Redefinition of tuple when using gtest and google sparsehash

Question

All test cases that somehow include <gtest/gtest.h> and <google/dense_hash_map> fail to build for me. Usually the later is included indirectly but I can reproduce the problem like this:

#include <gtest/gtest.h>
#include <google/dense_hash_map>

TEST(SparsehashTest, justPass) {
  ASSERT_TRUE(true);
};


int main(int argc, char** argv) {
  ::testing::InitGoogleTest(&argc, argv);
  return RUN_ALL_TESTS();
}

The problem:

In file included from /usr/include/c++/5/tr1/functional:39:0,
                 from /usr/local/include/sparsehash/dense_hash_map:106,
                 from /usr/local/include/google/dense_hash_map:34,
                 from /home/me/xxx/test/SparsehashTest.cpp:6:
/usr/include/c++/5/tr1/tuple:130:11: error: redefinition of ‘class std::tuple< <template-parameter-1-1> >’
     class tuple : public _Tuple_impl<0, _Elements...>
           ^
In file included from /home/me/xxx/third_party/googletest/googletest/include/gtest/internal/gtest-port.h:697:0,
                 from /home/me/xxx/third_party/googletest/googletest/include/gtest/internal/gtest-internal.h:40,
                 from /home/me/xxx/third_party/googletest/googletest/include/gtest/gtest.h:58,
                 from /home/me/xxx/test/SparsehashTest.cpp:5:
/usr/include/c++/5/tuple:463:11: error: previous definition of ‘class std::tuple< <template-parameter-1-1> >’
     class tuple : public _Tuple_impl<0, _Elements...>

So sparsehash includes /usr/include/c++/5/tr1/tuple whereas gtest includes /usr/include/c++/5/tuple and puts it in the tr1 namespace in gtest-port.h:

...
697: #include <tuple>
698: // C++11 puts its tuple into the ::std namespace rather than
699: // ::std::tr1.  gtest expects tuple to live in ::std::tr1, so put it there.
700: // This causes undefined behavior, but supported compilers react in
701: // the way we intend.
702: namespace std {
703: namespace tr1 {
704: using ::std::get;
705: using ::std::make_tuple;
706: using ::std::tuple;
707: using ::std::tuple_element;
708: using ::std::tuple_size;
709: }
...

I can understand why this causes problems, but so far I don't understand why this only seems to happen in my setup. I have google-sparsehash installed regularly (git clone and then ./configure && make && sudo make install) and my project is a CMake project that has a git submode for googletest and builds it as a dependency / subfolder. This setup works as intended for all tests that do not (indirectly) include the sparsehash headers.

EDIT: So it seems to compile if I add -DGTEST_HAS_TR1_TUPLE=0 -DGTEST_USE_OWN_TR1_TUPLE=0 as compiler flags. I'm not sure why this is necessary and if it's the right thing to do here

Answer 1

I found this thread because I had the same issue, and it provided enough clues that I managed to fix my issue by requesting that sparsehash be compiled with the c++11 compiler option:

./configure CXXFLAGS='-std=c++11'