From e9c5f4ab09b9ca66241e863b7d333ecc6bb4c38c Mon Sep 17 00:00:00 2001
From: Rico Tzschichholz <ricotz@ubuntu.com>
Date: Sun, 5 Apr 2020 14:45:34 +0200
Subject: [PATCH] vala: Warn about usage of override to implement abstract
 interface methods

Fixes criticals in GAsyncModule.visit_method()

    vala_symbol_get_parent_symbol: assertion 'self != NULL' failed

which were introduced with 12db9b7eeb1f53975010d89839d554b5fcf99831
---
 tests/Makefile.am                             |  1 +
 .../interface-abstract-async-override.vala    | 23 +++++++++++++++++++
 vala/valamethod.vala                          |  3 +++
 3 files changed, 27 insertions(+)
 create mode 100644 tests/objects/interface-abstract-async-override.vala

diff --git a/tests/Makefile.am b/tests/Makefile.am
index f87bcf2ba..cca6a2927 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -376,6 +376,7 @@ TESTS = \
 	objects/interface-base-access.vala \
 	objects/interface-inner-types.vala \
 	objects/interfaces.vala \
+	objects/interface-abstract-async-override.vala \
 	objects/interface-generics.vala \
 	objects/interface-property-base-access.vala \
 	objects/interface-property-base-impl.vala \
diff --git a/tests/objects/interface-abstract-async-override.vala b/tests/objects/interface-abstract-async-override.vala
new file mode 100644
index 000000000..2af7f4b86
--- /dev/null
+++ b/tests/objects/interface-abstract-async-override.vala
@@ -0,0 +1,23 @@
+interface IFoo : Object {
+	public abstract async int foo ();
+}
+
+class Bar : Object, IFoo {
+	public override async int foo () {
+		return 42;
+	}
+}
+
+MainLoop loop;
+
+void main () {
+	loop = new MainLoop ();
+
+	IFoo bar = new Bar ();
+	bar.foo.begin ((o,r) => {
+		assert (((IFoo) o).foo.end (r) == 42);
+		loop.quit ();
+	});
+	loop.run ();
+}
+
diff --git a/vala/valamethod.vala b/vala/valamethod.vala
index 817888309..35e0cc810 100644
--- a/vala/valamethod.vala
+++ b/vala/valamethod.vala
@@ -929,6 +929,9 @@ public class Vala.Method : Subroutine, Callable {
 				Report.error (source_reference, "A struct member `%s' cannot be marked as override, virtual, or abstract".printf (get_full_name ()));
 				return false;
 			}
+		} else if (overrides && base_method == null && base_interface_method != null && base_interface_method.is_abstract) {
+			Report.warning (source_reference, "`override' not required to implement `abstract' interface method `%s'".printf (base_interface_method.get_full_name ()));
+			overrides = false;
 		} else if (overrides && base_method == null && base_interface_method == null) {
 			Report.error (source_reference, "`%s': no suitable method found to override".printf (get_full_name ()));
 		} else if ((is_abstract || is_virtual || overrides) && access == SymbolAccessibility.PRIVATE) {
-- 
2.47.2