Add -fvisibility=hidden to interface targets

Author: jagerman

CMakeLists.txt

@@ -91,6 +91,9 @@ if(NOT (CMAKE_VERSION VERSION_LESS 3.0))  # CMake >= 3.0
                                                 $<BUILD_INTERFACE:${PYTHON_INCLUDE_DIRS}>
                                                 $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>)
   target_compile_options(pybind11 INTERFACE $<BUILD_INTERFACE:${PYBIND11_CPP_STANDARD}>)
+  if(NOT MSVC)
+    target_compile_options(pybind11 INTERFACE $<BUILD_INTERFACE:-fvisibility=hidden>)
+  endif()
 
   add_library(module INTERFACE)
   add_library(pybind11::module ALIAS module)

tools/pybind11Config.cmake.in

@@ -91,6 +91,9 @@ if(NOT TARGET ${PN}::pybind11)
     endif()
 
     set_property(TARGET ${PN}::pybind11 APPEND PROPERTY INTERFACE_COMPILE_OPTIONS "${PYBIND11_CPP_STANDARD}")
+    if(NOT MSVC)
+      set_property(TARGET ${PN}::pybind11 APPEND PROPERTY INTERFACE_COMPILE_OPTIONS "-fvisibility=hidden")
+    endif()
 
     get_property(_iid TARGET ${PN}::pybind11 PROPERTY INTERFACE_INCLUDE_DIRECTORIES)
     get_property(_ill TARGET ${PN}::module PROPERTY INTERFACE_LINK_LIBRARIES)