Index: src/Tuples/TupleAssignment.cc
===================================================================
--- src/Tuples/TupleAssignment.cc	(revision eb1be63b645cb5da861f6859dc39d92d005a72cd)
+++ src/Tuples/TupleAssignment.cc	(revision 3251b66d2af6556bfddea750ab342e114cfd355b)
@@ -504,6 +504,7 @@
 
 			std::vector< ast::ptr< ast::Expr > > match() override {
-				static UniqueName lhsNamer( "__massassign_L" );
-				static UniqueName rhsNamer( "__massassign_R" );
+				// temporary workaround for new and old ast to coexist and avoid name collision
+				static UniqueName lhsNamer( "__massassign_Ln" );
+				static UniqueName rhsNamer( "__massassign_Rn" );
 				// empty tuple case falls into this matcher
 				assert( lhs.empty() ? rhs.empty() : rhs.size() <= 1 );
@@ -534,6 +535,7 @@
 
 			std::vector< ast::ptr< ast::Expr > > match() override {
-				static UniqueName lhsNamer( "__multassign_L" );
-				static UniqueName rhsNamer( "__multassign_R" );
+				// temporary workaround for new and old ast to coexist and avoid name collision
+				static UniqueName lhsNamer( "__multassign_Ln" );
+				static UniqueName rhsNamer( "__multassign_Rn" );
 
 				if ( lhs.size() != rhs.size() ) return {};