[CMake] Use correct visibility for linked libraries in CMake

[phosek]

Summary

When linking shared library, we shouldn't need to export linked
libraries to dependents, but we still need to do that for static
library. We should be explicit about this in target_link_libraries,
otherwise other targets that depend on these such as sanitizers get
repeated (and possibly even conflicting) dependencies.

[phosek]

We hit this issue when trying to link libclang_rt.asan.so with static unwinder but shared libc++abi where we would get two different instances of libunwind, one from direct dependency and one from libc++abi.

[ldionne]

THANKS.

[ldionne]

Wait, actually, doesn't CMake handle that automatically? I think that for STATIC libraries, even PRIVATE dependencies are forwarded to dependents, no?

[phosek]

In D57456#1377406, @ldionne wrote:

Wait, actually, doesn't CMake handle that automatically? I think that for STATIC libraries, even PRIVATE dependencies are forwarded to dependents, no?

Let me try this, if that's true than we could use PRIVATE everywhere.

[phosek]

We can use PRIVATE everywhere, CMake handles static libraries correctly.

libcxx/lib/CMakeLists.txt

 endif()
 
 # Build the shared library.
 if (LIBCXX_ENABLE_SHARED)
   add_library(cxx_shared SHARED ${cxx_shared_sources})
   if(COMMAND llvm_setup_rpath)
     llvm_setup_rpath(cxx_shared)
   endif()
-  target_link_libraries(cxx_shared ${LIBCXX_LIBRARIES})
+  target_link_libraries(cxx_shared PRIVATE ${LIBCXX_LIBRARIES})
   set_target_properties(cxx_shared
     PROPERTIES
       LINK_FLAGS    "${LIBCXX_LINK_FLAGS}"
       OUTPUT_NAME   "c++"
       VERSION       "${LIBCXX_ABI_VERSION}.0"
       SOVERSION     "${LIBCXX_ABI_VERSION}"
   )
   list(APPEND LIBCXX_BUILD_TARGETS "cxx_shared")
   if (LIBCXX_INSTALL_SHARED_LIBRARY)
     list(APPEND LIBCXX_INSTALL_TARGETS "cxx_shared")
   endif()
   if(WIN32 AND NOT MINGW AND NOT "${CMAKE_HOST_SYSTEM_NAME}" STREQUAL "Windows")
     # Since we most likely do not have a mt.exe replacement, disable the
     # manifest bundling.  This allows a normal cmake invocation to pass which
     # will attempt to use the manifest tool to generate the bundled manifest
     set_target_properties(cxx_shared PROPERTIES
                           APPEND_STRING PROPERTY LINK_FLAGS " /MANIFEST:NO")
   endif()
 endif()
 
 # Build the static library.
 if (LIBCXX_ENABLE_STATIC)
   add_library(cxx_static STATIC ${cxx_static_sources})
-  target_link_libraries(cxx_static ${LIBCXX_LIBRARIES})
+  target_link_libraries(cxx_static PUBLIC ${LIBCXX_LIBRARIES})
   set(CMAKE_STATIC_LIBRARY_PREFIX "lib")
   set_target_properties(cxx_static
     PROPERTIES
       LINK_FLAGS    "${LIBCXX_LINK_FLAGS}"
       OUTPUT_NAME   "c++"
   )
   list(APPEND LIBCXX_BUILD_TARGETS "cxx_static")
   if (LIBCXX_INSTALL_STATIC_LIBRARY)

libcxxabi/src/CMakeLists.txt

 endif()
 
 # Build the shared library.
 if (LIBCXXABI_ENABLE_SHARED)
   add_library(cxxabi_shared SHARED ${cxxabi_shared_sources})
   if(COMMAND llvm_setup_rpath)
     llvm_setup_rpath(cxxabi_shared)
   endif()
-  target_link_libraries(cxxabi_shared ${LIBCXXABI_LIBRARIES} ${LIBCXXABI_SHARED_LIBRARIES})
+  target_link_libraries(cxxabi_shared PRIVATE ${LIBCXXABI_LIBRARIES} ${LIBCXXABI_SHARED_LIBRARIES})
   set_target_properties(cxxabi_shared
                         PROPERTIES
                           CXX_EXTENSIONS
                             OFF
                           CXX_STANDARD
                             11
                           CXX_STANDARD_REQUIRED
                             ON
if (TARGET unwind_static OR HAVE_LIBUNWIND)
       if(LIBUNWIND_HERMETIC_STATIC_LIBRARY)
         list(APPEND cxxabi_static_sources $<TARGET_OBJECTS:unwind_static_objects>)
       else()
         list(APPEND cxxabi_static_sources $<TARGET_OBJECTS:unwind_objects>)
       endif()
     endif()
   endif()
   add_library(cxxabi_static STATIC ${cxxabi_static_sources})
-  target_link_libraries(cxxabi_static ${LIBCXXABI_LIBRARIES} ${LIBCXXABI_STATIC_LIBRARIES})
+  target_link_libraries(cxxabi_static PUBLIC ${LIBCXXABI_LIBRARIES} ${LIBCXXABI_STATIC_LIBRARIES})
   set_target_properties(cxxabi_static
                         PROPERTIES
                           CXX_EXTENSIONS
                             OFF
                           CXX_STANDARD
                             11
                           CXX_STANDARD_REQUIRED
                             ON

libunwind/src/CMakeLists.txt

 endif()
 
 # Build the shared library.
 if (LIBUNWIND_ENABLE_SHARED)
   add_library(unwind_shared SHARED ${unwind_shared_sources})
   if(COMMAND llvm_setup_rpath)
     llvm_setup_rpath(unwind_shared)
   endif()
-  target_link_libraries(unwind_shared ${libraries})
+  target_link_libraries(unwind_shared PRIVATE ${libraries})
   set_target_properties(unwind_shared
                         PROPERTIES
                           LINK_FLAGS    "${LIBUNWIND_LINK_FLAGS}"
                           OUTPUT_NAME   "unwind"
                           VERSION       "1.0"
                           SOVERSION     "1")
   list(APPEND LIBUNWIND_BUILD_TARGETS "unwind_shared")
   if (LIBUNWIND_INSTALL_SHARED_LIBRARY)
     list(APPEND LIBUNWIND_INSTALL_TARGETS "unwind_shared")
   endif()
 endif()
 
 # Build the static library.
 if (LIBUNWIND_ENABLE_STATIC)
   add_library(unwind_static STATIC ${unwind_static_sources})
-  target_link_libraries(unwind_static ${libraries})
+  target_link_libraries(unwind_static PUBLIC ${libraries})
   set_target_properties(unwind_static
                         PROPERTIES
                           LINK_FLAGS    "${LIBUNWIND_LINK_FLAGS}"
                           OUTPUT_NAME   "unwind")
   list(APPEND LIBUNWIND_BUILD_TARGETS "unwind_static")
   if (LIBUNWIND_INSTALL_STATIC_LIBRARY)
     list(APPEND LIBUNWIND_INSTALL_TARGETS "unwind_static")
   endif()