Fix type checking when using generics in combination with subtypingbug615830

Fixes bug 615830.

5 files changed, 29 insertions, 13 deletions

diff --git a/tests/Makefile.am b/tests/Makefile.am
index b2caa7767..97e81c6ed 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -128,6 +128,7 @@ TESTS = \
 	delegates/bug703804.vala \
 	objects/chainup.vala \
 	objects/classes.vala \
+	objects/generics.vala \
 	objects/fields.vala \
 	objects/interfaces.vala \
 	objects/methods.vala \
@@ -171,6 +172,7 @@ TESTS = \
 	objects/bug751338.vala \
 	objects/bug767092.test \
 	objects/bug768823.test \
+	objects/bug615830.test \
 	errors/errors.vala \
 	errors/bug567181.vala \
 	errors/bug579101.vala \
diff --git a/tests/objects/bug615830.test b/tests/objects/bug615830.test
new file mode 100644
index 000000000..04742b3e1
--- /dev/null
+++ b/tests/objects/bug615830.test
@@ -0,0 +1,12 @@
+Invalid Code
+
+class Foo<T> {
+}
+
+class Bar<T> : Foo<T> {
+}
+
+int main (string[] args) {
+	Foo<int> f = new Bar<string> ();
+	return 0;
+}
diff --git a/tests/objects/generics.vala b/tests/objects/generics.vala
new file mode 100644
index 000000000..8b39db945
--- /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 02b4cf13f..2e799b3b1 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 cb1a575f5..3b43d3652 100644
--- a/vala/valasemanticanalyzer.vala
+++ b/vala/valasemanticanalyzer.vala
@@ -735,7 +735,7 @@ 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) {
+	public 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) {