field can be local: treat non-primitive fields as read/write (IDEA-52901)

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

@@ -15,9 +15,9 @@
  */
 package com.intellij.codeInspection.varScopeCanBeNarrowed;
 
+import com.intellij.codeInsight.CodeInsightUtil;
 import com.intellij.codeInsight.daemon.GroupNames;
 import com.intellij.codeInsight.daemon.ImplicitUsageProvider;
-import com.intellij.codeInsight.CodeInsightUtil;
 import com.intellij.codeInspection.InspectionsBundle;
 import com.intellij.codeInspection.LocalQuickFix;
 import com.intellij.codeInspection.ProblemDescriptor;
@@ -29,6 +29,7 @@ import com.intellij.openapi.editor.ScrollType;
 import com.intellij.openapi.extensions.Extensions;
 import com.intellij.openapi.fileEditor.FileEditorManager;
 import com.intellij.openapi.project.Project;
+import com.intellij.openapi.util.Ref;
 import com.intellij.psi.*;
 import com.intellij.psi.codeStyle.JavaCodeStyleManager;
 import com.intellij.psi.codeStyle.VariableKind;
@@ -153,13 +154,13 @@ public class FieldCanBeLocalInspection extends BaseLocalInspectionTool {
           }
         }
       }
-      final Collection<PsiVariable> writtenVariables = ControlFlowUtil.getWrittenVariables(controlFlow, 0, controlFlow.getSize(), false);
+      final Ref<Collection<PsiVariable>> writtenVariables = new Ref<Collection<PsiVariable>>();
       final List<PsiReferenceExpression> readBeforeWrites = ControlFlowUtil.getReadBeforeWrite(controlFlow);
       for (final PsiReferenceExpression readBeforeWrite : readBeforeWrites) {
         final PsiElement resolved = readBeforeWrite.resolve();
         if (resolved instanceof PsiField) {
           final PsiField field = (PsiField)resolved;
-          if (writtenVariables.contains(field)){
+          if (!(field.getType() instanceof PsiPrimitiveType) || getWrittenVariables(controlFlow, writtenVariables).contains(field)){
             PsiElement parent = body.getParent();
             if (!(parent instanceof PsiMethod) ||
                 !((PsiMethod)parent).isConstructor() ||
@@ -177,6 +178,13 @@ public class FieldCanBeLocalInspection extends BaseLocalInspectionTool {
     }
   }
 
+  private static Collection<PsiVariable> getWrittenVariables(ControlFlow controlFlow, Ref<Collection<PsiVariable>> writtenVariables) {
+    if (writtenVariables.get() == null) {
+      writtenVariables.set(ControlFlowUtil.getWrittenVariables(controlFlow, 0, controlFlow.getSize(), false));
+    }
+    return writtenVariables.get();
+  }
+
   private static void removeFieldsReferencedFromInitializers(final PsiClass aClass, final Set<PsiField> candidates) {
     aClass.accept(new JavaRecursiveElementWalkingVisitor() {
       @Override public void visitMethod(PsiMethod method) {

java/java-tests/testData/inspection/fieldCanBeLocal/localStateVar2InnerClass/expected.xml

@@ -0,0 +1,2 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<problems/>

java/java-tests/testData/inspection/fieldCanBeLocal/localStateVar2InnerClass/src/Test.java

@@ -0,0 +1,11 @@
+import java.util.*;
+public class Outer {
+  private Map<String, String> value = new HashMap<String, String>();
+
+  public class Inner {
+
+    public Inner(String s) {
+      if (!value.containsKey(s)) value.put(s, "");
+    }
+  }
+}

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

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

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

@@ -0,0 +1,8 @@
+import java.util.*;
+public class Test {
+  private final Map<String, String> myModuleToOutput = new HashMap<String, String>();
+
+  void foo() {
+    if (myModuleToOutput.containsKey(null)) myModuleToOutput.put("", "");
+  }
+}

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

@@ -26,4 +26,6 @@ public class FieldCanBeLocalTest extends InspectionTestCase {
   public void testStaticAccess() throws Exception { doTest(); }
   public void testInnerClassConstructor() throws Exception { doTest(); }
   public void testLocalVar2InnerClass() throws Exception { doTest(); }
+  public void testStateField() throws Exception { doTest(); }
+  public void testLocalStateVar2InnerClass() throws Exception { doTest(); }
 }