Rewrite HashMapHasherDefault based on type traits - it is now possible to declare a default hashing function for any type.

Remove cross-project includes from `hashfuncs.h`.
Improve hashing function for `Color` (based on values instead of `String`).
Move `Variant` comparison from `hash_map.h` to `dictionary.cpp` (`VariantComparatorDictionary`), where it's used.
Remove now unnecessary `HashableHasher`.

Author: Ivorforce

core/math/aabb.h

@@ -32,6 +32,7 @@
 
 #include "core/math/plane.h"
 #include "core/math/vector3.h"
+#include "core/templates/hashfuncs.h"
 
 /**
  * AABB (Axis Aligned Bounding Box)
@@ -131,6 +132,16 @@ struct [[nodiscard]] AABB {
 		return position + (size * 0.5f);
 	}
 
+	uint32_t hash() const {
+		uint32_t h = hash_murmur3_one_real(position.x);
+		h = hash_murmur3_one_real(position.y, h);
+		h = hash_murmur3_one_real(position.z, h);
+		h = hash_murmur3_one_real(size.x, h);
+		h = hash_murmur3_one_real(size.y, h);
+		h = hash_murmur3_one_real(size.z, h);
+		return hash_fmix32(h);
+	}
+
 	operator String() const;
 
 	AABB() = default;

core/math/color.h

@@ -31,6 +31,7 @@
 #pragma once
 
 #include "core/math/math_funcs.h"
+#include "core/templates/hashfuncs.h"
 
 class String;
 
@@ -237,6 +238,14 @@ struct [[nodiscard]] Color {
 	_FORCE_INLINE_ void set_ok_hsl_s(float p_s) { set_ok_hsl(get_ok_hsl_h(), p_s, get_ok_hsl_l(), a); }
 	_FORCE_INLINE_ void set_ok_hsl_l(float p_l) { set_ok_hsl(get_ok_hsl_h(), get_ok_hsl_s(), p_l, a); }
 
+	uint32_t hash() const {
+		uint32_t h = hash_murmur3_one_float(r);
+		h = hash_murmur3_one_float(r, h);
+		h = hash_murmur3_one_float(b, h);
+		h = hash_murmur3_one_float(a, h);
+		return hash_fmix32(h);
+	}
+
 	constexpr Color() :
 			r(0), g(0), b(0), a(1) {}
 

core/math/delaunay_3d.h

@@ -33,6 +33,7 @@
 #include "core/math/aabb.h"
 #include "core/math/projection.h"
 #include "core/math/vector3.h"
+#include "core/math/vector3i.h"
 #include "core/templates/list.h"
 #include "core/templates/local_vector.h"
 #include "core/templates/oa_hash_map.h"

core/math/geometry_3d.h

@@ -30,8 +30,10 @@
 
 #pragma once
 
+#include "core/math/color.h"
 #include "core/math/delaunay_3d.h"
 #include "core/math/face3.h"
+#include "core/math/vector2.h"
 #include "core/templates/local_vector.h"
 #include "core/templates/vector.h"
 

core/math/rect2.h

@@ -32,6 +32,7 @@
 
 #include "core/error/error_macros.h"
 #include "core/math/vector2.h"
+#include "core/templates/hashfuncs.h"
 
 class String;
 struct Rect2i;
@@ -361,6 +362,14 @@ struct [[nodiscard]] Rect2 {
 	operator String() const;
 	operator Rect2i() const;
 
+	uint32_t hash() const {
+		uint32_t h = hash_murmur3_one_real(position.x);
+		h = hash_murmur3_one_real(position.y, h);
+		h = hash_murmur3_one_real(size.x, h);
+		h = hash_murmur3_one_real(size.y, h);
+		return hash_fmix32(h);
+	}
+
 	Rect2() = default;
 	constexpr Rect2(real_t p_x, real_t p_y, real_t p_width, real_t p_height) :
 			position(Point2(p_x, p_y)),

core/math/rect2i.h

@@ -32,6 +32,7 @@
 
 #include "core/error/error_macros.h"
 #include "core/math/vector2i.h"
+#include "core/templates/hashfuncs.h"
 
 class String;
 struct Rect2;
@@ -226,6 +227,14 @@ struct [[nodiscard]] Rect2i {
 	operator String() const;
 	operator Rect2() const;
 
+	uint32_t hash() const {
+		uint32_t h = hash_murmur3_one_32(uint32_t(position.x));
+		h = hash_murmur3_one_32(uint32_t(position.y), h);
+		h = hash_murmur3_one_32(uint32_t(size.x), h);
+		h = hash_murmur3_one_32(uint32_t(size.y), h);
+		return hash_fmix32(h);
+	}
+
 	Rect2i() = default;
 	constexpr Rect2i(int p_x, int p_y, int p_width, int p_height) :
 			position(Point2i(p_x, p_y)),

core/math/vector2.h

@@ -32,6 +32,7 @@
 
 #include "core/error/error_macros.h"
 #include "core/math/math_funcs.h"
+#include "core/templates/hashfuncs.h"
 
 class String;
 struct Vector2i;
@@ -185,6 +186,12 @@ struct [[nodiscard]] Vector2 {
 	operator String() const;
 	operator Vector2i() const;
 
+	uint32_t hash() const {
+		uint32_t h = hash_murmur3_one_real(x);
+		h = hash_murmur3_one_real(y, h);
+		return hash_fmix32(h);
+	}
+
 	// NOLINTBEGIN(cppcoreguidelines-pro-type-member-init)
 	constexpr Vector2() :
 			x(0), y(0) {}

core/math/vector2i.h

@@ -32,6 +32,7 @@
 
 #include "core/error/error_macros.h"
 #include "core/math/math_funcs.h"
+#include "core/templates/hashfuncs.h"
 
 class String;
 struct Vector2;
@@ -142,6 +143,12 @@ struct [[nodiscard]] Vector2i {
 	operator String() const;
 	operator Vector2() const;
 
+	uint32_t hash() const {
+		uint32_t h = hash_murmur3_one_32(uint32_t(x));
+		h = hash_murmur3_one_32(uint32_t(y), h);
+		return hash_fmix32(h);
+	}
+
 	// NOLINTBEGIN(cppcoreguidelines-pro-type-member-init)
 	constexpr Vector2i() :
 			x(0), y(0) {}

core/math/vector3.h

@@ -189,6 +189,13 @@ struct [[nodiscard]] Vector3 {
 	operator String() const;
 	operator Vector3i() const;
 
+	uint32_t hash() const {
+		uint32_t h = hash_murmur3_one_real(x);
+		h = hash_murmur3_one_real(y, h);
+		h = hash_murmur3_one_real(z, h);
+		return hash_fmix32(h);
+	}
+
 	constexpr Vector3() :
 			x(0), y(0), z(0) {}
 	constexpr Vector3(real_t p_x, real_t p_y, real_t p_z) :

core/math/vector3i.h

@@ -32,6 +32,7 @@
 
 #include "core/error/error_macros.h"
 #include "core/math/math_funcs.h"
+#include "core/templates/hashfuncs.h"
 
 class String;
 struct Vector3;
@@ -133,6 +134,13 @@ struct [[nodiscard]] Vector3i {
 	operator String() const;
 	operator Vector3() const;
 
+	uint32_t hash() const {
+		uint32_t h = hash_murmur3_one_32(uint32_t(x));
+		h = hash_murmur3_one_32(uint32_t(y), h);
+		h = hash_murmur3_one_32(uint32_t(z), h);
+		return hash_fmix32(h);
+	}
+
 	constexpr Vector3i() :
 			x(0), y(0), z(0) {}
 	constexpr Vector3i(int32_t p_x, int32_t p_y, int32_t p_z) :