make method static: fix method refs in method body

EA-120553 - assert: MakeMethodStaticProcessor.changeSelfUsage

java/java-impl/src/com/intellij/refactoring/makeStatic/MakeMethodStaticProcessor.java

@@ -96,8 +96,25 @@ public class MakeMethodStaticProcessor extends MakeMethodOrClassStaticProcessor<
   }
 
   protected void changeSelfUsage(SelfUsageInfo usageInfo) throws IncorrectOperationException {
-    PsiElement parent = usageInfo.getElement().getParent();
-    LOG.assertTrue(parent instanceof PsiMethodCallExpression);
+    PsiElement element = usageInfo.getElement();
+    PsiElement parent = element.getParent();
+    if (element instanceof PsiMethodReferenceExpression) {
+      if (needLambdaConversion((PsiMethodReferenceExpression)element)) {
+        PsiMethodCallExpression methodCallExpression = getMethodCallExpression((PsiMethodReferenceExpression)element);
+        if (methodCallExpression == null) return;
+        parent = methodCallExpression;
+      }
+      else {
+        PsiElementFactory factory = JavaPsiFacade.getElementFactory(parent.getProject());
+        PsiClass memberClass = myMember.getContainingClass();
+        LOG.assertTrue(memberClass != null);
+        PsiElement qualifier = ((PsiMethodReferenceExpression)element).getQualifier();
+        LOG.assertTrue(qualifier != null);
+        qualifier.replace(factory.createReferenceExpression(memberClass));
+        return;
+      }
+    }
+    LOG.assertTrue(parent instanceof PsiMethodCallExpression, parent);
     PsiMethodCallExpression methodCall = (PsiMethodCallExpression) parent;
     final PsiExpression qualifier = methodCall.getMethodExpression().getQualifierExpression();
     if (qualifier != null) qualifier.delete();
@@ -271,13 +288,9 @@ public class MakeMethodStaticProcessor extends MakeMethodOrClassStaticProcessor<
 
     PsiReferenceExpression methodRef = (PsiReferenceExpression) element;
     if (methodRef instanceof PsiMethodReferenceExpression && needLambdaConversion((PsiMethodReferenceExpression)methodRef)) {
-      PsiLambdaExpression lambdaExpression =
-        LambdaRefactoringUtil.convertMethodReferenceToLambda(((PsiMethodReferenceExpression)methodRef), true, true);
-      List<PsiExpression> returnExpressions = LambdaUtil.getReturnExpressions(lambdaExpression);
-      if (returnExpressions.size() != 1) return;
-      PsiExpression expression = returnExpressions.get(0);
-      if (!(expression instanceof PsiMethodCallExpression)) return;
-      methodRef = ((PsiMethodCallExpression)expression).getMethodExpression();
+      PsiMethodCallExpression expression = getMethodCallExpression((PsiMethodReferenceExpression)methodRef);
+      if (expression == null) return;
+      methodRef = expression.getMethodExpression();
     }
     PsiElement parent = methodRef.getParent();
 
@@ -359,6 +372,16 @@ public class MakeMethodStaticProcessor extends MakeMethodOrClassStaticProcessor<
     }
   }
 
+  private static PsiMethodCallExpression getMethodCallExpression(PsiMethodReferenceExpression methodRef) {
+    PsiLambdaExpression lambdaExpression =
+      LambdaRefactoringUtil.convertMethodReferenceToLambda(methodRef, true, true);
+    List<PsiExpression> returnExpressions = LambdaUtil.getReturnExpressions(lambdaExpression);
+    if (returnExpressions.size() != 1) return null;
+    PsiExpression expression = returnExpressions.get(0);
+    if (!(expression instanceof PsiMethodCallExpression)) return null;
+    return (PsiMethodCallExpression)expression;
+  }
+
   private boolean needLambdaConversion(PsiMethodReferenceExpression methodRef) {
     if (mySettings.isMakeFieldParameters()) {
       return true;

java/java-tests/testData/refactoring/makeMethodStatic/afterMethodReferenceInTheSameMethod.java

@@ -0,0 +1,13 @@
+import java.util.List;
+import java.util.function.BiConsumer;
+
+class IWalker {
+  public static void walk(I e) {
+    e.getChildren().forEach(IWalker::walk);
+    final BiConsumer<IWalker, I> walk = (iWalker, e1) -> IWalker.walk(e1);
+  }
+
+  interface I {
+    List<I> getChildren();
+  }
+}

java/java-tests/testData/refactoring/makeMethodStatic/beforeMethodReferenceInTheSameMethod.java

@@ -0,0 +1,13 @@
+import java.util.List;
+import java.util.function.BiConsumer;
+
+class IWalker {
+  public void w<caret>alk(I e) {
+    e.getChildren().forEach(this::walk);
+    final BiConsumer<IWalker, I> walk = IWalker::walk;
+  }
+
+  interface I {
+    List<I> getChildren();
+  }
+}

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

@@ -207,6 +207,10 @@ public class MakeMethodStaticTest extends LightRefactoringTestCase {
     doTest(false);
   }
 
+  public void testMethodReferenceInTheSameMethod() {
+    doTest(false);
+  }
+
   public void testExpandMethodReference() {
     doTest(true);
   }