C++11: GCC 4.8 static thread_local std::unique_ptr undefined reference

Question

I need to store a unique pointer for every thread that will be accessed through a macro. I thought I should solve this with a singleton and static thread_local std::unique_ptr o

Answer 1

I experimented with this by defining a do-nothing ctor for Yay in Yay.hpp:

- Yay() = delete;
+ Yay() {}

When I did that, the error message became:

/tmp/cc8gDxIg.o: In function `TLS wrapper function for Yay::yay':
main.cpp:(.text._ZTWN3Yay3yayE[_ZTWN3Yay3yayE]+0x5): undefined reference to `TLS init function for Yay::yay'

That led me to GCC bug 55800. The bug exists in GCC versions up through 4.8.2, and is fixed in 4.8.3 and 4.9. In discussion threads I found on duplicate GCC bug 59364, the decision has been made not to back port the fix. Therefore, your assembler hack appears to be the only solution available until you move to 4.9.