lambda: treat fields used for write inside lambda same way as anonymous classes (IDEA-92085)

java/java-impl/src/com/intellij/codeInspection/varScopeCanBeNarrowed/FieldCanBeLocalInspection.java

@@ -152,6 +152,15 @@ public class FieldCanBeLocalInspection extends BaseLocalInspectionTool {
         }
       }
 
+      @Override
+      public void visitLambdaExpression(PsiLambdaExpression expression) {
+        super.visitLambdaExpression(expression);
+        final PsiElement body = expression.getBody();
+        if (body != null) {
+          checkCodeBlock(body, candidates, usedFields);
+        }
+      }
+
       @Override
       public void visitClassInitializer(PsiClassInitializer initializer) {
         super.visitClassInitializer(initializer);
@@ -160,7 +169,7 @@ public class FieldCanBeLocalInspection extends BaseLocalInspectionTool {
     });
   }
 
-  private static void checkCodeBlock(final PsiCodeBlock body, final Set<PsiField> candidates, Set<PsiField> usedFields) {
+  private static void checkCodeBlock(final PsiElement body, final Set<PsiField> candidates, Set<PsiField> usedFields) {
     try {
       final ControlFlow controlFlow = ControlFlowFactory.getInstance(body.getProject()).getControlFlow(body, AllVariablesControlFlowPolicy.getInstance());
       final List<PsiVariable> usedVars = ControlFlowUtil.getUsedVariables(controlFlow, 0, controlFlow.getSize());

java/java-tests/testData/inspection/fieldCanBeLocal/fieldUsedForWritingInLambda/expected.xml

@@ -0,0 +1,3 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<problems>
+</problems>

java/java-tests/testData/inspection/fieldCanBeLocal/fieldUsedForWritingInLambda/src/Test.java

@@ -0,0 +1,13 @@
+class Test {
+    private int f;
+
+    void foo () {
+        f = 0;
+        int k = f;
+    }
+
+    int bar () {
+        f = 5;
+        return f;
+    }
+}

java/java-tests/testData/inspection/fieldCanBeLocal/twoMethods/src/Test.java

@@ -1,13 +1,10 @@
 class Test {
-    private int f;
+  private int f;
 
-    void foo () {
-        f = 0;
-        int k = f;
-    }
+  public void bar() {
+    foo(() -> {f++;});
+  }
 
-    int bar () {
-        f = 5;
-        return f;
-    }
+  private void foo(Runnable r) {
+  }
 }

java/java-tests/testSrc/com/intellij/codeInspection/FieldCanBeLocalTest.java

@@ -32,6 +32,7 @@ public class FieldCanBeLocalTest extends InspectionTestCase {
   public void testInnerClassFieldInitializer() throws Exception {doTest();}
   public void testFieldUsedInConstantInitialization() throws Exception {doTest();}
   public void testFieldWithImmutableType() throws Exception {doTest();}
+  public void testFieldUsedForWritingInLambda() throws Exception {doTest();}
   public void testIgnoreAnnotated() throws Exception {
     final FieldCanBeLocalInspection inspection = new FieldCanBeLocalInspection();
     inspection.EXCLUDE_ANNOS.add(Deprecated.class.getName());