assign weaker access: find method to implement (IDEA-153610)

java/java-analysis-impl/src/com/intellij/codeInsight/daemon/impl/analysis/HighlightMethodUtil.java

@@ -1327,6 +1327,7 @@ public class HighlightMethodUtil {
 
   static HighlightInfo checkOverrideEquivalentInheritedMethods(PsiClass aClass, PsiFile containingFile, @NotNull LanguageLevel languageLevel) {
     String description = null;
+    boolean appendImplementMethodFix = true;
     final Collection<HierarchicalMethodSignature> visibleSignatures = aClass.getVisibleSignatures();
     PsiResolveHelper resolveHelper = JavaPsiFacade.getInstance(aClass.getProject()).getResolveHelper();
     Ultimate:
@@ -1360,6 +1361,7 @@ public class HighlightMethodUtil {
                                                          HighlightUtil.formatClass(containingClass),
                                                          JavaHighlightUtil.formatMethod(superMethod),
                                                          HighlightUtil.formatClass(superMethod.getContainingClass()));
+            appendImplementMethodFix = false;
             break Ultimate;
           }
         }
@@ -1383,7 +1385,11 @@ public class HighlightMethodUtil {
     if (description != null) {
       // show error info at the class level
       TextRange textRange = HighlightNamesUtil.getClassDeclarationTextRange(aClass);
-      return HighlightInfo.newHighlightInfo(HighlightInfoType.ERROR).range(textRange).descriptionAndTooltip(description).create();
+      final HighlightInfo highlightInfo = HighlightInfo.newHighlightInfo(HighlightInfoType.ERROR).range(textRange).descriptionAndTooltip(description).create();
+      if (appendImplementMethodFix) {
+        QuickFixAction.registerQuickFixAction(highlightInfo, QUICK_FIX_FACTORY.createImplementMethodsFix(aClass));
+      }
+      return highlightInfo;
     }
     return null;
   }

java/java-psi-impl/src/com/intellij/codeInsight/generation/OverrideImplementExploreUtil.java

@@ -52,6 +52,14 @@ public class OverrideImplementExploreUtil {
       PsiUtilCore.ensureValid(method);
 
       if (method.hasModifierProperty(PsiModifier.STATIC) || !resolveHelper.isAccessible(method, aClass, aClass)) continue;
+      for (HierarchicalMethodSignature superMethodSignature : signature.getSuperSignatures()) {
+        final PsiMethod superMethod = superMethodSignature.getMethod();
+        if (PsiUtil.getAccessLevel(superMethod.getModifierList()) > PsiUtil.getAccessLevel(method.getModifierList())) {
+          method = superMethod;
+          break;
+        }
+      }
+
       PsiClass hisClass = method.getContainingClass();
       if (hisClass == null) continue;
       // filter non-immediate super constructors

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/implementMethods/afterAssignWeakerAccess.java

@@ -0,0 +1,13 @@
+// "Implement methods" "true"
+class B {
+    protected void f() {}
+}
+interface A {
+    void f();
+}
+class D extends B implements A {
+    @Override
+    public void f() {
+        <caret>
+    }
+}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/implementMethods/beforeAssignWeakerAccess.java

@@ -0,0 +1,8 @@
+// "Implement methods" "true"
+class B {
+    protected void f() {}
+}
+interface A {
+    void f();
+}
+<caret>class D extends B implements A {}

java/java-tests/testSrc/com/intellij/codeInsight/OverrideImplementTest.groovy

@@ -68,6 +68,39 @@ interface B extends A {
 """
   }
 
+  public void testImplementInterfaceWhenClassProvidesProtectedImplementation() {
+    myFixture.addClass """\
+interface A {
+  void f();
+}
+"""
+    myFixture.addClass """\
+class B {
+  protected void f() {}
+}
+"""
+
+    def file = myFixture.addClass("""\
+class C extends B implements A {
+   <caret>
+}
+""").containingFile.virtualFile
+    myFixture.configureFromExistingVirtualFile(file)
+
+    def Presentation presentation = new Presentation()
+    presentation.setText(ActionsBundle.message("action.ImplementMethods.text"))
+    CommandProcessor.instance.executeCommand(project, { invokeAction(true) }, presentation.text, null)
+
+    myFixture.checkResult """\
+class C extends B implements A {
+    @Override
+    public void f() {
+        <caret>
+    }
+}
+"""
+  }
+
   public void testImplementSameNamedInterfaces() {
     myFixture.addClass """\
 class Main1 {