Two possible ways to fix drawable to avoid the const problem, but not quite right.

meson.build

@@ -54,6 +54,10 @@ executable('sfml-original', 'sfml-const/original.cpp',
   override_options: exe_defaults,
   dependencies: dependencies)
 
-executable('sfml-fixed1', 'sfml-const/fixed.cpp',
+executable('sfml-fix1', 'sfml-const/fix1.cpp',
+  override_options: exe_defaults,
+  dependencies: dependencies)
+
+executable('sfml-fix2', 'sfml-const/fix2.cpp',
   override_options: exe_defaults,
   dependencies: dependencies)

sfml-const/fix1.cpp

@@ -1,9 +1,9 @@
 #include <iostream>
-#include "constness.hpp"
+#include "fix1.hpp"
 
 using std::cout;
 
-void Shape::draw(RenderTarget& target) const {
+void Shape::draw(RenderTarget& target) {
   cout << "shape draw\n";
 }
 

sfml-const/fix1.hpp

@@ -12,5 +12,5 @@ class Drawable {
 
 class Shape : public Drawable {
   public:
-  void draw(RenderTarget& target) const override;
+  void draw(RenderTarget& target) override;
 };

sfml-const/fix2.cpp

@@ -0,0 +1,26 @@
+#include <iostream>
+#include "fix2.hpp"
+
+using std::cout;
+
+void RenderTarget::draw(const Drawable& drawable) {
+  drawable.draw(*this);
+}
+
+void Shape::draw(RenderTarget& target) const {
+  cout << "shape draw\n";
+}
+
+void Shape::render_to(RenderTarget &target) {
+  cout << "shape render_to instead\n";
+}
+
+int main() {
+  RenderTarget target;
+  Shape shape;
+
+  target.draw(shape);
+
+  shape.render_to(target);
+  return 0;
+}

sfml-const/fix2.hpp

@@ -0,0 +1,27 @@
+#pragma once
+
+class Drawable;
+
+class RenderTarget {
+  public:
+    void draw(const Drawable& drawable);
+};
+
+class Drawable {
+  public:
+    /*
+     * NOTE: This requires const because RenderTarget
+     * pass itself in as a *this which is always const.
+     * If you need to draw without const then invert it
+     * then use shape.render_to(target) instead.
+     */
+    virtual void draw(RenderTarget& target) const = 0;
+
+    virtual void render_to(RenderTarget& target) = 0;
+};
+
+class Shape : public Drawable {
+  public:
+  void draw(RenderTarget& target) const override;
+  void render_to(RenderTarget &target) override;
+};

sfml-const/original.cpp

@@ -1,5 +1,5 @@
 #include <iostream>
-#include "constness.hpp"
+#include "original.hpp"
 
 using std::cout;