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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [concepts] What is the return type of local parameters of requires expressions?"
href="https://bugs.llvm.org/show_bug.cgi?id=45622">45622</a>
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<th>Summary</th>
<td>[concepts] What is the return type of local parameters of requires expressions?
</td>
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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
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
</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>llvm@marehr.dialup.fu-berlin.de
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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>
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<pre>What should I expect when I write the following concept:
```c++
#include <utility>
#include <type_traits>
template <typename t, typename u>
concept same_as = std::is_same_v<t, u>;
template <typename t>
concept foo = requires(t v)
{
{v} -> same_as<t &>;
};
// all of them work with gcc and msvc
static_assert(foo<int>); // fails with clang
static_assert(foo<int const>); // fails with clang
static_assert(foo<int &&>); // fails with clang
static_assert(foo<int &>);
static_assert(foo<int const &>);
```
<a href="https://godbolt.org/z/MGpfZF">https://godbolt.org/z/MGpfZF</a>
gcc and msvc accept theses cases. Are they wrong, or is clang wrong in this
regard?
I created a bug at gcc. After playing with my original example a bit more, I
found out that it seems that clang behaves differently.
<a href="https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94673">https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94673</a></pre>
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