Reduce unnecessary COW on Vector by make writing explicit

This commit makes operator[] on Vector const and adds a write proxy to it.  From
now on writes to Vectors need to happen through the .write proxy. So for
instance:

Vector<int> vec;
vec.push_back(10);
std::cout << vec[0] << std::endl;
vec.write[0] = 20;

Failing to use the .write proxy will cause a compilation error.

In addition COWable datatypes can now embed a CowData pointer to their data.
This means that String, CharString, and VMap no longer use or derive from
Vector.

_ALWAYS_INLINE_ and _FORCE_INLINE_ are now equivalent for debug and non-debug
builds. This is a lot faster for Vector in the editor and while running tests.
The reason why this difference used to exist is because force-inlined methods
used to give a bad debugging experience. After extensive testing with modern
compilers this is no longer the case.

1 files changed, 2 insertions, 2 deletions

diff --git a/core/io/resource_format_binary.cpp b/core/io/resource_format_binary.cpp
index 0c626c197b..02c2c6ce1a 100644
--- a/core/io/resource_format_binary.cpp
+++ b/core/io/resource_format_binary.cpp
@@ -894,7 +894,7 @@ void ResourceInteractiveLoaderBinary::open(FileAccess *p_f) {
 	for (uint32_t i = 0; i < string_table_size; i++) {
 
 		StringName s = get_unicode_string();
-		string_map[i] = s;
+		string_map.write[i] = s;
 	}
 
 	print_bl("strings: " + itos(string_table_size));
@@ -1834,7 +1834,7 @@ Error ResourceFormatSaverBinaryInstance::save(const String &p_path, const RES &p
 	save_order.resize(external_resources.size());
 
 	for (Map<RES, int>::Element *E = external_resources.front(); E; E = E->next()) {
-		save_order[E->get()] = E->key();
+		save_order.write[E->get()] = E->key();
 	}
 
 	for (int i = 0; i < save_order.size(); i++) {