Attempt 3 to address issues with pthreads needed only for certain systems

Author: rcarson3

cmake/thirdpartylibraries/SetupThirdPartyLibraries.cmake

@@ -144,6 +144,9 @@ endif()
 ################################
 # Threads (platform-specific)
 ################################
+
+set(EXACONSTIT_THREADS_EXPLICIT_LINK FALSE CACHE INTERNAL "Whether explicit thread linking is required")
+
 if(UNIX AND NOT APPLE)
     find_package(Threads REQUIRED)
     include(CheckCXXSourceCompiles)
@@ -194,14 +197,7 @@ if(UNIX AND NOT APPLE)
     # Register if needed
     if(NOT THREADS_IMPLICIT_LINK)
         message(STATUS "  Result: Explicit pthread linking REQUIRED")
-        
-        if(TARGET Threads::Threads)
-            blt_import_library(NAME      threads
-                              LIBRARIES  Threads::Threads)
-        else()
-            blt_import_library(NAME      threads
-                              LIBRARIES  ${CMAKE_THREAD_LIBS_INIT})
-        endif()
+        set(EXACONSTIT_THREADS_EXPLICIT_LINK TRUE CACHE INTERNAL "Whether explicit thread linking is required")
     else()
         message(STATUS "  Result: pthread implicitly linked (no action needed)")
     endif()

src/CMakeLists.txt

@@ -82,7 +82,7 @@ endif()
 set(EXACONSTIT_DEPENDS)
 
 exaconstit_fill_depends_list(LIST_NAME  EXACONSTIT_DEPENDS
-                             DEPENDS_ON  mfem ecmech snls RAJA camp mpi threads)
+                             DEPENDS_ON  mfem ecmech snls RAJA camp mpi)
 
 if (${BLT_VERSION} VERSION_GREATER_EQUAL 0.6.0)
     if(ENABLE_CUDA)
@@ -112,6 +112,13 @@ if(ENABLE_CALIPER)
     list(APPEND EXACONSTIT_DEPENDS caliper)
 endif()
 
+if(UNIX AND NOT APPLE AND TARGET Threads::Threads)
+    # Check if we determined explicit linking is needed
+    if(EXACONSTIT_THREADS_EXPLICIT_LINK)
+        list(APPEND EXACONSTIT_DEPENDS Threads::Threads)
+    endif()
+endif()
+
 list(APPEND EXACONSTIT_DEPENDS ${DYNAMIC_LOADING_LIBS})
 
 message("-- EXACONSTIT_DEPENDS: ${EXACONSTIT_DEPENDS}")