
friend void foo(int) requires (N == 1) { std::cout << "1\n"; }
friend void foo(int) requires (N == 2) { std::cout << "2\n"; }
operator int() const { return 0; }
};
int main() {
foo(S<1>{}); // 1
foo(S<2>{});
// error: definition with same mangled
// name '...' as another definition
}
which is arguably incorrect, as the two, separate (by separate
requires-clauses) friend declarations (that are also definitions) should not
generate the same mangled name.
---
(Constrained hidden non-template friends was added as per NS US115 of P2103R0;
<a href="http://open-std.org/JTC1/SC22/WG21/docs/papers/2020/p2103r0.html">http://open-std.org/JTC1/SC22/WG21/docs/papers/2020/p2103r0.html</a>)</pre>
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