Java: Don't offer "Invert If Condition" if the code structure is broken (IDEA-177291)

java/java-impl/src/com/intellij/codeInsight/intention/impl/InvertIfConditionAction.java

@@ -10,6 +10,7 @@ import com.intellij.openapi.util.TextRange;
 import com.intellij.psi.*;
 import com.intellij.psi.codeStyle.CodeStyleManager;
 import com.intellij.psi.controlFlow.*;
+import com.intellij.psi.tree.IElementType;
 import com.intellij.psi.util.PsiTreeUtil;
 import com.intellij.psi.util.PsiUtil;
 import com.intellij.util.ArrayUtilRt;
@@ -17,6 +18,7 @@ import com.intellij.util.IncorrectOperationException;
 import com.siyeh.ig.psiutils.BoolUtils;
 import com.siyeh.ig.psiutils.CommentTracker;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.util.List;
 import java.util.Objects;
@@ -41,17 +43,32 @@ public class InvertIfConditionAction extends PsiElementBaseIntentionAction {
           .filter(prefixExpr -> PsiUtil.skipParenthesizedExprDown(prefixExpr.getOperand()) == null)
           .first() != null) return false;
     if (element instanceof PsiKeyword) {
-      PsiKeyword keyword = (PsiKeyword) element;
-      if ((keyword.getTokenType() == JavaTokenType.IF_KEYWORD || keyword.getTokenType() == JavaTokenType.ELSE_KEYWORD)
-          && keyword.getParent() == ifStatement) {
-        return true;
+      if (element.getParent() != ifStatement) {
+        return false;
+      }
+      final IElementType tokenType = ((PsiKeyword)element).getTokenType();
+      if (tokenType != JavaTokenType.IF_KEYWORD && tokenType != JavaTokenType.ELSE_KEYWORD) {
+        return false;
+      }
+    }
+    else {
+      final TextRange condTextRange = condition.getTextRange();
+      if (condTextRange == null || !condTextRange.contains(offset)) {
+        return false;
       }
     }
-    final TextRange condTextRange = condition.getTextRange();
-    if (condTextRange == null) return false;
-    if (!condTextRange.contains(offset)) return false;
     PsiElement block = findCodeBlock(ifStatement);
-    return block != null;
+    if (block == null) {
+      return false;
+    }
+    if (PsiUtil.skipParenthesizedExprDown(ifStatement.getCondition()) == null) {
+      return true;
+    }
+    // check that the code structure isn't broken completely
+    ControlFlow localFlow = buildControlFlow(block);
+    int startThenOffset = getThenOffset(localFlow, ifStatement);
+    int afterIfOffset = localFlow.getEndOffset(ifStatement);
+    return startThenOffset >= 0 && afterIfOffset >= 0;
   }
 
   @Override
@@ -150,7 +167,11 @@ public class InvertIfConditionAction extends PsiElementBaseIntentionAction {
     return null;
   }
 
-  private static ControlFlow buildControlFlow(PsiElement element) {
+  @NotNull
+  private static ControlFlow buildControlFlow(@Nullable PsiElement element) {
+    if (element == null) {
+      return ControlFlow.EMPTY;
+    }
     try {
       return ControlFlowFactory.getInstance(element.getProject()).getControlFlow(element, LocalsOrMyInstanceFieldsControlFlowPolicy.getInstance(), false);
     }

java/java-psi-impl/src/com/intellij/psi/controlFlow/ControlFlowUtil.java

@@ -1623,6 +1623,7 @@ public class ControlFlowUtil {
      * Push an arc of the graph (oldOffset -> newOffset)
      */
     void push(int oldOffset, int newOffset) {
+      LOG.assertTrue(oldOffset >= 0, "negative offset is pushed to walk-through stack");
       if (size >= newOffsets.length) {
         oldOffsets = ArrayUtil.realloc(oldOffsets, size * 3 / 2);
         newOffsets = ArrayUtil.realloc(newOffsets, size * 3 / 2);

java/java-tests/testData/codeInsight/invertIfCondition/beforeBrokenCodeContinueWithoutLoop.java

@@ -0,0 +1,10 @@
+// "Invert 'if' condition" "false"
+class C {
+  boolean foo() {
+    {
+      if (tr<caret>ue) continue;
+      if (false) return false;
+    }
+    return true;
+  }
+}

java/java-tests/testData/codeInsight/invertIfCondition/beforeBrokenCodeContinueWithoutLoopCaretAtIf.java

@@ -0,0 +1,10 @@
+// "Invert 'if' condition" "false"
+class C {
+  boolean foo() {
+    {
+      <caret>if (true) continue;
+      if (false) return false;
+    }
+    return true;
+  }
+}

java/java-tests/testData/codeInsight/invertIfCondition/beforeBrokenCodeMissingSemicolon.java

@@ -0,0 +1,13 @@
+// "Invert 'if' condition" "false"
+
+class P {
+  Object x;
+  static final String Y = "y";
+
+  public P foo(P a, P b) {
+    if (x <caret>instanceof String) Baz
+    a.bar(b, P.Y);
+    return a;
+  }
+  void bar(P p, String s) { }
+}