Adjust to the moving target called the C++ standard. Apparently nowadays it's not allowed to define an explicit copy constructor but not an assignment operator. Consequently, defining the explicit copy constructor in terms of the implicit/automatic assignment operator for general convenience no longer works. Add assignment operators. Caution: not tested with the IBM compiler, but there's no particular reason it shouldn't work.

--- a/anagram/agcore/tree.cpp	Mon May 30 23:32:56 2022 -0400
+++ b/anagram/agcore/tree.cpp	Mon May 30 23:46:22 2022 -0400
@@ -37,6 +37,10 @@
   : KeyedObjectRegister<parse_tree_map>(t)
 {}
 
+void ParseTree::operator = (const ParseTree &t) {
+  KeyedObjectRegister<parse_tree_map>::operator = (t);
+}
+
 ParseTree::ParseTree(CharSetExpression *x)
   : KeyedObjectRegister<parse_tree_map>(parse_tree_map(x))
 {