Allow to disable EIGEN3 even if it's found on disk

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1a4a245..03b4b09 100644 (file)
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -217,21 +217,25 @@ if(enable_ns3)
 endif()
 
 ### Check for Eigen library
-set(SIMGRID_HAVE_EIGEN3 OFF)
-find_package (Eigen3 3.3 CONFIG
-              HINTS ${EIGEN3_HINT})
-if (Eigen3_FOUND)
-  set(SIMGRID_HAVE_EIGEN3 ON) 
-  message(STATUS "Found Eigen3: ${EIGEN3_INCLUDE_DIR}")
-  include_directories(${EIGEN3_INCLUDE_DIR})
-  if ("3.3.4" VERSION_EQUAL EIGEN3_VERSION_STRING AND CMAKE_COMPILER_IS_GNUCC)
-    message(STATUS "Avoid build error of Eigen3 v3.3.4 using -Wno-error=int-in-bool-context")
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-error=int-in-bool-context")
+if ((NOT DEFINED EIGEN3_HINT) OR (NOT EIGEN3_HINT STRLESS_EQUAL "OFF"))
+  set(SIMGRID_HAVE_EIGEN3 OFF)
+  find_package (Eigen3 3.3 CONFIG
+                HINTS ${EIGEN3_HINT})
+  if (Eigen3_FOUND)
+    set(SIMGRID_HAVE_EIGEN3 ON)
+    message(STATUS "Found Eigen3: ${EIGEN3_INCLUDE_DIR}")
+    include_directories(${EIGEN3_INCLUDE_DIR})
+    if ("3.3.4" VERSION_EQUAL EIGEN3_VERSION_STRING AND CMAKE_COMPILER_IS_GNUCC)
+      message(STATUS "Avoid build error of Eigen3 v3.3.4 using -Wno-error=int-in-bool-context")
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-error=int-in-bool-context")
+    endif()
+  else()
+    message(STATUS "Disabling model BMF because Eigen3 was not found. If it's installed, use EIGEN3_HINT to hint cmake about the location of Eigen3Config.cmake")
   endif()
+  mark_as_advanced(Eigen3_DIR)
 else()
-  message(STATUS "Disabling model BMF because Eigen3 was not found. If it's installed, use EIGEN3_HINT to hint cmake about the location of Eigen3Config.cmake")
+  message(STATUS "Disabling Eigen3 as requested by the user (EIGEN3_HINT is set to 'OFF')")
 endif()
-mark_as_advanced(Eigen3_DIR)
 
 # Check for our JSON dependency
 set(SIMGRID_HAVE_JSON 0)

diff --git a/docs/source/Installing_SimGrid.rst b/docs/source/Installing_SimGrid.rst
index 477b53e..7d26867 100644 (file)
--- a/docs/source/Installing_SimGrid.rst
+++ b/docs/source/Installing_SimGrid.rst
@@ -108,7 +108,7 @@ Eigen3 (optional)
   - On Debian / Ubuntu: ``apt install libeigen3-dev``
   - On CentOS / Fedora: ``dnf install eigen3-devel``
   - On macOS with homebrew: ``brew install eigen``
-  - Use EIGEN3_HINT to specify where it's installed if cmake doesn't find it automatically.
+  - Use EIGEN3_HINT to specify where it's installed if cmake doesn't find it automatically. Set EIGEN3_HINT=OFF to disable detection even if it could be found.
 JSON (optional, for the DAG wfcommons loader)
   - On Debian / Ubuntu: ``apt install nlohmann-json3-dev``
   - Use nlohmann_json_HINT to specify where it's installed if cmake doesn't find it automatically.
@@ -269,6 +269,7 @@ NS3_HINT (empty by default)
 
 EIGEN3_HINT (empty by default)
   Alternative path into which Eigen3 should be searched for.
+  Providing the value OFF as an hint will disable the detection alltogether.
 
 SIMGRID_PYTHON_LIBDIR (auto-detected)
   Where to install the Python module library. By default, it is set to the cmake Python3_SITEARCH variable if installing to /usr,