diff --git a/vhdlpp/expression.cc b/vhdlpp/expression.cc
index 8c2061968..7029092ac 100644
--- a/vhdlpp/expression.cc
+++ b/vhdlpp/expression.cc
@@ -659,7 +659,7 @@ void ExpName::visit(ExprVisitor& func)
       func(this);
 }
 
-int ExpName::index_t::emit(ostream&out, Entity*ent, ScopeBase*scope)
+int ExpName::index_t::emit(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       int errors = 0;
 
diff --git a/vhdlpp/expression.h b/vhdlpp/expression.h
index bed415af5..1df357f4d 100644
--- a/vhdlpp/expression.h
+++ b/vhdlpp/expression.h
@@ -97,11 +97,11 @@ class Expression : public LineInfo {
 	// The emit virtual method is called by architecture emit to
 	// output the generated code for the expression. The derived
 	// class fills in the details of what exactly happened.
-      virtual int emit(ostream&out, Entity*ent, ScopeBase*scope) =0;
+      virtual int emit(ostream&out, Entity*ent, ScopeBase*scope) const =0;
 
 	// The emit_package virtual message is similar, but is called
 	// in a package context and to emit SV packages.
-      virtual int emit_package(std::ostream&out);
+      virtual int emit_package(std::ostream&out) const;
 
 	// The evaluate virtual method tries to evaluate expressions
 	// to constant literal values. Return true and set the val
@@ -176,7 +176,7 @@ class ExpUnary : public Expression {
       inline void write_to_stream_operand1(std::ostream&fd) const
       { operand1_->write_to_stream(fd); }
 
-      int emit_operand1(ostream&out, Entity*ent, ScopeBase*scope);
+      int emit_operand1(ostream&out, Entity*ent, ScopeBase*scope) const;
       void dump_operand1(ostream&out, int indent = 0) const;
 
     private:
@@ -202,8 +202,8 @@ class ExpBinary : public Expression {
     protected:
 
       int elaborate_exprs(Entity*, ScopeBase*, const VType*);
-      int emit_operand1(ostream&out, Entity*ent, ScopeBase*scope);
-      int emit_operand2(ostream&out, Entity*ent, ScopeBase*scope);
+      int emit_operand1(ostream&out, Entity*ent, ScopeBase*scope) const;
+      int emit_operand2(ostream&out, Entity*ent, ScopeBase*scope) const;
 
       bool eval_operand1(Entity*ent, ScopeBase*scope, int64_t&val) const;
       bool eval_operand2(Entity*ent, ScopeBase*scope, int64_t&val) const;
@@ -308,15 +308,15 @@ class ExpAggregate : public Expression {
       const VType*fit_type(Entity*ent, ScopeBase*scope, const VTypeArray*atype) const;
       int elaborate_expr(Entity*ent, ScopeBase*scope, const VType*ltype);
       void write_to_stream(std::ostream&fd) const;
-      int emit(ostream&out, Entity*ent, ScopeBase*scope);
+      int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
       void dump(ostream&out, int indent = 0) const;
       void visit(ExprVisitor& func);
 
     private:
       int elaborate_expr_array_(Entity*ent, ScopeBase*scope, const VTypeArray*ltype);
       int elaborate_expr_record_(Entity*ent, ScopeBase*scope, const VTypeRecord*ltype);
-      int emit_array_(ostream&out, Entity*ent, ScopeBase*scope, const VTypeArray*ltype);
-      int emit_record_(ostream&out, Entity*ent, ScopeBase*scope, const VTypeRecord*ltype);
+      int emit_array_(ostream&out, Entity*ent, ScopeBase*scope, const VTypeArray*ltype) const;
+      int emit_record_(ostream&out, Entity*ent, ScopeBase*scope, const VTypeRecord*ltype) const;
 
     private:
 	// This is the elements as directly parsed.
@@ -342,7 +342,7 @@ class ExpArithmetic : public ExpBinary {
 
       int elaborate_expr(Entity*ent, ScopeBase*scope, const VType*ltype);
       void write_to_stream(std::ostream&fd) const;
-      int emit(ostream&out, Entity*ent, ScopeBase*scope);
+      int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
       virtual bool evaluate(Entity*ent, ScopeBase*scope, int64_t&val) const;
       void dump(ostream&out, int indent = 0) const;
 
@@ -386,7 +386,7 @@ class ExpObjAttribute : public ExpAttribute {
 
       inline const ExpName* peek_base() const { return base_; }
 
-      int emit(ostream&out, Entity*ent, ScopeBase*scope);
+      int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
       const VType*probe_type(Entity*ent, ScopeBase*scope) const;
       int elaborate_expr(Entity*ent, ScopeBase*scope, const VType*ltype);
       void write_to_stream(std::ostream&fd) const;
@@ -408,7 +408,7 @@ class ExpTypeAttribute : public ExpAttribute {
 
       inline const VType* peek_base() const { return base_; }
 
-      int emit(ostream&out, Entity*ent, ScopeBase*scope);
+      int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
       const VType*probe_type(Entity*ent, ScopeBase*scope) const;
       int elaborate_expr(Entity*ent, ScopeBase*scope, const VType*ltype);
       void write_to_stream(std::ostream&fd) const;
@@ -434,7 +434,7 @@ class ExpBitstring : public Expression {
       const VType*fit_type(Entity*ent, ScopeBase*scope, const VTypeArray*atype) const;
       int elaborate_expr(Entity*ent, ScopeBase*scope, const VType*ltype);
       void write_to_stream(std::ostream&fd) const;
-      int emit(ostream&out, Entity*ent, ScopeBase*scope);
+      int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
       void dump(ostream&out, int indent = 0) const;
 
     private:
@@ -454,7 +454,7 @@ class ExpCharacter : public Expression {
       const VType*fit_type(Entity*ent, ScopeBase*scope, const VTypeArray*atype) const;
       int elaborate_expr(Entity*ent, ScopeBase*scope, const VType*ltype);
       void write_to_stream(std::ostream&fd) const;
-      int emit(ostream&out, Entity*ent, ScopeBase*scope);
+      int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
       bool is_primary(void) const;
       void dump(ostream&out, int indent = 0) const;
 
@@ -462,7 +462,7 @@ class ExpCharacter : public Expression {
 
     private:
       int emit_primitive_bit_(ostream&out, Entity*ent, ScopeBase*scope,
-			      const VTypePrimitive*etype);
+			      const VTypePrimitive*etype) const;
 
     private:
       char value_;
@@ -482,7 +482,7 @@ class ExpConcat : public Expression {
       const VType*fit_type(Entity*ent, ScopeBase*scope, const VTypeArray*atype) const;
       int elaborate_expr(Entity*ent, ScopeBase*scope, const VType*ltype);
       void write_to_stream(std::ostream&fd) const;
-      int emit(ostream&out, Entity*ent, ScopeBase*scope);
+      int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
       bool is_primary(void) const;
       void dump(ostream&out, int indent = 0) const;
       void visit(ExprVisitor& func);
@@ -513,8 +513,8 @@ class ExpConditional : public Expression {
 	    inline void set_condition(Expression*cond) { cond_ = cond; }
 
 	    int elaborate_expr(Entity*ent, ScopeBase*scope, const VType*lt);
-	    int emit_option(ostream&out, Entity*ent, ScopeBase*scope);
-	    int emit_default(ostream&out, Entity*ent, ScopeBase*scope);
+	    int emit_option(ostream&out, Entity*ent, ScopeBase*scope) const;
+	    int emit_default(ostream&out, Entity*ent, ScopeBase*scope) const;
 	    void dump(ostream&out, int indent = 0) const;
             std::list<Expression*>& extract_true_clause() { return true_clause_; }
             void visit(ExprVisitor& func);
@@ -534,7 +534,7 @@ class ExpConditional : public Expression {
       const VType*probe_type(Entity*ent, ScopeBase*scope) const;
       int elaborate_expr(Entity*ent, ScopeBase*scope, const VType*ltype);
       void write_to_stream(std::ostream&fd) const;
-      int emit(ostream&out, Entity*ent, ScopeBase*scope);
+      int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
       void dump(ostream&out, int indent = 0) const;
       void visit(ExprVisitor& func);
 
@@ -574,7 +574,7 @@ class ExpEdge : public ExpUnary {
       inline fun_t edge_fun() const { return fun_; }
 
       void write_to_stream(std::ostream&fd) const;
-      int emit(ostream&out, Entity*ent, ScopeBase*scope);
+      int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
       void dump(ostream&out, int indent = 0) const;
 
     private:
@@ -600,7 +600,7 @@ class ExpFunc : public Expression {
       const VType*probe_type(Entity*ent, ScopeBase*scope) const;
       int elaborate_expr(Entity*ent, ScopeBase*scope, const VType*ltype);
       void write_to_stream(std::ostream&fd) const;
-      int emit(ostream&out, Entity*ent, ScopeBase*scope);
+      int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
       void dump(ostream&out, int indent = 0) const;
       void visit(ExprVisitor& func); // NOTE: does not handle expressions in subprogram
 
@@ -622,8 +622,8 @@ class ExpInteger : public Expression {
       const VType*probe_type(Entity*ent, ScopeBase*scope) const;
       int elaborate_expr(Entity*ent, ScopeBase*scope, const VType*ltype);
       void write_to_stream(std::ostream&fd) const;
-      int emit(ostream&out, Entity*ent, ScopeBase*scope);
-      int emit_package(std::ostream&out);
+      int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
+      int emit_package(std::ostream&out) const;
       bool is_primary(void) const { return true; }
       bool evaluate(Entity*ent, ScopeBase*scope, int64_t&val) const;
       void dump(ostream&out, int indent = 0) const;
@@ -645,8 +645,8 @@ class ExpReal : public Expression {
       const VType*probe_type(Entity*ent, ScopeBase*scope) const;
       int elaborate_expr(Entity*ent, ScopeBase*scope, const VType*ltype);
       void write_to_stream(std::ostream&fd) const;
-      int emit(ostream&out, Entity*ent, ScopeBase*scope);
-      int emit_package(std::ostream&out);
+      int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
+      int emit_package(std::ostream&out) const;
       bool is_primary(void) const;
       void dump(ostream&out, int indent = 0) const;
       virtual ostream& dump_inline(ostream&out) const;
@@ -672,7 +672,7 @@ class ExpLogical : public ExpBinary {
 
       int elaborate_expr(Entity*ent, ScopeBase*scope, const VType*ltype);
       void write_to_stream(std::ostream&fd) const;
-      int emit(ostream&out, Entity*ent, ScopeBase*scope);
+      int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
       void dump(ostream&out, int indent = 0) const;
 
     private:
@@ -705,7 +705,7 @@ class ExpName : public Expression {
       const VType* fit_type(Entity*ent, ScopeBase*scope, const VTypeArray*host) const;
       int elaborate_expr(Entity*ent, ScopeBase*scope, const VType*ltype);
       void write_to_stream(std::ostream&fd) const;
-      int emit(ostream&out, Entity*ent, ScopeBase*scope);
+      int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
       bool is_primary(void) const;
       bool evaluate(Entity*ent, ScopeBase*scope, int64_t&val) const;
       bool symbolic_compare(const Expression*that) const;
@@ -726,7 +726,7 @@ class ExpName : public Expression {
                 delete offset_;
           }
 
-          int emit(ostream&out, Entity*ent, ScopeBase*scope);
+          int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
 
       private:
           Expression*idx_;
@@ -740,14 +740,14 @@ class ExpName : public Expression {
       const VType* probe_prefix_type_(Entity*ent, ScopeBase*scope) const;
       const VType* probe_prefixed_type_(Entity*ent, ScopeBase*scope) const;
 
-      int emit_as_prefix_(ostream&out, Entity*ent, ScopeBase*scope);
+      int emit_as_prefix_(ostream&out, Entity*ent, ScopeBase*scope) const;
 
 	// There are some workarounds required for constant arrays/records, as
 	// they are currently emitted as flat localparams (without any type
 	// information). The following workarounds adjust the access indices
 	// to select appropriate parts of the localparam.
       bool try_workarounds_(ostream&out, Entity*ent, ScopeBase*scope,
-                            list<index_t*>&indices, int&data_size);
+                            list<index_t*>&indices, int&data_size) const;
 
       bool check_const_array_workaround_(const VTypeArray*arr, ScopeBase*scope,
                                          list<index_t*>&indices, int&data_size) const;
@@ -756,7 +756,7 @@ class ExpName : public Expression {
                                           list<index_t*>&indices, int&data_size) const;
 
       int emit_workaround_(ostream&out, Entity*ent, ScopeBase*scope,
-                           const list<index_t*>&indices, int field_size);
+                           const list<index_t*>&indices, int field_size) const;
 
     private:
       std::auto_ptr<ExpName> prefix_;
@@ -793,7 +793,7 @@ class ExpRelation : public ExpBinary {
       const VType* probe_type(Entity*ent, ScopeBase*scope) const;
       int elaborate_expr(Entity*ent, ScopeBase*scope, const VType*ltype);
       void write_to_stream(std::ostream&fd) const;
-      int emit(ostream&out, Entity*ent, ScopeBase*scope);
+      int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
       void dump(ostream&out, int indent = 0) const;
 
     private:
@@ -813,7 +813,7 @@ class ExpShift : public ExpBinary {
 
       int elaborate_expr(Entity*ent, ScopeBase*scope, const VType*ltype);
       void write_to_stream(std::ostream&fd) const;
-      int emit(ostream&out, Entity*ent, ScopeBase*scope);
+      int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
       bool evaluate(Entity*ent, ScopeBase*scope, int64_t&val) const;
       void dump(ostream&out, int indent = 0) const;
 
@@ -833,7 +833,7 @@ class ExpString : public Expression {
       const VType*fit_type(Entity*ent, ScopeBase*scope, const VTypeArray*atype) const;
       int elaborate_expr(Entity*ent, ScopeBase*scope, const VType*ltype);
       void write_to_stream(std::ostream&fd) const;
-      int emit(ostream&out, Entity*ent, ScopeBase*scope);
+      int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
       bool is_primary(void) const;
       void dump(ostream&out, int indent = 0) const;
       const std::string& get_value() const { return value_; }
@@ -843,7 +843,7 @@ class ExpString : public Expression {
       static std::string escape_quot(const std::string& str);
 
     private:
-      int emit_as_array_(ostream&out, Entity*ent, ScopeBase*scope, const VTypeArray*arr);
+      int emit_as_array_(ostream&out, Entity*ent, ScopeBase*scope, const VTypeArray*arr) const;
 
     private:
       std::string value_;
@@ -858,7 +858,7 @@ class ExpUAbs : public ExpUnary {
       Expression*clone() const { return new ExpUAbs(peek_operand()->clone()); }
 
       void write_to_stream(std::ostream&fd) const;
-      int emit(ostream&out, Entity*ent, ScopeBase*scope);
+      int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
       void dump(ostream&out, int indent = 0) const;
 };
 
@@ -871,7 +871,7 @@ class ExpUNot : public ExpUnary {
       Expression*clone() const { return new ExpUNot(peek_operand()->clone()); }
 
       void write_to_stream(std::ostream&fd) const;
-      int emit(ostream&out, Entity*ent, ScopeBase*scope);
+      int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
       void dump(ostream&out, int indent = 0) const;
 };
 
@@ -890,7 +890,7 @@ class ExpCast : public Expression {
             return base_->elaborate_expr(ent, scope, type_);
       }
       void write_to_stream(std::ostream&fd) const;
-      int emit(ostream&out, Entity*ent, ScopeBase*scope);
+      int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
       void dump(ostream&out, int indent = 0) const;
       void visit(ExprVisitor& func);
 
@@ -913,7 +913,7 @@ class ExpNew : public Expression {
 
       // There is no 'new' in VHDL - do not emit anything
       void write_to_stream(std::ostream&) const {};
-      int emit(ostream&out, Entity*ent, ScopeBase*scope);
+      int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
       void dump(ostream&out, int indent = 0) const;
       void visit(ExprVisitor& func);
 
@@ -931,7 +931,7 @@ class ExpTime : public Expression {
 
         int elaborate_expr(Entity*ent, ScopeBase*scope, const VType*ltype);
         void write_to_stream(std::ostream&) const;
-        int emit(ostream&out, Entity*ent, ScopeBase*scope);
+        int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
         //bool evaluate(Entity*ent, ScopeBase*scope, int64_t&val) const;
         void dump(ostream&out, int indent = 0) const;
 
@@ -966,7 +966,7 @@ class ExpRange : public Expression {
 
         int elaborate_expr(Entity*ent, ScopeBase*scope, const VType*ltype);
         void write_to_stream(std::ostream&) const;
-        int emit(ostream&out, Entity*ent, ScopeBase*scope);
+        int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
         void dump(ostream&out, int indent = 0) const;
     private:
         // Regular range related fields
diff --git a/vhdlpp/expression_emit.cc b/vhdlpp/expression_emit.cc
index 8a22c5500..a940a32cc 100644
--- a/vhdlpp/expression_emit.cc
+++ b/vhdlpp/expression_emit.cc
@@ -62,7 +62,7 @@ inline static int emit_logic(char val, ostream& out, const VTypePrimitive::type_
     return 0;
 }
 
-int Expression::emit(ostream&out, Entity*, ScopeBase*)
+int Expression::emit(ostream&out, Entity*, ScopeBase*) const
 {
       out << " /* " << get_fileline() << ": internal error: "
 	  << "I don't know how to emit this expression! "
@@ -70,7 +70,7 @@ int Expression::emit(ostream&out, Entity*, ScopeBase*)
       return 1;
 }
 
-int Expression::emit_package(ostream&out)
+int Expression::emit_package(ostream&out) const
 {
       out << " /* " << get_fileline() << ": internal error: "
 	  << "I don't know how to emit_package this expression! "
@@ -83,7 +83,7 @@ bool Expression::is_primary(void) const
       return false;
 }
 
-int ExpBinary::emit_operand1(ostream&out, Entity*ent, ScopeBase*scope)
+int ExpBinary::emit_operand1(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       int errors = 0;
       bool oper_primary = operand1_->is_primary();
@@ -93,7 +93,7 @@ int ExpBinary::emit_operand1(ostream&out, Entity*ent, ScopeBase*scope)
       return errors;
 }
 
-int ExpBinary::emit_operand2(ostream&out, Entity*ent, ScopeBase*scope)
+int ExpBinary::emit_operand2(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       int errors = 0;
       bool oper_primary = operand2_->is_primary();
@@ -103,14 +103,14 @@ int ExpBinary::emit_operand2(ostream&out, Entity*ent, ScopeBase*scope)
       return errors;
 }
 
-int ExpUnary::emit_operand1(ostream&out, Entity*ent, ScopeBase*scope)
+int ExpUnary::emit_operand1(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       int errors = 0;
       errors += operand1_->emit(out, ent, scope);
       return errors;
 }
 
-int ExpAggregate::emit(ostream&out, Entity*ent, ScopeBase*scope)
+int ExpAggregate::emit(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       if (peek_type() == 0) {
 	    out << "/* " << get_fileline() << ": internal error: "
@@ -134,7 +134,7 @@ int ExpAggregate::emit(ostream&out, Entity*ent, ScopeBase*scope)
       return 1;
 }
 
-int ExpAggregate::emit_array_(ostream&out, Entity*ent, ScopeBase*scope, const VTypeArray*atype)
+int ExpAggregate::emit_array_(ostream&out, Entity*ent, ScopeBase*scope, const VTypeArray*atype) const
 {
       int errors = 0;
 
@@ -194,8 +194,8 @@ int ExpAggregate::emit_array_(ostream&out, Entity*ent, ScopeBase*scope, const VT
       if(use_msb < use_lsb)
         swap(use_msb, use_lsb);
 
-      map<int64_t,choice_element*> element_map;
-      choice_element*element_other = 0;
+      map<int64_t,const choice_element*> element_map;
+      const choice_element*element_other = 0;
 
       bool positional_section = true;
       int64_t positional_idx = use_msb;
@@ -283,7 +283,7 @@ int ExpAggregate::emit_array_(ostream&out, Entity*ent, ScopeBase*scope, const VT
 
       out << "{";
       for (int64_t idx = use_msb ; idx >= use_lsb ; idx -= 1) {
-	    choice_element*cur = element_map[idx];
+	    const choice_element*cur = element_map[idx];
 	    if (cur == 0)
 		  cur = element_other;
 
@@ -303,7 +303,7 @@ int ExpAggregate::emit_array_(ostream&out, Entity*ent, ScopeBase*scope, const VT
       return errors;
 }
 
-int ExpAggregate::emit_record_(ostream&out, Entity*ent, ScopeBase*scope, const VTypeRecord*)
+int ExpAggregate::emit_record_(ostream&out, Entity*ent, ScopeBase*scope, const VTypeRecord*) const
 {
       int errors = 0;
 
@@ -331,7 +331,7 @@ int ExpAggregate::emit_record_(ostream&out, Entity*ent, ScopeBase*scope, const V
       return errors;
 }
 
-int ExpObjAttribute::emit(ostream&out, Entity*ent, ScopeBase*scope)
+int ExpObjAttribute::emit(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       int errors = 0;
 
@@ -372,7 +372,7 @@ int ExpObjAttribute::emit(ostream&out, Entity*ent, ScopeBase*scope)
       return errors;
 }
 
-int ExpTypeAttribute::emit(ostream&out, Entity*ent, ScopeBase*scope)
+int ExpTypeAttribute::emit(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       int errors = 0;
 
@@ -409,7 +409,7 @@ int ExpTypeAttribute::emit(ostream&out, Entity*ent, ScopeBase*scope)
       return errors;
 }
 
-int ExpArithmetic::emit(ostream&out, Entity*ent, ScopeBase*scope)
+int ExpArithmetic::emit(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       int errors = 0;
 
@@ -463,7 +463,7 @@ int ExpArithmetic::emit(ostream&out, Entity*ent, ScopeBase*scope)
       return errors;
 }
 
-int ExpBitstring::emit(ostream&out, Entity*, ScopeBase*)
+int ExpBitstring::emit(ostream&out, Entity*, ScopeBase*) const
 {
       int errors = 0;
 
@@ -475,7 +475,7 @@ int ExpBitstring::emit(ostream&out, Entity*, ScopeBase*)
 }
 
 int ExpCharacter::emit_primitive_bit_(ostream&out, Entity*, ScopeBase*,
-				      const VTypePrimitive*etype)
+				      const VTypePrimitive*etype) const
 {
       out << "1'b";
       int res = emit_logic(value_, out, etype->type());
@@ -488,7 +488,7 @@ int ExpCharacter::emit_primitive_bit_(ostream&out, Entity*, ScopeBase*,
       return res;
 }
 
-int ExpCharacter::emit(ostream&out, Entity*ent, ScopeBase*scope)
+int ExpCharacter::emit(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       const VType*etype = peek_type();
       const VTypeArray*array;
@@ -519,7 +519,7 @@ bool ExpConcat::is_primary(void) const
       return true;
 }
 
-int ExpConcat::emit(ostream&out, Entity*ent, ScopeBase*scope)
+int ExpConcat::emit(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       int errors = 0;
       out << "{";
@@ -530,7 +530,7 @@ int ExpConcat::emit(ostream&out, Entity*ent, ScopeBase*scope)
       return errors;
 }
 
-int ExpConditional::emit(ostream&out, Entity*ent, ScopeBase*scope)
+int ExpConditional::emit(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       int errors = 0;
       out << "(";
@@ -538,10 +538,10 @@ int ExpConditional::emit(ostream&out, Entity*ent, ScopeBase*scope)
 	// Draw out any when-else expressions. These are all the else_
 	// clauses besides the last.
       if (options_.size() > 1) {
-	    list<case_t*>::iterator last = options_.end();
+	    list<case_t*>::const_iterator last = options_.end();
 	    --last;
 
-	    for (list<case_t*>::iterator cur = options_.begin()
+	    for (list<case_t*>::const_iterator cur = options_.begin()
 		       ; cur != last ; ++cur) {
 		  errors += (*cur)->emit_option(out, ent, scope);
 	    }
@@ -560,7 +560,7 @@ int ExpConditional::emit(ostream&out, Entity*ent, ScopeBase*scope)
       return errors;
 }
 
-int ExpConditional::case_t::emit_option(ostream&out, Entity*ent, ScopeBase*scope)
+int ExpConditional::case_t::emit_option(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       int errors = 0;
       assert(cond_ != 0);
@@ -582,7 +582,7 @@ int ExpConditional::case_t::emit_option(ostream&out, Entity*ent, ScopeBase*scope
       return errors;
 }
 
-int ExpConditional::case_t::emit_default(ostream&out, Entity*ent, ScopeBase*scope)
+int ExpConditional::case_t::emit_default(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       int errors = 0;
 	// Trailing else must have no condition.
@@ -599,7 +599,7 @@ int ExpConditional::case_t::emit_default(ostream&out, Entity*ent, ScopeBase*scop
       return errors;
 }
 
-int ExpEdge::emit(ostream&out, Entity*ent, ScopeBase*scope)
+int ExpEdge::emit(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       int errors = 0;
       switch (fun_) {
@@ -616,7 +616,7 @@ int ExpEdge::emit(ostream&out, Entity*ent, ScopeBase*scope)
       return errors;
 }
 
-int ExpFunc::emit(ostream&out, Entity*ent, ScopeBase*scope)
+int ExpFunc::emit(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       int errors = 0;
 
@@ -642,25 +642,25 @@ int ExpFunc::emit(ostream&out, Entity*ent, ScopeBase*scope)
       return errors;
 }
 
-int ExpInteger::emit(ostream&out, Entity*, ScopeBase*)
+int ExpInteger::emit(ostream&out, Entity*, ScopeBase*) const
 {
       out << "32'd" << value_;
       return 0;
 }
 
-int ExpInteger::emit_package(ostream&out)
+int ExpInteger::emit_package(ostream&out) const
 {
       out << value_;
       return 0;
 }
 
-int ExpReal::emit(ostream&out, Entity*, ScopeBase*)
+int ExpReal::emit(ostream&out, Entity*, ScopeBase*) const
 {
       out << value_;
       return 0;
 }
 
-int ExpReal::emit_package(ostream&out)
+int ExpReal::emit_package(ostream&out) const
 {
       out << value_;
       return 0;
@@ -671,7 +671,7 @@ bool ExpReal::is_primary(void) const
       return true;
 }
 
-int ExpLogical::emit(ostream&out, Entity*ent, ScopeBase*scope)
+int ExpLogical::emit(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       int errors = 0;
 
@@ -703,7 +703,7 @@ int ExpLogical::emit(ostream&out, Entity*ent, ScopeBase*scope)
       return errors;
 }
 
-int ExpName::emit_as_prefix_(ostream&out, Entity*ent, ScopeBase*scope)
+int ExpName::emit_as_prefix_(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       int errors = 0;
       if (prefix_.get()) {
@@ -721,7 +721,7 @@ int ExpName::emit_as_prefix_(ostream&out, Entity*ent, ScopeBase*scope)
       return errors;
 }
 
-int ExpName::emit(ostream&out, Entity*ent, ScopeBase*scope)
+int ExpName::emit(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       int errors = 0;
       int field_size = 0;
@@ -763,7 +763,7 @@ int ExpName::emit(ostream&out, Entity*ent, ScopeBase*scope)
 }
 
 bool ExpName::try_workarounds_(ostream&out, Entity*ent, ScopeBase*scope,
-        list<index_t*>& indices, int& data_size)
+        list<index_t*>& indices, int& data_size) const
 {
     Expression*exp = NULL;
     bool wrkand_required = false;
@@ -860,7 +860,7 @@ bool ExpName::check_const_record_workaround_(const VTypeRecord*rec,
 }
 
 int ExpName::emit_workaround_(ostream&out, Entity*ent, ScopeBase*scope,
-        const list<index_t*>& indices, int field_size)
+        const list<index_t*>& indices, int field_size) const
 {
     int errors = 0;
 
@@ -882,7 +882,7 @@ bool ExpName::is_primary(void) const
       return true;
 }
 
-int ExpRelation::emit(ostream&out, Entity*ent, ScopeBase*scope)
+int ExpRelation::emit(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       int errors = 0;
       errors += emit_operand1(out, ent, scope);
@@ -912,7 +912,7 @@ int ExpRelation::emit(ostream&out, Entity*ent, ScopeBase*scope)
       return errors;
 }
 
-int ExpShift::emit(ostream&out, Entity*ent, ScopeBase*scope)
+int ExpShift::emit(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       int errors = 0;
 
@@ -947,7 +947,7 @@ bool ExpString::is_primary(void) const
       return true;
 }
 
-int ExpString::emit(ostream& out, Entity*ent, ScopeBase*scope)
+int ExpString::emit(ostream& out, Entity*ent, ScopeBase*scope) const
 {
       const VTypeArray*arr;
       const VType*type = peek_type();
@@ -962,7 +962,7 @@ int ExpString::emit(ostream& out, Entity*ent, ScopeBase*scope)
       return 0;
 }
 
-int ExpString::emit_as_array_(ostream& out, Entity*, ScopeBase*, const VTypeArray*arr)
+int ExpString::emit_as_array_(ostream& out, Entity*, ScopeBase*, const VTypeArray*arr) const
 {
       int errors = 0;
       assert(arr->dimensions() == 1);
@@ -1010,7 +1010,7 @@ std::string ExpString::escape_quot(const std::string& str)
       return result;
 }
 
-int ExpUAbs::emit(ostream&out, Entity*ent, ScopeBase*scope)
+int ExpUAbs::emit(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       int errors = 0;
       out << "abs(";
@@ -1019,7 +1019,7 @@ int ExpUAbs::emit(ostream&out, Entity*ent, ScopeBase*scope)
       return errors;
 }
 
-int ExpUNot::emit(ostream&out, Entity*ent, ScopeBase*scope)
+int ExpUNot::emit(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       int errors = 0;
 
@@ -1035,7 +1035,7 @@ int ExpUNot::emit(ostream&out, Entity*ent, ScopeBase*scope)
       return errors;
 }
 
-int ExpCast::emit(ostream&out, Entity*ent, ScopeBase*scope)
+int ExpCast::emit(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       int errors = 0;
       errors += type_->emit_def(out, empty_perm_string);
@@ -1045,7 +1045,7 @@ int ExpCast::emit(ostream&out, Entity*ent, ScopeBase*scope)
       return errors;
 }
 
-int ExpNew::emit(ostream&out, Entity*ent, ScopeBase*scope)
+int ExpNew::emit(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       int errors = 0;
       out << "new[";
@@ -1054,7 +1054,7 @@ int ExpNew::emit(ostream&out, Entity*ent, ScopeBase*scope)
       return errors;
 }
 
-int ExpTime::emit(ostream&out, Entity*, ScopeBase*)
+int ExpTime::emit(ostream&out, Entity*, ScopeBase*) const
 {
       out << amount_;
 
@@ -1070,7 +1070,7 @@ int ExpTime::emit(ostream&out, Entity*, ScopeBase*)
       return 0;
 }
 
-int ExpRange::emit(ostream&out, Entity*ent, ScopeBase*scope)
+int ExpRange::emit(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       int errors = 0;