[vala/wip/issue/1121] vala: Don't allow assigning GtkChild fields/properties

[Rico Tzschichholz <ricotz src gnome org>]

commit 1794ac7b4e9e5b3a75305aa443902cc3d626becd
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Sat Jan 16 10:05:30 2021 +0100

    vala: Don't allow assigning GtkChild fields/properties
    
    These are handled exclusively by GtkBuilder
    
    See https://gitlab.gnome.org/GNOME/vala/issues/1121

 vala/valaassignment.vala      | 6 ++++++
 vala/valaproperty.vala        | 7 ++++++-
 vala/valaunaryexpression.vala | 5 +++++
 3 files changed, 17 insertions(+), 1 deletion(-)
---
diff --git a/vala/valaassignment.vala b/vala/valaassignment.vala
index 79090ad9b..4ffc75735 100644
--- a/vala/valaassignment.vala
+++ b/vala/valaassignment.vala
@@ -178,6 +178,12 @@ public class Vala.Assignment : Expression {
                                return false;
                        }
 
+                       if (ma.symbol_reference.get_attribute ("GtkChild") != null) {
+                               error = true;
+                               Report.error (source_reference, "Assignment of [GtkChild] `%s' is not 
allowed", ma.symbol_reference.get_full_name ());
+                               return false;
+                       }
+
                        if (ma.symbol_reference is DynamicProperty) {
                                // target_type not available for dynamic properties
                        } else {
diff --git a/vala/valaproperty.vala b/vala/valaproperty.vala
index 2fc1b4d60..163a1bb0a 100644
--- a/vala/valaproperty.vala
+++ b/vala/valaproperty.vala
@@ -492,7 +492,12 @@ public class Vala.Property : Symbol, Lockable {
                        get_accessor.check (context);
                }
                if (set_accessor != null) {
-                       set_accessor.check (context);
+                       if (get_attribute ("GtkChild") != null) {
+                               Report.warning (set_accessor.source_reference, "[GtkChild] property `%s' is 
not allowed to have `set' accessor", get_full_name ());
+                               set_accessor = null;
+                       } else {
+                               set_accessor.check (context);
+                       }
                }
 
                if (initializer != null && field == null && !is_abstract) {
diff --git a/vala/valaunaryexpression.vala b/vala/valaunaryexpression.vala
index 76c31cd7a..4bf6d4bc4 100644
--- a/vala/valaunaryexpression.vala
+++ b/vala/valaunaryexpression.vala
@@ -229,6 +229,11 @@ public class Vala.UnaryExpression : Expression {
                                Report.error (source_reference, "ref and out method arguments can only be 
used with fields, parameters, local variables, and array element access");
                                return false;
                        }
+                       if (inner.symbol_reference.get_attribute ("GtkChild") != null) {
+                               error = true;
+                               Report.error (source_reference, "Assignment of [GtkChild] `%s' is not 
allowed", inner.symbol_reference.get_full_name ());
+                               return false;
+                       }
                        break;
                default:
                        error = true;