extract method: exclude unused type parameters mentioned in return type (IDEA-58456)

java/java-impl/src/com/intellij/refactoring/extractMethod/ExtractMethodProcessor.java

@@ -299,7 +299,7 @@ public class ExtractMethodProcessor implements MatchProvider {
         if (myOutputVariable != null) {
           elements = ArrayUtil.append(myElements, myOutputVariable, PsiElement.class);
         }
-        if (myCodeFragmentMember != null) {
+        if (myCodeFragmentMember != null && myReturnType == ((PsiMethod)myCodeFragmentMember).getReturnType()) {
           elements = ArrayUtil.append(myElements, ((PsiMethod)myCodeFragmentMember).getReturnTypeElement(), PsiElement.class);
         }
       }

java/java-tests/testData/refactoring/extractMethod/UnusedGenerics.java

@@ -0,0 +1,6 @@
+class Test {
+  public <T> T method(Class<T> clazz) {
+    <selection>System.out.println();</selection>
+    return null;
+  }
+}

java/java-tests/testData/refactoring/extractMethod/UnusedGenerics_after.java

@@ -0,0 +1,10 @@
+class Test {
+  public <T> T method(Class<T> clazz) {
+      newMethod();
+      return null;
+  }
+
+    private void newMethod() {
+        System.out.println();
+    }
+}

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

@@ -372,6 +372,10 @@ public class ExtractMethodTest extends LightCodeInsightTestCase {
     doTest();
   }
 
+  public void testUnusedGenerics() throws Exception {
+    doTest();
+  }
+
   public void testParamsUsedInLocalClass() throws Exception {
     doTest();
   }