convert anonym to inner: ignore used type params as they would be propagated anyway (IDEA-87171)

java/java-impl/src/com/intellij/refactoring/anonymousToInner/AnonymousToInnerHandler.java

@@ -240,7 +240,7 @@ public class AnonymousToInnerHandler implements RefactoringActionHandler {
   }
 
   private Boolean cachedNeedsThis = null;
-  private boolean needsThis() {
+  public boolean needsThis() {
     if(cachedNeedsThis == null) {
 
       ElementNeedsThis memberNeedsThis = new ElementNeedsThis(myTargetClass, myAnonClass);

java/java-impl/src/com/intellij/refactoring/util/classMembers/ElementNeedsThis.java

@@ -41,9 +41,14 @@ public class ElementNeedsThis extends ClassThisReferencesVisitor {
     if (classMember == null || classMember.equals(myMember)) return;
     if (classMember.hasModifierProperty(PsiModifier.STATIC)) return;
 
+    if (ignoreUsedTypeParams() && classMember instanceof PsiTypeParameter) return;
     myResult = true;
   }
 
+  protected boolean ignoreUsedTypeParams() {
+    return myMember != null;
+  }
+
   protected void visitExplicitThis(PsiClass referencedClass, PsiThisExpression reference) {
     myResult = true;
   }

java/java-tests/testData/refactoring/anonymousToInner/canBeStatic.java

@@ -0,0 +1,14 @@
+public class Foo {
+    public<T> void foo() {
+        Predicate<T> predicate = ne<caret>w Predicate<T>() {
+            @Override
+            public boolean test(T t) {
+                return false;
+            }
+        };
+    }
+
+    private interface Predicate<K> {
+        boolean test(K t);
+    }
+}

java/java-tests/testData/refactoring/anonymousToInner/canBeStatic_after.java

@@ -0,0 +1,16 @@
+public class Foo {
+    public<T> void foo() {
+        Predicate<T> predicate = new MyPredicate<T>();
+    }
+
+    private interface Predicate<K> {
+        boolean test(K t);
+    }
+
+    private static class MyPredicate<T> implements Predicate<T> {
+        @Override
+        public boolean test(T t) {
+            return false;
+        }
+    }
+}

java/java-tests/testSrc/com/intellij/refactoring/AnonymousToInnerTest.java

@@ -37,6 +37,22 @@ public class AnonymousToInnerTest extends LightCodeInsightTestCase {
   public void testInsideInterface() throws Exception {  // IDEADEV-29446
     doTest("MyRunnable", true);
   }
+  
+  public void testCanBeStatic() throws Exception {
+    configureByFile(TEST_ROOT + getTestName(true) + ".java");
+    AnonymousToInnerHandler handler = new AnonymousToInnerHandler(){
+      @Override
+      protected boolean showRefactoringDialog() {
+        myNewClassName = "MyPredicate";
+        myMakeStatic = !needsThis();
+        return true;
+      }
+    };
+    handler.invoke(getProject(), myEditor, myFile, null);
+    assertFalse(handler.needsThis());
+    checkResultByFile(TEST_ROOT + getTestName(true) + "_after.java");
+  }
+  
 
   private void doTest(final String newClassName, final boolean makeStatic) throws Exception {
     configureByFile(TEST_ROOT + getTestName(true) + ".java");