Could not build with Folly on Mac using AppleClang due --copy-dt-needed-entries flag

[uilianries]

Hello!

When trying to build rocksdb 10.5.1 on my Mac M1, using AppleClang as compiler and using external Folly, CMake fails when trying to find Thread with the following error:

-- Performing Test CMAKE_HAVE_LIBC_PTHREAD
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD - Failed
-- Looking for pthread_create in pthreads
-- Looking for pthread_create in pthreads - not found
-- Looking for pthread_create in pthread
-- Looking for pthread_create in pthread - not found
-- Check if compiler accepts -pthread
-- Check if compiler accepts -pthread - no
CMake Error at /opt/homebrew/share/cmake/Modules/FindPackageHandleStandardArgs.cmake:227 (message):
  Could NOT find Threads (missing: Threads_FOUND)
Call Stack (most recent call first):
  /opt/homebrew/share/cmake/Modules/FindPackageHandleStandardArgs.cmake:591 (_FPHSA_FAILURE_MESSAGE)
  /opt/homebrew/share/cmake/Modules/FindThreads.cmake:226 (find_package_handle_standard_args)
  CMakeLists.txt:634 (find_package)


-- Configuring incomplete, errors occurred!

Reading the CMake configure log to obtain a more detailed output I can see:

-
    kind: "try_compile-v1"
    backtrace:
      - "/opt/homebrew/share/cmake/Modules/FindThreads.cmake:136 (try_compile)"
      - "/opt/homebrew/share/cmake/Modules/FindThreads.cmake:179 (_threads_check_flag_pthread)"
      - "CMakeLists.txt:634 (find_package)"
    checks:
      - "Check if compiler accepts -pthread"
    directories:
      source: "/Users/uilian/.conan2/p/b/rocksde5d29833fc26/b/build/Release/CMakeFiles/CMakeScratch/TryCompile-gVC6Sc"
      binary: "/Users/uilian/.conan2/p/b/rocksde5d29833fc26/b/build/Release/CMakeFiles/CMakeScratch/TryCompile-gVC6Sc"
    cmakeVariables:
      CMAKE_C_FLAGS: " -march=armv8-a+crc+crypto -Wno-unused-function"
      CMAKE_C_FLAGS_DEBUG: "-g"
      CMAKE_EXE_LINKER_FLAGS: " -Wl,--copy-dt-needed-entries"
      CMAKE_MODULE_PATH: "/Users/uilian/.conan2/p/b/opens21f4e935f46db/p/lib/cmake;/Users/uilian/.conan2/p/b/rocksde5d29833fc26/b/build/Release/generators;/Users/uilian/.conan2/p/b/opens21f4e935f46db/p/lib/cmake;/Users/uilian/.conan2/p/b/rocksde
5d29833fc26/b/src/cmake/modules/"
      CMAKE_OSX_ARCHITECTURES: "arm64"
      CMAKE_OSX_DEPLOYMENT_TARGET: ""
      CMAKE_OSX_SYSROOT: "/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX15.5.sdk"
      CMAKE_POSITION_INDEPENDENT_CODE: "ON"
    buildResult:
      variable: "THREADS_HAVE_PTHREAD_ARG"
      cached: true
      stdout: |
        Change Dir: '/Users/uilian/.conan2/p/b/rocksde5d29833fc26/b/build/Release/CMakeFiles/CMakeScratch/TryCompile-gVC6Sc'
        
        Run Build Command(s): /opt/homebrew/bin/ninja -v cmTC_a6c38
        [1/2] /usr/bin/cc   -march=armv8-a+crc+crypto -Wno-unused-function  -arch arm64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX15.5.sdk -fPIE -MD -MT CMakeFiles/cmTC_a6c38.dir/CheckFor
Pthreads.c.o -MF CMakeFiles/cmTC_a6c38.dir/CheckForPthreads.c.o.d -o CMakeFiles/cmTC_a6c38.dir/CheckForPthreads.c.o -c /Users/uilian/.conan2/p/b/rocksde5d29833fc26/b/build/Release/CMakeFiles/CMakeScratch/TryCompile-gVC6Sc/CheckForPthreads.c
        [2/2] : && /usr/bin/cc -march=armv8-a+crc+crypto -Wno-unused-function  -arch arm64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX15.5.sdk -Wl,-search_paths_first -Wl,-headerpad_max_in
stall_names  -Wl,--copy-dt-needed-entries CMakeFiles/cmTC_a6c38.dir/CheckForPthreads.c.o -o cmTC_a6c38  -pthread && :
        FAILED: [code=1] cmTC_a6c38 
        : && /usr/bin/cc -march=armv8-a+crc+crypto -Wno-unused-function  -arch arm64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX15.5.sdk -Wl,-search_paths_first -Wl,-headerpad_max_install_
names  -Wl,--copy-dt-needed-entries CMakeFiles/cmTC_a6c38.dir/CheckForPthreads.c.o -o cmTC_a6c38  -pthread && :
        ld: unknown options: --copy-dt-needed-entries 
        clang: error: linker command failed with exit code 1 (use -v to see invocation)
        ninja: build stopped: subcommand failed.
        
      exitCode: 1
  -

The error is caused because Clang does not support **--copy-dt-needed-entries **, but GCC supports it.

The following logic is listed here:

https://github.com/facebook/rocksdb/blob/v10.5.1/CMakeLists.txt#L637

Using the following patch should mitigate the current error:

diff --git a/CMakeLists.txt b/CMakeLists.txt
index ef93aa2..713d4c1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -634,7 +634,9 @@ if(USE_FOLLY)
   add_compile_definitions(USE_FOLLY FOLLY_NO_CONFIG HAVE_CXX11_ATOMIC)
   list(APPEND THIRDPARTY_LIBS Folly::folly)
   set(FOLLY_LIBS Folly::folly)
-  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -Wl,--copy-dt-needed-entries")
+  if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+    set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -Wl,--copy-dt-needed-entries")
+  endif()
 endif()
 find_package(Threads REQUIRED)

Regards!