Fix type checking when using generics in combination with subtyping

https://bugzilla.gnome.org/show_bug.cgi?id=615830

6 files changed, 47 insertions, 17 deletions

diff --git a/tests/Makefile.am b/tests/Makefile.am
index 4e684a7..0fd49d9 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -130,6 +130,7 @@ TESTS = \
 	delegates/bug703804.vala \
 	objects/chainup.vala \
 	objects/classes.vala \
+	objects/generics.vala \
 	objects/fields.vala \
 	objects/interfaces.vala \
 	objects/methods.vala \
@@ -173,6 +174,8 @@ TESTS = \
 	objects/bug751338.vala \
 	objects/bug767092.test \
 	objects/bug768823.test \
+	objects/bug615830-1.test \
+	objects/bug615830-2.test \
 	errors/errors.vala \
 	errors/bug567181.vala \
 	errors/bug579101.vala \
diff --git a/tests/objects/bug615830-1.test b/tests/objects/bug615830-1.test
new file mode 100644
index 0000000..0283ce4
--- /dev/null
+++ b/tests/objects/bug615830-1.test
@@ -0,0 +1,11 @@
+Invalid Code
+
+class Foo<T> {
+}
+
+class Bar<T> : Foo<T> {
+}
+
+void main (string[] args) {
+	Foo<int> f = new Bar<string> ();
+}
diff --git a/tests/objects/bug615830-2.test b/tests/objects/bug615830-2.test
new file mode 100644
index 0000000..88b2493
--- /dev/null
+++ b/tests/objects/bug615830-2.test
@@ -0,0 +1,12 @@
+Invalid Code
+
+struct Foo<T> {
+	int x;
+}
+
+struct Bar<T> : Foo<T> {
+}
+
+void main (string[] args) {
+	Foo<int> f = Bar<string> ();
+}
diff --git a/tests/objects/generics.vala b/tests/objects/generics.vala
new file mode 100644
index 0000000..8b39db9
--- /dev/null
+++ b/tests/objects/generics.vala
@@ -0,0 +1,7 @@
+void main() {
+	// Support generic types without type arguments for non-generic
+	// functions that are agnostic with regard to the actual type arguments.
+
+	GLib.HashTable<int, string> h = (GLib.HashTable) null;
+	(void) h;
+}
diff --git a/vala/valadatatype.vala b/vala/valadatatype.vala
index 2277224..5fe8c7b 100644
--- a/vala/valadatatype.vala
+++ b/vala/valadatatype.vala
@@ -303,20 +303,19 @@ public abstract class Vala.DataType : CodeNode {
 			return true;
 		}
 
-		if (data_type == target_type.data_type) {
+		if (data_type != null && target_type.data_type != null && data_type.is_subtype_of (target_type.data_type)) {
+			var base_type = SemanticAnalyzer.get_instance_base_type_for_member(this, target_type.data_type, this);
 			// check compatibility of generic type arguments
-			if (type_argument_list != null
-			    && type_argument_list.size > 0
-			    && type_argument_list.size == target_type.get_type_arguments ().size) {
-				for (int i = 0; i < type_argument_list.size; i++) {
-					var type_arg = type_argument_list[i];
-					var target_type_arg = target_type.get_type_arguments ()[i];
+			var base_type_args = base_type.get_type_arguments();
+			var target_type_args = target_type.get_type_arguments();
+			if (base_type_args.size == target_type_args.size) {
+				for (int i = 0; i < base_type_args.size; i++) {
 					// mutable generic types require type argument equality,
 					// not just one way compatibility
 					// as we do not currently have immutable generic container types,
 					// the additional check would be very inconvenient, so we
 					// skip the additional check for now
-					if (!type_arg.compatible (target_type_arg)) {
+					if (!base_type_args[i].compatible (target_type_args[i])) {
 						return false;
 					}
 				}
@@ -341,10 +340,6 @@ public abstract class Vala.DataType : CodeNode {
 			}
 		}
 
-		if (data_type != null && target_type.data_type != null && data_type.is_subtype_of (target_type.data_type)) {
-			return true;
-		}
-
 		return false;
 	}
 
diff --git a/vala/valasemanticanalyzer.vala b/vala/valasemanticanalyzer.vala
index 5a83c9b..ef023e1 100644
--- a/vala/valasemanticanalyzer.vala
+++ b/vala/valasemanticanalyzer.vala
@@ -721,11 +721,13 @@ public class Vala.SemanticAnalyzer : CodeVisitor {
 
 	private static DataType? get_instance_base_type (DataType instance_type, DataType base_type, CodeNode node_reference) {
 		// construct a new type reference for the base type with correctly linked type arguments
-		ReferenceType instance_base_type;
-		if (base_type.data_type is Class) {
-			instance_base_type = new ObjectType ((Class) base_type.data_type);
+		DataType instance_base_type;
+		if (base_type.data_type is ObjectTypeSymbol) {
+			instance_base_type = new ObjectType ((ObjectTypeSymbol) base_type.data_type);
+		} else if (base_type.data_type is Struct) {
+			instance_base_type = new StructValueType ((Struct) base_type.data_type);
 		} else {
-			instance_base_type = new ObjectType ((Interface) base_type.data_type);
+			assert_not_reached ();
 		}
 		foreach (DataType type_arg in base_type.get_type_arguments ()) {
 			// resolve type argument specified in base type (possibly recursively for nested generic types)
@@ -735,7 +737,7 @@ public class Vala.SemanticAnalyzer : CodeVisitor {
 		return instance_base_type;
 	}
 
-	static DataType? get_instance_base_type_for_member (DataType derived_instance_type, TypeSymbol type_symbol, CodeNode node_reference) {
+	internal static DataType? get_instance_base_type_for_member (DataType derived_instance_type, TypeSymbol type_symbol, CodeNode node_reference) {
 		DataType instance_type = derived_instance_type;
 
 		while (instance_type is PointerType) {