Index: src/Validate/ImplementEnumFunc.cpp
===================================================================
--- src/Validate/ImplementEnumFunc.cpp	(revision fb2e9169400799aaa1ef921982323d9b17c85548)
+++ src/Validate/ImplementEnumFunc.cpp	(revision cdb4eaa683e28a6751e0b414eb1f7d519898ac0c)
@@ -156,9 +156,4 @@
                                          const ast::ObjectDecl* dstParam,
                                          const ast::ObjectDecl* srcParam) {
-        // const CodeLocation& location = func->location;
-        // auto& params = func->params;
-        // assert(2 == params.size());
-        // auto dstParam = params.front().strict_as<ast::ObjectDecl>();
-        // auto srcParam = params.back().strict_as<ast::ObjectDecl>();
         return new ast::CompoundStmt(
             location,
@@ -440,5 +435,5 @@
 
     auto addOneExpr = ast::UntypedExpr::createCall( location,
-        "?+?",
+        succ? "?+?": "?-?",
         {new ast::VariableExpr(location, param),
         ast::ConstantExpr::from_int(location, 1)}