Refactors the memnew_placement.

With this commit the macro `memnew_placement` uses the standard memory
placement syntax: `new (mem) TheClass()`, and removes the outdated and
not used syntax:
```
_ALWAYS_INLINE_ void *operator new(size_t p_size, void *p_pointer, size_t check, const char *p_description) {
```

Thanks to this change, the function `memnew_placement` call is compatible with
any class, and can also initialize classes with non-empty constructor:
```
// This is valid, like before.
memnew_placement(mem, Variant);

// This works too:
memnew_placement(mem, Variant(123));
```

1 files changed, 4 insertions, 10 deletions

diff --git a/core/os/memory.h b/core/os/memory.h
index 9d09626b8c..f67384a17e 100644
--- a/core/os/memory.h
+++ b/core/os/memory.h
@@ -35,6 +35,7 @@
 #include "core/templates/safe_refcount.h"
 
 #include <stddef.h>
+#include <new>
 
 #ifndef PAD_ALIGN
 #define PAD_ALIGN 16 //must always be greater than this at much
@@ -92,15 +93,8 @@ _ALWAYS_INLINE_ T *_post_initialize(T *p_obj) {
 
 #define memnew(m_class) _post_initialize(new ("") m_class)
 
-_ALWAYS_INLINE_ void *operator new(size_t p_size, void *p_pointer, size_t check, const char *p_description) {
-	//void *failptr=0;
-	//ERR_FAIL_COND_V( check < p_size , failptr); /** bug, or strange compiler, most likely */
-
-	return p_pointer;
-}
-
 #define memnew_allocator(m_class, m_allocator) _post_initialize(new (m_allocator::alloc) m_class)
-#define memnew_placement(m_placement, m_class) _post_initialize(new (m_placement, sizeof(m_class), "") m_class)
+#define memnew_placement(m_placement, m_class) _post_initialize(new (m_placement) m_class)
 
 _ALWAYS_INLINE_ bool predelete_handler(void *) {
 	return true;
@@ -140,7 +134,7 @@ void memdelete_allocator(T *p_class) {
 #define memnew_arr(m_class, m_count) memnew_arr_template<m_class>(m_count)
 
 template <typename T>
-T *memnew_arr_template(size_t p_elements, const char *p_descr = "") {
+T *memnew_arr_template(size_t p_elements) {
 	if (p_elements == 0) {
 		return nullptr;
 	}
@@ -158,7 +152,7 @@ T *memnew_arr_template(size_t p_elements, const char *p_descr = "") {
 
 		/* call operator new */
 		for (size_t i = 0; i < p_elements; i++) {
-			new (&elems[i], sizeof(T), p_descr) T;
+			new (&elems[i]) T;
 		}
 	}