Index: src/GenPoly/Box.cc
===================================================================
--- src/GenPoly/Box.cc	(revision 7ed7b4a80c819b4f40dcf617aefc52c4682f81bc)
+++ src/GenPoly/Box.cc	(revision 44547b021e0a0a8176807a187bc5c1c80a63e39b)
@@ -97,13 +97,16 @@
 			void passArgTypeVars( ApplicationExpr *appExpr, Type *parmType, Type *argBaseType, std::list< Expression *>::iterator &arg, const TyVarMap &exprTyVars, std::set< std::string > &seenTypes );
 			/// passes extra type parameters into a polymorphic function application
-			void passTypeVars( ApplicationExpr *appExpr, Type *polyRetType, std::list< Expression *>::iterator &arg, const TyVarMap &exprTyVars );
+			/// Returns an iterator to the first argument after the added
+			/// arguments, which are added at the beginning.
+			std::list< Expression *>::iterator passTypeVars( ApplicationExpr *appExpr, Type *polyRetType, const TyVarMap &exprTyVars );
 			/// wraps a function application with a new temporary for the out-parameter return value
-			Expression *addRetParam( ApplicationExpr *appExpr, std::list< Expression *>::iterator arg, Type *retType );
+			/// The new out-parameter is the new first parameter.
+			Expression *addRetParam( ApplicationExpr *appExpr, Type *retType );
 			/// wraps a function application returning a polymorphic type with a new temporary for the out-parameter return value
-			Expression *addDynRetParam( ApplicationExpr *appExpr, std::list< Expression *>::iterator arg, Type *polyType );
+			Expression *addDynRetParam( ApplicationExpr *appExpr, Type *polyType );
 			/// Converts a function call into a call of the adapter with the
 			/// original function as the first argument (all other arguments
 			/// are pushed back). May adjust return value.
-			Expression *applyAdapter( ApplicationExpr *appExpr, std::list< Expression *>::iterator arg, FunctionType *function, const TyVarMap &exprTyVars );
+			Expression *applyAdapter( ApplicationExpr *appExpr, FunctionType *function );
 			/// Modifies the `arg`, replacing it with a boxed expression
 			/// that matches `formal` under the current TyVarMap.
@@ -555,9 +558,10 @@
 		}
 
-		void Pass1::passTypeVars( ApplicationExpr *appExpr, Type *polyRetType, std::list< Expression *>::iterator &arg, const TyVarMap &exprTyVars ) {
+		std::list< Expression *>::iterator Pass1::passTypeVars( ApplicationExpr *appExpr, Type *polyRetType, const TyVarMap &exprTyVars ) {
+			assert( env );
+			std::list< Expression *>::iterator arg = appExpr->args.begin();
 			// pass size/align for type variables
 			for ( std::pair<std::string, TypeDecl::Data> const & tyParam : exprTyVars ) {
 				ResolvExpr::EqvClass eqvClass;
-				assert( env );
 				if ( tyParam.second.isComplete ) {
 					Type *concrete = env->lookup( tyParam.first );
@@ -574,5 +578,5 @@
 
 			// add size/align for generic types to parameter list
-			if ( ! appExpr->get_function()->result ) return;
+			if ( ! appExpr->get_function()->result ) return arg;
 			FunctionType *funcType = getFunctionType( appExpr->get_function()->get_result() );
 			assert( funcType );
@@ -595,4 +599,5 @@
 				passArgTypeVars( appExpr, (*fnParm)->get_type(), argType, arg, exprTyVars, seenTypes );
 			}
+			return arg;
 		}
 
@@ -603,5 +608,5 @@
 		}
 
-		Expression *Pass1::addRetParam( ApplicationExpr *appExpr, std::list< Expression *>::iterator arg, Type *retType ) {
+		Expression *Pass1::addRetParam( ApplicationExpr *appExpr, Type *retType ) {
 			// Create temporary to hold return value of polymorphic function and produce that temporary as a result
 			// using a comma expression.
@@ -623,6 +628,6 @@
 				paramExpr = new AddressExpr( paramExpr );
 			} // if
-			arg = appExpr->args.insert( arg, paramExpr ); // add argument to function call
-			arg++;
+			// Add argument to function call.
+			appExpr->args.push_front( paramExpr );
 			// Build a comma expression to call the function and emulate a normal return.
 			CommaExpr *commaExpr = new CommaExpr( appExpr, retExpr );
@@ -666,17 +671,17 @@
 		}
 
-		Expression *Pass1::addDynRetParam( ApplicationExpr *appExpr, std::list< Expression *>::iterator arg, Type *dynType ) {
+		Expression *Pass1::addDynRetParam( ApplicationExpr *appExpr, Type *dynType ) {
 			Type *concrete = replaceWithConcrete( dynType, env );
 			// add out-parameter for return value
-			return addRetParam( appExpr, arg, concrete );
-		}
-
-		Expression *Pass1::applyAdapter( ApplicationExpr *appExpr, std::list< Expression *>::iterator arg, FunctionType *function, const TyVarMap &tyVars ) {
+			return addRetParam( appExpr, concrete );
+		}
+
+		Expression *Pass1::applyAdapter( ApplicationExpr *appExpr, FunctionType *function ) {
 			Expression *ret = appExpr;
 //			if ( ! function->get_returnVals().empty() && isPolyType( function->get_returnVals().front()->get_type(), tyVars ) ) {
-			if ( isDynRet( function, tyVars ) ) {
-				ret = addRetParam( appExpr, arg, function->returnVals.front()->get_type() );
+			if ( isDynRet( function, scopeTyVars ) ) {
+				ret = addRetParam( appExpr, function->returnVals.front()->get_type() );
 			} // if
-			std::string mangleName = mangleAdapterName( function, tyVars );
+			std::string mangleName = mangleAdapterName( function, scopeTyVars );
 			std::string adapterName = makeAdapterName( mangleName );
 
@@ -1097,6 +1102,4 @@
 
 			Expression *ret = appExpr;
-
-			std::list< Expression *>::iterator arg = appExpr->get_args().begin();
 			std::list< Expression *>::iterator paramBegin = appExpr->get_args().begin();
 
@@ -1119,5 +1122,5 @@
 				// std::cerr << "dynRetType: " << dynRetType << std::endl;
 				Type *concRetType = appExpr->get_result()->isVoid() ? nullptr : appExpr->get_result();
-				ret = addDynRetParam( appExpr, arg, concRetType ); // xxx - used to use dynRetType instead of concRetType
+				ret = addDynRetParam( appExpr, concRetType ); // xxx - used to use dynRetType instead of concRetType
 			} else if ( needsAdapter( function, scopeTyVars ) && ! needsAdapter( function, exprTyVars) ) { // xxx - exprTyVars is used above...?
 				// xxx - the ! needsAdapter check may be incorrect. It seems there is some situation where an adapter is applied where it shouldn't be, and this fixes it for some cases. More investigation is needed.
@@ -1127,15 +1130,15 @@
 				// std::cerr << *env << std::endl;
 				// change the application so it calls the adapter rather than the passed function
-				ret = applyAdapter( appExpr, arg, function, scopeTyVars );
+				ret = applyAdapter( appExpr, function );
 			} // if
-			arg = appExpr->get_args().begin();
 
 			Type *concRetType = replaceWithConcrete( dynRetType, env );
-			passTypeVars( appExpr, concRetType, arg, exprTyVars ); // xxx - used to use dynRetType instead of concRetType; this changed so that the correct type paramaters are passed for return types (it should be the concrete type's parameters, not the formal type's)
+			std::list< Expression *>::iterator arg =
+				passTypeVars( appExpr, concRetType, exprTyVars ); // xxx - used to use dynRetType instead of concRetType; this changed so that the correct type paramaters are passed for return types (it should be the concrete type's parameters, not the formal type's)
 			addInferredParams( appExpr, arg, function, exprTyVars );
 
-			arg = paramBegin;
-
-			boxParams( appExpr, arg, function, exprTyVars );
+			// This needs to point at the original first argument.
+			boxParams( appExpr, paramBegin, function, exprTyVars );
+
 			passAdapters( appExpr, function, exprTyVars );