field can be local extended: suggest read only fields used in e.g. constructor once as can be local; process inner class constructors as methods (IDEA-52670)

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

@@ -153,17 +153,21 @@ public class FieldCanBeLocalInspection extends BaseLocalInspectionTool {
           }
         }
       }
+      final Collection<PsiVariable> writtenVariables = ControlFlowUtil.getWrittenVariables(controlFlow, 0, controlFlow.getSize(), false);
       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;
-          PsiElement parent = body.getParent();
-          if (!(parent instanceof PsiMethod) ||
-              !((PsiMethod)parent).isConstructor() ||
-              field.getInitializer() == null ||
-              field.hasModifierProperty(PsiModifier.STATIC)) {
-            candidates.remove(field);
+          if (writtenVariables.contains(field)){
+            PsiElement parent = body.getParent();
+            if (!(parent instanceof PsiMethod) ||
+                !((PsiMethod)parent).isConstructor() ||
+                field.getInitializer() == null ||
+                field.hasModifierProperty(PsiModifier.STATIC) ||
+                !PsiTreeUtil.isAncestor(((PsiMethod)parent).getContainingClass(), field, true)) {
+              candidates.remove(field);
+            }
           }
         }
       }

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

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

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

@@ -0,0 +1,11 @@
+public class Outer {
+  private int value = 0;
+
+  public class Inner {
+    private final int myValue;
+
+    public Inner() {
+      myValue = value++;
+    }
+  }
+}

java/java-tests/testData/inspection/fieldCanBeLocal/localVar2InnerClass/expected.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<problems>
+  <problem>
+    <file>Test.java</file>
+    <line>2</line>
+    <problem_class severity="WARNING" attribute_key="WARNING_ATTRIBUTES">Field can be local</problem_class>
+    <description>Field can be converted to a local variable</description>
+  </problem>
+</problems>

java/java-tests/testData/inspection/fieldCanBeLocal/localVar2InnerClass/src/Test.java

@@ -0,0 +1,11 @@
+public class Outer {
+  private int value = 0;
+
+  public class Inner {
+    private final int myValue;
+
+    public Inner() {
+      myValue = value;
+    }
+  }
+}

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

@@ -24,4 +24,6 @@ public class FieldCanBeLocalTest extends InspectionTestCase {
   public void testConstructor () throws Exception { doTest(); }
   public void testStaticFinal() throws Exception { doTest(); }
   public void testStaticAccess() throws Exception { doTest(); }
+  public void testInnerClassConstructor() throws Exception { doTest(); }
+  public void testLocalVar2InnerClass() throws Exception { doTest(); }
 }