[build] Default symbol visibility to hidden for all targets (#4545)

Taichi can be used by external applications that has conflicting
dependencies such as ImGui or Vulkan. In order to avoid any conflicts or
nasty bugs, enforce the visibility to 'hidden' by default so only the
public API is exported.

This moves the config to the global property instead of the per target
property

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)