define non-sized deallocator and memory counting debugging

 * it turned out to be possible to provoke memory_usage
   overflows or underruns, resulting in unrecoverable states
 * a possible reason can be that at least with G++ 5.4.0,
   the compiler would sometimes call the (default) non-sized
   delete followed by our custom sized delete/deallocator.
 * This was true even after compiling Scintilla with -fsized-deallocation.
 * therefore we provide an empty non-sized delete now.
 * memory_usage counting can now be debugged by uncommenting
   DEBUG_MAGIC in memory.cpp. This uses a magic value to detect
   instrumented allocations being mixed with non-instrumented
   allocations.
 * simplified the global sized-deallocation functions
   (they are identical to the Object-class allocators).

1 files changed, 5 insertions, 3 deletions

diff --git a/src/memory.h b/src/memory.h
index 903fd16..693a208 100644
--- a/src/memory.h
+++ b/src/memory.h
@@ -40,9 +40,11 @@ namespace SciTECO {
  * scalars (e.g. new char[5]).
  *
  * C++14 (supported by GCC >= 5) has global sized delete
- * replacements which would be effective in the entire application
- * but we're still using the base-class approach since
- * we must support the older compilers anyway.
+ * replacements which would be effective in the entire application.
+ * We're using them too if support is detected and there is
+ * also a fallback using malloc_usable_size().
+ * Another fallback with a size field would be possible
+ * but is probably not worth the trouble.
  */
 class Object {
 public: