source/blender/blenkernel/intern/mesh_mirror.cc

@@ -336,8 +336,8 @@ Mesh *BKE_mesh_mirror_apply_mirror_on_axis_for_modifier(MirrorModifierData *mmd,
     const blender::BoundedBitSpan src = mesh->runtime->subsurf_optimal_display_edges;
     result->runtime->subsurf_optimal_display_edges.resize(result->totedge);
     blender::MutableBoundedBitSpan dst = result->runtime->subsurf_optimal_display_edges;
-    dst.slice({0, src.size()}).copy_from(src);
-    dst.slice({src.size(), src.size()}).copy_from(src);
+    dst.take_front(src.size()).copy_from(src);
+    dst.take_back(src.size()).copy_from(src);
   }
 
   /* handle uvs,

source/blender/blenlib/BLI_bit_span.hh

@@ -110,6 +110,16 @@ class BitSpan {
     return {data_, bit_range_.slice(range)};
   }
 
+  BitSpan take_front(const int64_t n) const
+  {
+    return {data_, bit_range_.take_front(n)};
+  }
+
+  BitSpan take_back(const int64_t n) const
+  {
+    return {data_, bit_range_.take_back(n)};
+  }
+
   const BitInt *data() const
   {
     return data_;
@@ -195,6 +205,11 @@ class BoundedBitSpan : public BitSpan {
   {
     return bit_range_.size() & BitIndexMask;
   }
+
+  BoundedBitSpan take_front(const int64_t n) const
+  {
+    return {data_, bit_range_.take_front(n)};
+  }
 };
 
 /** Same as #BitSpan, but also allows modifying the referenced bits. */
@@ -237,6 +252,16 @@ class MutableBitSpan {
     return {data_, bit_range_.slice(range)};
   }
 
+  MutableBitSpan take_front(const int64_t n) const
+  {
+    return {data_, bit_range_.take_front(n)};
+  }
+
+  MutableBitSpan take_back(const int64_t n) const
+  {
+    return {data_, bit_range_.take_back(n)};
+  }
+
   BitInt *data() const
   {
     return data_;
@@ -331,6 +356,11 @@ class MutableBoundedBitSpan : public MutableBitSpan {
     return bit_range_.size() & BitIndexMask;
   }
 
+  MutableBoundedBitSpan take_front(const int64_t n) const
+  {
+    return {data_, bit_range_.take_front(n)};
+  }
+
   void copy_from(const BitSpan other);
   void copy_from(const BoundedBitSpan other);
 };