Blenkernel: move DerivedMesh.c to c++

Required changes to make it compile with clang tidy:
* Use c++ includes like (e.g. climits instead limits.h).
* Insert type casts when casting from void* to something else.
* Replace NULL with nullptr.
* Insert casts from int to enum.
* Replace designed initializers (not supported in C++ yet).
* Use blender::Vector instead of BLI_array_staticdeclare (does not compile with C++).
* Replace typedef statements.

Ref T83357.

source/blender/blenkernel/BKE_mesh.h

@@ -678,7 +678,7 @@ void BKE_mesh_calc_edges_loose(struct Mesh *mesh);
 void BKE_mesh_calc_edges(struct Mesh *mesh, bool keep_existing_edges, const bool select_new_edges);
 void BKE_mesh_calc_edges_tessface(struct Mesh *mesh);
 
-/* In DerivedMesh.c */
+/* In DerivedMesh.cc */
 void BKE_mesh_wrapper_deferred_finalize(struct Mesh *me_eval,
                                         const CustomData_MeshMasks *cd_mask_finalize);
 

source/blender/blenkernel/BKE_mesh_runtime.h

@@ -57,9 +57,9 @@ void BKE_mesh_runtime_verttri_from_looptri(struct MVertTri *r_verttri,
                                            const struct MLoopTri *looptri,
                                            int looptri_num);
 
-/* NOTE: the functions below are defined in DerivedMesh.c, and are intended to be moved
+/* NOTE: the functions below are defined in DerivedMesh.cc, and are intended to be moved
  * to a more suitable location when that file is removed.
- * They should also be renamed to use conventions from BKE, not old DerivedMesh.c.
+ * They should also be renamed to use conventions from BKE, not old DerivedMesh.cc.
  * For now keep the names similar to avoid confusion. */
 struct Mesh *mesh_get_eval_final(struct Depsgraph *depsgraph,
                                  struct Scene *scene,

source/blender/blenkernel/CMakeLists.txt

@@ -66,7 +66,7 @@ set(SRC
   intern/CCGSubSurf.c
   intern/CCGSubSurf_legacy.c
   intern/CCGSubSurf_util.c
-  intern/DerivedMesh.c
+  intern/DerivedMesh.cc
   intern/action.c
   intern/addon.c
   intern/anim_data.c

source/blender/blenkernel/intern/mesh_convert.c

@@ -1460,7 +1460,7 @@ Mesh *BKE_mesh_create_derived_for_modifier(struct Depsgraph *depsgraph,
   return result;
 }
 
-/* This is a Mesh-based copy of the same function in DerivedMesh.c */
+/* This is a Mesh-based copy of the same function in DerivedMesh.cc */
 static void shapekey_layers_to_keyblocks(Mesh *mesh_src, Mesh *mesh_dst, int actshape_uid)
 {
   KeyBlock *kb;

source/blender/modifiers/intern/MOD_cloth.c

@@ -116,7 +116,7 @@ static void deformVerts(ModifierData *md,
     mesh_src = (Mesh *)BKE_id_copy_ex(NULL, (ID *)mesh, NULL, LIB_ID_COPY_LOCALIZE);
   }
 
-  /* TODO(sergey): For now it actually duplicates logic from DerivedMesh.c
+  /* TODO(sergey): For now it actually duplicates logic from DerivedMesh.cc
    * and needs some more generic solution. But starting experimenting with
    * this so close to the release is not that nice..
    *