From 3832ae62f147fc0643386cfa7bcd2446e7eddcc4 Mon Sep 17 00:00:00 2001
From: Matthias Maier <tamiko@43-1.org>
Date: Tue, 26 May 2020 22:43:11 -0500
Subject: [PATCH] address review comments

---
 .../configure/configure_1_cpp_taskflow.cmake  | 26 +++++++++++++++++++
 .../macros/macro_deal_ii_package_handle.cmake |  5 +++-
 cmake/modules/FindCPP_TASKFLOW.cmake          |  2 +-
 3 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/cmake/configure/configure_1_cpp_taskflow.cmake b/cmake/configure/configure_1_cpp_taskflow.cmake
index c16290664a..b7f6b42263 100644
--- a/cmake/configure/configure_1_cpp_taskflow.cmake
+++ b/cmake/configure/configure_1_cpp_taskflow.cmake
@@ -19,6 +19,32 @@
 #
 
 
+MACRO(FEATURE_CPP_TASKFLOW_FIND_EXTERNAL var)
+  FIND_PACKAGE(CPP_TASKFLOW)
+
+  IF(CPP_TASKFLOW_FOUND)
+    SET(${var} TRUE)
+  ENDIF()
+
+  IF(CPP_TASKFLOW_VERSION VERSION_LESS "2.4")
+    # Clear the previously determined version numbers to avoid confusion
+    SET(CPP_TASKFLOW_VERSION "bundled")
+    SET(CPP_TASKFLOW_VERSION_MAJOR "")
+    SET(CPP_TASKFLOW_VERSION_MINOR "")
+
+    MESSAGE(STATUS
+      "The externally provided Cpp Taskflow library is older than version 2.4, "
+      "which cannot be used with deal.II."
+      )
+    SET(CPP_TASKFLOW_ADDITIONAL_ERROR_STRING
+      "The externally provided Cpp Taskflow library is older than version\n"
+      "2.4, which is the oldest version compatible with deal.II."
+      )
+    SET(${var} FALSE)
+  ENDIF()
+ENDMACRO()
+
+
 MACRO(FEATURE_CPP_TASKFLOW_CONFIGURE_BUNDLED)
   LIST(APPEND CPP_TASKFLOW_BUNDLED_INCLUDE_DIRS ${CPP_TASKFLOW_FOLDER}/include)
 ENDMACRO()
diff --git a/cmake/macros/macro_deal_ii_package_handle.cmake b/cmake/macros/macro_deal_ii_package_handle.cmake
index d7c8ce851d..4c148eeab0 100644
--- a/cmake/macros/macro_deal_ii_package_handle.cmake
+++ b/cmake/macros/macro_deal_ii_package_handle.cmake
@@ -154,7 +154,10 @@ MACRO(DEAL_II_PACKAGE_HANDLE _feature _var)
     ENDFOREACH()
 
     #
-    # Remove certain system libraries from the link interface
+    # Remove certain system libraries from the link interface. This is
+    # purely cosmetic (we always implicitly link against the C library, and
+    # we always set up threading by linking against libpthread.so if
+    # necessary).
     #
     FOREACH(_suffix LIBRARIES LIBRARIES_DEBUG LIBRARIES_RELEASE)
       IF(NOT "${${_feature}_${_suffix}}" STREQUAL "")
diff --git a/cmake/modules/FindCPP_TASKFLOW.cmake b/cmake/modules/FindCPP_TASKFLOW.cmake
index 791a914a5d..6c486fd134 100644
--- a/cmake/modules/FindCPP_TASKFLOW.cmake
+++ b/cmake/modules/FindCPP_TASKFLOW.cmake
@@ -22,7 +22,7 @@
 #   CPP_TASKFLOW_VERSION
 #
 
-SET(CPP_TASKFLOW_DIR "" CACHE PATH "An optional hint to a CPP CPP_TASKFLOW installation")
+SET(CPP_TASKFLOW_DIR "" CACHE PATH "An optional hint to a Cpp Taskflow installation")
 SET_IF_EMPTY(CPP_TASKFLOW_DIR "$ENV{CPP_TASKFLOW_DIR}")
 
 FIND_PACKAGE(CPP_TASKFLOW_CONFIG
-- 
2.39.5