Sculpt: Rewrite BMLog to support customdata and geometry undo steps

* Inline the two lines from BKE_mesh_from_bmesh_nomain we need.
* IDMap no longer flags its attributes as temporary.
  They're now explicitly deleted when the BMLog is.

@@ -1120,3 +1120,3 @@
   Mesh *mesh = static_cast<Mesh *>(BKE_id_new_nomain(ID_ME, nullptr));
   BM_mesh_bm_to_me(nullptr, bm, mesh, params);
-  BKE_mesh_copy_parameters_for_eval(mesh, me_settings);
+  if (me_settings) { /* BMLog calls this with me_settings as null. */

@@ -195,7 +195,6 @@
 #include "intern/bmesh_edgeloop.h"
 #include "intern/bmesh_interp.h"
 #include "intern/bmesh_iterators.h"
-#include "intern/bmesh_log.h"

@@ -0,0 +1,409 @@
+#include "MEM_guardedalloc.h"

@@ -0,0 +73,4 @@
+void BM_idmap_clear_attributes_mesh(Mesh *me);
+
+/* Elem -> ID. */
+template<typename T = BMElem> BLI_INLINE int BM_idmap_get_id(BMIdMap *map, T *elem)

@@ -27,0 +46,4 @@
+using blender::Vector;
+
+/* Avoid C++ runtime type ids. */
+enum BMLogSetType { LOG_SET_DIFF, LOG_SET_FULL };

@@ -27,0 +61,4 @@
+    return false;
+  }
+
+  CustomData test_a = *data_a;

@@ -27,0 +114,4 @@
+
+  CustomData_update_typemap(dest);
+}
+

@@ -27,0 +130,4 @@
+    CustomData_bmesh_set_default(source, dest_block);
+  }
+
+  void *scratch = alloca(dest->totsize);

@@ -27,0 +159,4 @@
+};
+
+template<typename T> struct LogElemAlloc {
+  BLI_mempool *pool;

@@ -27,0 +164,4 @@
+  class iterator {
+    LogElemAlloc<T> *alloc;
+    BLI_mempool_iter iter;
+    void *elem = nullptr, *first;

@@ -27,0 +280,4 @@
+};
+
+struct BMLogFace : public BMLogElem<BMFace> {
+  Vector<int, 3> verts;

@@ -27,0 +301,4 @@
+
+struct BMLogSetBase {
+  BMLogSetType type;
+  BMLogEntry *entry = nullptr; /* Parent entry */

@@ -27,0 +311,4 @@
+  {
+    return "";
+  }
+  virtual void undo(BMesh * /*bm*/, BMLogCallbacks * /*callbacks*/) {}

@@ -27,0 +364,4 @@
+  BMLogSetFullMesh(BMesh *bm, BMLogEntry *entry, BMIdMap *idmap)
+      : BMLogSetBase(entry, LOG_SET_FULL)
+  {
+    printf("Log full mesh\n");

@@ -27,0 +371,4 @@
+
+    /* Ensure we write idmap attrs. */
+    set_idlayer_temporary_flag(&bm->vdata, BM_VERT, false);
+    set_idlayer_temporary_flag(&bm->edata, BM_EDGE, false);

@@ -27,0 +400,4 @@
+
+  void swap(BMesh *bm)
+  {
+    CustomData_MeshMasks cd_mask_extra = {0, 0, 0, 0, 0};

@@ -27,0 +419,4 @@
+
+    BMeshFromMeshParams params2 = {};
+    params2.cd_mask_extra = cd_mask_extra;
+    params2.calc_face_normal = params2.add_key_index = params2.use_shapekey = false;

@@ -27,0 +435,4 @@
+    bm->shapenr = shapenr;
+
+    bm->elem_index_dirty |= BM_VERT | BM_EDGE | BM_FACE;
+    bm->elem_table_dirty |= BM_VERT | BM_EDGE | BM_FACE;

@@ -27,0 +464,4 @@
+    }
+  }
+
+  Mesh *mesh = nullptr;

@@ -27,0 +494,4 @@
+      return "loop";
+    case BM_FACE:
+      return "face";
+    default:

@@ -27,0 +518,4 @@
+struct BMLogEntry {
+  BMLogEntry *next = nullptr, *prev = nullptr;
+
+  Vector<BMLogSetBase *> sets;

@@ -27,0 +581,4 @@
+    return nullptr;
+  }
+
+  void copy_custom_data(CustomData *source, CustomData *dest, void *src_block, void **dest_block)

@@ -27,0 +638,4 @@
+    CustomData_free(&pdata, 0);
+  }
+
+  void print()

@@ -47,3 +71,2 @@
-int BM_log_length(const BMLog *log);
+BMLog *BM_log_from_existing_entries_create(BMesh *bm, BMLogEntry *entry, bool for_redo);
 
-/** Apply a consistent ordering to BMesh vertices and faces. */

@@ -15,3 +47,2 @@
 
-typedef struct BMLog BMLog;
-typedef struct BMLogEntry BMLogEntry;
+struct BMLogCallbacks {

@@ -0,0 +1,2 @@
+#include "intern/bmesh_log.h"

@@ -21,0 +56,4 @@
+
+/* `customdata_layout_is_same` and `customdata_copy_all_layout` are
+ *  used internally by BMLog and probably don't have much use elsewhere.
+ *  They ignore all copy-on-write semantics which makes sense since this

@@ -21,0 +68,4 @@
+  }
+
+  for (int i : IndexRange(data_a->totlayer)) {
+    CustomDataLayer &layer_a = data_a->layers[i];

@@ -21,0 +84,4 @@
+/* Copies all customdata layers without allocating data
+ * and without respect to type masks or NO_COPY/etc flags.
+ */
+static void customdata_copy_all_layout(const CustomData *source, CustomData *dest)

@@ -21,0 +302,4 @@
+
+#if 0
+    bm->elem_index_dirty |= BM_VERT | BM_EDGE | BM_FACE;
+    bm->elem_table_dirty |= BM_VERT | BM_EDGE | BM_FACE;

@@ -103,1 +118,4 @@
 
+  /* Now log full mesh again after triangulation. */
+  if (for_undo && ss->bm->totface != faces_num) {
+    BM_log_full_mesh(ss->bm, ss->bm_log);