codegen: Use properly checked implicit interface implementations

Collect implicit interface implementations in AST and avoid doing the same
checks twice.

This caused double vfunc assignments if an implementation is provided while
a method with the same name is available in prerequisite class.

See https://bugzilla.gnome.org/show_bug.cgi?id=536863
and https://bugzilla.gnome.org/show_bug.cgi?id=652098

Fixes https://gitlab.gnome.org/GNOME/vala/issues/548

5 files changed, 83 insertions, 24 deletions

diff --git a/codegen/valagtypemodule.vala b/codegen/valagtypemodule.vala
index bb971c1c4..3dd0f2c48 100644
--- a/codegen/valagtypemodule.vala
+++ b/codegen/valagtypemodule.vala
@@ -1472,32 +1472,18 @@ public class Vala.GTypeModule : GErrorModule {
 		}
 
 		// connect inherited implementations
-		foreach (Method m in iface.get_methods ()) {
-			if (m.is_abstract) {
-				Method cl_method = null;
-				var base_class = cl;
-				while (base_class != null && cl_method == null) {
-					cl_method = base_class.scope.lookup (m.name) as Method;
-					base_class = base_class.base_class;
-				}
-				if (base_class != null && cl_method.parent_symbol != cl) {
-					// method inherited from base class
-
-					var base_method = cl_method;
-					if (cl_method.base_interface_method != null) {
-						base_method = cl_method.base_interface_method;
-					} else if (cl_method.base_method != null) {
-						//FIXME should this ever be possible here?
-						base_method = cl_method.base_method;
-					}
+		var it = cl.get_implicit_implementations ().map_iterator ();
+		while (it.next ()) {
+			Method m = it.get_key ();
+			if (m.parent_symbol == iface) {
+				Method base_method = it.get_value ();
 
-					generate_method_declaration (base_method, cfile);
+				generate_method_declaration (base_method, cfile);
 
-					CCodeExpression cfunc = new CCodeIdentifier (get_ccode_name (base_method));
-					cfunc = cast_method_pointer (base_method, cfunc, iface);
-					var ciface = new CCodeIdentifier ("iface");
-					ccode.add_assignment (new CCodeMemberAccess.pointer (ciface, get_ccode_vfunc_name (m)), cfunc);
-				}
+				CCodeExpression cfunc = new CCodeIdentifier (get_ccode_name (base_method));
+				cfunc = cast_method_pointer (m, cfunc, iface);
+				var ciface = new CCodeIdentifier ("iface");
+				ccode.add_assignment (new CCodeMemberAccess.pointer (ciface, get_ccode_vfunc_name (m)), cfunc);
 			}
 		}
 
diff --git a/tests/Makefile.am b/tests/Makefile.am
index f62e5f2c3..a62998b1b 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -254,6 +254,8 @@ TESTS = \
 	objects/chainup.vala \
 	objects/class_only.vala \
 	objects/classes.vala \
+	objects/classes-interfaces.vala \
+	objects/classes-implicit-implementation.vala \
 	objects/compact-class.vala \
 	objects/compact-class-destructor.vala \
 	objects/constructor-variadic.test \
diff --git a/tests/objects/classes-implicit-implementation.vala b/tests/objects/classes-implicit-implementation.vala
new file mode 100644
index 000000000..3931b34bc
--- /dev/null
+++ b/tests/objects/classes-implicit-implementation.vala
@@ -0,0 +1,36 @@
+interface IFoo : Object {
+	public abstract int foo ();
+}
+
+interface IBar : Object {
+}
+
+class Bar : Object {
+	public int foo () {
+		assert_not_reached ();
+		return -1;
+	}
+}
+
+class Baz : Object {
+	public int foo () {
+		return 23;
+	}
+}
+
+class Foo : Bar, IFoo {
+	public int foo () {
+		return 42;
+	}
+}
+
+class Faz : Baz, IFoo, IBar {
+}
+
+void main () {
+	var foo = new Foo ();
+	assert (foo.foo () == 42);
+
+	var baz = new Baz ();
+	assert (baz.foo () == 23);
+}
diff --git a/tests/objects/classes-interfaces.vala b/tests/objects/classes-interfaces.vala
new file mode 100644
index 000000000..9f2474653
--- /dev/null
+++ b/tests/objects/classes-interfaces.vala
@@ -0,0 +1,27 @@
+class Base : Object {
+	public void foo () {
+	}
+}
+
+interface IFoo : Base {
+	public abstract string foo ();
+}
+
+interface IBar : Base {
+	public abstract int foo ();
+}
+
+class Manam : Base, IFoo, IBar {
+	public int IBar.foo () {
+		return 23;
+	}
+	public string IFoo.foo () {
+		return "foo";
+	}
+}
+
+void main () {
+	var manam = new Manam ();
+	assert (((IFoo) manam).foo () == "foo");
+	assert (((IBar) manam).foo () == 23);
+}
diff --git a/vala/valaclass.vala b/vala/valaclass.vala
index 81bc6ba91..419e72d93 100644
--- a/vala/valaclass.vala
+++ b/vala/valaclass.vala
@@ -110,6 +110,7 @@ public class Vala.Class : ObjectTypeSymbol {
 	private bool? _is_singleton;
 
 	private List<DataType> base_types = new ArrayList<DataType> ();
+	private HashMap<Method,Method> implicit_implementations = new HashMap<Method,Method> ();
 
 	/**
 	 * Specifies the default construction method.
@@ -305,6 +306,10 @@ public class Vala.Class : ObjectTypeSymbol {
 		}
 	}
 
+	public HashMap<Method,Method> get_implicit_implementations () {
+		return implicit_implementations;
+	}
+
 	/**
 	 * Adds the specified property as a member to this class.
 	 *
@@ -748,6 +753,9 @@ public class Vala.Class : ObjectTypeSymbol {
 										impl.version.check (source_reference);
 										impl.used = true;
 										implemented = true;
+										if (impl.base_interface_method == null) {
+											implicit_implementations.set (m, impl);
+										}
 										break;
 									}
 								}