use find_package(Threads)

cmake/Modules/ClhepVariables.cmake

@@ -187,11 +187,11 @@ macro( _clhep_check_cxxstd )
   ##message(STATUS "_clhep_check_cxxstd debug: CLHEP_BUILD_CXXSTD HAVE_STDCXX: ${CLHEP_BUILD_CXXSTD} ${HAVE_STDCXX}")
   if( DEFINED HAVE_STDCXX )
     if( ${CMAKE_CXX_COMPILER_ID} STREQUAL "Clang" )
-	set( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${CLHEP_BUILD_CXXSTD} -pthread" )
+	set( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${CLHEP_BUILD_CXXSTD}" )
     elseif( ${CMAKE_CXX_COMPILER_ID} STREQUAL "Intel" )
-	set( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${CLHEP_BUILD_CXXSTD} -pthread" )
+	set( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${CLHEP_BUILD_CXXSTD" )
     elseif(CMAKE_COMPILER_IS_GNUCXX)
-	set( CMAKE_CXX_FLAGS "${CLHEP_BUILD_CXXSTD} -pthread ${CMAKE_CXX_FLAGS} -D_GNU_SOURCE" )
+	set( CMAKE_CXX_FLAGS "${CLHEP_BUILD_CXXSTD} ${CMAKE_CXX_FLAGS} -D_GNU_SOURCE" )
     else()
       message(STATUS "clhep_set_compiler_flags: Do not know how to set ${CLHEP_BUILD_CXXSTD} extensions for ${CMAKE_CXX_COMPILER_ID}")
     endif()
@@ -203,10 +203,16 @@ macro( clhep_set_compiler_flags )
   if(NOT CMAKE_BUILD_TYPE)
     set(CMAKE_BUILD_TYPE RelWithDebInfo CACHE STRING "" FORCE)
   endif()
+  # find pthread
+  set(THREADS_PREFER_PTHREAD_FLAG ON)
+  find_package(Threads)
   ##message(STATUS "clhep_set_compiler_flags debug: CMAKE_CXX_FLAGS: ${CMAKE_CXX_FLAGS}")
   message(STATUS "cmake build type is ${CMAKE_BUILD_TYPE}")
-     _clhep_check_cxxstd()
-     message(STATUS "enable c++11 extensions: ${CMAKE_CXX_FLAGS}")
+  _clhep_check_cxxstd()
+  if(THREADS_HAVE_PTHREAD_ARG) 
+	set( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -pthread" )
+  endif()
+  message(STATUS "enable c++11 extensions: ${CMAKE_CXX_FLAGS}")
   if( CLHEP_DEBUG_MESSAGES )
     message(STATUS "clhep_set_compiler_flags debug: CMAKE_CXX_FLAGS: ${CMAKE_CXX_FLAGS}")
     message(STATUS "clhep_set_compiler_flags debug: cmake compilers ${CMAKE_CXX_COMPILER} ${CMAKE_C_COMPILER}")
@@ -229,6 +235,14 @@ macro( clhep_set_compiler_flags )
   elseif(CMAKE_COMPILER_IS_GNUCXX)
     set(CMAKE_CXX_FLAGS "-O -ansi -pedantic -Wall -D_GNU_SOURCE ${CMAKE_CXX_FLAGS}")
   endif()
+  # linker flags
+    if (${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
+      set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -Wl,-undefined,error")
+    else()
+      set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -Wl,--no-undefined")
+    endif()
+  message(STATUS "setting CMAKE_SHARED_LINKER_FLAGS ${CMAKE_SHARED_LINKER_FLAGS}")
+  # override flags for Windows cl
   if( ${CMAKE_SYSTEM_NAME} MATCHES "Windows" )
     ##message( STATUS "system is Windows" )
     ##message( STATUS "CMAKE_BASE_NAME is ${CMAKE_BASE_NAME}" )
@@ -237,14 +251,9 @@ macro( clhep_set_compiler_flags )
       ##message( STATUS "incoming basic compiler flags are ${CMAKE_CXX_FLAGS}")
       set(CMAKE_C_FLAGS "/EHsc /nologo /GR /MD /D USING_VISUAL")
       set(CMAKE_CXX_FLAGS "/EHsc /nologo /GR /MD /D USING_VISUAL")
+      set(CMAKE_SHARED_LINKER_FLAGS "/EHsc /nologo /GR /MD /D USING_VISUAL")
     endif()
   endif()
-  # linker flags
-    if (${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
-      set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -Wl,-undefined,error")
-    else()
-      set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -Wl,--no-undefined")
-    endif()
   clhep_autoconf_variables()
   message( STATUS "compiling with ${clhep_cxx_compiler} ${CMAKE_CXX_FLAGS} ${CXXFLAGS}")
 endmacro( clhep_set_compiler_flags )