Index: src/AST/Chain.hpp
===================================================================
--- src/AST/Chain.hpp	(revision 4864a73f6af536425f476d1b447d232e82bd4edf)
+++ src/AST/Chain.hpp	(revision 4864a73f6af536425f476d1b447d232e82bd4edf)
@@ -0,0 +1,63 @@
+//
+// Cforall Version 1.0.0 Copyright (C) 2019 University of Waterloo
+//
+// The contents of this file are covered under the licence agreement in the
+// file "LICENCE" distributed with Cforall.
+//
+// Chain.hpp --
+//
+// Author           : Thierry Delisle
+// Created On       : Wed Jun 05 14:11:52 2019
+// Last Modified By :
+// Last Modified On :
+// Update Count     :
+//
+
+#include "Node.hpp"
+
+namespace ast {
+
+template<typename T>
+struct _chain_mutator;
+
+template<typename node_t, Node::ref_type ref_t>
+struct _chain_mutator<ptr_base<node_t, ref_t>>;
+
+template<template <class...> class container_t, typename node_t, Node::ref_type ref_t>
+struct _chain_mutator<container_t<ptr_base<node_t, ref_t>>>;
+
+template<typename node_t, Node::ref_type ref_t>
+struct _chain_mutator<ptr_base<node_t, ref_t>> {
+	ptr_base<node_t, ref_t> & base;
+
+	template<typename actual_node_t, typename child_t>
+	auto operator()( child_t actual_node_t::*child ) {
+		auto n = mutate(base.get());
+		actual_node_t * node = strict_dynamic_cast<actual_node_t *>(n);
+		base = node;
+		return _chain_mutator< typename std::remove_reference< decltype(node->*child) >::type >{node->*child};
+	}
+
+	node_t * operator->() {
+		auto n = mutate(base.get());
+		base = n;
+		return n;
+	}
+};
+
+template<template <class...> class container_t, typename node_t, Node::ref_type ref_t>
+struct _chain_mutator<container_t<ptr_base<node_t, ref_t>>> {
+	container_t<ptr_base<node_t, ref_t>> & base;
+
+	auto operator[]( size_t i ) {
+		return _chain_mutator<ptr_base<node_t, ref_t>>{base[i]};
+	}
+};
+
+
+template< typename node_t, Node::ref_type ref_t >
+auto chain_mutate( ptr_base<node_t, ref_t> & base ) {
+	return _chain_mutator<ptr_base<node_t, ref_t>>{ base };
+}
+
+}
Index: src/AST/Node.cpp
===================================================================
--- src/AST/Node.cpp	(revision 2a8f0c1669168188e34b22dccd9a154ce2c7ba79)
+++ src/AST/Node.cpp	(revision 4864a73f6af536425f476d1b447d232e82bd4edf)
@@ -34,4 +34,7 @@
 template< typename node_t, enum ast::Node::ref_type ref_t >
 void ast::ptr_base<node_t, ref_t>::_dec( const node_t * node ) { node->decrement(ref_t); }
+
+template< typename node_t, enum ast::Node::ref_type ref_t >
+void ast::ptr_base<node_t, ref_t>::_check() const { if(node) assert(node->was_ever_strong == false || node->strong_count > 0); }
 
 template< typename node_t, enum ast::Node::ref_type ref_t >
Index: src/AST/Node.hpp
===================================================================
--- src/AST/Node.hpp	(revision 2a8f0c1669168188e34b22dccd9a154ce2c7ba79)
+++ src/AST/Node.hpp	(revision 4864a73f6af536425f476d1b447d232e82bd4edf)
@@ -46,4 +46,6 @@
 	};
 
+	bool unique() const { return strong_count == 1; }
+
 private:
 	/// Make a copy of this node; should be overridden in subclass with more precise return type
@@ -56,8 +58,9 @@
 	mutable size_t strong_count = 0;
 	mutable size_t weak_count = 0;
+	mutable bool was_ever_strong = false;
 
 	void increment(ref_type ref) const {
 		switch (ref) {
-			case ref_type::strong: strong_count++; break;
+			case ref_type::strong: strong_count++; was_ever_strong = true; break;
 			case ref_type::weak  : weak_count  ++; break;
 		}
@@ -176,13 +179,13 @@
 	}
 
-	const node_t * get() const { return  node; }
-	const node_t * operator->() const { return  node; }
-	const node_t & operator* () const { return *node; }
-	explicit operator bool() const { return node; }
-	operator const node_t * () const { return node; }
+	const node_t * get() const { _check(); return  node; }
+	const node_t * operator->() const { _check(); return  node; }
+	const node_t & operator* () const { _check(); return *node; }
+	explicit operator bool() const { _check(); return node; }
+	operator const node_t * () const { _check(); return node; }
 
 	/// wrapper for convenient access to dynamic_cast
 	template<typename o_node_t>
-	const o_node_t * as() const { return dynamic_cast<const o_node_t *>(node); }
+	const o_node_t * as() const { _check(); return dynamic_cast<const o_node_t *>(node); }
 
 	/// wrapper for convenient access to strict_dynamic_cast
@@ -208,4 +211,5 @@
 	void _inc( const node_t * other );
 	void _dec( const node_t * other );
+	void _check() const;
 
 protected:
Index: src/ResolvExpr/Resolver.cc
===================================================================
--- src/ResolvExpr/Resolver.cc	(revision 2a8f0c1669168188e34b22dccd9a154ce2c7ba79)
+++ src/ResolvExpr/Resolver.cc	(revision 4864a73f6af536425f476d1b447d232e82bd4edf)
@@ -27,4 +27,5 @@
 #include "typeops.h"                     // for extractResultType
 #include "Unify.h"                       // for unify
+#include "AST/Chain.hpp"
 #include "AST/Decl.hpp"
 #include "AST/Init.hpp"
@@ -407,8 +408,8 @@
 
 	void Resolver_old::previsit( ObjectDecl * objectDecl ) {
-		// To handle initialization of routine pointers, e.g., int (*fp)(int) = foo(), means that 
-		// class-variable initContext is changed multiple time because the LHS is analysed twice. 
-		// The second analysis changes initContext because of a function type can contain object 
-		// declarations in the return and parameter types. So each value of initContext is 
+		// To handle initialization of routine pointers, e.g., int (*fp)(int) = foo(), means that
+		// class-variable initContext is changed multiple time because the LHS is analysed twice.
+		// The second analysis changes initContext because of a function type can contain object
+		// declarations in the return and parameter types. So each value of initContext is
 		// retained, so the type on the first analysis is preserved and used for selecting the RHS.
 		GuardValue( currentObject );
@@ -447,5 +448,5 @@
 
 	void Resolver_old::postvisit( FunctionDecl * functionDecl ) {
-		// default value expressions have an environment which shouldn't be there and trips up 
+		// default value expressions have an environment which shouldn't be there and trips up
 		// later passes.
 		// xxx - it might be necessary to somehow keep the information from this environment, but I
@@ -939,14 +940,14 @@
 	///////////////////////////////////////////////////////////////////////////
 
-	class Resolver_new final 
-	: public ast::WithSymbolTable, public ast::WithGuards, 
-	  public ast::WithVisitorRef<Resolver_new>, public ast::WithShortCircuiting, 
+	class Resolver_new final
+	: public ast::WithSymbolTable, public ast::WithGuards,
+	  public ast::WithVisitorRef<Resolver_new>, public ast::WithShortCircuiting,
 	  public ast::WithStmtsToAdd<> {
-	
+
 		ast::ptr< ast::Type > functionReturn = nullptr;
 		// ast::CurrentObject currentObject = nullptr;
 		// bool inEnumDecl = false;
 
-	public: 
+	public:
 		Resolver_new() = default;
 		Resolver_new( const ast::SymbolTable & syms ) { symtab = syms; }
@@ -991,19 +992,23 @@
 
 	const ast::FunctionDecl * Resolver_new::postvisit( const ast::FunctionDecl * functionDecl ) {
-		// default value expressions have an environment which shouldn't be there and trips up 
+		// default value expressions have an environment which shouldn't be there and trips up
 		// later passes.
 		ast::ptr< ast::FunctionDecl > ret = functionDecl;
 		for ( unsigned i = 0; i < functionDecl->type->params.size(); ++i ) {
 			const ast::ptr<ast::DeclWithType> & d = functionDecl->type->params[i];
-			
+
 			if ( const ast::ObjectDecl * obj = d.as< ast::ObjectDecl >() ) {
 				if ( const ast::SingleInit * init = obj->init.as< ast::SingleInit >() ) {
 					if ( init->value->env == nullptr ) continue;
 					// clone initializer minus the initializer environment
-					strict_dynamic_cast< ast::SingleInit * >(
-						strict_dynamic_cast< ast::ObjectDecl * >( 
-							ret.get_and_mutate()->type.get_and_mutate()->params[i].get_and_mutate()
-						)->init.get_and_mutate()
-					)->value.get_and_mutate()->env = nullptr;
+					ast::chain_mutate( ret )
+						( &ast::FunctionDecl::type )
+							( &ast::FunctionType::params )
+								[i]
+								( &ast::ObjectDecl::init )
+									( &ast::SingleInit::value )->env = nullptr;
+
+					assert( functionDecl != ret.get() || functionDecl->unique() );
+					assert( ! ret->type->params[i].strict_as< ast::ObjectDecl >()->init.strict_as< ast::SingleInit >()->value->env );
 				}
 			}