lambda->anonym: preserve param names (IDEA-90718)

plugins/IntentionPowerPak/src/com/siyeh/ipp/types/ReplaceLambdaWithAnonymousIntention.java

@@ -51,6 +51,7 @@ public class ReplaceLambdaWithAnonymousIntention extends Intention {
   protected void processIntention(Editor editor, @NotNull PsiElement element) throws IncorrectOperationException {
     final PsiLambdaExpression lambdaExpression = PsiTreeUtil.getParentOfType(element, PsiLambdaExpression.class);
     LOG.assertTrue(lambdaExpression != null);
+    final PsiParameter[] paramListCopy = ((PsiParameterList)lambdaExpression.getParameterList().copy()).getParameters();
     PsiType functionalInterfaceType = lambdaExpression.getFunctionalInterfaceType();
     LOG.assertTrue(functionalInterfaceType != null);
     functionalInterfaceType = GenericsUtil.eliminateWildcards(functionalInterfaceType);
@@ -69,6 +70,14 @@ public class ReplaceLambdaWithAnonymousIntention extends Intention {
     final List<PsiGenerationInfo<PsiMethod>> infos = OverrideImplementUtil.overrideOrImplement(anonymousClass, method);
     if (infos != null && infos.size() == 1) {
       final PsiMethod member = infos.get(0).getPsiMember();
+      final PsiParameter[] parameters = member.getParameterList().getParameters();
+      for (int i = 0; i < parameters.length; i++) {
+        final PsiParameter parameter = parameters[i];
+        final String lambdaParamName = paramListCopy[i].getName();
+        if (lambdaParamName != null) {
+          parameter.setName(lambdaParamName);
+        }
+      }
       PsiCodeBlock codeBlock = member.getBody();
       LOG.assertTrue(codeBlock != null);
       codeBlock = (PsiCodeBlock)codeBlock.replace(psiElementFactory.createCodeBlockFromText(blockText, null));

plugins/IntentionPowerPak/test/com/siyeh/ipp/types/lambda2anonymous/RenameParams.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2000-2012 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+class Test {
+    interface Some {
+        void test(int p1, int p2);
+    }
+
+    {
+        Some some = (i1,<caret> i2) -> {
+            System.out.println(i1 + i2);
+        };
+    }
+}

plugins/IntentionPowerPak/test/com/siyeh/ipp/types/lambda2anonymous/RenameParams_after.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2000-2012 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+class Test {
+    interface Some {
+        void test(int p1, int p2);
+    }
+
+    {
+        Some some = new Some() {
+            @Override
+            public void test(int i1, int i2) {
+                <selection>System.out.println(i1 + i2);</selection>
+            }
+        };
+    }
+}

plugins/IntentionPowerPak/testSrc/com/siyeh/ipp/types/ReplaceLambdaWithAnonymousIntentionTest.java

@@ -31,6 +31,10 @@ public class ReplaceLambdaWithAnonymousIntentionTest extends IPPTestCase {
     doTest();
   }
 
+  public void testRenameParams() {
+    doTest();
+  }
+
   public void testInsertFinal() {
     doTest();
   }