Painless: Special Case def (#32871)

This removes def from the classes map in PainlessLookup and instead always special 
cases it. This prevents potential calls against the def type that shouldn't be made and 
forces all cases of def throughout Painless code to be special cased.

Author: jdconrad

modules/lang-painless/src/main/java/org/elasticsearch/painless/ScriptClassInfo.java

@@ -21,6 +21,7 @@
 
 import org.elasticsearch.painless.lookup.PainlessLookup;
 import org.elasticsearch.painless.lookup.PainlessLookupUtility;
+import org.elasticsearch.painless.lookup.def;
 
 import java.lang.invoke.MethodType;
 import java.lang.reflect.Field;
@@ -190,7 +191,7 @@ private static Class<?> definitionTypeForClass(PainlessLookup painlessLookup, Cl
             componentType = componentType.getComponentType();
         }
 
-        if (painlessLookup.lookupPainlessClass(componentType) == null) {
+        if (componentType != def.class && painlessLookup.lookupPainlessClass(componentType) == null) {
             throw new IllegalArgumentException(unknownErrorMessageSource.apply(componentType));
         }
 

modules/lang-painless/src/main/java/org/elasticsearch/painless/lookup/PainlessLookup.java

@@ -26,6 +26,7 @@
 import java.util.Set;
 import java.util.function.Function;
 
+import static org.elasticsearch.painless.lookup.PainlessLookupUtility.DEF_CLASS_NAME;
 import static org.elasticsearch.painless.lookup.PainlessLookupUtility.buildPainlessConstructorKey;
 import static org.elasticsearch.painless.lookup.PainlessLookupUtility.buildPainlessFieldKey;
 import static org.elasticsearch.painless.lookup.PainlessLookupUtility.buildPainlessMethodKey;
@@ -47,7 +48,7 @@ public final class PainlessLookup {
     public boolean isValidCanonicalClassName(String canonicalClassName) {
         Objects.requireNonNull(canonicalClassName);
 
-        return canonicalClassNamesToClasses.containsKey(canonicalClassName);
+        return DEF_CLASS_NAME.equals(canonicalClassName) || canonicalClassNamesToClasses.containsKey(canonicalClassName);
     }
 
     public Class<?> canonicalTypeNameToType(String canonicalTypeName) {

modules/lang-painless/src/main/java/org/elasticsearch/painless/lookup/PainlessLookupBuilder.java

@@ -211,9 +211,6 @@ public static PainlessLookup buildFromWhitelists(List<Whitelist> whitelists) {
     public PainlessLookupBuilder() {
         canonicalClassNamesToClasses = new HashMap<>();
         classesToPainlessClassBuilders = new HashMap<>();
-
-        canonicalClassNamesToClasses.put(DEF_CLASS_NAME, def.class);
-        classesToPainlessClassBuilders.put(def.class, new PainlessClassBuilder());
     }
 
     private Class<?> canonicalTypeNameToType(String canonicalTypeName) {
@@ -225,7 +222,7 @@ private boolean isValidType(Class<?> type) {
             type = type.getComponentType();
         }
 
-        return classesToPainlessClassBuilders.containsKey(type);
+        return type == def.class || classesToPainlessClassBuilders.containsKey(type);
     }
 
     public void addPainlessClass(ClassLoader classLoader, String javaClassName, boolean importClassName) {

modules/lang-painless/src/main/java/org/elasticsearch/painless/lookup/PainlessLookupUtility.java

@@ -82,7 +82,7 @@ public static Class<?> canonicalTypeNameToType(String canonicalTypeName, Map<Str
         Objects.requireNonNull(canonicalTypeName);
         Objects.requireNonNull(canonicalClassNamesToClasses);
 
-        Class<?> type = canonicalClassNamesToClasses.get(canonicalTypeName);
+        Class<?> type = DEF_CLASS_NAME.equals(canonicalTypeName) ? def.class : canonicalClassNamesToClasses.get(canonicalTypeName);
 
         if (type != null) {
             return type;
@@ -105,7 +105,7 @@ public static Class<?> canonicalTypeNameToType(String canonicalTypeName, Map<Str
             }
 
             canonicalTypeName = canonicalTypeName.substring(0, canonicalTypeName.indexOf('['));
-            type = canonicalClassNamesToClasses.get(canonicalTypeName);
+            type = DEF_CLASS_NAME.equals(canonicalTypeName) ? def.class : canonicalClassNamesToClasses.get(canonicalTypeName);
 
             if (type != null) {
                 char arrayBraces[] = new char[arrayDimensions];