Fix Tpetra 64 bit global ordinate errors

Tpetra requires long long as global ordinate type, which does not always match with std::int64_t. Therefore, configure stage fails with default Tpetra settings. Changed signed_global_index_type in types.h to reflect this too. Also added hopefully helpful CMake messages in case the Tpetra check fails. If it is global index related it will offer two ways to make Tpetra usable in deal.II.
dealii · Sep 18, 2023 · 31bf623 · 31bf623
1 parent 4e1c906
commit 31bf623
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Showing 2 changed files with 45 additions and 5 deletions.
diff --git a/cmake/configure/configure_20_trilinos.cmake b/cmake/configure/configure_20_trilinos.cmake
@@ -241,7 +241,7 @@ macro(feature_trilinos_find_external var)
       add_flags(CMAKE_REQUIRED_FLAGS "${DEAL_II_CXX_FLAGS} ${DEAL_II_LINKER_FLAGS}")
 
       if(DEAL_II_WITH_64BIT_INDICES)
-        set(_global_index_type "std::int64_t")
+        set(_global_index_type "long long")
       else()
         set(_global_index_type "int")
       endif()
@@ -272,9 +272,45 @@ macro(feature_trilinos_find_external var)
       else()
         message(
           STATUS
-          "Tpetra was found but is not usable! Disabling Tpetra support."
+          "Tpetra was found but is not usable! Disabling Tpetra support and searching for common errors."
           )
         set(TRILINOS_WITH_TPETRA OFF)
+
+        check_cxx_symbol_exists(HAVE_TPETRA_INT_LONG_LONG "TpetraCore_config.h" DEAL_II_HAVE_TPETRA_INT_LONG_LONG)
+        check_cxx_symbol_exists(HAVE_TPETRA_INT_INT "TpetraCore_config.h" DEAL_II_HAVE_TPETRA_INT_INT)
+
+        if(DEAL_II_HAVE_TPETRA_INT_INT AND DEAL_II_WITH_64BIT_INDICES)
+          message(
+            STATUS 
+            "  Tpetra is installed with 32 bit global indices but you want to build deal.II with 64. "
+          )
+          message(
+            STATUS 
+            "  Either rebuild Trilinos with -DTPETRA_INST_INT_INT=OFF and -DTPETRA_INST_LONG_LONG=ON "
+          )
+          message(
+            STATUS 
+            "  or clean and reconfigure deal.II with -DDEAL_II_WITH_64_BIT_INDICES=OFF."
+          )
+        elseif(DEAL_II_HAVE_TPETRA_INT_LONG_LONG AND NOT DEAL_II_WITH_64BIT_INDICES)
+          message(
+            STATUS 
+            "  Tpetra is installed with 64 bit global indices but you want to build deal.II with 32. "
+          )
+          message(
+            STATUS
+            "  Either rebuild Trilinos with -DTPETRA_INST_INT_INT=ON and -DTPETRA_INST_LONG_LONG=OFF "
+          )
+          message(
+            STATUS
+            "  or clean and reconfigure deal.II with -DDEAL_II_WITH_64_BIT_INDICES=ON."
+          )
+        else()
+          message(
+            STATUS 
+            "  No supported global index configuration of Trilions found."
+          )
+        endif()
       endif()
       reset_cmake_required()
     endif()

diff --git a/include/deal.II/base/types.h b/include/deal.II/base/types.h
@@ -79,15 +79,19 @@ namespace types
 #ifdef DEAL_II_WITH_64BIT_INDICES
   using global_dof_index = std::uint64_t;
 #else
-  using global_dof_index  = unsigned int;
+  using global_dof_index        = unsigned int;
 #endif
 
   /**
    * Signed version of global_dof_index.
    * This is useful for interacting with Trilinos' Tpetra that only works well
    * with a signed global ordinal type.
    */
-  using signed_global_dof_index = std::make_signed_t<global_dof_index>;
+#ifdef DEAL_II_WITH_64BIT_INDICES
+  using signed_global_dof_index = long long;
+#else
+  using signed_global_dof_index = int;
+#endif
 
   /**
    * An identifier that denotes the MPI type associated with
@@ -115,7 +119,7 @@ namespace types
 #ifdef DEAL_II_WITH_64BIT_INDICES
   using global_cell_index = std::uint64_t;
 #else
-  using global_cell_index = unsigned int;
+  using global_cell_index       = unsigned int;
 #endif
 
   /**