Issue sevntu-checkstyle#743: fix compiling issues with checkstyle 8.21

sevntu-checks/src/main/java/com/github/sevntu/checkstyle/checks/coding/DiamondOperatorForVariableDefinitionCheck.java

@@ -83,7 +83,7 @@ public void visitToken(DetailAST variableDefNode) {
                         && newNode.findFirstToken(TokenTypes.ARRAY_DECLARATOR) == null) {
                     final DetailAST typeArgs = getFirstTypeArgumentsToken(newNode);
 
-                    if (varDefArguments.equalsTree(typeArgs)) {
+                    if (typeArgs != null && isTreeEqual(varDefArguments, typeArgs)) {
                         log(typeArgs, MSG_KEY);
                     }
                 }
@@ -113,4 +113,46 @@ private static DetailAST getFirstTypeArgumentsToken(DetailAST rootToken) {
         return resultNode;
     }
 
+    /**
+     * Checks if the 2 given trees have the same children, type, and text.
+     * @param left One of the trees to compare.
+     * @param right The other tree to compare.
+     * @return {@code true} if the trees are equal.
+     */
+    private static boolean isTreeEqual(DetailAST left, DetailAST right) {
+        boolean result;
+
+        if (isAstEqual(left, right)) {
+            result = true;
+
+            DetailAST leftChild = left.getFirstChild();
+            DetailAST rightChild = right.getFirstChild();
+
+            while (leftChild != rightChild) {
+                if (!isTreeEqual(leftChild, rightChild)) {
+                    result = false;
+                    break;
+                }
+
+                leftChild = leftChild.getNextSibling();
+                rightChild = rightChild.getNextSibling();
+            }
+        }
+        else {
+            result = false;
+        }
+
+        return result;
+    }
+
+    /**
+     * Checks if the 2 given ASTs have the same type and text.
+     * @param left One of the ASTs to compare.
+     * @param right The other AST to compare.
+     * @return {@code true} if the ASTs are equal.
+     */
+    private static boolean isAstEqual(DetailAST left, DetailAST right) {
+        return left.getType() == right.getType() && left.getText().equals(right.getText());
+    }
+
 }

sevntu-checks/src/main/java/com/github/sevntu/checkstyle/checks/coding/ForbidCCommentsInMethodsCheck.java

@@ -41,13 +41,10 @@ public class ForbidCCommentsInMethodsCheck extends AbstractCheck {
      */
     public static final String MSG_KEY = "forbid.c.comments.in.the.method.body";
 
-    /** AST to use for null checks because {@link Deque} doesn't allow null elements. */
-    private static final DetailAST NULL_AST = new DetailAST();
-
     /** Method stack. */
     private final Deque<DetailAST> scopeStack = new ArrayDeque<>();
 
-    /** Reference to current method. */
+    /** Reference to current token being tracked. */
     private DetailAST methodAst;
 
     @Override
@@ -76,7 +73,7 @@ public boolean isCommentNodesRequired() {
 
     @Override
     public void beginTree(DetailAST rootAST) {
-        methodAst = NULL_AST;
+        methodAst = rootAST;
     }
 
     @Override
@@ -85,13 +82,11 @@ public void visitToken(DetailAST ast) {
 
         switch (ast.getType()) {
             case TokenTypes.METHOD_DEF:
-                methodAst = ast;
-                break;
             case TokenTypes.OBJBLOCK:
-                methodAst = NULL_AST;
+                methodAst = ast;
                 break;
             default:
-                if (methodAst != NULL_AST) {
+                if (methodAst.getType() == TokenTypes.METHOD_DEF) {
                     final DetailAST lcurly = methodAst.findFirstToken(TokenTypes.SLIST);
                     if (lcurly != null
                             && (ast.getLineNo() > lcurly.getLineNo()

sevntu-checks/src/main/java/com/github/sevntu/checkstyle/checks/design/ForbidWildcardAsReturnTypeCheck.java

@@ -25,7 +25,6 @@
 import java.util.Set;
 import java.util.regex.Pattern;
 
-import antlr.collections.AST;
 import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
 import com.puppycrawl.tools.checkstyle.api.DetailAST;
 import com.puppycrawl.tools.checkstyle.api.TokenTypes;
@@ -305,9 +304,9 @@ private static boolean isInsideInterfaceDefinition(DetailAST methodDefAst) {
      * @return the set of modifier Strings for aMethodDefAST
      */
     private static Set<String> getModifiers(DetailAST methodDefAst) {
-        final AST modifiersAst = methodDefAst.getFirstChild();
+        final DetailAST modifiersAst = methodDefAst.getFirstChild();
         final Set<String> modifiersSet = new HashSet<>();
-        AST modifierAst = modifiersAst.getFirstChild();
+        DetailAST modifierAst = modifiersAst.getFirstChild();
         while (modifierAst != null) {
             modifiersSet.add(modifierAst.getText());
             modifierAst = modifierAst.getNextSibling();

sevntu-checks/src/test/resources/com/github/sevntu/checkstyle/checks/coding/InputDiamondOperatorForVariableDefinitionCheck.java

@@ -60,10 +60,10 @@ public int compare(Object s1, Object s2) {
     private transient Map<Method, String> shadowMatchCache = new ConcurrentHashMap<Method, String>(32);
 
     private Predicate<File> inputCsvFilesFilter = new Predicate<File>() {
-    	public boolean apply(File input)
-		{
-			return false;
-		}
+        public boolean apply(File input)
+        {
+            return false;
+        }
     };
 
     String str = new String("");
@@ -91,6 +91,12 @@ public void doSmth() {
     java.util.Date date = new java.util.Date();
     static java.util.Map<List<String>, String> myMap2 = new java.util.TreeMap<List<String>, String>();
     static java.util.Map<List<String>, String> myMap3 = new TreeMap<List<String>, String>();
+
+    static List<String> myMap4 = new InputDiamondOperatorForVariableDefinitionCheck.Inner();
+    static H006_ComplexConstructors<Integer> instance = new <String>H006_ComplexConstructors<Integer>(0, "");
+
+    private static class Inner extends ArrayList<String> {}
+    private static class H006_ComplexConstructors<T> {
+        public <V> H006_ComplexConstructors(T t, V v) {}
+    }
 }
-
-