[vala/0.50] codegen: Don't leak memory of already assigned out-parameter on error

[Rico Tzschichholz <ricotz src gnome org>]

commit b293575308ff106407a7c0bd87acb4469badc028
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Thu Dec 31 09:55:16 2020 +0100

    codegen: Don't leak memory of already assigned out-parameter on error
    
    Fixes https://gitlab.gnome.org/GNOME/vala/issues/1123

 codegen/valaccodebasemodule.vala                   | 11 ++++++
 codegen/valagasyncmodule.vala                      |  4 +++
 codegen/valagerrormodule.vala                      |  6 ++++
 tests/Makefile.am                                  |  2 ++
 .../asynchronous/out-parameter-free-on-error.vala  | 31 +++++++++++++++++
 tests/methods/parameter-out-free-on-error.vala     | 39 ++++++++++++++++++++++
 6 files changed, 93 insertions(+)
---
diff --git a/codegen/valaccodebasemodule.vala b/codegen/valaccodebasemodule.vala
index 699ad7ae8..68c31946c 100644
--- a/codegen/valaccodebasemodule.vala
+++ b/codegen/valaccodebasemodule.vala
@@ -3966,6 +3966,17 @@ public abstract class Vala.CCodeBaseModule : CodeGenerator {
                }
        }
 
+       public void append_out_param_free (Method? m) {
+               if (m == null) {
+                       return;
+               }
+               foreach (Parameter param in m.get_parameters ()) {
+                       if (param.direction == ParameterDirection.OUT && param.variable_type.is_disposable 
()) {
+                               ccode.add_expression (destroy_parameter (param));
+                       }
+               }
+       }
+
        public bool variable_accessible_in_finally (LocalVariable local) {
                if (current_try == null) {
                        return false;
diff --git a/codegen/valagasyncmodule.vala b/codegen/valagasyncmodule.vala
index f39f86c6e..c9946599f 100644
--- a/codegen/valagasyncmodule.vala
+++ b/codegen/valagasyncmodule.vala
@@ -743,8 +743,12 @@ public class Vala.GAsyncModule : GtkModule {
                set_error.add_argument (error_expr);
                ccode.add_expression (set_error);
 
+               // free local variables
                append_local_free (current_symbol);
 
+               // free possibly already assigned out-parameter
+               append_out_param_free (current_method);
+
                // We already returned the error above, we must not return anything else here.
                var unref = new CCodeFunctionCall (new CCodeIdentifier ("g_object_unref"));
                unref.add_argument (async_result_expr);
diff --git a/codegen/valagerrormodule.vala b/codegen/valagerrormodule.vala
index fedc424ae..d724c3c3a 100644
--- a/codegen/valagerrormodule.vala
+++ b/codegen/valagerrormodule.vala
@@ -104,6 +104,9 @@ public class Vala.GErrorModule : CCodeDelegateModule {
                // free local variables
                append_local_free (current_symbol);
 
+               // free possibly already assigned out-parameter
+               append_out_param_free (current_method);
+
                if (current_method is CreationMethod && current_method.parent_symbol is Class) {
                        var cl = (Class) current_method.parent_symbol;
                        ccode.add_expression (destroy_value (new GLibValue (new ObjectType (cl), new 
CCodeIdentifier ("self"), true)));
@@ -123,6 +126,9 @@ public class Vala.GErrorModule : CCodeDelegateModule {
                        append_local_free (current_symbol);
                }
 
+               // free possibly already assigned out-parameter
+               append_out_param_free (current_method);
+
                cfile.add_include ("glib.h");
 
                var ccritical = new CCodeFunctionCall (new CCodeIdentifier ("g_critical"));
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 6abc62ddf..ba21f788a 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -161,6 +161,7 @@ TESTS = \
        methods/extern.vala \
        methods/iterator.vala \
        methods/parameter-fixed-array-initializer.vala \
+       methods/parameter-out-free-on-error.vala \
        methods/parameter-ref-array-resize.vala \
        methods/parameter-ref-array-resize-captured.vala \
        methods/parameter-ref-delegate.vala \
@@ -628,6 +629,7 @@ TESTS = \
        asynchronous/constructor-argument-check.vala \
        asynchronous/finish-name.vala \
        asynchronous/generator.vala \
+       asynchronous/out-parameter-free-on-error.vala \
        asynchronous/out-parameter-invalid.test \
        asynchronous/params-array-invalid.test \
        asynchronous/result-pos.vala \
diff --git a/tests/asynchronous/out-parameter-free-on-error.vala 
b/tests/asynchronous/out-parameter-free-on-error.vala
new file mode 100644
index 000000000..a81d3df55
--- /dev/null
+++ b/tests/asynchronous/out-parameter-free-on-error.vala
@@ -0,0 +1,31 @@
+errordomain FooError {
+       FAIL
+}
+
+class Manam : Object {
+}
+
+async void foo_async (Manam i, out Manam o) throws FooError {
+       o = i;
+       throw new FooError.FAIL ("foo");
+}
+
+async void run () {
+       var manam = new Manam ();
+       assert (manam.ref_count == 1);
+       try {
+               Manam minim;
+               yield foo_async (manam, out minim);
+       } catch {
+       }
+       assert (manam.ref_count == 2);
+       loop.quit ();
+}
+
+MainLoop loop;
+
+void main () {
+       loop = new MainLoop ();
+       run.begin ();
+       loop.run ();
+}
diff --git a/tests/methods/parameter-out-free-on-error.vala b/tests/methods/parameter-out-free-on-error.vala
new file mode 100644
index 000000000..ee9716b87
--- /dev/null
+++ b/tests/methods/parameter-out-free-on-error.vala
@@ -0,0 +1,39 @@
+errordomain FooError {
+       FAIL
+}
+
+class Manam : Object {
+}
+
+void foo (Manam i, out Manam o) throws FooError {
+       o = i;
+       throw new FooError.FAIL ("foo");
+}
+
+void bar (Manam i, out unowned Manam o) throws FooError {
+       o = i;
+       throw new FooError.FAIL ("bar");
+}
+
+void main () {
+       {
+               var manam = new Manam ();
+               assert (manam.ref_count == 1);
+               try {
+                       Manam minim;
+                       foo (manam, out minim);
+               } catch (FooError e) {
+               }
+               assert (manam.ref_count == 1);
+       }
+       {
+               var manam = new Manam ();
+               assert (manam.ref_count == 1);
+               try {
+                       unowned Manam minim;
+                       bar (manam, out minim);
+               } catch (FooError e) {
+               }
+               assert (manam.ref_count == 1);
+       }
+}