From 73bf70d3324730b15f9a603692659b07a8c4071a Mon Sep 17 00:00:00 2001
From: Heiko Thiel <heiko.thiel@hpi.de>
Date: Fri, 24 May 2019 23:52:38 +0200
Subject: [PATCH] Add thread library of the system by Threads::Threads instead
 of -pthread flag. This commit also fix
 "//lib/x86_64-linux-gnu/libpthread.so.0: error adding symbols: DSO missing
 from command line". This issue was caused by missing linking of thread
 library in PCL_ADD_LIBRARY.

---
 CMakeLists.txt          |  9 ++++-----
 cmake/pcl_targets.cmake | 15 +++------------
 2 files changed, 7 insertions(+), 17 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4e85b59046f..1e2d0e43497 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -112,10 +112,6 @@ if(CMAKE_COMPILER_IS_GNUCXX)
     set(CMAKE_CXX_FLAGS "-Wabi -Wall -Wextra -Wno-unknown-pragmas -fno-strict-aliasing -Wno-format-extra-args -Wno-sign-compare -Wno-invalid-offsetof -Wno-conversion ${SSE_FLAGS_STR}")
   endif()
 
-  if(NOT ANDROID)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -pthread")
-  endif()
-
   if("${CMAKE_SHARED_LINKER_FLAGS}" STREQUAL "" AND NOT CMAKE_SYSTEM_NAME STREQUAL "Darwin")
     set(CMAKE_SHARED_LINKER_FLAGS "-Wl,--as-needed")
   endif()
@@ -179,7 +175,7 @@ endif()
 
 if(CMAKE_COMPILER_IS_PATHSCALE)
   if("${CMAKE_CXX_FLAGS}" STREQUAL "${CMAKE_CXX_FLAGS_DEFAULT}")
-    set(CMAKE_CXX_FLAGS "-Wno-uninitialized -zerouv -pthread -mp")
+    set(CMAKE_CXX_FLAGS "-Wno-uninitialized -zerouv -mp")
   endif()
   if("${CMAKE_SHARED_LINKER_FLAGS}" STREQUAL "")
     set(CMAKE_SHARED_LINKER_FLAGS "-mp")
@@ -280,6 +276,9 @@ else()
   message(STATUS "Not found OpenMP")
 endif()
 
+# Threads (required)
+find_package(Threads REQUIRED)
+
 # Eigen (required)
 find_package(Eigen 3.1 REQUIRED)
 include_directories(SYSTEM ${EIGEN_INCLUDE_DIRS})
diff --git a/cmake/pcl_targets.cmake b/cmake/pcl_targets.cmake
index 5ae0f1129a7..a50d0d0998a 100644
--- a/cmake/pcl_targets.cmake
+++ b/cmake/pcl_targets.cmake
@@ -223,7 +223,7 @@ function(PCL_ADD_LIBRARY _name)
   PCL_ADD_VERSION_INFO(${_name})
   target_compile_features(${_name} PUBLIC ${PCL_CXX_COMPILE_FEATURES})
   # must link explicitly against boost.
-  target_link_libraries(${_name} ${Boost_LIBRARIES})
+  target_link_libraries(${_name} ${Boost_LIBRARIES} Threads::Threads)
   if((UNIX AND NOT ANDROID) OR MINGW)
     target_link_libraries(${_name} m)
   endif()
@@ -302,11 +302,7 @@ function(PCL_ADD_EXECUTABLE _name)
   endif()
   PCL_ADD_VERSION_INFO(${_name})
   # must link explicitly against boost.
-  if(UNIX AND NOT ANDROID)
-    target_link_libraries(${_name} ${Boost_LIBRARIES} pthread m ${CLANG_LIBRARIES})
-  else()
-    target_link_libraries(${_name} ${Boost_LIBRARIES})
-  endif()
+  target_link_libraries(${_name} ${Boost_LIBRARIES} Threads::Threads)
 
   if(WIN32 AND MSVC)
     set_target_properties(${_name} PROPERTIES DEBUG_OUTPUT_NAME ${_name}${CMAKE_DEBUG_POSTFIX}
@@ -384,12 +380,7 @@ macro(PCL_ADD_TEST _name _exename)
   #target_link_libraries(${_exename} ${GTEST_BOTH_LIBRARIES} ${PCL_ADD_TEST_LINK_WITH})
   target_link_libraries(${_exename} ${PCL_ADD_TEST_LINK_WITH} ${CLANG_LIBRARIES})
 
-  if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
-    target_link_libraries(${_exename} pthread)
-  elseif(UNIX AND NOT ANDROID)
-    # GTest >= 1.5 requires pthread and CMake's 2.8.4 FindGTest is broken
-    target_link_libraries(${_exename} pthread)
-  endif()
+  target_link_libraries(${_exename} Threads::Threads)
 
   # must link explicitly against boost only on Windows
   target_link_libraries(${_exename} ${Boost_LIBRARIES})