rename: don't change qualifier on rename with collisions

java/java-impl/src/com/intellij/refactoring/rename/RenameJavaMethodProcessor.java

@@ -131,7 +131,7 @@ public class RenameJavaMethodProcessor extends RenameJavaMemberProcessor {
   private static void fixNameCollisionsWithInnerClassMethod(final PsiElement element, final String newName,
                                                             final Set<PsiMethod> methodAndOverriders, final Set<PsiClass> containingClasses,
                                                             final boolean isStatic) throws IncorrectOperationException {
-    if (!(element instanceof PsiReferenceExpression)) return;
+    if (!(element instanceof PsiReferenceExpression) || ((PsiReferenceExpression)element).getQualifierExpression() != null) return;
     PsiElement elem = ((PsiReferenceExpression)element).resolve();
 
     if (elem instanceof PsiMethod) {

java/java-tests/testData/refactoring/renameCollisions/RenameConflictNoQualification.java

@@ -0,0 +1,19 @@
+interface A {
+    default void <caret>m() {}
+    default void f() {
+        m();
+    }
+}
+
+class Client1 implements A {
+    Client2 a;
+    @Override
+    public void m() {
+        a.m();
+    }
+}
+
+class Client2 implements A {
+    @Override
+    public void f() { }
+}

java/java-tests/testData/refactoring/renameCollisions/RenameConflictNoQualification.java.after

@@ -0,0 +1,19 @@
+interface A {
+    default void f() {}
+    default void f() {
+        f();
+    }
+}
+
+class Client1 implements A {
+    Client2 a;
+    @Override
+    public void f() {
+        a.f();
+    }
+}
+
+class Client2 implements A {
+    @Override
+    public void f() { }
+}

java/java-tests/testSrc/com/intellij/java/refactoring/RenameCollisionsTest.java

@@ -162,6 +162,9 @@ public class RenameCollisionsTest extends LightRefactoringTestCase {
   public void testRenameVarParamToOuterConst() {
     doTest("STATIC_FIELD");
   }
+  public void testRenameConflictNoQualification() {
+    BaseRefactoringProcessor.ConflictsInTestsException.withIgnoredConflicts(() -> doTest("f"));
+  }
 
   public void testRenameLocalVariableHidesFieldInAnonymous() {
     try {