vala: Require lvalue access of delegate target/destroy "fields"

In addition to c054da918a40f8ef93c1a006034fb6ab4717c135

See https://gitlab.gnome.org/GNOME/vala/issues/857

4 files changed, 31 insertions, 2 deletions

diff --git a/codegen/valaccodememberaccessmodule.vala b/codegen/valaccodememberaccessmodule.vala
index 7e052b6a1..ece18564c 100644
--- a/codegen/valaccodememberaccessmodule.vala
+++ b/codegen/valaccodememberaccessmodule.vala
@@ -140,14 +140,14 @@ public abstract class Vala.CCodeMemberAccessModule : CCodeControlFlowModule {
 				Report.error (expr.source_reference, "unsupported use of target field of delegate without target");
 			}
 			CCodeExpression delegate_target_destroy_notify;
-			set_cvalue (expr, get_delegate_target_cexpression (expr.inner, out delegate_target_destroy_notify));
+			set_cvalue (expr, get_delegate_target_cexpression (expr.inner, out delegate_target_destroy_notify) ?? new CCodeConstant ("NULL"));
 		} else if (expr.symbol_reference is DelegateDestroyField) {
 			if (!((DelegateType) expr.inner.value_type).delegate_symbol.has_target) {
 				Report.error (expr.source_reference, "unsupported use of destroy field of delegate without target");
 			}
 			CCodeExpression delegate_target_destroy_notify;
 			get_delegate_target_cexpression (expr.inner, out delegate_target_destroy_notify);
-			set_cvalue (expr, delegate_target_destroy_notify);
+			set_cvalue (expr, delegate_target_destroy_notify ?? new CCodeConstant ("NULL"));
 		} else if (expr.symbol_reference is GenericDupField) {
 			set_cvalue (expr, get_dup_func_expression (expr.inner.value_type, expr.source_reference));
 		} else if (expr.symbol_reference is GenericDestroyField) {
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 7d3859832..c3fad8451 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -427,6 +427,7 @@ TESTS = \
 	delegates/lambda-outer-constant.test \
 	delegates/lambda-shared-closure.vala \
 	delegates/member-target-destroy.vala \
+	delegates/member-target-destroy-2.vala \
 	delegates/reference_transfer.vala \
 	delegates/return-array-null-terminated.vala \
 	delegates/wrapper.vala \
diff --git a/tests/delegates/member-target-destroy-2.vala b/tests/delegates/member-target-destroy-2.vala
new file mode 100644
index 000000000..62ecd263a
--- /dev/null
+++ b/tests/delegates/member-target-destroy-2.vala
@@ -0,0 +1,20 @@
+delegate void FooFunc ();
+
+void bar (string s) {
+	assert (s == "foo");
+}
+
+void foo (owned FooFunc func) {
+	assert (func.target == "foo");
+	assert (func.destroy == g_free);
+	func ();
+}
+
+void main () {
+	FooFunc func = (FooFunc) bar;
+
+	func.target = "foo".dup ();
+	func.destroy = g_free;
+
+	foo ((owned) func);
+}
diff --git a/vala/valamemberaccess.vala b/vala/valamemberaccess.vala
index 10c59d34c..e06cb1d14 100644
--- a/vala/valamemberaccess.vala
+++ b/vala/valamemberaccess.vala
@@ -1063,6 +1063,14 @@ public class Vala.MemberAccess : Expression {
 			}
 		}
 
+		if (symbol_reference is DelegateTargetField || symbol_reference is DelegateDestroyField) {
+			inner.lvalue = true;
+			if (ma != null) {
+				ma.lvalue = true;
+				ma.check_lvalue_access ();
+			}
+		}
+
 		if (symbol_reference is Method && ((Method) symbol_reference).get_attribute ("DestroysInstance") != null) {
 			unowned Class? cl = ((Method) symbol_reference).parent_symbol as Class;
 			if (cl != null && cl.is_compact && ma != null) {