[build] Default symbol visibility to hidden for all targets

cmake/TaichiCore.cmake

@@ -8,7 +8,14 @@ option(TI_WITH_CC "Build with the C backend" ON)
 option(TI_WITH_VULKAN "Build with the Vulkan backend" OFF)
 option(TI_WITH_DX11 "Build with the DX11 backend" OFF)
 option(TI_EMSCRIPTENED "Build using emscripten" OFF)
-set(_TI_SYMBOL_VISIBILITY default)
+
+# Force symbols to be 'hidden' by default so nothing is exported from the Taichi
+# library including the third-party dependencies.
+# As Taichi can be used by external projects, some of the internal dependencies
+# such as Vulkan, ImGui, etc. could be in conflict with the dependencies of those
+# projects.
+set(CMAKE_CXX_VISIBILITY_PRESET hidden)
+set(CMAKE_VISIBILITY_INLINES_HIDDEN ON)
 
 if(TI_EMSCRIPTENED)
     set(TI_WITH_LLVM OFF)
@@ -225,7 +232,6 @@ endif()
 # everywhere in python.
 set(CORE_LIBRARY_NAME taichi_isolated_core)
 add_library(${CORE_LIBRARY_NAME} OBJECT ${TAICHI_CORE_SOURCE})
-set_target_properties(${CORE_LIBRARY_NAME} PROPERTIES CXX_VISIBILITY_PRESET ${_TI_SYMBOL_VISIBILITY})
 
 if (APPLE)
     # Ask OS X to minic Linux dynamic linking behavior
@@ -390,10 +396,6 @@ if (NOT WIN32)
         # Linux
         target_link_libraries(${CORE_LIBRARY_NAME} stdc++fs X11)
         target_link_libraries(${CORE_LIBRARY_NAME} -static-libgcc -static-libstdc++)
-        if ((NOT TI_EXPORT_CORE) AND (NOT ${_TI_SYMBOL_VISIBILITY} STREQUAL hidden)) # expose api for CHI IR Builder
-            message(WARNING "Using linker.map to hide symbols!")
-            target_link_libraries(${CORE_LIBRARY_NAME} -Wl,--version-script,${CMAKE_CURRENT_SOURCE_DIR}/misc/linker.map)
-        endif ()
         # Avoid glibc dependencies
         if (TI_WITH_VULKAN)
             target_link_libraries(${CORE_LIBRARY_NAME} -Wl,--wrap=log2f)
@@ -426,7 +428,6 @@ if(NOT TI_EMSCRIPTENED)
         add_library(${CORE_WITH_PYBIND_LIBRARY_NAME} SHARED)
     endif ()
 
-    set_target_properties(${CORE_WITH_PYBIND_LIBRARY_NAME} PROPERTIES CXX_VISIBILITY_PRESET ${_TI_SYMBOL_VISIBILITY})
     # Remove symbols from static libs: https://stackoverflow.com/a/14863432/12003165
     if (LINUX)
         target_link_options(${CORE_WITH_PYBIND_LIBRARY_NAME} PUBLIC -Wl,--exclude-libs=ALL)