From 869b5c8918674d6069652b2b688e4faf59c87ffe Mon Sep 17 00:00:00 2001
From: Jan Beich <jbeich@FreeBSD.org>
Date: Tue, 17 Apr 2018 06:46:22 +0000
Subject: [PATCH] Explicitly link against -lpthread on Unix

/usr/bin/ld.lld: error: undefined symbol: pthread_condattr_init
>>> referenced by src/3rdParty/salomesmesh/src/SMESH/SMESH_Mesh.cpp
>>>               src/3rdParty/salomesmesh/CMakeFiles/SMESH.dir/src/SMESH/SMESH_Mesh.cpp.o:(boost::condition_variable::condition_variable())

/usr/bin/ld.lld: error: undefined symbol: pthread_condattr_setclock
>>> referenced by src/3rdParty/salomesmesh/src/SMESH/SMESH_Mesh.cpp
>>>               src/3rdParty/salomesmesh/CMakeFiles/SMESH.dir/src/SMESH/SMESH_Mesh.cpp.o:(boost::condition_variable::condition_variable())

/usr/bin/ld.lld: error: undefined symbol: pthread_condattr_destroy
>>> referenced by src/3rdParty/salomesmesh/src/SMESH/SMESH_Mesh.cpp
>>>               src/3rdParty/salomesmesh/CMakeFiles/SMESH.dir/src/SMESH/SMESH_Mesh.cpp.o:(boost::condition_variable::condition_variable())
---
 CMakeLists.txt | 5 +++++
 1 file changed, 5 insertions(+)

diff --git CMakeLists.txt CMakeLists.txt
index cc06f908642..7230ae70de8 100644
--- CMakeLists.txt
+++ CMakeLists.txt
@@ -596,6 +596,11 @@ endif(${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
     find_package(Boost ${BOOST_MIN_VERSION}
         COMPONENTS filesystem program_options regex signals system thread REQUIRED)
 
+    if(UNIX AND NOT APPLE)
+        # Boost.Thread 1.67+ headers reference pthread_condattr_*
+        list(APPEND Boost_LIBRARIES pthread)
+    endif()
+
     IF(NOT Boost_FOUND)
         MESSAGE(FATAL_ERROR "========================================\n"
                             "boost not found, install the components:\n"