glibc test tst-thread_local1.cc fails to compile with latest GCC

[Ellcey, Steve]

I have built the latest glibc sources with a ToT GCC and am trying to run the glibc testsuite now.  I ran into a couple of
new warnings that I fixed (locally) and am now looking at nptl/tst-thread_local1.cc which dies with:

tst-thread_local1.cc:172:7: error: ‘thread’ is not a member of ‘std’
       std::thread thr{[func] {func (nullptr);}};

Does anyone know what is going on here?  If I compile a small test program:

#include <thread>
int main(int, char **){
    std::thread tt;
}

With G++ 5.4 (using -std=c++11) this test program compiles. but with ToT GCC, it dies with:

g++ -std=c++11 thread.cc -lpthread -o x
thread.cc: In function ‘int main(int, char**)’:
thread.cc:5:5: error: ‘thread’ is not a member of ‘std’
     std::thread tt;
     ^~~
thread.cc:5:5: note: suggested alternative: ‘fread’
     std::thread tt;
     ^~~
     fread


Is there some C++ standard change that I am not aware of or some other header file I need to include?

Steve Ellcey