Allocator macro style and comments, remove unused vargs.

Author: evoskuil

include/bitcoin/system/allocator.hpp

@@ -279,13 +279,26 @@ inline bool operator==(const allocator<Left>& left,
 
 using byte_allocator = allocator<uint8_t>;
 
-#define CREATE(Type, allocate, ...) \
-    allocate.new_object<Type>(__VA_ARGS__), allocate.deleter<Type>(), allocate
+// If Type accepts an allocator on construct (e.g. vector) then
+// std::uses_allocator_construction_args supplies the allocator.
+
+// Create a pointer to an instance of Type presumed to be allocated and
+// constructed by allocator, and pass it and deleter and allocator as:
+// shared_ptr<Type>(Type*, allocate.deleter<Type>(), allocate)
 #define POINTER(Type, allocate, ptr) \
     ptr, allocate.deleter<Type>(), allocate
-#define INPLACE(ptr, Type, allocate, ...) \
-    allocate.construct<std::shared_ptr<const Type>>(ptr, __VA_ARGS__, \
-        allocate.deleter<Type>(), allocate)
+
+// Create a pointer to an instance of Type allocated and constructed by
+// allocator, and pass it and deleter and allocator as:
+// shared_ptr<Type>(allocate.new_object<Type>(...), allocate.deleter<Type>(), allocate)
+#define CREATE(Type, allocate, ...) \
+    POINTER(Type, allocate, allocate.new_object<Type>(__VA_ARGS__))
+
+// Construct a shared_ptr to allocated instance (ptr) of const Type on an
+// allocated address (at) passing deleter and allocator to shared_ptr construct.
+#define INPLACE(at, Type, allocate, ptr) \
+    allocate.construct<std::shared_ptr<const Type>>( \
+        at, ptr, allocate.deleter<Type>(), allocate)
 
 // TODO: replace above macros with parameter pack expansion.
 ////template <typename Type, typename Allocator, typename... Args>