11 files changed, 42 insertions, 23 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 85827e01af5..3e97e393f17 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1756,6 +1756,7 @@ elseif(CMAKE_C_COMPILER_ID MATCHES "MSVC")
     "/wd4828"  # The file contains a character that is illegal
     "/wd4996"  # identifier was declared deprecated
     "/wd4661"  # no suitable definition provided for explicit template instantiation request
+    "/wd4848"  # 'no_unique_address' is a vendor extension in C++17
     # errors:
     "/we4013"  # 'function' undefined; assuming extern returning int
     "/we4133"  # incompatible pointer types
diff --git a/source/blender/blenlib/BLI_array.hh b/source/blender/blenlib/BLI_array.hh
index 91dfc81ae27..813277d9968 100644
--- a/source/blender/blenlib/BLI_array.hh
+++ b/source/blender/blenlib/BLI_array.hh
@@ -64,10 +64,10 @@ class Array {
   int64_t size_;
 
   /** Used for allocations when the inline buffer is too small. */
-  Allocator allocator_;
+  BLI_NO_UNIQUE_ADDRESS Allocator allocator_;
 
   /** A placeholder buffer that will remain uninitialized until it is used. */
-  TypedBuffer<T, InlineBufferCapacity> inline_buffer_;
+  BLI_NO_UNIQUE_ADDRESS TypedBuffer<T, InlineBufferCapacity> inline_buffer_;
 
  public:
   /**
diff --git a/source/blender/blenlib/BLI_generic_array.hh b/source/blender/blenlib/BLI_generic_array.hh
index e1b6b29874a..4b917434264 100644
--- a/source/blender/blenlib/BLI_generic_array.hh
+++ b/source/blender/blenlib/BLI_generic_array.hh
@@ -33,7 +33,7 @@ class GArray {
   void *data_ = nullptr;
   int64_t size_ = 0;
 
-  Allocator allocator_;
+  BLI_NO_UNIQUE_ADDRESS Allocator allocator_;
 
  public:
   /**
diff --git a/source/blender/blenlib/BLI_linear_allocator.hh b/source/blender/blenlib/BLI_linear_allocator.hh
index 6532c59a846..deb6ea3b5fd 100644
--- a/source/blender/blenlib/BLI_linear_allocator.hh
+++ b/source/blender/blenlib/BLI_linear_allocator.hh
@@ -18,7 +18,7 @@ namespace blender {
 
 template<typename Allocator = GuardedAllocator> class LinearAllocator : NonCopyable, NonMovable {
  private:
-  Allocator allocator_;
+  BLI_NO_UNIQUE_ADDRESS Allocator allocator_;
   Vector<void *> owned_buffers_;
   Vector<Span<char>> unused_borrowed_buffers_;
 
diff --git a/source/blender/blenlib/BLI_map.hh b/source/blender/blenlib/BLI_map.hh
index d76aa46502d..55233676ed8 100644
--- a/source/blender/blenlib/BLI_map.hh
+++ b/source/blender/blenlib/BLI_map.hh
@@ -130,10 +130,10 @@ class Map {
   uint64_t slot_mask_;
 
   /** This is called to hash incoming keys. */
-  Hash hash_;
+  BLI_NO_UNIQUE_ADDRESS Hash hash_;
 
   /** This is called to check equality of two keys. */
-  IsEqual is_equal_;
+  BLI_NO_UNIQUE_ADDRESS IsEqual is_equal_;
 
   /** The max load factor is 1/2 = 50% by default. */
 #define LOAD_FACTOR 1, 2
diff --git a/source/blender/blenlib/BLI_memory_utils.hh b/source/blender/blenlib/BLI_memory_utils.hh
index d7c41ae88a8..940542c9f1d 100644
--- a/source/blender/blenlib/BLI_memory_utils.hh
+++ b/source/blender/blenlib/BLI_memory_utils.hh
@@ -317,30 +317,36 @@ template<typename T> using destruct_ptr = std::unique_ptr<T, DestructValueAtAddr
  * An `AlignedBuffer` is a byte array with at least the given size and alignment. The buffer will
  * not be initialized by the default constructor.
  */
-template<size_t Size, size_t Alignment> class alignas(Alignment) AlignedBuffer {
- private:
-  /* Don't create an empty array. This causes problems with some compilers. */
-  char buffer_[(Size > 0) ? Size : 1];
+template<size_t Size, size_t Alignment> class AlignedBuffer {
+  struct Empty {
+  };
+  struct alignas(Alignment) Sized {
+    /* Don't create an empty array. This causes problems with some compilers. */
+    std::byte buffer_[Size > 0 ? Size : 1];
+  };
+
+  using BufferType = std::conditional_t<Size == 0, Empty, Sized>;
+  BLI_NO_UNIQUE_ADDRESS BufferType buffer_;
 
  public:
   operator void *()
   {
-    return buffer_;
+    return this;
   }
 
   operator const void *() const
   {
-    return buffer_;
+    return this;
   }
 
   void *ptr()
   {
-    return buffer_;
+    return this;
   }
 
   const void *ptr() const
   {
-    return buffer_;
+    return this;
   }
 };
 
@@ -351,7 +357,7 @@ template<size_t Size, size_t Alignment> class alignas(Alignment) AlignedBuffer {
  */
 template<typename T, int64_t Size = 1> class TypedBuffer {
  private:
-  AlignedBuffer<sizeof(T) * (size_t)Size, alignof(T)> buffer_;
+  BLI_NO_UNIQUE_ADDRESS AlignedBuffer<sizeof(T) * (size_t)Size, alignof(T)> buffer_;
 
  public:
   operator T *()
diff --git a/source/blender/blenlib/BLI_set.hh b/source/blender/blenlib/BLI_set.hh
index 99acae43571..62de4b79e41 100644
--- a/source/blender/blenlib/BLI_set.hh
+++ b/source/blender/blenlib/BLI_set.hh
@@ -136,10 +136,10 @@ class Set {
   uint64_t slot_mask_;
 
   /** This is called to hash incoming keys. */
-  Hash hash_;
+  BLI_NO_UNIQUE_ADDRESS Hash hash_;
 
   /** This is called to check equality of two keys. */
-  IsEqual is_equal_;
+  BLI_NO_UNIQUE_ADDRESS IsEqual is_equal_;
 
   /** The max load factor is 1/2 = 50% by default. */
 #define LOAD_FACTOR 1, 2
diff --git a/source/blender/blenlib/BLI_stack.hh b/source/blender/blenlib/BLI_stack.hh
index a06515a7781..ed123f43a6b 100644
--- a/source/blender/blenlib/BLI_stack.hh
+++ b/source/blender/blenlib/BLI_stack.hh
@@ -96,7 +96,7 @@ class Stack {
   int64_t size_;
 
   /** The buffer used to implement small object optimization. */
-  TypedBuffer<T, InlineBufferCapacity> inline_buffer_;
+  BLI_NO_UNIQUE_ADDRESS TypedBuffer<T, InlineBufferCapacity> inline_buffer_;
 
   /**
    * A chunk referencing the inline buffer. This is always the bottom-most chunk.
@@ -105,7 +105,7 @@ class Stack {
   Chunk inline_chunk_;
 
   /** Used for allocations when the inline buffer is not large enough. */
-  Allocator allocator_;
+  BLI_NO_UNIQUE_ADDRESS Allocator allocator_;
 
  public:
   /**
diff --git a/source/blender/blenlib/BLI_utildefines.h b/source/blender/blenlib/BLI_utildefines.h
index b8407a5453f..7f9470a9111 100644
--- a/source/blender/blenlib/BLI_utildefines.h
+++ b/source/blender/blenlib/BLI_utildefines.h
@@ -843,6 +843,18 @@ extern bool BLI_memory_is_zero(const void *arr, size_t arr_size);
  */
 #define BLI_ENABLE_IF(condition) typename std::enable_if_t<(condition)> * = nullptr
 
+#if defined(_MSC_VER)
+#  define BLI_NO_UNIQUE_ADDRESS [[msvc::no_unique_address]]
+#elif defined(__has_cpp_attribute)
+#  if __has_cpp_attribute(no_unique_address)
+#    define BLI_NO_UNIQUE_ADDRESS [[no_unique_address]]
+#  else
+#    define BLI_NO_UNIQUE_ADDRESS
+#  endif
+#else
+#  define BLI_NO_UNIQUE_ADDRESS [[no_unique_address]]
+#endif
+
 /** \} */
 
 #ifdef __cplusplus
diff --git a/source/blender/blenlib/BLI_vector.hh b/source/blender/blenlib/BLI_vector.hh
index acf47f67168..c23d846d277 100644
--- a/source/blender/blenlib/BLI_vector.hh
+++ b/source/blender/blenlib/BLI_vector.hh
@@ -84,10 +84,10 @@ class Vector {
   T *capacity_end_;
 
   /** Used for allocations when the inline buffer is too small. */
-  Allocator allocator_;
+  BLI_NO_UNIQUE_ADDRESS Allocator allocator_;
 
   /** A placeholder buffer that will remain uninitialized until it is used. */
-  TypedBuffer<T, InlineBufferCapacity> inline_buffer_;
+  BLI_NO_UNIQUE_ADDRESS TypedBuffer<T, InlineBufferCapacity> inline_buffer_;
 
   /**
    * Store the size of the vector explicitly in debug builds. Otherwise you'd always have to call
diff --git a/source/blender/blenlib/BLI_vector_set.hh b/source/blender/blenlib/BLI_vector_set.hh
index 4ae1bf9000d..b0a3696f245 100644
--- a/source/blender/blenlib/BLI_vector_set.hh
+++ b/source/blender/blenlib/BLI_vector_set.hh
@@ -117,10 +117,10 @@ class VectorSet {
   uint64_t slot_mask_;
 
   /** This is called to hash incoming keys. */
-  Hash hash_;
+  BLI_NO_UNIQUE_ADDRESS Hash hash_;
 
   /** This is called to check equality of two keys. */
-  IsEqual is_equal_;
+  BLI_NO_UNIQUE_ADDRESS IsEqual is_equal_;
 
   /** The max load factor is 1/2 = 50% by default. */
 #define LOAD_FACTOR 1, 2