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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - non-type template argument constexpr when passed by reference"
href="https://bugs.llvm.org/show_bug.cgi?id=52044">52044</a>
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<th>Summary</th>
<td>non-type template argument constexpr when passed by reference
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<th>Product</th>
<td>clang
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<th>Version</th>
<td>12.0
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<th>Hardware</th>
<td>PC
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<th>OS</th>
<td>Linux
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>normal
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>C++
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>alexeytech@gmail.com
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<th>CC</th>
<td>blitzrakete@gmail.com, dgregor@apple.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
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<pre>Hi,
the following code does not work with clang++ 12 and trunk version
***
#include<cstring>
#include<array>
template<size_t N> struct S {
static constexpr size_t n = N;
};
template<size_t N>
void foo(const S<N> &s) {
std::array<char, s.n> arr;
}
int main() {
foo(S<3>{});
}
***
It fails with error
error: non-type template argument is not a constant expression
std::array<char, s.n> arr;
The gcc and msvc compile this snippet without issues
(<a href="https://godbolt.org/z/ffGna7xE8">https://godbolt.org/z/ffGna7xE8</a>)
Interestingly, if I remove the reference in foo argument type - it works.
Surprisingly the clang 12 from the LLVM windows bundle also works.
Regards,
Alex</pre>
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