Merge pull request #82980 from Repiteo/c#-godotsharp-nullable-structs

[C#] Enable nullability for variant structs

17 files changed, 86 insertions, 35 deletions

diff --git a/modules/mono/glue/GodotSharp/GodotSharp/Core/Aabb.cs b/modules/mono/glue/GodotSharp/GodotSharp/Core/Aabb.cs
index cc99225a33..57b5b09ebb 100644
--- a/modules/mono/glue/GodotSharp/GodotSharp/Core/Aabb.cs
+++ b/modules/mono/glue/GodotSharp/GodotSharp/Core/Aabb.cs
@@ -1,6 +1,9 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.InteropServices;
 
+#nullable enable
+
 namespace Godot
 {
     /// <summary>
@@ -689,7 +692,7 @@ namespace Godot
         /// </summary>
         /// <param name="obj">The object to compare with.</param>
         /// <returns>Whether or not the AABB and the object are equal.</returns>
-        public override readonly bool Equals(object obj)
+        public override readonly bool Equals([NotNullWhen(true)] object? obj)
         {
             return obj is Aabb other && Equals(other);
         }
@@ -739,7 +742,7 @@ namespace Godot
         /// Converts this <see cref="Aabb"/> to a string with the given <paramref name="format"/>.
         /// </summary>
         /// <returns>A string representation of this AABB.</returns>
-        public readonly string ToString(string format)
+        public readonly string ToString(string? format)
         {
             return $"{_position.ToString(format)}, {_size.ToString(format)}";
         }
diff --git a/modules/mono/glue/GodotSharp/GodotSharp/Core/Basis.cs b/modules/mono/glue/GodotSharp/GodotSharp/Core/Basis.cs
index b4f7b82f60..589d6596f0 100644
--- a/modules/mono/glue/GodotSharp/GodotSharp/Core/Basis.cs
+++ b/modules/mono/glue/GodotSharp/GodotSharp/Core/Basis.cs
@@ -1,7 +1,10 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.InteropServices;
 using System.ComponentModel;
 
+#nullable enable
+
 namespace Godot
 {
     /// <summary>
@@ -1090,7 +1093,7 @@ namespace Godot
         /// </summary>
         /// <param name="obj">The object to compare with.</param>
         /// <returns>Whether or not the basis matrix and the object are exactly equal.</returns>
-        public override readonly bool Equals(object obj)
+        public override readonly bool Equals([NotNullWhen(true)] object? obj)
         {
             return obj is Basis other && Equals(other);
         }
@@ -1140,7 +1143,7 @@ namespace Godot
         /// Converts this <see cref="Basis"/> to a string with the given <paramref name="format"/>.
         /// </summary>
         /// <returns>A string representation of this basis.</returns>
-        public readonly string ToString(string format)
+        public readonly string ToString(string? format)
         {
             return $"[X: {X.ToString(format)}, Y: {Y.ToString(format)}, Z: {Z.ToString(format)}]";
         }
diff --git a/modules/mono/glue/GodotSharp/GodotSharp/Core/Color.cs b/modules/mono/glue/GodotSharp/GodotSharp/Core/Color.cs
index 293e680067..772209064c 100644
--- a/modules/mono/glue/GodotSharp/GodotSharp/Core/Color.cs
+++ b/modules/mono/glue/GodotSharp/GodotSharp/Core/Color.cs
@@ -1,7 +1,10 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.InteropServices;
 using Godot.NativeInterop;
 
+#nullable enable
+
 namespace Godot
 {
     /// <summary>
@@ -1274,7 +1277,7 @@ namespace Godot
         /// </summary>
         /// <param name="obj">The other object to compare.</param>
         /// <returns>Whether or not the color and the other object are equal.</returns>
-        public override readonly bool Equals(object obj)
+        public override readonly bool Equals([NotNullWhen(true)] object? obj)
         {
             return obj is Color other && Equals(other);
         }
@@ -1324,7 +1327,7 @@ namespace Godot
         /// Converts this <see cref="Color"/> to a string with the given <paramref name="format"/>.
         /// </summary>
         /// <returns>A string representation of this color.</returns>
-        public readonly string ToString(string format)
+        public readonly string ToString(string? format)
         {
             return $"({R.ToString(format)}, {G.ToString(format)}, {B.ToString(format)}, {A.ToString(format)})";
         }
diff --git a/modules/mono/glue/GodotSharp/GodotSharp/Core/Plane.cs b/modules/mono/glue/GodotSharp/GodotSharp/Core/Plane.cs
index 85b2b02c45..f5dc34d824 100644
--- a/modules/mono/glue/GodotSharp/GodotSharp/Core/Plane.cs
+++ b/modules/mono/glue/GodotSharp/GodotSharp/Core/Plane.cs
@@ -1,6 +1,9 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.InteropServices;
 
+#nullable enable
+
 namespace Godot
 {
     /// <summary>
@@ -382,7 +385,7 @@ namespace Godot
         /// </summary>
         /// <param name="obj">The other object to compare.</param>
         /// <returns>Whether or not the plane and the other object are exactly equal.</returns>
-        public override readonly bool Equals(object obj)
+        public override readonly bool Equals([NotNullWhen(true)] object? obj)
         {
             return obj is Plane other && Equals(other);
         }
@@ -430,7 +433,7 @@ namespace Godot
         /// Converts this <see cref="Plane"/> to a string with the given <paramref name="format"/>.
         /// </summary>
         /// <returns>A string representation of this plane.</returns>
-        public readonly string ToString(string format)
+        public readonly string ToString(string? format)
         {
             return $"{_normal.ToString(format)}, {_d.ToString(format)}";
         }
diff --git a/modules/mono/glue/GodotSharp/GodotSharp/Core/Projection.cs b/modules/mono/glue/GodotSharp/GodotSharp/Core/Projection.cs
index 155e90ff24..4c9e21fb79 100644
--- a/modules/mono/glue/GodotSharp/GodotSharp/Core/Projection.cs
+++ b/modules/mono/glue/GodotSharp/GodotSharp/Core/Projection.cs
@@ -1,6 +1,9 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.InteropServices;
 
+#nullable enable
+
 namespace Godot
 {
     /// <summary>
@@ -586,7 +589,7 @@ namespace Godot
         public readonly Vector2 GetFarPlaneHalfExtents()
         {
             var res = GetProjectionPlane(Planes.Far).Intersect3(GetProjectionPlane(Planes.Right), GetProjectionPlane(Planes.Top));
-            return new Vector2(res.Value.X, res.Value.Y);
+            return res is null ? default : new Vector2(res.Value.X, res.Value.Y);
         }
 
         /// <summary>
@@ -597,7 +600,7 @@ namespace Godot
         public readonly Vector2 GetViewportHalfExtents()
         {
             var res = GetProjectionPlane(Planes.Near).Intersect3(GetProjectionPlane(Planes.Right), GetProjectionPlane(Planes.Top));
-            return new Vector2(res.Value.X, res.Value.Y);
+            return res is null ? default : new Vector2(res.Value.X, res.Value.Y);
         }
 
         /// <summary>
@@ -981,7 +984,7 @@ namespace Godot
         /// </summary>
         /// <param name="obj">The object to compare with.</param>
         /// <returns>Whether or not the vector and the object are equal.</returns>
-        public override readonly bool Equals(object obj)
+        public override readonly bool Equals([NotNullWhen(true)] object? obj)
         {
             return obj is Projection other && Equals(other);
         }
@@ -1018,7 +1021,7 @@ namespace Godot
         /// Converts this <see cref="Projection"/> to a string with the given <paramref name="format"/>.
         /// </summary>
         /// <returns>A string representation of this projection.</returns>
-        public readonly string ToString(string format)
+        public readonly string ToString(string? format)
         {
             return $"{X.X.ToString(format)}, {X.Y.ToString(format)}, {X.Z.ToString(format)}, {X.W.ToString(format)}\n" +
                 $"{Y.X.ToString(format)}, {Y.Y.ToString(format)}, {Y.Z.ToString(format)}, {Y.W.ToString(format)}\n" +
diff --git a/modules/mono/glue/GodotSharp/GodotSharp/Core/Quaternion.cs b/modules/mono/glue/GodotSharp/GodotSharp/Core/Quaternion.cs
index 3d45913586..2344e8c510 100644
--- a/modules/mono/glue/GodotSharp/GodotSharp/Core/Quaternion.cs
+++ b/modules/mono/glue/GodotSharp/GodotSharp/Core/Quaternion.cs
@@ -1,6 +1,9 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.InteropServices;
 
+#nullable enable
+
 namespace Godot
 {
     /// <summary>
@@ -769,7 +772,7 @@ namespace Godot
         /// </summary>
         /// <param name="obj">The other object to compare.</param>
         /// <returns>Whether or not the quaternion and the other object are exactly equal.</returns>
-        public override readonly bool Equals(object obj)
+        public override readonly bool Equals([NotNullWhen(true)] object? obj)
         {
             return obj is Quaternion other && Equals(other);
         }
@@ -817,7 +820,7 @@ namespace Godot
         /// Converts this <see cref="Quaternion"/> to a string with the given <paramref name="format"/>.
         /// </summary>
         /// <returns>A string representation of this quaternion.</returns>
-        public readonly string ToString(string format)
+        public readonly string ToString(string? format)
         {
             return $"({X.ToString(format)}, {Y.ToString(format)}, {Z.ToString(format)}, {W.ToString(format)})";
         }
diff --git a/modules/mono/glue/GodotSharp/GodotSharp/Core/Rect2.cs b/modules/mono/glue/GodotSharp/GodotSharp/Core/Rect2.cs
index babb26960b..71a35ab809 100644
--- a/modules/mono/glue/GodotSharp/GodotSharp/Core/Rect2.cs
+++ b/modules/mono/glue/GodotSharp/GodotSharp/Core/Rect2.cs
@@ -1,6 +1,9 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.InteropServices;
 
+#nullable enable
+
 namespace Godot
 {
     /// <summary>
@@ -427,7 +430,7 @@ namespace Godot
         /// </summary>
         /// <param name="obj">The other object to compare.</param>
         /// <returns>Whether or not the rect and the other object are exactly equal.</returns>
-        public override readonly bool Equals(object obj)
+        public override readonly bool Equals([NotNullWhen(true)] object? obj)
         {
             return obj is Rect2 other && Equals(other);
         }
@@ -475,7 +478,7 @@ namespace Godot
         /// Converts this <see cref="Rect2"/> to a string with the given <paramref name="format"/>.
         /// </summary>
         /// <returns>A string representation of this rect.</returns>
-        public readonly string ToString(string format)
+        public readonly string ToString(string? format)
         {
             return $"{_position.ToString(format)}, {_size.ToString(format)}";
         }
diff --git a/modules/mono/glue/GodotSharp/GodotSharp/Core/Rect2I.cs b/modules/mono/glue/GodotSharp/GodotSharp/Core/Rect2I.cs
index 49fba02b54..ef7e9eacd8 100644
--- a/modules/mono/glue/GodotSharp/GodotSharp/Core/Rect2I.cs
+++ b/modules/mono/glue/GodotSharp/GodotSharp/Core/Rect2I.cs
@@ -1,6 +1,9 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.InteropServices;
 
+#nullable enable
+
 namespace Godot
 {
     /// <summary>
@@ -398,7 +401,7 @@ namespace Godot
         /// </summary>
         /// <param name="obj">The other object to compare.</param>
         /// <returns>Whether or not the rect and the other object are equal.</returns>
-        public override readonly bool Equals(object obj)
+        public override readonly bool Equals([NotNullWhen(true)] object? obj)
         {
             return obj is Rect2I other && Equals(other);
         }
@@ -435,7 +438,7 @@ namespace Godot
         /// Converts this <see cref="Rect2I"/> to a string with the given <paramref name="format"/>.
         /// </summary>
         /// <returns>A string representation of this rect.</returns>
-        public readonly string ToString(string format)
+        public readonly string ToString(string? format)
         {
             return $"{_position.ToString(format)}, {_size.ToString(format)}";
         }
diff --git a/modules/mono/glue/GodotSharp/GodotSharp/Core/Rid.cs b/modules/mono/glue/GodotSharp/GodotSharp/Core/Rid.cs
index 350626389b..fccae94eac 100644
--- a/modules/mono/glue/GodotSharp/GodotSharp/Core/Rid.cs
+++ b/modules/mono/glue/GodotSharp/GodotSharp/Core/Rid.cs
@@ -1,8 +1,11 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using Godot.NativeInterop;
 
+#nullable enable
+
 namespace Godot
 {
     /// <summary>
@@ -71,7 +74,7 @@ namespace Godot
         /// </summary>
         /// <param name="obj">The other object to compare.</param>
         /// <returns>Whether or not the color and the other object are equal.</returns>
-        public override readonly bool Equals(object obj)
+        public override readonly bool Equals([NotNullWhen(true)] object? obj)
         {
             return obj is Rid other && Equals(other);
         }
diff --git a/modules/mono/glue/GodotSharp/GodotSharp/Core/Transform2D.cs b/modules/mono/glue/GodotSharp/GodotSharp/Core/Transform2D.cs
index 386f587464..3443277fee 100644
--- a/modules/mono/glue/GodotSharp/GodotSharp/Core/Transform2D.cs
+++ b/modules/mono/glue/GodotSharp/GodotSharp/Core/Transform2D.cs
@@ -1,7 +1,10 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 
+#nullable enable
+
 namespace Godot
 {
     /// <summary>
@@ -606,7 +609,7 @@ namespace Godot
         /// </summary>
         /// <param name="obj">The object to compare with.</param>
         /// <returns>Whether or not the transform and the object are exactly equal.</returns>
-        public override readonly bool Equals(object obj)
+        public override readonly bool Equals([NotNullWhen(true)] object? obj)
         {
             return obj is Transform2D other && Equals(other);
         }
@@ -656,7 +659,7 @@ namespace Godot
         /// Converts this <see cref="Transform2D"/> to a string with the given <paramref name="format"/>.
         /// </summary>
         /// <returns>A string representation of this transform.</returns>
-        public readonly string ToString(string format)
+        public readonly string ToString(string? format)
         {
             return $"[X: {X.ToString(format)}, Y: {Y.ToString(format)}, O: {Origin.ToString(format)}]";
         }
diff --git a/modules/mono/glue/GodotSharp/GodotSharp/Core/Transform3D.cs b/modules/mono/glue/GodotSharp/GodotSharp/Core/Transform3D.cs
index 2d09259dcb..f80c0bd8dd 100644
--- a/modules/mono/glue/GodotSharp/GodotSharp/Core/Transform3D.cs
+++ b/modules/mono/glue/GodotSharp/GodotSharp/Core/Transform3D.cs
@@ -1,7 +1,10 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.InteropServices;
 using System.ComponentModel;
 
+#nullable enable
+
 namespace Godot
 {
     /// <summary>
@@ -630,7 +633,7 @@ namespace Godot
         /// </summary>
         /// <param name="obj">The object to compare with.</param>
         /// <returns>Whether or not the transform and the object are exactly equal.</returns>
-        public override readonly bool Equals(object obj)
+        public override readonly bool Equals([NotNullWhen(true)] object? obj)
         {
             return obj is Transform3D other && Equals(other);
         }
@@ -680,7 +683,7 @@ namespace Godot
         /// Converts this <see cref="Transform3D"/> to a string with the given <paramref name="format"/>.
         /// </summary>
         /// <returns>A string representation of this transform.</returns>
-        public readonly string ToString(string format)
+        public readonly string ToString(string? format)
         {
             return $"[X: {Basis.X.ToString(format)}, Y: {Basis.Y.ToString(format)}, Z: {Basis.Z.ToString(format)}, O: {Origin.ToString(format)}]";
         }
diff --git a/modules/mono/glue/GodotSharp/GodotSharp/Core/Vector2.cs b/modules/mono/glue/GodotSharp/GodotSharp/Core/Vector2.cs
index 4842dbc9af..a27a1ab1cf 100644
--- a/modules/mono/glue/GodotSharp/GodotSharp/Core/Vector2.cs
+++ b/modules/mono/glue/GodotSharp/GodotSharp/Core/Vector2.cs
@@ -1,6 +1,9 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.InteropServices;
 
+#nullable enable
+
 namespace Godot
 {
     /// <summary>
@@ -954,7 +957,7 @@ namespace Godot
         /// </summary>
         /// <param name="obj">The object to compare with.</param>
         /// <returns>Whether or not the vector and the object are equal.</returns>
-        public override readonly bool Equals(object obj)
+        public override readonly bool Equals([NotNullWhen(true)] object? obj)
         {
             return obj is Vector2 other && Equals(other);
         }
@@ -1016,7 +1019,7 @@ namespace Godot
         /// Converts this <see cref="Vector2"/> to a string with the given <paramref name="format"/>.
         /// </summary>
         /// <returns>A string representation of this vector.</returns>
-        public readonly string ToString(string format)
+        public readonly string ToString(string? format)
         {
             return $"({X.ToString(format)}, {Y.ToString(format)})";
         }
diff --git a/modules/mono/glue/GodotSharp/GodotSharp/Core/Vector2I.cs b/modules/mono/glue/GodotSharp/GodotSharp/Core/Vector2I.cs
index 215bb4df8c..104e30981f 100644
--- a/modules/mono/glue/GodotSharp/GodotSharp/Core/Vector2I.cs
+++ b/modules/mono/glue/GodotSharp/GodotSharp/Core/Vector2I.cs
@@ -1,6 +1,9 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.InteropServices;
 
+#nullable enable
+
 namespace Godot
 {
     /// <summary>
@@ -535,7 +538,7 @@ namespace Godot
         /// </summary>
         /// <param name="obj">The object to compare with.</param>
         /// <returns>Whether or not the vector and the object are equal.</returns>
-        public override readonly bool Equals(object obj)
+        public override readonly bool Equals([NotNullWhen(true)] object? obj)
         {
             return obj is Vector2I other && Equals(other);
         }
@@ -572,7 +575,7 @@ namespace Godot
         /// Converts this <see cref="Vector2I"/> to a string with the given <paramref name="format"/>.
         /// </summary>
         /// <returns>A string representation of this vector.</returns>
-        public readonly string ToString(string format)
+        public readonly string ToString(string? format)
         {
             return $"({X.ToString(format)}, {Y.ToString(format)})";
         }
diff --git a/modules/mono/glue/GodotSharp/GodotSharp/Core/Vector3.cs b/modules/mono/glue/GodotSharp/GodotSharp/Core/Vector3.cs
index d26d4662a0..54d698345f 100644
--- a/modules/mono/glue/GodotSharp/GodotSharp/Core/Vector3.cs
+++ b/modules/mono/glue/GodotSharp/GodotSharp/Core/Vector3.cs
@@ -1,6 +1,9 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.InteropServices;
 
+#nullable enable
+
 namespace Godot
 {
     /// <summary>
@@ -1056,7 +1059,7 @@ namespace Godot
         /// </summary>
         /// <param name="obj">The object to compare with.</param>
         /// <returns>Whether or not the vector and the object are equal.</returns>
-        public override readonly bool Equals(object obj)
+        public override readonly bool Equals([NotNullWhen(true)] object? obj)
         {
             return obj is Vector3 other && Equals(other);
         }
@@ -1118,7 +1121,7 @@ namespace Godot
         /// Converts this <see cref="Vector3"/> to a string with the given <paramref name="format"/>.
         /// </summary>
         /// <returns>A string representation of this vector.</returns>
-        public readonly string ToString(string format)
+        public readonly string ToString(string? format)
         {
             return $"({X.ToString(format)}, {Y.ToString(format)}, {Z.ToString(format)})";
         }
diff --git a/modules/mono/glue/GodotSharp/GodotSharp/Core/Vector3I.cs b/modules/mono/glue/GodotSharp/GodotSharp/Core/Vector3I.cs
index fe74ec8884..4af9fd878b 100644
--- a/modules/mono/glue/GodotSharp/GodotSharp/Core/Vector3I.cs
+++ b/modules/mono/glue/GodotSharp/GodotSharp/Core/Vector3I.cs
@@ -1,6 +1,9 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.InteropServices;
 
+#nullable enable
+
 namespace Godot
 {
     /// <summary>
@@ -590,7 +593,7 @@ namespace Godot
         /// </summary>
         /// <param name="obj">The object to compare with.</param>
         /// <returns>Whether or not the vector and the object are equal.</returns>
-        public override readonly bool Equals(object obj)
+        public override readonly bool Equals([NotNullWhen(true)] object? obj)
         {
             return obj is Vector3I other && Equals(other);
         }
@@ -627,7 +630,7 @@ namespace Godot
         /// Converts this <see cref="Vector3I"/> to a string with the given <paramref name="format"/>.
         /// </summary>
         /// <returns>A string representation of this vector.</returns>
-        public readonly string ToString(string format)
+        public readonly string ToString(string? format)
         {
             return $"({X.ToString(format)}, {Y.ToString(format)}, {Z.ToString(format)})";
         }
diff --git a/modules/mono/glue/GodotSharp/GodotSharp/Core/Vector4.cs b/modules/mono/glue/GodotSharp/GodotSharp/Core/Vector4.cs
index eeaef5e46e..87c01ad5ea 100644
--- a/modules/mono/glue/GodotSharp/GodotSharp/Core/Vector4.cs
+++ b/modules/mono/glue/GodotSharp/GodotSharp/Core/Vector4.cs
@@ -1,6 +1,9 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.InteropServices;
 
+#nullable enable
+
 namespace Godot
 {
     /// <summary>
@@ -838,7 +841,7 @@ namespace Godot
         /// </summary>
         /// <param name="obj">The object to compare with.</param>
         /// <returns>Whether or not the vector and the object are equal.</returns>
-        public override readonly bool Equals(object obj)
+        public override readonly bool Equals([NotNullWhen(true)] object? obj)
         {
             return obj is Vector4 other && Equals(other);
         }
@@ -900,7 +903,7 @@ namespace Godot
         /// Converts this <see cref="Vector4"/> to a string with the given <paramref name="format"/>.
         /// </summary>
         /// <returns>A string representation of this vector.</returns>
-        public readonly string ToString(string format)
+        public readonly string ToString(string? format)
         {
             return $"({X.ToString(format)}, {Y.ToString(format)}, {Z.ToString(format)}, {W.ToString(format)})";
         }
diff --git a/modules/mono/glue/GodotSharp/GodotSharp/Core/Vector4I.cs b/modules/mono/glue/GodotSharp/GodotSharp/Core/Vector4I.cs
index a0a4393523..7d4d3dd353 100644
--- a/modules/mono/glue/GodotSharp/GodotSharp/Core/Vector4I.cs
+++ b/modules/mono/glue/GodotSharp/GodotSharp/Core/Vector4I.cs
@@ -1,6 +1,9 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.InteropServices;
 
+#nullable enable
+
 namespace Godot
 {
     /// <summary>
@@ -611,7 +614,7 @@ namespace Godot
         /// </summary>
         /// <param name="obj">The object to compare with.</param>
         /// <returns>Whether or not the vector and the object are equal.</returns>
-        public override readonly bool Equals(object obj)
+        public override readonly bool Equals([NotNullWhen(true)] object? obj)
         {
             return obj is Vector4I other && Equals(other);
         }
@@ -648,7 +651,7 @@ namespace Godot
         /// Converts this <see cref="Vector4I"/> to a string with the given <paramref name="format"/>.
         /// </summary>
         /// <returns>A string representation of this vector.</returns>
-        public readonly string ToString(string format)
+        public readonly string ToString(string? format)
         {
             return $"({X.ToString(format)}, {Y.ToString(format)}, {Z.ToString(format)}), {W.ToString(format)})";
         }