SPR-6525: avoid need to use #root for method parameter references

org.springframework.expression/src/main/java/org/springframework/expression/spel/ast/MethodReference.java

@@ -52,7 +52,14 @@ public class MethodReference extends SpelNodeImpl {
 		TypedValue currentContext = state.getActiveContextObject();
 		Object[] arguments = new Object[getChildCount()];
 		for (int i = 0; i < arguments.length; i++) {
-			arguments[i] = children[i].getValueInternal(state).getValue();
+			// Make the root object the active context again for evaluating the parameter
+			// expressions
+			try {
+				state.pushActiveContextObject(state.getRootContextObject());
+				arguments[i] = children[i].getValueInternal(state).getValue();
+			} finally {
+				state.popActiveContextObject();	
+			}
 		}
 		if (currentContext.getValue() == null) {
 			if (nullSafe) {

org.springframework.expression/src/test/java/org/springframework/expression/spel/EvaluationTests.java

@@ -367,7 +367,27 @@ public class EvaluationTests extends ExpressionTestCase {
 	public void testTernaryOperatorWithNullValue() {
 		parser.parseExpression("null ? 0 : 1").getValue();
 	}
+	
+	@Test
+	public void methodCallWithRootReferenceThroughParameter() {
+		evaluate("placeOfBirth.doubleIt(inventions.length)", 18, Integer.class);
+	}
 
+	@Test
+	public void ctorCallWithRootReferenceThroughParameter() {
+		evaluate("new org.springframework.expression.spel.testresources.PlaceOfBirth(inventions[0].toString()).city", "Telephone repeater", String.class);
+	}
+
+	@Test
+	public void fnCallWithRootReferenceThroughParameter() {
+		evaluate("#reverseInt(inventions.length, inventions.length, inventions.length)", "int[3]{9,9,9}", int[].class);
+	}
+	
+	@Test
+	public void methodCallWithRootReferenceThroughParameterThatIsAFunctionCall() {
+		evaluate("placeOfBirth.doubleIt(#reverseInt(inventions.length,2,3)[2])", 18, Integer.class);
+	}
+	
 	@Test
 	public void testIndexer03() {
 		evaluate("'christian'[8]", "n", String.class);