[vala] Fix regression when coalescing: value owned if either of the two is owned

[Luca Bruno <lucabru src gnome org>]

commit 517d25a5daf7016b6af85173af184eb7e6b5e9c4
Author: Luca Bruno <lucabru src gnome org>
Date:   Sun Jan 26 18:06:43 2014 +0100

    Fix regression when coalescing: value owned if either of the two is owned

 tests/control-flow/bug639482.vala |   10 ++++++++++
 vala/valabinaryexpression.vala    |   20 ++++++++++++++++++--
 2 files changed, 28 insertions(+), 2 deletions(-)
---
diff --git a/tests/control-flow/bug639482.vala b/tests/control-flow/bug639482.vala
index 27a8e20..4a0a550 100644
--- a/tests/control-flow/bug639482.vala
+++ b/tests/control-flow/bug639482.vala
@@ -1,4 +1,14 @@
+public string test() throws Error {
+       return "foo";
+}
+
 void main () {
        string empty = null;
        assert ((false ? "A" : (empty ?? "B")) == "B");
+
+       string foo = "bar" ?? test ();
+       assert (foo == "bar");
+
+       foo = empty ?? test ();
+       assert (foo == "foo");
 }
diff --git a/vala/valabinaryexpression.vala b/vala/valabinaryexpression.vala
index 9c1ef4c..bdd9e5e 100644
--- a/vala/valabinaryexpression.vala
+++ b/vala/valabinaryexpression.vala
@@ -198,8 +198,24 @@ public class Vala.BinaryExpression : Expression {
                                error = true;
                                return false;
                        }
-                       
-                       var local = new LocalVariable (left.value_type != null ? left.value_type.copy () : 
null, get_temp_name (), left, source_reference);
+
+                       if (!right.check (context)) {
+                               error = true;
+                               return false;
+                       }
+
+                       DataType local_type = null;
+                       if (left.value_type != null) {
+                               local_type = left.value_type.copy ();
+                               if (right.value_type != null && right.value_type.value_owned) {
+                                       // value owned if either left or right is owned
+                                       local_type.value_owned = true;
+                               }
+                       } else if (right.value_type != null) {
+                               local_type = right.value_type.copy ();
+                       }
+               
+                       var local = new LocalVariable (local_type, get_temp_name (), left, source_reference);
                        var decl = new DeclarationStatement (local, source_reference);
 
                        var right_stmt = new ExpressionStatement (new Assignment (new MemberAccess.simple 
(local.name, right.source_reference), right, AssignmentOperator.SIMPLE, right.source_reference), 
right.source_reference);