let's just use C++17 ok

CMakeLists.txt

@@ -3,7 +3,7 @@ project(swan)
 
 find_package(SFML 2.5 COMPONENTS graphics system window REQUIRED)
 
-add_compile_options(-Wall -Wextra -Wpedantic -Wno-unused-parameter -g -fsanitize=address)
+add_compile_options(-std=c++17 -Wall -Wextra -Wpedantic -Wno-unused-parameter -g -fsanitize=address)
 add_link_options(-fsanitize=address)
 include_directories("${PROJECT_SOURCE_DIR}/libswan/include")
 

core.mod/src/entities/EntPlayer.cc

@@ -1,10 +1,5 @@
 #include "EntPlayer.h"
 
-const float EntPlayer::FORCE = 600;
-const float EntPlayer::FRICTION = 100;
-const float EntPlayer::MASS = 80;
-const Swan::Vec2 EntPlayer::SIZE = Swan::Vec2(1, 2);
-
 void EntPlayer::draw(Swan::Win &win) {
 	body_.outline(win);
 }

core.mod/src/entities/EntPlayer.h

@@ -18,8 +18,8 @@ public:
 	void update(Swan::WorldPlane &plane, float dt) override;
 
 private:
-	static const float FORCE;
-	static const float FRICTION;
-	static const float MASS;
-	static const Swan::Vec2 SIZE;
+	static constexpr float FORCE = 600;
+	static constexpr float FRICTION = 100;
+	static constexpr float MASS = 80;
+	static constexpr Swan::Vec2 SIZE = Swan::Vec2(1, 2);
 };