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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - clang fails to generate defaulted move constructor upon template instantiation"
href="https://bugs.llvm.org/show_bug.cgi?id=39649">39649</a>
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<th>Summary</th>
<td>clang fails to generate defaulted move constructor upon template instantiation
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>unspecified
</td>
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<th>Hardware</th>
<td>All
</td>
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<th>OS</th>
<td>MacOS X
</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
</td>
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<th>Component</th>
<td>C++11
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>wdehnen64@gmail.com
</td>
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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>I couldn't reduce the error below this three file example:
// file unit.h:
#include <vector>
template<typename T>
struct foo
{
std::vector<T> data;
foo(foo&&) = default; // no code generated, even if odr-used.
foo(std::vector<T>&&v) : data(std::move(v)) {}
};
extern template struct foo<int>; // indicates instantiation elsewhere
// file unit.cc:
#include "unit.h"
template struct foo<int>; // forces instantiation
// file main.cc:
#include "unit.h"
struct bar
{
foo<int> f;
bar(foo<int>&&x) : f(std::move(x)) {}
};
bar makeBar()
{
foo<int> f(std::vector<int>(5));
return {std::move(f)};
}
int main()
{
bar x=makeBar();
}
clang++ -std=c++11 main.cc unit.cc
produces:
Undefined symbols for architecture x86_64:
"foo<int>::foo(foo<int>&&)", referenced from:
bar::bar(foo<int>&&) in main.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)</pre>
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