commit 50e7b3cee4e099189d0954e361a0af4f39c3a368
author Louis Dionne <ldionne@apple.com> Thu May 02 17:43:48 2019 +0000
committer Copybara-Service <copybara-worker@google.com> Thu Aug 27 18:58:17 2020 -0700
tree 71ab4eff60ba9a039774329aff3365c14d38b6c1
parent 5b6fb0259adcdcefc4c0a227da60e79d200996ed

[libc++][CMake] Link against libSystem on Apple platforms

Instead of manually linking against libm/librt/libpthread, we should be
linking against libSystem on Apple platforms, and only that. libm and
libpthread are symlinks to libSystem anyway.

llvm-svn: 359808
GitOrigin-RevId: 223ed705d0d3c3b07f00202a04447df836c05df8

cmake/config-ix.cmake

diff --git a/cmake/config-ix.cmake b/cmake/config-ix.cmake
index 730ee7e..23ae710 100644
--- a/cmake/config-ix.cmake
+++ b/cmake/config-ix.cmake
@@ -80,8 +80,15 @@
   set(LIBCXX_HAS_PTHREAD_LIB NO)
   set(LIBCXX_HAS_M_LIB NO)
   set(LIBCXX_HAS_RT_LIB NO)
+  set(LIBCXX_HAS_SYSTEM_LIB NO)
+elseif(APPLE)
+  check_library_exists(System write "" LIBCXX_HAS_SYSTEM_LIB)
+  set(LIBCXX_HAS_PTHREAD_LIB NO)
+  set(LIBCXX_HAS_M_LIB NO)
+  set(LIBCXX_HAS_RT_LIB NO)
 else()
   check_library_exists(pthread pthread_create "" LIBCXX_HAS_PTHREAD_LIB)
   check_library_exists(m ccos "" LIBCXX_HAS_M_LIB)
   check_library_exists(rt clock_gettime "" LIBCXX_HAS_RT_LIB)
+  set(LIBCXX_HAS_SYSTEM_LIB NO)
 endif()

src/CMakeLists.txt

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 3c31548..5d9cc01 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -140,6 +140,10 @@
   target_add_compile_flags_if_supported(${target} PRIVATE "/Zl")
   target_add_link_flags_if_supported(${target} PRIVATE "/nodefaultlib")
 
+  if (LIBCXX_HAS_SYSTEM_LIB)
+    target_link_libraries(${target} PUBLIC System)
+  endif()
+
   if (LIBCXX_HAS_PTHREAD_LIB)
     target_link_libraries(${target} PUBLIC pthread)
   endif()