[vala/0.52] vala: Require lvalue access of delegate target/destroy "fields"

[Rico Tzschichholz <ricotz src gnome org>]

commit b2c656d0520de44c0053db5238cbd00136847cc3
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Sun Jan 16 19:25:51 2022 +0100

    vala: Require lvalue access of delegate target/destroy "fields"
    
    In addition to c054da918a40f8ef93c1a006034fb6ab4717c135
    
    See https://gitlab.gnome.org/GNOME/vala/issues/857

 codegen/valaccodememberaccessmodule.vala     |  4 ++--
 tests/Makefile.am                            |  1 +
 tests/delegates/member-target-destroy-2.vala | 20 ++++++++++++++++++++
 vala/valamemberaccess.vala                   |  8 ++++++++
 4 files changed, 31 insertions(+), 2 deletions(-)
---
diff --git a/codegen/valaccodememberaccessmodule.vala b/codegen/valaccodememberaccessmodule.vala
index 455827b26..fa412ae5f 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 c3f6dc613..f68930da6 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -431,6 +431,7 @@ 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 b68676e44..5f90a8449 100644
--- a/vala/valamemberaccess.vala
+++ b/vala/valamemberaccess.vala
@@ -1093,6 +1093,14 @@ 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) {