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, 7 insertions, 7 deletions

diff --git a/scene/resources/bit_mask.cpp b/scene/resources/bit_mask.cpp
index 29ffefd9d6..85e36abf4e 100644
--- a/scene/resources/bit_mask.cpp
+++ b/scene/resources/bit_mask.cpp
@@ -130,7 +130,7 @@ void BitMap::set_bit(const Point2 &p_pos, bool p_value) {
 	else
 		b &= ~(1 << bbit);
 
-	bitmask[bbyte] = b;
+	bitmask.write[bbyte] = b;
 }
 
 bool BitMap::get_bit(const Point2 &p_pos) const {
@@ -322,8 +322,8 @@ Vector<Vector2> BitMap::_march_square(const Rect2i &rect, const Point2i &start)
 		curx += stepx;
 		cury += stepy;
 		if (stepx == prevx && stepy == prevy) {
-			_points[_points.size() - 1].x = (float)(curx - rect.position.x);
-			_points[_points.size() - 1].y = (float)(cury + rect.position.y);
+			_points.write[_points.size() - 1].x = (float)(curx - rect.position.x);
+			_points.write[_points.size() - 1].y = (float)(cury + rect.position.y);
 		} else {
 			_points.push_back(Vector2((float)(curx - rect.position.x), (float)(cury + rect.position.y)));
 		}
@@ -373,11 +373,11 @@ static Vector<Vector2> rdp(const Vector<Vector2> &v, float optimization) {
 		Vector<Vector2> left, right;
 		left.resize(index);
 		for (int i = 0; i < index; i++) {
-			left[i] = v[i];
+			left.write[i] = v[i];
 		}
 		right.resize(v.size() - index);
 		for (int i = 0; i < right.size(); i++) {
-			right[i] = v[index + i];
+			right.write[i] = v[index + i];
 		}
 		Vector<Vector2> r1 = rdp(left, optimization);
 		Vector<Vector2> r2 = rdp(right, optimization);
@@ -385,7 +385,7 @@ static Vector<Vector2> rdp(const Vector<Vector2> &v, float optimization) {
 		int middle = r1.size();
 		r1.resize(r1.size() + r2.size());
 		for (int i = 0; i < r2.size(); i++) {
-			r1[middle + i] = r2[i];
+			r1.write[middle + i] = r2[i];
 		}
 		return r1;
 	} else {
@@ -412,7 +412,7 @@ static Vector<Vector2> reduce(const Vector<Vector2> &points, const Rect2i &rect,
 	Vector2 last = result[result.size() - 1];
 
 	if (last.y > result[0].y && last.distance_to(result[0]) < ep * 0.5f) {
-		result[0].y = last.y;
+		result.write[0].y = last.y;
 		result.resize(result.size() - 1);
 	}
 	return result;