[vala] GValue: Fix cast from nullable GLib.Value

[Jürg Billeter <juergbi src gnome org>]

commit 0c0ec3b013e5f266425c65b5a0743bb1bb655e63
Author: Marc-André Lureau <marcandre lureau gmail com>
Date:   Fri Oct 30 00:39:05 2009 +0100

    GValue: Fix cast from nullable GLib.Value
    
    Fixes bug 585050.

 codegen/valaccodebasemodule.vala |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)
---
diff --git a/codegen/valaccodebasemodule.vala b/codegen/valaccodebasemodule.vala
index 7a1b455..2266fb6 100644
--- a/codegen/valaccodebasemodule.vala
+++ b/codegen/valaccodebasemodule.vala
@@ -4005,7 +4005,15 @@ internal class Vala.CCodeBaseModule : CCodeModule {
 		    && expr.type_reference.get_type_id () != null) {
 			// explicit conversion from GValue
 			var ccall = new CCodeFunctionCall (get_value_getter_function (expr.type_reference));
-			ccall.add_argument (new CCodeUnaryExpression (CCodeUnaryOperator.ADDRESS_OF, (CCodeExpression) expr.inner.ccodenode));
+			CCodeExpression gvalue;
+			if (expr.inner.value_type.nullable) {
+				// cast from Value?, no need to get address
+				gvalue = (CCodeExpression) expr.inner.ccodenode;
+			} else {
+				// value getter function expects pointer to GValue, get address of non-null Value
+				gvalue = new CCodeUnaryExpression (CCodeUnaryOperator.ADDRESS_OF, (CCodeExpression) expr.inner.ccodenode);
+			}
+			ccall.add_argument (gvalue);
 			expr.ccodenode = ccall;
 			if (expr.type_reference is ArrayType) {
 				// null-terminated string array