GROOVY-10011: STC: instanceof refines declared type for diamond operator (closes #1545)

Author: eric-milles

src/main/java/org/codehaus/groovy/transform/stc/StaticTypeCheckingVisitor.java

@@ -5546,11 +5546,15 @@ private ClassNode resolveGenericsWithContext(final Map<GenericsTypeName, Generic
     }
 
     private ClassNode getDeclaredOrInferredType(final Expression expression) {
+        ClassNode declaredOrInferred;
         // in case of "T t = new ExtendsOrImplementsT()", return T for the expression type
         if (expression instanceof Variable && !((Variable) expression).isDynamicTyped()) {
-            return getOriginalDeclarationType(expression); // GROOVY-9996
+            declaredOrInferred = getOriginalDeclarationType(expression); // GROOVY-9996
+        } else {
+            declaredOrInferred = getType(expression);
         }
-        return getInferredTypeFromTempInfo(expression, getType(expression));
+        // GROOVY-10011: apply instanceof constraints to either option
+        return getInferredTypeFromTempInfo(expression, declaredOrInferred);
     }
 
     private static ClassNode getDeclaringClass(final MethodNode method, final Expression arguments) {

src/test/groovy/transform/stc/GenericsSTCTest.groovy

@@ -343,6 +343,25 @@ class GenericsSTCTest extends StaticTypeCheckingTestCase {
         '''
     }
 
+    // GROOVY-10011
+    void testDiamondInferrenceFromConstructor8b() {
+        assertScript '''
+            @groovy.transform.TupleConstructor(defaults=false)
+            class C<T> {
+                T p
+            }
+            interface I { }
+            class D implements I { }
+
+            void test(I i) {
+                if (i instanceof D) {
+                    C<D> cd = new C<>(i)
+                }
+            }
+            test(new D())
+        '''
+    }
+
     void testDiamondInferrenceFromConstructor9() {
         assertScript '''
             abstract class A<X> { }