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<base href="https://bugs.llvm.org/">
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<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - concepts-related information does not propogated through precompiled headers"
href="https://bugs.llvm.org/show_bug.cgi?id=45115">45115</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>concepts-related information does not propogated through precompiled headers
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>10.0
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</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>vopl@bk.ru
</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>$ cat pch.hpp
#pragma once
template <class T> concept CncChar = sizeof(char)==sizeof(T);
template <class T> concept CncInt = sizeof(int)==sizeof(T);
template <class T> void f() requires CncInt<T> {}
template <class T> void f() requires CncChar<T> {}
$ cat main.cpp
//clang++ -std=gnu++2a pch.hpp -o pch.hpp.pch
//clang++ -std=gnu++2a -include-pch pch.hpp.pch -c main.cpp
#include "pch.hpp"
int main()
{
f<int>();
return 0;
}
# try compile main.cpp WITHOUT precompiled headers
$ clang++ -std=gnu++2a -c main.cpp && echo OK
OK
$
$
$# try compile main.cpp WITH precompiled headers - fail
$ clang++ -std=gnu++2a pch.hpp -o pch.hpp.pch
$ clang++ -std=gnu++2a -include-pch pch.hpp.pch -c main.cpp
main.cpp:8:5: error: no matching function for call to 'f'
f<int>();
^~~~~~
./pch.hpp:7:25: note: candidate template ignored: constraints not satisfied
[with T = int]
template <class T> void f() requires CncChar<T> {}
^
./pch.hpp:7:38: note: because 'int' does not satisfy 'CncChar'
template <class T> void f() requires CncChar<T> {}
^
./pch.hpp:3:38: note: because 'sizeof(char) == sizeof(int)' (1 == 4) evaluated
to false
template <class T> concept CncChar = sizeof(char)==sizeof(T);
^
1 error generated.</pre>
</div>
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