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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - thread-local static variable i"
href="https://bugs.llvm.org/show_bug.cgi?id=42111">42111</a>
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<th>Summary</th>
<td>thread-local static variable i
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>8.0
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>C++
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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</tr>
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<th>Reporter</th>
<td>eyalroz@technion.ac.il
</td>
</tr>
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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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<p>
<div>
<pre>Relevant StackOverflow question: <a href="https://stackoverflow.com/q/52471237/1593077">https://stackoverflow.com/q/52471237/1593077</a>
Consider the following program:
#include <iostream>
#include <thread>
using std::cout;
using std::endl;
template <typename T>
class Something {
public:
struct TLBookkeeping {
TLBookkeeping() {
std::cout << "TLBookkeeping() " << std::this_thread::get_id() <<
std::endl;
}
};
static void foo();
static thread_local TLBookkeeping bookkeeping_;
};
template <typename T>
thread_local typename Something<T>::TLBookkeeping Something<T>::bookkeeping_;
template <typename T>
void Something<T>::foo() {
std::cout << &bookkeeping_ << std::endl;
std::cout << &bookkeeping_ << std::endl;
}
namespace {
struct Struct {};
}
int main() {
Something<Struct>::foo();
}
If we compile and run it, we get:
TLBookkeeping() 140713161373504
0x7ffa55ffb73f
TLBookkeeping() 140713161373504
0x7ffa55ffb73f
i.e. the static TLBookeeping variable is constructed twice. IIANM, this
shouldn't happen; and compiling with GCC doesn't cause this behavior.</pre>
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