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/scene/resources/convex_polygon_shape.cpp b/scene/resources/convex_polygon_shape.cpp
index a2e0996996..fa9369d3bc 100644
--- a/scene/resources/convex_polygon_shape.cpp
+++ b/scene/resources/convex_polygon_shape.cpp
@@ -46,8 +46,8 @@ Vector<Vector3> ConvexPolygonShape::_gen_debug_mesh_lines() {
 			Vector<Vector3> lines;
 			lines.resize(md.edges.size() * 2);
 			for (int i = 0; i < md.edges.size(); i++) {
-				lines[i * 2 + 0] = md.vertices[md.edges[i].a];
-				lines[i * 2 + 1] = md.vertices[md.edges[i].b];
+				lines.write[i * 2 + 0] = md.vertices[md.edges[i].a];
+				lines.write[i * 2 + 1] = md.vertices[md.edges[i].b];
 			}
 			return lines;
 		}