failing test for unary minus

idea/src/org/jetbrains/jet/codegen/ExpressionCodegen.java

@@ -581,6 +581,23 @@ public class ExpressionCodegen extends JetVisitor {
         }
     }
 
+    @Override
+    public void visitPrefixExpression(JetPrefixExpression expression) {
+        DeclarationDescriptor op = bindingContext.resolveReferenceExpression(expression.getOperationSign());
+        if (op instanceof FunctionDescriptor) {
+            JetType returnType = bindingContext.getExpressionType(expression);
+            final Type asmType = typeMapper.mapType(returnType);
+            DeclarationDescriptor cls = op.getContainingDeclaration();
+            if (isNumberPrimitive(cls) && op.getName().equals("minus")) {
+                gen(expression.getBaseExpression(), asmType);
+                v.neg(asmType);
+                myStack.push(StackValue.onStack(asmType));
+                return;
+            }
+        }
+        throw new UnsupportedOperationException("Don't know how to generate this prefix expression");
+    }
+
     @Override
     public void visitProperty(JetProperty property) {
         PropertyDescriptor propertyDescriptor = bindingContext.getPropertyDescriptor(property);

idea/tests/org/jetbrains/jet/codegen/NamespaceGenTest.java

@@ -336,6 +336,12 @@ public class NamespaceGenTest extends LightCodeInsightFixtureTestCase {
         assertTrue(delta <= 1.0);
     }
 
+    public void testNeg() throws Exception {
+        loadText("fun foo(a: Int): Int = -a");
+        final Method main = generateFunction();
+        assertEquals(-10, main.invoke(null, 10));
+    }
+
     private void binOpTest(final String text, final Object arg1, final Object arg2, final Object expected) throws Exception {
         loadText(text);
         System.out.println(generateToText());