Enable C in test/CMakeLists.txt; add int main() {} to quick.cpp

test/CMakeLists.txt

@@ -8,6 +8,8 @@ if(NOT HAVE_BOOST_TEST)
   return()
 endif()
 
+enable_language(C)
+
 set(tests_common arithmetic array comparison control debug facilities list logical punctuation selection seq slot stringize tuple variadic isempty)
 set(tests_c ${tests_common})
 set(tests_cpp ${tests_common} iteration repetition quick)

test/quick.cpp

@@ -37,3 +37,7 @@ BEGIN BOOST_PP_GREATER(1, 2) == 0 END
 BEGIN BOOST_PP_GREATER_EQUAL(2, 1) == 1 END
 BEGIN BOOST_PP_GREATER_EQUAL(1, 2) == 0 END
 BEGIN BOOST_PP_GREATER_EQUAL(2, 2) == 1 END
+
+int main()
+{
+}