Compare parameter types for virtual methods and their invoker methods (…

…fixes #175)

generator/src/main/java/io/github/jwharm/javagi/gir/Method.java

@@ -49,6 +49,7 @@ public VirtualMethod invokerFor() {
                 .filter(VirtualMethod.class::isInstance)
                 .map(VirtualMethod.class::cast)
                 .filter(vm -> name().equals(vm.attr("invoker")))
+                .filter(vm -> vm.equalTypeSignature(this))
                 .findAny()
                 .orElse(null);
     }

generator/src/main/java/io/github/jwharm/javagi/gir/VirtualMethod.java

@@ -39,11 +39,50 @@ public Method invoker() {
                 .filter(Method.class::isInstance)
                 .map(Method.class::cast)
                 .filter(m -> invoker.equals(m.name()))
+                .filter(this::equalTypeSignature)
                 .findAny()
                 .orElse(null);
     }
 
     public String overrideVisibility() {
         return attr("java-gi-override-visibility");
     }
+
+    /*
+     * Check if the invoker method has the same type signature as this virtual
+     * method.
+     *
+     * We deliberately don't compare the return types, because two Java methods
+     * with the same name and parameter types but different return types will
+     * not compile.
+     */
+    boolean equalTypeSignature(Method m) {
+        // Compare instance parameter type
+        if (different(parameters().instanceParameter(),
+                      m.parameters().instanceParameter()))
+            return false;
+
+        // Compare exceptions
+        if (throws_() != m.throws_())
+            return false;
+
+        List<Parameter> params1 = parameters().parameters();
+        List<Parameter> params2 = m.parameters().parameters();
+
+        // Compare number of parameters
+        if (params1.size() != params2.size())
+            return false;
+
+        // Compare parameter types
+        for (int i = 0; i < params1.size(); i++)
+            if (different(params1.get(i), params2.get(i)))
+                return false;
+
+        return true;
+    }
+
+    // Return true when these types would be different in Java
+    private boolean different(TypedValue a, TypedValue b) {
+        return !a.anyType().typeName().equals(b.anyType().typeName());
+    }
 }

generator/src/main/java/io/github/jwharm/javagi/patches/GObjectPatch.java

@@ -131,22 +131,6 @@ public GirElement patch(GirElement element, String namespace) {
             return r;
         }
 
-        /*
-         * GObject.notify() is defined as a virtual method with an invoker
-         * method, but the parameters are different. Remove the invoker
-         * attribute, so they will be treated as separate methods.
-         */
-        if (element instanceof VirtualMethod vm
-                && "notify".equals(vm.name())
-                && "Object".equals(vm.parameters()
-                                     .instanceParameter()
-                                     .type().name()))
-            return new VirtualMethod(
-                    Map.of("name", "notify"),
-                    vm.children(),
-                    vm.platforms()
-            );
-
         /*
          * Workaround for https://gitlab.gnome.org/GNOME/glib/-/issues/3524
          */

generator/src/main/java/io/github/jwharm/javagi/patches/GioPatch.java

@@ -155,7 +155,7 @@ public GirElement patch(GirElement element, String namespace) {
 
         /*
          * File.prefixMatches() is defined as a virtual method with invoker
-         * method hasPrefix(), but the parameters are different. Remove the
+         * method hasPrefix(), but the parameters are swapped. Remove the
          * invoker attribute, so they will be treated as separate methods.
          */
         if (element instanceof VirtualMethod vm