field can be final: assigned from lambda in constructor (IDEA-170073)

java/java-analysis-impl/src/com/intellij/codeInspection/canBeFinal/CanBeFinalAnnotator.java

@@ -19,6 +19,7 @@ import com.intellij.codeInsight.daemon.impl.analysis.JavaHighlightUtil;
 import com.intellij.codeInspection.reference.*;
 import com.intellij.psi.*;
 import com.intellij.psi.controlFlow.*;
+import com.intellij.psi.util.PsiTreeUtil;
 import com.intellij.util.containers.ContainerUtil;
 import org.jetbrains.annotations.NotNull;
 
@@ -99,17 +100,22 @@ class CanBeFinalAnnotator extends RefGraphAnnotatorEx {
                                RefElement refFrom,
                                boolean referencedFromClassInitializer,
                                boolean forReading,
-                               boolean forWriting) {
+                               boolean forWriting,
+                               PsiElement referenceElement) {
     if (!(refWhat instanceof RefField)) return;
     if (!(refFrom instanceof RefMethod) ||
         !((RefMethod)refFrom).isConstructor() ||
         ((PsiField)refWhat.getElement()).hasInitializer() ||
         ((RefMethod)refFrom).getOwnerClass() != ((RefField)refWhat).getOwnerClass() ||
         ((RefField)refWhat).isStatic()) {
-      if (!referencedFromClassInitializer  && forWriting) {
+      if (forWriting &&
+          !(referencedFromClassInitializer && PsiTreeUtil.getParentOfType(referenceElement, PsiLambdaExpression.class, true) == null)) {
         ((RefFieldImpl)refWhat).setFlag(false, CAN_BE_FINAL_MASK);
       }
     }
+    else if (forWriting && PsiTreeUtil.getParentOfType(referenceElement, PsiLambdaExpression.class, true) != null) {
+      ((RefFieldImpl)refWhat).setFlag(false, CAN_BE_FINAL_MASK);
+    }
   }
 
   @Override

java/java-analysis-impl/src/com/intellij/codeInspection/reference/RefFieldImpl.java

@@ -76,7 +76,7 @@ public class RefFieldImpl extends RefJavaElementImpl implements RefField {
     }
     
     setUsedQualifiedOutsidePackageFlag(refFrom, expressionFrom);
-    getRefManager().fireNodeMarkedReferenced(this, refFrom, referencedFromClassInitializer, forReading, forWriting);
+    getRefManager().fireNodeMarkedReferenced(this, refFrom, referencedFromClassInitializer, forReading, forWriting, expressionFrom);
   }
 
   @Override

java/java-analysis-impl/src/com/intellij/codeInspection/reference/RefJavaElementImpl.java

@@ -260,7 +260,7 @@ public abstract class RefJavaElementImpl extends RefElementImpl implements RefJa
   protected void markReferenced(final RefElementImpl refFrom, PsiElement psiFrom, PsiElement psiWhat, final boolean forWriting, boolean forReading, PsiReferenceExpression expressionFrom) {
     addInReference(refFrom);
     setUsedQualifiedOutsidePackageFlag(refFrom, expressionFrom);
-    getRefManager().fireNodeMarkedReferenced(this, refFrom, false, forReading, forWriting);
+    getRefManager().fireNodeMarkedReferenced(this, refFrom, false, forReading, forWriting, expressionFrom);
   }
 
   void setUsedQualifiedOutsidePackageFlag(RefElementImpl refFrom, PsiReferenceExpression expressionFrom) {

java/java-tests/testData/inspection/canBeFinal/assignedFromLambda/expected.xml

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

java/java-tests/testData/inspection/canBeFinal/assignedFromLambda/src/Foo.java

@@ -0,0 +1,8 @@
+abstract class Foo {
+    private String foo;
+
+    public A(String foo) {
+        this.foo = foo;
+        Runnable r = () -> {this.foo = "";};
+    }
+}

java/java-tests/testData/inspection/canBeFinal/assignedFromLambdaInClassInitializer/expected.xml

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

java/java-tests/testData/inspection/canBeFinal/assignedFromLambdaInClassInitializer/src/Foo.java

@@ -0,0 +1,6 @@
+abstract class Foo {
+    private String foo = "1";
+    {
+        Runnable r = () -> {this.foo = "";};
+    }
+}

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

@@ -47,6 +47,14 @@ public class CanBeFinalTest extends InspectionTestCase {
     doTest();
   }
 
+  public void testassignedFromLambda() {
+    doTest();
+  }
+  
+  public void testassignedFromLambdaInClassInitializer() {
+    doTest();
+  }
+
   public void testsimpleClassInheritance() {
     doTest();
   }

platform/analysis-api/src/com/intellij/codeInspection/reference/RefGraphAnnotator.java

@@ -55,6 +55,26 @@ public abstract class RefGraphAnnotator {
                                boolean referencedFromClassInitializer) {
   }
 
+   /**
+   * Called when a reference to the specified element has been found.
+   *
+   * @param refWhat                        the referenced element.
+   * @param refFrom                        the referencing element.
+   * @param referencedFromClassInitializer if true, {@code refFrom} is a class and the reference
+   *                                       has been found in its initializer block.
+   * @param forReading                     used for reading
+   * @param forWriting                     used for writing
+   * @param referenceElement               reference element in refFrom
+   */
+  public void onMarkReferenced(RefElement refWhat,
+                               RefElement refFrom,
+                               boolean referencedFromClassInitializer,
+                               boolean forReading,
+                               boolean forWriting,
+                               PsiElement referenceElement) {
+    onMarkReferenced(refWhat, refFrom, referencedFromClassInitializer, forReading, forWriting);
+  }
+  
   /**
    * Called when a reference to the specified element has been found.
    *

platform/analysis-impl/src/com/intellij/codeInspection/reference/RefManagerImpl.java

@@ -169,6 +169,17 @@ public class RefManagerImpl extends RefManager {
       annotator.onMarkReferenced(refWhat, refFrom, referencedFromClassInitializer, forReading, forWriting);
     }
   }
+  
+  void fireNodeMarkedReferenced(RefElement refWhat,
+                                RefElement refFrom,
+                                boolean referencedFromClassInitializer,
+                                final boolean forReading,
+                                final boolean forWriting,
+                                PsiElement element) {
+    for (RefGraphAnnotator annotator : myGraphAnnotators) {
+      annotator.onMarkReferenced(refWhat, refFrom, referencedFromClassInitializer, forReading, forWriting, element);
+    }
+  }
 
   public void fireNodeMarkedReferenced(PsiElement what, PsiElement from) {
     for (RefGraphAnnotator annotator : myGraphAnnotators) {