[LinearSolver.Direct] Fix metis dependency (#4450)

* Link dynamically with embedded metis to comply conda-forge rules

* export all symbols (for MSVC)

* Use external 5.1.0 metis or fallback to embedded code linked dynamically

* fix comments in metis cmake module

* ADD find or fetch mechanism

* Remove embeded metis and put linkage to private

* Fix metis dependency but still not the best fix

* test

* Put back public linkage

* Revert "Put back public linkage"

This reverts commit 71baa47.

* Clean

* cleaning #2

* Use SOFA_ALLOW_FETCH_DEPENDENCIES cmake option for metis

* Add missing CImg to list of fetchable dependencies in doc

* Update applications/plugins/SofaMatrix/CMakeLists.txt

Co-authored-by: Frederick Roy <fredroy@users.noreply.github.com>

---------

Co-authored-by: Frederick Roy <froy@lnrobo.com>
Co-authored-by: Paul Baksic <30337881+bakpaul@users.noreply.github.com>
Co-authored-by: bakpaul <bakpaul@hotmail.fr>
Co-authored-by: Paul Baksic <paul.baksic@outlook.fr>
Co-authored-by: Frederick Roy <fredroy@users.noreply.github.com>

CMakeLists.txt

@@ -37,7 +37,7 @@ option(SOFA_BUILD_RELEASE_PACKAGE "Run package specific configure" OFF)
 # Option to allow some dependencies such as cxxopts to be fetched by cmake if
 # the package is not found
 option(SOFA_ALLOW_FETCH_DEPENDENCIES "Allow compatible dependencies to be fetched if the package is not found by cmake.
-  List of dependencies that can be fetched: cxxopts, gtest" ON)
+  List of dependencies that can be fetched: cxxopts, gtest, metis, CImg" ON)
 
 # Option to accelerate the compilation
 # see https://cmake.org/cmake/help/v3.16/command/target_precompile_headers.html

Sofa/Component/LinearSolver/Direct/CMakeLists.txt

@@ -59,12 +59,19 @@ set(SOURCE_FILES
     ${SOFACOMPONENTLINEARSOLVERDIRECT_SOURCE_DIR}/TypedMatrixLinearSystem[BTDMatrix].cpp
 )
 
-sofa_find_package(metis QUIET) # Unix users can have an installed version of metis
-if(NOT metis_FOUND)
-    message(STATUS "${PROJECT_NAME}: using built-in metis library")
-    option(METIS-GKLIB_GKRAND "enable GKRAND support" ON) #GKRAND support allows the portability of random number generation across different architectures
-    add_subdirectory(extlibs/metis-5.1.0)
+find_package(metis 5.1.0 EXACT QUIET)
+if(NOT metis_FOUND AND SOFA_ALLOW_FETCH_DEPENDENCIES)
+    message("Sofa.Component.LinearSolver.Direct: DEPENDENCY metis NOT FOUND. SOFA_ALLOW_FETCH_DEPENDENCIES is ON, fetching metis...")
+    include(FetchContent)
+    FetchContent_Declare(metis
+            GIT_REPOSITORY https://github.com/sofa-framework/METIS
+            GIT_TAG v5.1.0-ModernInstall
+    )
+    FetchContent_MakeAvailable(metis)
+elseif (NOT metis_FOUND)
+    message(FATAL_ERROR "Sofa.Component.LinearSolver.Direct: DEPENDENCY metis NOT FOUND. SOFA_ALLOW_FETCH_DEPENDENCIES is OFF and thus cannot be fetched. Install metis (version=5.1.0), or enable SOFA_ALLOW_FETCH_DEPENDENCIES to fix this issue.")
 endif()
+
 sofa_set_01(SOFA_COMPONENT_LINEARSOLVER_DIRECT_HAVE_METIS VALUE TRUE)
 
 # make sure you have threads for AsyncSparseLDLSolver
@@ -75,8 +82,9 @@ sofa_find_package(Sofa.Component.LinearSolver.Iterative REQUIRED) # Only for Mat
 sofa_find_package(Sofa.Component.LinearSolver.Ordering REQUIRED)
 
 add_library(${PROJECT_NAME} SHARED ${HEADER_FILES} ${SOURCE_FILES} ${WRAPPER_FILES})
+
 target_link_libraries(${PROJECT_NAME} PUBLIC Sofa.Simulation.Core Sofa.Component.LinearSolver.Iterative Sofa.Component.LinearSolver.Ordering)
-target_link_libraries(${PROJECT_NAME} PUBLIC metis)
+target_link_libraries(${PROJECT_NAME} PRIVATE metis)
 target_link_libraries(${PROJECT_NAME} PUBLIC Threads::Threads)
 
 sofa_create_package_with_targets(

Sofa/Component/LinearSolver/Direct/Sofa.Component.LinearSolver.DirectConfig.cmake.in

@@ -9,10 +9,6 @@ find_package(Threads QUIET REQUIRED)
 
 set(SOFA_COMPONENT_LINEARSOLVER_DIRECT_HAVE_METIS @SOFA_COMPONENT_LINEARSOLVER_DIRECT_HAVE_METIS@)
 
-if(SOFA_COMPONENT_LINEARSOLVER_DIRECT_HAVE_METIS)
-    find_package(Metis QUIET REQUIRED HINTS "${CMAKE_CURRENT_LIST_DIR}/..")
-endif()
-
 if(NOT TARGET @PROJECT_NAME@)
     include("${CMAKE_CURRENT_LIST_DIR}/@PROJECT_NAME@Targets.cmake")
 endif()