<html>
<head>
<base href="https://bugs.llvm.org/">
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Overload resolution with using-declaration and constraints doesn't consider base function template"
href="https://bugs.llvm.org/show_bug.cgi?id=49869">49869</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Overload resolution with using-declaration and constraints doesn't consider base function template
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Windows NT
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>C++2a
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>barry.revzin@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>blitzrakete@gmail.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
</td>
</tr></table>
<p>
<div>
<pre>Consider:
#include <concepts>
struct A {};
struct Base {
#ifdef OK
static constexpr int foo(int) { return 1; }
#else
static constexpr int foo(auto) { return 1; }
#endif
};
struct Derived : Base {
using Base::foo;
template <std::same_as<A> T>
static constexpr int foo(T) { return 2; }
};
static_assert(Derived::foo(42) == 1);
static_assert(Derived::foo(A{}) == 2);
With -DOK this compiles. Otherwise, the call to Derived::foo(42) fails with
<source>:19:15: error: no matching function for call to 'foo'
static_assert(Derived::foo(42) == 1);
^~~~~~~~~~~~
<source>:16:26: note: candidate template ignored: constraints not satisfied
[with T = int]
static constexpr int foo(T) { return 2; }
^
<source>:15:20: note: because 'std::same_as<int, A>' evaluated to false
template <std::same_as<A> T>
^
The base candidate is considered and used when it's not a template, but not
considered at all when it is a template. This seems related to whether the
Derived function template uses constraints or not.</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>