copy constructors in AlgConses

when copying an algebraic type extension from the definition to the implementation module

frontend/check.icl

@@ -1441,6 +1441,9 @@ where
 		add_type_def td=:{td_pos, td_rhs = UncheckedAlgConses type_ext_ident conses} new_type_defs new_cons_defs new_selector_defs conversion_table icl_sizes icl_decl_symbols cs
 			# (conses,(new_cons_defs,conversion_table,icl_sizes,icl_decl_symbols,cs)) = copy_and_redirect_cons_symbols com_cons_defs td_pos conses (new_cons_defs,conversion_table,icl_sizes,icl_decl_symbols,cs)
 			= ([{ td & td_rhs = UncheckedAlgConses type_ext_ident conses} : new_type_defs],new_cons_defs,new_selector_defs,conversion_table,icl_sizes,icl_decl_symbols,cs)
+		add_type_def td=:{td_pos, td_rhs = AlgConses conses type_ext_ident} new_type_defs new_cons_defs new_selector_defs conversion_table icl_sizes icl_decl_symbols cs
+			# (conses,(new_cons_defs,conversion_table,icl_sizes,icl_decl_symbols,cs)) = copy_and_redirect_cons_symbols com_cons_defs td_pos conses (new_cons_defs,conversion_table,icl_sizes,icl_decl_symbols,cs)
+			= ([{ td & td_rhs = AlgConses conses type_ext_ident} : new_type_defs],new_cons_defs,new_selector_defs,conversion_table,icl_sizes,icl_decl_symbols,cs)
 		add_type_def td new_type_defs new_cons_defs new_selector_defs conversion_table icl_sizes icl_decl_symbols cs
 			= ([td : new_type_defs],new_cons_defs,new_selector_defs,conversion_table,icl_sizes,icl_decl_symbols,cs) 
 	add_dcl_definition _ _ result = result