anonymous -> lambda: allow field shadowing when suggesting new local names (IDEA-157288)

java/java-analysis-impl/src/com/intellij/codeInspection/AnonymousCanBeLambdaInspection.java

@@ -344,7 +344,7 @@ public class AnonymousCanBeLambdaInspection extends BaseJavaBatchLocalInspection
       PsiVariable local = iterator.next();
       final String localName = local.getName();
       if (localName == null ||
-          helper.resolveReferencedVariable(localName, lambdaExpression) == null ||
+          shadowingResolve(localName, lambdaExpression, helper) ||
           !PsiTreeUtil.isAncestor(lambdaExpression, local, false)) {
         iterator.remove();
         namesOfVariablesInTheBlock.add(localName);
@@ -352,6 +352,11 @@ public class AnonymousCanBeLambdaInspection extends BaseJavaBatchLocalInspection
     }
   }
 
+  private static boolean shadowingResolve(String localName, PsiLambdaExpression lambdaExpression, PsiResolveHelper helper) {
+    final PsiVariable variable = helper.resolveReferencedVariable(localName, lambdaExpression);
+    return variable == null || variable instanceof PsiField;
+  }
+
   private static class ReplaceWithLambdaFix implements LocalQuickFix, HighPriorityAction {
     @NotNull
     @Override

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/anonymous2lambda/afterFieldShadowing.java

@@ -0,0 +1,10 @@
+// "Replace with lambda" "true"
+class Test {
+  Integer s;
+  private void m() {
+    Runnable r = () -> {
+      System.out.println(s);
+      Integer s = Test.this.s;
+    };
+  }
+}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/anonymous2lambda/beforeFieldShadowing.java

@@ -0,0 +1,13 @@
+// "Replace with lambda" "true"
+class Test {
+  Integer s;
+  private void m() {
+    Runnable r = new Runna<caret>ble() {
+      @Override
+      public void run() {
+        System.out.println(s);
+        Integer s = Test.this.s;
+      }
+    };
+  }
+}