From 6d7d152e4830feb9f606e63d8f424b6730159a5e Mon Sep 17 00:00:00 2001
From: Bas Leijdekkers <basleijdekkers@gmail.com>
Date: Tue, 13 Oct 2020 16:41:49 +0200
Subject: [PATCH] IG: recognize commented out else branch after if statement

GitOrigin-RevId: bd9aba9697230eebfac151a279b8988897f1bd50
---
 .../maturity/CommentedOutCodeInspection.java   | 18 ++++++++++++++----
 .../CommentedOutCode.after.java                | 13 +++++++++++++
 .../commented_out_code/CommentedOutCode.java   | 17 +++++++++++++++++
 3 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/plugins/InspectionGadgets/src/com/siyeh/ig/maturity/CommentedOutCodeInspection.java b/plugins/InspectionGadgets/src/com/siyeh/ig/maturity/CommentedOutCodeInspection.java
index d9bedcce539c..538caa866afe 100644
--- a/plugins/InspectionGadgets/src/com/siyeh/ig/maturity/CommentedOutCodeInspection.java
+++ b/plugins/InspectionGadgets/src/com/siyeh/ig/maturity/CommentedOutCodeInspection.java
@@ -4,6 +4,7 @@ package com.siyeh.ig.maturity;
 import com.intellij.codeInspection.ProblemDescriptor;
 import com.intellij.codeInspection.ui.SingleIntegerFieldOptionsPanel;
 import com.intellij.codeInspection.util.InspectionMessage;
+import com.intellij.core.JavaPsiBundle;
 import com.intellij.ide.highlighter.JavaFileType;
 import com.intellij.openapi.editor.Document;
 import com.intellij.openapi.project.Project;
@@ -190,6 +191,9 @@ public class CommentedOutCodeInspection extends BaseInspection {
         parent = method.getParent();
       }
     }
+    else if (parent instanceof PsiField) {
+      parent = parent.getParent();
+    }
     else if (parent instanceof PsiClass) {
       final PsiClass aClass = (PsiClass)parent;
       if (!ClassUtils.isInsideClassBody(context, aClass)) {
@@ -205,7 +209,8 @@ public class CommentedOutCodeInspection extends BaseInspection {
     else {
       fragment = factory.createCodeBlockCodeFragment(text, context, false);
     }
-    return !isInvalidCode(fragment);
+    final boolean allowDanglingElse = PsiTreeUtil.getPrevSiblingOfType(context, PsiStatement.class) instanceof PsiIfStatement;
+    return !isInvalidCode(fragment, allowDanglingElse);
   }
 
   static String getCommentText(PsiComment comment) {
@@ -232,7 +237,7 @@ public class CommentedOutCodeInspection extends BaseInspection {
     return (comment.getTokenType() == JavaTokenType.END_OF_LINE_COMMENT) ? StringUtil.trimStart(comment.getText(), "//") : null;
   }
 
-  static boolean isInvalidCode(PsiElement element) {
+  static boolean isInvalidCode(PsiElement element, boolean allowDanglingElse) {
     final PsiElement firstChild = element.getFirstChild();
     final PsiElement lastChild = element.getLastChild();
     final boolean strict = firstChild == lastChild && firstChild instanceof PsiExpressionStatement;
@@ -245,18 +250,20 @@ public class CommentedOutCodeInspection extends BaseInspection {
         return true;
       }
     }
-    final CodeVisitor visitor = new CodeVisitor(strict);
+    final CodeVisitor visitor = new CodeVisitor(strict, allowDanglingElse);
     element.accept(visitor);
     return visitor.isInvalidCode();
   }
 
   private static class CodeVisitor extends JavaRecursiveElementWalkingVisitor {
     private final boolean myStrict;
+    private final boolean myAllowDanglingElse;
     private boolean invalidCode = false;
     private boolean codeFound = false;
 
-    private CodeVisitor(boolean strict) {
+    private CodeVisitor(boolean strict, boolean allowDanglingElse) {
       myStrict = strict;
+      myAllowDanglingElse = allowDanglingElse;
     }
 
     @Override
@@ -275,6 +282,9 @@ public class CommentedOutCodeInspection extends BaseInspection {
 
     @Override
     public void visitErrorElement(@NotNull PsiErrorElement element) {
+      if (myAllowDanglingElse && !codeFound && JavaPsiBundle.message("else.without.if").equals(element.getErrorDescription())) {
+        return;
+      }
       invalidCode = true;
       stopWalking();
     }
diff --git a/plugins/InspectionGadgets/test/com/siyeh/igtest/maturity/commented_out_code/CommentedOutCode.after.java b/plugins/InspectionGadgets/test/com/siyeh/igtest/maturity/commented_out_code/CommentedOutCode.after.java
index aa299cedeb2a..898d0c1577b3 100644
--- a/plugins/InspectionGadgets/test/com/siyeh/igtest/maturity/commented_out_code/CommentedOutCode.after.java
+++ b/plugins/InspectionGadgets/test/com/siyeh/igtest/maturity/commented_out_code/CommentedOutCode.after.java
@@ -8,6 +8,19 @@ class CommentedOutCode /* extends Object */ {
   //// VARIABLE STATE \\\\
   private String s;
 
+  private String field;
+
+
+  private static int danglingElse(int i) {
+    if (i == 3) {
+      System.out.println(i);
+    }
+      return i;
+    //else if (i == 4) {
+    //  System.exit(-1);
+    //}
+  }
+
   int x(int i) {
     new Object() {
 
diff --git a/plugins/InspectionGadgets/test/com/siyeh/igtest/maturity/commented_out_code/CommentedOutCode.java b/plugins/InspectionGadgets/test/com/siyeh/igtest/maturity/commented_out_code/CommentedOutCode.java
index 58d68a98a531..935cc391b411 100644
--- a/plugins/InspectionGadgets/test/com/siyeh/igtest/maturity/commented_out_code/CommentedOutCode.java
+++ b/plugins/InspectionGadgets/test/com/siyeh/igtest/maturity/commented_out_code/CommentedOutCode.java
@@ -9,6 +9,23 @@ class CommentedOutCode /* extends Object */ {
   //// VARIABLE STATE \\\\
   private String s;
 
+  <warning descr="Commented out code (1 line)">//</warning> void x() {}
+  private String field;
+
+
+  private static int danglingElse(int i) {
+    if (i == 3) {
+      System.out.println(i);
+    }
+    <warning descr="Commented out code (3 lines)">//</warning>else if (i == 4) {
+    //  System.exit(-1);
+    //}
+    return i;
+    //else if (i == 4) {
+    //  System.exit(-1);
+    //}
+  }
+
   int x(int i) {
     new Object() {