commit df9206778fe9ff1bdd56d975c29c43dfe1e66de7
Author: Christopher James Halse Rogers <christopher.halse.rogers@canonical.com>
Date:   Fri Nov 23 15:26:53 2018 +1100

    Export only YAML_CPP_API-tagged symbols on Linux.
    
    This marks classes tagged with YAML_CPP_API with visibility("default"), to
    explicitly export them, and then makes the default visibility "hidden" via
    -fvisibility=hidden.
    
    This reduces the number of exported symbols by more than 50%, which has
    a small application start-up time and memory useage benefit. It also
    makes it more feasible to audit the set of exported symbols in automated
    ABI compatibility systems.

--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -43,6 +43,14 @@
 set(not-msvc $<NOT:$<CXX_COMPILER_ID:MSVC>>)
 set(msvc-shared_rt $<BOOL:${YAML_MSVC_SHARED_RT}>)
 
+if(CMAKE_SYSTEM_NAME MATCHES "Linux")
+   set(CMAKE_CXX_VISIBILITY_PRESET hidden)
+   if (POLICY CMP0063)
+       cmake_policy(SET CMP0063 NEW)
+   endif()
+   add_definitions(-DYAML_CPP_USE_VISIBILITY)
+endif()
+
 if (NOT DEFINED CMAKE_MSVC_RUNTIME_LIBRARY)
   set(CMAKE_MSVC_RUNTIME_LIBRARY
     MultiThreaded$<$<CONFIG:Debug>:Debug>$<${msvc-shared_rt}:DLL>)
--- a/include/yaml-cpp/dll.h
+++ b/include/yaml-cpp/dll.h
@@ -27,7 +27,11 @@
 #define YAML_CPP_API __declspec(dllimport)
 #endif  // yaml_cpp_EXPORTS
 #else   // YAML_CPP_DLL
+#ifdef YAML_CPP_USE_VISIBILITY
+#define YAML_CPP_API __attribute__ ((visibility("default")))
+#else
 #define YAML_CPP_API
+#endif // YAML_CPP_USE_VISIBILITY
 #endif  // YAML_CPP_DLL
 
 #endif  // DLL_H_62B23520_7C8E_11DE_8A39_0800200C9A66