hopefully fixed the compile issue on Linux

CMakeLists.txt

@@ -234,6 +234,13 @@ endif ()
 
 if (STORM_USE_LTO)
     set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -flto")
+    
+    # Fix for problems that occured when using LTO on gcc. This should be removed when it's
+    # not needed anymore as it makes the the already long link-step potentially longer.
+    if (STORM_COMPILER_GCC)
+        set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -flto-partition=none")
+    endif()
+    
     message(STATUS "Storm - Enabling link-time optimizations.")
 else()
     message(STATUS "Storm - Disabling link-time optimizations.")

resources/3rdparty/CMakeLists.txt

@@ -364,12 +364,13 @@ include(${STORM_3RDPARTY_SOURCE_DIR}/include_xerces.cmake)
 ##
 #############################################################
 
+if(STORM_USE_LTO)
 ExternalProject_Add(
         sylvan
         DOWNLOAD_COMMAND ""
         PREFIX "sylvan"
         SOURCE_DIR ${STORM_3RDPARTY_SOURCE_DIR}/sylvan
-        CMAKE_ARGS -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER} -DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER} -DSYLVAN_BUILD_DOCS=OFF -DSYLVAN_BUILD_EXAMPLES=OFF -DCMAKE_BUILD_TYPE=Release -DCMAKE_POSITION_INDEPENDENT_CODE=ON -DUSE_CARL=ON -Dcarl_INCLUDE_DIR=${carl_INCLUDE_DIR} -DSYLVAN_PORTABLE=${STORM_PORTABLE} -Dcarl_LIBRARIES=${carl_LIBRARIES} -DBUILD_SHARED_LIBS=OFF -DSYLVAN_BUILD_TESTS=OFF
+        CMAKE_ARGS -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER} -DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER} -DSYLVAN_BUILD_DOCS=OFF -DSYLVAN_BUILD_EXAMPLES=OFF -DCMAKE_BUILD_TYPE=Release -DCMAKE_POSITION_INDEPENDENT_CODE=ON -DUSE_CARL=ON -Dcarl_INCLUDE_DIR=${carl_INCLUDE_DIR} -DSYLVAN_PORTABLE=${STORM_PORTABLE} -Dcarl_LIBRARIES=${carl_LIBRARIES} -DBUILD_SHARED_LIBS=OFF -DSYLVAN_BUILD_TESTS=OFF -DSYLVAN_USE_LTO=ON
         BINARY_DIR ${STORM_3RDPARTY_BINARY_DIR}/sylvan
         BUILD_IN_SOURCE 0
         INSTALL_COMMAND ""
@@ -377,7 +378,26 @@ ExternalProject_Add(
         LOG_CONFIGURE ON
         LOG_BUILD ON
         BUILD_BYPRODUCTS ${STORM_3RDPARTY_BINARY_DIR}/sylvan/src/libsylvan${STATIC_EXT}
+        BUILD_ALWAYS 1
 )
+else()
+ExternalProject_Add(
+        sylvan
+        DOWNLOAD_COMMAND ""
+        PREFIX "sylvan"
+        SOURCE_DIR ${STORM_3RDPARTY_SOURCE_DIR}/sylvan
+        CMAKE_ARGS -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER} -DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER} -DSYLVAN_BUILD_DOCS=OFF -DSYLVAN_BUILD_EXAMPLES=OFF -DCMAKE_BUILD_TYPE=Release -DCMAKE_POSITION_INDEPENDENT_CODE=ON -DUSE_CARL=ON -Dcarl_INCLUDE_DIR=${carl_INCLUDE_DIR} -DSYLVAN_PORTABLE=${STORM_PORTABLE} -Dcarl_LIBRARIES=${carl_LIBRARIES} -DBUILD_SHARED_LIBS=OFF -DSYLVAN_BUILD_TESTS=OFF -DSYLVAN_USE_LTO=OFF
+        BINARY_DIR ${STORM_3RDPARTY_BINARY_DIR}/sylvan
+        BUILD_IN_SOURCE 0
+        INSTALL_COMMAND ""
+        INSTALL_DIR ${STORM_3RDPARTY_BINARY_DIR}/sylvan
+        LOG_CONFIGURE ON
+        LOG_BUILD ON
+        BUILD_BYPRODUCTS ${STORM_3RDPARTY_BINARY_DIR}/sylvan/src/libsylvan${STATIC_EXT}
+        BUILD_ALWAYS 1
+)
+endif()
+
 ExternalProject_Get_Property(sylvan source_dir)
 ExternalProject_Get_Property(sylvan binary_dir)
 set(Sylvan_INCLUDE_DIR "${source_dir}/src")

resources/3rdparty/sylvan/CMakeLists.txt

@@ -1,12 +1,11 @@
 cmake_minimum_required(VERSION 3.1)
 
-project(sylvan VERSION 1.2.0)
+project(sylvan LANGUAGES C CXX VERSION 1.2.0)
 
 set(PROJECT_DESCRIPTION "Sylvan, a parallel decision diagram library")
 set(PROJECT_URL "https://github.com/trolando/sylvan")
 
 message(STATUS "CMake build configuration for Sylvan ${PROJECT_VERSION}")
-enable_language(C CXX)
 
 set(CMAKE_C_STANDARD 11)
 set(CMAKE_C_STANDARD_REQUIRED ON)
@@ -34,6 +33,20 @@ if (NOT SYLVAN_PORTABLE)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -march=native")
 endif()
 
+if (SYLVAN_USE_LTO)
+    message(STATUS "Sylvan - Enabling LTO.")
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -flto -flto-partition=none")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -flto -flto-partition=none")
+    
+    # For GCC, we need to set the ar/ranlib commands to use the gcc wrappers to account for LTO.
+    if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
+        message(STATUS "Sylvan - Setting ar/ranlib to account for LTO.")
+        set(CMAKE_AR gcc-ar CACHE FILEPATH "Archiver" FORCE)
+        set(CMAKE_RANLIB gcc-ranlib CACHE FILEPATH "Ranlib" FORCE)
+        message(STATUS "Sylvan - ar/ranlib are ${CMAKE_AR} and ${CMAKE_RANLIB}, respectively.")
+    endif()
+endif()
+
 option(WITH_COVERAGE "Add generation of test coverage" OFF)
 if(WITH_COVERAGE)
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O0 -g -coverage")