[vala/wip/issue/1121: 1/2] vala: GtkChild fields/properties must be declared as unowned

[Rico Tzschichholz <ricotz src gnome org>]

commit f78932e3dbcdba5660800b816e7dc8752771f0d5
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Sat Jan 16 10:05:30 2021 +0100

    vala: GtkChild fields/properties must be declared as unowned
    
    The backing field won't be assigned to hold a dedicated reference.
    gtk_widget_class_bind_template_child_full will make it point to the
    instance owned by GtkBuilder.
    
    This avoids doing a rogue (but safe) call of _g_object_unref0 on already
    disposed child.
    
    Fixes https://gitlab.gnome.org/GNOME/vala/issues/1121

 vala/valafield.vala    | 5 +++++
 vala/valaproperty.vala | 9 +++++++++
 2 files changed, 14 insertions(+)
---
diff --git a/vala/valafield.vala b/vala/valafield.vala
index bee686222..731249e71 100644
--- a/vala/valafield.vala
+++ b/vala/valafield.vala
@@ -104,6 +104,11 @@ public class Vala.Field : Variable, Lockable {
                        return false;
                }
 
+               if (get_attribute ("GtkChild") != null && variable_type.value_owned) {
+                       Report.warning (source_reference, "[GtkChild] fields must be declared as `unowned'");
+                       variable_type.value_owned = false;
+               }
+
                variable_type.check (context);
                if (!external_package) {
                        context.analyzer.check_type (variable_type);
diff --git a/vala/valaproperty.vala b/vala/valaproperty.vala
index 2c73fcbc4..2fc1b4d60 100644
--- a/vala/valaproperty.vala
+++ b/vala/valaproperty.vala
@@ -116,6 +116,11 @@ public class Vala.Property : Symbol, Lockable {
                                                Report.error (source_reference, "Property setter must have a 
body");
                                        }
                                        if (!get_has_body && !set_has_body) {
+                                               if (get_attribute ("GtkChild") != null && 
property_type.value_owned) {
+                                                       Report.warning (source_reference, "[GtkChild] 
properties must be declared as `unowned'");
+                                                       property_type.value_owned = false;
+                                               }
+
                                                /* automatic property accessor body generation */
                                                _field = new Field ("_%s".printf (name), property_type.copy 
(), initializer, source_reference);
                                                _field.access = SymbolAccessibility.PRIVATE;
@@ -468,6 +473,10 @@ public class Vala.Property : Symbol, Lockable {
                        return false;
                }
 
+               if (field != null) {
+                       field.check (context);
+               }
+
                property_type.check (context);
                if (!external_package) {
                        context.analyzer.check_type (property_type);