From dd303a0903379709da76329a0e33300b617c442f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20Fournier?= <clement.fournier76@gmail.com>
Date: Tue, 25 Aug 2020 02:12:03 +0200
Subject: [PATCH] Remove default implementation

---
 .../src/main/java/net/sourceforge/pmd/lang/ast/Node.java | 9 +++------
 .../pmd/lang/xml/ast/internal/XmlNodeWrapper.java        | 5 +++++
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/lang/ast/Node.java b/pmd-core/src/main/java/net/sourceforge/pmd/lang/ast/Node.java
index b2972344d3..8d919f1114 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/lang/ast/Node.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/lang/ast/Node.java
@@ -289,13 +289,10 @@ public interface Node {
      * @implSpec A typical implementation will check the type of the visitor to
      *     be that of the language specific visitor, then call the most specific
      *     visit method of this Node. This is typically implemented by having
-     *     a different override per concrete node class (no shortcuts).
+     *     a different override per concrete node class (no shortcuts). If the
+     *     visitor is not handled, call {@link AstVisitor#cannotVisit(Node, Object)}.
      */
-    // TODO remove the default implementation, convert all visitors to be generic
-    default <P, R> R acceptVisitor(AstVisitor<? super P, ? extends R> visitor, P data) {
-        // override me
-        throw new IllegalArgumentException("Unsupported visitor" + visitor + " for node " + this);
-    }
+    <P, R> R acceptVisitor(AstVisitor<? super P, ? extends R> visitor, P data);
 
 
     /**
diff --git a/pmd-xml/src/main/java/net/sourceforge/pmd/lang/xml/ast/internal/XmlNodeWrapper.java b/pmd-xml/src/main/java/net/sourceforge/pmd/lang/xml/ast/internal/XmlNodeWrapper.java
index 282c0b1e4d..3895703a29 100644
--- a/pmd-xml/src/main/java/net/sourceforge/pmd/lang/xml/ast/internal/XmlNodeWrapper.java
+++ b/pmd-xml/src/main/java/net/sourceforge/pmd/lang/xml/ast/internal/XmlNodeWrapper.java
@@ -15,6 +15,7 @@ import org.w3c.dom.NamedNodeMap;
 import org.w3c.dom.NodeList;
 import org.w3c.dom.Text;
 
+import net.sourceforge.pmd.lang.ast.AstVisitor;
 import net.sourceforge.pmd.lang.rule.xpath.Attribute;
 import net.sourceforge.pmd.lang.xml.ast.XmlNode;
 import net.sourceforge.pmd.util.CompoundIterator;
@@ -161,6 +162,10 @@ class XmlNodeWrapper implements XmlNode {
         return new CompoundIterator<>(iterators.toArray(it));
     }
 
+    @Override
+    public <P, R> R acceptVisitor(AstVisitor<? super P, ? extends R> visitor, P data) {
+        return visitor.cannotVisit(this, data);
+    }
 
     @Override
     public org.w3c.dom.Node getNode() {