Merge pull request #1996 from DLR-AMR/feature-ignore_warnings_in_tests

Bugfix: Ignore warnings when executing CMake tests

Author: holke

CMakeLists.txt

@@ -169,6 +169,17 @@ else()
     set( SC_BUILD_EXAMPLES ${T8CODE_BUILD_TPL_EXAMPLES} )
     set( SC_BUILD_TESTING ${T8CODE_BUILD_TPL_TESTS} )
 
+    # When executing CMake tests for libsc, i.e. check_c_source_compiles/check_cxx_source_compiles and others
+    # we need to ignore the -Werror option, since these tests often produce warnings (see check_mpicommshared.cmake for example).
+    # If theses warnings are interpreted as errors, the test fails even though we want it to pass.
+    # This behaviour caused a serious bug and did not initialize our shared memory. See https://github.com/DLR-AMR/t8code/issues/1985.
+    set( T8CODE_OLD_CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS}" )
+    if (WIN32)
+        set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} /w" )
+    else()
+        set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -w" )
+    endif()
+
     # Capture the list of variables before adding the subdirectory to mark the added ones as advanced.
     get_cmake_property(_vars_before_sc VARIABLES )
     list( APPEND CMAKE_MESSAGE_CONTEXT "sc" )
@@ -219,6 +230,10 @@ else()
         message(WARNING "mpi.h not found!")
     endif()
     ########################## End of fix for OpenMPI ############################################
+
+    # Reactivate previous CMAKE_REQUIRED_FLAGS  
+    set( CMAKE_REQUIRED_FLAGS "${T8CODE_OLD_CMAKE_REQUIRED_FLAGS}" )
+    unset( T8CODE_OLD_CMAKE_REQUIRED_FLAGS )
 endif()
 
 if ( T8CODE_USE_SYSTEM_P4EST )