diff --git a/PExpr.h b/PExpr.h
index f91025e70..78c3055bb 100644
--- a/PExpr.h
+++ b/PExpr.h
@@ -412,7 +412,7 @@ class PEIdent : public PExpr {
 	// the values written to the msb/lsb arguments. If there are
 	// invalid bits (xz) in either expression, then the defined
 	// flag is set to *false*.
-      bool calculate_parts_(Design*, NetScope*, long&msb, long&lsb, bool&defined) const;
+      void calculate_parts_(Design*, NetScope*, long&msb, long&lsb, bool&defined) const;
       NetExpr* calculate_up_do_base_(Design*, NetScope*, bool need_const) const;
 
       bool calculate_up_do_width_(Design*, NetScope*, unsigned long&wid) const;
@@ -426,7 +426,7 @@ class PEIdent : public PExpr {
 	//    [2:0][x]     - BAD
 	//    [y][x]       - BAD
 	// Leave the last index for special handling.
-      bool calculate_packed_indices_(Design*des, NetScope*scope, NetNet*net,
+      bool calculate_packed_indices_(Design*des, NetScope*scope, const NetNet*net,
 				     std::list<long>&prefix_indices) const;
 
     private:
@@ -554,7 +554,7 @@ class PEIdent : public PExpr {
 				     bool var_allowed_in_sv) const;
 
 
-      bool eval_part_select_(Design*des, NetScope*scope, NetNet*sig,
+      bool eval_part_select_(Design*des, NetScope*scope, const NetNet*sig,
 			     long&midx, long&lidx) const;
 };
 
@@ -959,8 +959,8 @@ class PECallFunction : public PExpr {
       NetExpr* elaborate_expr_method_(Design*des, NetScope*scope,
 				      symbol_search_results&search_results)
 				      const;
-      NetExpr* elaborate_expr_method_par_(Design*des, NetScope*scope,
-					  symbol_search_results&search_results)
+      NetExpr* elaborate_expr_method_par_(Design*des, const NetScope*scope,
+					  const symbol_search_results&search_results)
 					  const;
 
 
@@ -972,16 +972,16 @@ class PECallFunction : public PExpr {
       unsigned test_width_sfunc_(Design*des, NetScope*scope,
 			         width_mode_t&mode);
       unsigned test_width_method_(Design*des, NetScope*scope,
-				  symbol_search_results&search_results,
+				  const symbol_search_results&search_results,
 				  width_mode_t&mode);
 
       NetExpr*elaborate_base_(Design*des, NetScope*scope, NetScope*dscope,
 			      unsigned flags) const;
 
       unsigned elaborate_arguments_(Design*des, NetScope*scope,
-				    NetFuncDef*def, bool need_const,
-				    std::vector<NetExpr*>&parms,
-				    unsigned parm_off) const;
+                                    const NetFuncDef*def, bool need_const,
+                                    std::vector<NetExpr*>&parms,
+                                    unsigned parm_off) const;
 };
 
 /*
diff --git a/PGate.cc b/PGate.cc
index 59ad57048..6da02060e 100644
--- a/PGate.cc
+++ b/PGate.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1999-2021 Stephen Williams (steve@icarus.com)
+ * Copyright (c) 1999-2025 Stephen Williams (steve@icarus.com)
  *
  *    This source code is free software; you can redistribute it
  *    and/or modify it in source code form under the terms of the GNU
@@ -148,7 +148,7 @@ PGAssign::~PGAssign()
 
 PGBuiltin::PGBuiltin(Type t, perm_string name,
 		     list<PExpr*>*pins,
-		     list<PExpr*>*del)
+		     const list<PExpr*>*del)
 : PGate(name, pins, del), type_(t)
 {
 }
diff --git a/PGate.h b/PGate.h
index bdad01489..d171f2230 100644
--- a/PGate.h
+++ b/PGate.h
@@ -159,7 +159,7 @@ class PGBuiltin  : public PGate {
     public:
       explicit PGBuiltin(Type t, perm_string name,
 			 std::list<PExpr*>*pins,
-			 std::list<PExpr*>*del);
+			 const std::list<PExpr*>*del);
       explicit PGBuiltin(Type t, perm_string name,
 			 std::list<PExpr*>*pins,
 			 PExpr*del);
@@ -244,7 +244,7 @@ class PGModule  : public PGate {
       void elaborate_udp_(Design*, PUdp  *udp, NetScope*scope) const;
       void elaborate_scope_mod_(Design*des, Module*mod, NetScope*sc) const;
       void elaborate_scope_mod_instances_(Design*des, Module*mod, NetScope*sc) const;
-      bool elaborate_sig_mod_(Design*des, NetScope*scope, Module*mod) const;
+      bool elaborate_sig_mod_(Design*des, NetScope*scope, const Module*mod) const;
 	// Not currently used.
 #if 0
       bool elaborate_sig_udp_(Design*des, NetScope*scope, PUdp*udp) const;
diff --git a/Statement.h b/Statement.h
index 283d7424d..6e5e8d7a3 100644
--- a/Statement.h
+++ b/Statement.h
@@ -265,7 +265,7 @@ class PCallTask  : public Statement {
 				     ivl_type_t type,
 				     perm_string method_name,
 				     const char*sys_task_name) const;
-      bool test_task_calls_ok_(Design*des, NetScope*scope) const;
+      bool test_task_calls_ok_(Design*des, const NetScope*scope) const;
 
       PPackage*package_;
       pform_name_t path_;
@@ -463,7 +463,7 @@ class PEventStatement  : public Statement {
       NetProc* elaborate_st(Design*des, NetScope*scope, NetProc*st) const;
 
       NetProc* elaborate_wait(Design*des, NetScope*scope, NetProc*st) const;
-      NetProc* elaborate_wait_fork(Design*des, NetScope*scope) const;
+      NetProc* elaborate_wait_fork(Design*des, const NetScope*scope) const;
 
     private:
       std::vector<PEEvent*>expr_;
diff --git a/elab_expr.cc b/elab_expr.cc
index fe5dc8f20..73eed88ac 100644
--- a/elab_expr.cc
+++ b/elab_expr.cc
@@ -1519,7 +1519,7 @@ static NetFuncDef* find_function_definition(Design*des, NetScope*,
 }
 
 unsigned PECallFunction::test_width_method_(Design*, NetScope*,
-					    symbol_search_results&search_results,
+					    const symbol_search_results&search_results,
 					    width_mode_t&)
 {
       if (!gn_system_verilog())
@@ -3024,7 +3024,7 @@ NetExpr* PECallFunction::elaborate_base_(Design*des, NetScope*scope, NetScope*ds
       if (! check_call_matches_definition_(des, dscope))
 	    return 0;
 
-      NetFuncDef*def = dscope->func_def();
+      const NetFuncDef*def = dscope->func_def();
 
       bool need_const = NEED_CONST & flags;
 
@@ -3124,7 +3124,7 @@ NetExpr* PECallFunction::elaborate_base_(Design*des, NetScope*scope, NetScope*ds
  * def->port(0) will be the "this" argument and should be skipped.
  */
 unsigned PECallFunction::elaborate_arguments_(Design*des, NetScope*scope,
-					      NetFuncDef*def, bool need_const,
+					      const NetFuncDef*def, bool need_const,
 					      vector<NetExpr*>&parms,
 					      unsigned parm_off) const
 {
@@ -3408,7 +3408,7 @@ NetExpr* PECallFunction::elaborate_expr_method_(Design*des, NetScope*scope,
 		  return 0;
 	    }
 
-	    NetFuncDef*def = method->func_def();
+	    const NetFuncDef*def = method->func_def();
 	    ivl_assert(*this, def);
 
 	    NetNet*res = method->find_signal(method->basename());
@@ -3509,8 +3509,8 @@ NetExpr* PECallFunction::elaborate_expr_method_(Design*des, NetScope*scope,
  * expression of some sort (it's a parameter value) and most methods are
  * stable in the sense that they generate a constant value for a constant input.
  */
-NetExpr* PECallFunction::elaborate_expr_method_par_(Design*des, NetScope*scope,
-						    symbol_search_results&search_results)
+NetExpr* PECallFunction::elaborate_expr_method_par_(Design*des, const NetScope*scope,
+						    const symbol_search_results&search_results)
 						    const
 {
       ivl_assert(*this, search_results.par_val);
@@ -4047,7 +4047,7 @@ NetExpr* PEFNumber::elaborate_expr(Design*, NetScope*, unsigned, unsigned) const
       return tmp;
 }
 
-bool PEIdent::calculate_packed_indices_(Design*des, NetScope*scope, NetNet*net,
+bool PEIdent::calculate_packed_indices_(Design*des, NetScope*scope, const NetNet*net,
 					list<long>&prefix_indices) const
 {
       unsigned dimensions = net->unpacked_dimensions() + net->packed_dimensions();
@@ -4120,7 +4120,7 @@ bool PEIdent::calculate_bits_(Design*des, NetScope*scope,
  * function calculates their values. Note that this method does *not*
  * convert the values to canonical form.
  */
-bool PEIdent::calculate_parts_(Design*des, NetScope*scope,
+void PEIdent::calculate_parts_(Design*des, NetScope*scope,
 			       long&msb, long&lsb, bool&defined) const
 {
       defined = true;
@@ -4173,7 +4173,6 @@ bool PEIdent::calculate_parts_(Design*des, NetScope*scope,
 
       delete msb_ex;
       delete lsb_ex;
-      return true;
 }
 
 bool PEIdent::calculate_up_do_width_(Design*des, NetScope*scope,
@@ -5274,9 +5273,7 @@ NetExpr* PEIdent::elaborate_expr_param_part_(Design*des, NetScope*scope,
 {
       long msv, lsv;
       bool parts_defined_flag;
-      bool flag = calculate_parts_(des, scope, msv, lsv, parts_defined_flag);
-      if (!flag)
-	    return 0;
+      calculate_parts_(des, scope, msv, lsv, parts_defined_flag);
 
       const NetEConst*par_ex = dynamic_cast<const NetEConst*> (par);
       ivl_assert(*this, par_ex);
@@ -5851,9 +5848,7 @@ NetExpr* PEIdent::elaborate_expr_net_part_(Design*des, NetScope*scope,
 
       long msv, lsv;
       bool parts_defined_flag;
-      bool flag = calculate_parts_(des, scope, msv, lsv, parts_defined_flag);
-      if (!flag)
-	    return 0;
+      calculate_parts_(des, scope, msv, lsv, parts_defined_flag);
 
 	/* But wait... if the part select expressions are not fully
 	   defined, then fall back on the tested width. */
@@ -6722,7 +6717,7 @@ NetExpr* PENewClass::elaborate_expr_constructor_(Design*des, NetScope*scope,
       }
 
 
-      NetFuncDef*def = new_scope->func_def();
+      const NetFuncDef*def = new_scope->func_def();
       if (def == 0) {
 	    cerr << get_fileline() << ": internal error: "
 		 << "Scope " << scope_path(new_scope)
diff --git a/elab_lval.cc b/elab_lval.cc
index bde944622..4f1859c43 100644
--- a/elab_lval.cc
+++ b/elab_lval.cc
@@ -254,7 +254,7 @@ NetAssign_* PEIdent::elaborate_lval(Design*des,
 NetAssign_*PEIdent::elaborate_lval_var_(Design *des, NetScope *scope,
 				        bool is_force, bool is_cassign,
 					NetNet *reg, ivl_type_t data_type,
-					pform_name_t tail_path) const
+					const pform_name_t tail_path) const
 {
 	// We are processing the tail of a string of names. For
 	// example, the Verilog may be "a.b.c", so we are processing
@@ -761,8 +761,7 @@ bool PEIdent::elaborate_lval_net_part_(Design*des,
 	// values into msb and lsb.
       long msb, lsb;
       bool parts_defined_flag;
-      bool flag = calculate_parts_(des, scope, msb, lsb, parts_defined_flag);
-      if (!flag) return false;
+      calculate_parts_(des, scope, msb, lsb, parts_defined_flag);
 
       NetNet*reg = lv->sig();
       ivl_assert(*this, reg);
diff --git a/elab_net.cc b/elab_net.cc
index c5bfb6165..b615ae5db 100644
--- a/elab_net.cc
+++ b/elab_net.cc
@@ -206,7 +206,7 @@ bool PEConcat::is_collapsible_net(Design*des, NetScope*scope,
  * results, which may be the whole vector, or a single bit, or
  * anything in between. The values are in canonical indices.
  */
-bool PEIdent::eval_part_select_(Design*des, NetScope*scope, NetNet*sig,
+bool PEIdent::eval_part_select_(Design*des, NetScope*scope, const NetNet*sig,
 				long&midx, long&lidx) const
 {
       list<long> prefix_indices;
diff --git a/elab_scope.cc b/elab_scope.cc
index b51410088..bd9065fd3 100644
--- a/elab_scope.cc
+++ b/elab_scope.cc
@@ -58,7 +58,7 @@
 
 using namespace std;
 
-void set_scope_timescale(Design*des, NetScope*scope, PScope*pscope)
+void set_scope_timescale(Design*des, NetScope*scope, const PScope*pscope)
 {
       scope->time_unit(pscope->time_unit);
       scope->time_precision(pscope->time_precision);
diff --git a/elab_sig.cc b/elab_sig.cc
index 0bb89f21f..575105eb1 100644
--- a/elab_sig.cc
+++ b/elab_sig.cc
@@ -90,8 +90,8 @@ void Statement::elaborate_sig(Design*, NetScope*) const
 {
 }
 
-static void sig_check_data_type(Design*des, NetScope*scope,
-			        PWire *wire, NetNet *sig)
+static void sig_check_data_type(Design*des, const NetScope*scope,
+			        const PWire *wire, NetNet *sig)
 {
       ivl_type_t type = sig->net_type();
 
@@ -141,8 +141,8 @@ static void sig_check_data_type(Design*des, NetScope*scope,
       }
 }
 
-static void sig_check_port_type(Design*des, NetScope*scope,
-			        PWire *wire, NetNet *sig)
+static void sig_check_port_type(Design*des, const NetScope*scope,
+			        const PWire *wire, const NetNet *sig)
 {
       if (sig->port_type() == NetNet::PREF) {
 	    cerr << wire->get_fileline() << ": sorry: "
@@ -460,7 +460,7 @@ bool PGAssign::elaborate_sig(Design*, NetScope*) const
 }
 
 bool PGModule::elaborate_sig_mod_(Design*des, NetScope*scope,
-				  Module*rmod) const
+				  const Module*rmod) const
 {
       bool flag = true;
 
diff --git a/elaborate.cc b/elaborate.cc
index 23406a7d1..05432eb8f 100644
--- a/elaborate.cc
+++ b/elaborate.cc
@@ -60,7 +60,7 @@
 using namespace std;
 
 // Implemented in elab_scope.cc
-extern void set_scope_timescale(Design*des, NetScope*scope, PScope*pscope);
+extern void set_scope_timescale(Design*des, NetScope*scope, const PScope*pscope);
 
 void PGate::elaborate(Design*, NetScope*) const
 {
@@ -1203,7 +1203,7 @@ static void isolate_and_connect(Design*des, NetScope*scope, const PGModule*mod,
 
 void elaborate_unpacked_port(Design *des, NetScope *scope, NetNet *port_net,
 			     PExpr *expr, NetNet::PortType port_type,
-			     Module *mod, unsigned int port_idx)
+			     const Module *mod, unsigned int port_idx)
 {
       NetNet *expr_net = elaborate_unpacked_array(des, scope, *expr, port_net,
 						  expr);
@@ -3360,7 +3360,7 @@ NetProc* PChainConstructor::elaborate(Design*des, NetScope*scope) const
       if (NetScope*new_scope = class_super->get_constructor()) {
 
 	    int missing_parms = 0;
-	    NetFuncDef*def = new_scope->func_def();
+	    const NetFuncDef*def = new_scope->func_def();
 	    ivl_assert(*this, def);
 
 	    NetESignal*eres = new NetESignal(var_this);
@@ -4052,7 +4052,7 @@ NetProc* PCallTask::elaborate_method_(Design*des, NetScope*scope,
  * task call is allowed in the current context. If so, return true. If
  * not, print an error message and return false;
  */
-bool PCallTask::test_task_calls_ok_(Design*des, NetScope*scope) const
+bool PCallTask::test_task_calls_ok_(Design*des, const NetScope*scope) const
 {
       if (scope->in_func()) {
 	    cerr << get_fileline() << ": error: Functions cannot enable/call "
@@ -4130,7 +4130,7 @@ NetProc* PCallTask::elaborate_void_function_(Design*des, NetScope*scope,
 NetProc* PCallTask::elaborate_build_call_(Design*des, NetScope*scope,
 					  NetScope*task, NetExpr*use_this) const
 {
-      NetBaseDef*def = 0;
+      const NetBaseDef*def = 0;
       if (task->type() == NetScope::TASK) {
 	    def = task->task_def();
 
@@ -4147,7 +4147,7 @@ NetProc* PCallTask::elaborate_build_call_(Design*des, NetScope*scope,
 	    }
 
       } else if (task->type() == NetScope::FUNC) {
-	    NetFuncDef*tmp = task->func_def();
+	    const NetFuncDef*tmp = task->func_def();
 	    if (!tmp->is_void())
 		  return elaborate_non_void_function_(des, scope);
 	    def = tmp;
@@ -5271,7 +5271,7 @@ NetProc* PEventStatement::elaborate_wait(Design*des, NetScope*scope,
  *
  *     @(0) <noop>;
  */
-NetProc* PEventStatement::elaborate_wait_fork(Design*des, NetScope*scope) const
+NetProc* PEventStatement::elaborate_wait_fork(Design*des, const NetScope*scope) const
 {
       ivl_assert(*this, scope);
       ivl_assert(*this, expr_.size() == 1);
@@ -6259,7 +6259,7 @@ void PSpecPath::elaborate(Design*des, NetScope*scope) const
 		  delay_value[idx] = des->scale_to_precision(fn.as_ulong64(),
 		                                             scope);
 
-	    } else if (NetECReal*rcon = dynamic_cast<NetECReal*>(cur)) {
+	    } else if (const NetECReal*rcon = dynamic_cast<NetECReal*>(cur)) {
 		  delay_value[idx] = get_scaled_time_from_real(des, scope,
 		                                               rcon);
 
diff --git a/expr_synth.cc b/expr_synth.cc
index eea33c99f..8699602b6 100644
--- a/expr_synth.cc
+++ b/expr_synth.cc
@@ -31,7 +31,7 @@
 
 using namespace std;
 
-static NetNet* convert_to_real_const(Design*des, NetScope*scope, NetEConst*expr)
+static NetNet* convert_to_real_const(Design*des, NetScope*scope, const NetEConst*expr)
 {
       verireal vrl(expr->value().as_double());
       NetECReal rlval(vrl);
@@ -53,7 +53,7 @@ static bool process_binary_args(Design*des, NetScope*scope, NetExpr*root,
 	         cases of constants, which can be converted more directly. */
 	    if (left->expr_type() == IVL_VT_REAL) {
 		  lsig = left->synthesize(des, scope, root);
-	    } else if (NetEConst*tmpc = dynamic_cast<NetEConst*> (left)) {
+	    } else if (const NetEConst*tmpc = dynamic_cast<NetEConst*> (left)) {
 		  lsig = convert_to_real_const(des, scope, tmpc);
 	    } else {
 		  NetNet*tmp = left->synthesize(des, scope, root);
@@ -62,7 +62,7 @@ static bool process_binary_args(Design*des, NetScope*scope, NetExpr*root,
 
 	    if (right->expr_type() == IVL_VT_REAL) {
 		  rsig = right->synthesize(des, scope, root);
-	    } else if (NetEConst*tmpc = dynamic_cast<NetEConst*> (right)) {
+	    } else if (const NetEConst*tmpc = dynamic_cast<NetEConst*> (right)) {
 		  rsig = convert_to_real_const(des, scope, tmpc);
 	    } else {
 		  NetNet*tmp = right->synthesize(des, scope, root);
@@ -1483,7 +1483,7 @@ NetNet* NetESignal::synthesize(Design*des, NetScope*scope, NetExpr*root)
       return tmp;
 }
 
-static NetEvWait* make_func_trigger(Design*des, NetScope*scope, NetExpr*root)
+static NetEvWait* make_func_trigger(Design*des, NetScope*scope, const NetExpr*root)
 {
       NetEvWait*trigger = 0;
 
diff --git a/lexor.lex b/lexor.lex
index ef291f9d6..8f6c87a4b 100644
--- a/lexor.lex
+++ b/lexor.lex
@@ -920,7 +920,7 @@ void lex_end_table()
       BEGIN(INITIAL);
 }
 
-static unsigned truncate_to_integer_width(verinum::V*bits, unsigned size)
+static unsigned truncate_to_integer_width(const verinum::V*bits, unsigned size)
 {
       if (size <= integer_width) return size;
 
diff --git a/map_named_args.cc b/map_named_args.cc
index fc108feef..e43db84b6 100644
--- a/map_named_args.cc
+++ b/map_named_args.cc
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2023 Lars-Peter Clausen <lars@metafoo.de>
+// SPDX-FileCopyrightText: 2023-2025 Lars-Peter Clausen <lars@metafoo.de>
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #include "PExpr.h"
@@ -62,7 +62,7 @@ std::vector<PExpr*> map_named_args(Design *des,
       return args;
 }
 
-std::vector<PExpr*> map_named_args(Design *des, NetBaseDef *def,
+std::vector<PExpr*> map_named_args(Design *des, const NetBaseDef *def,
 				   const std::vector<named_pexpr_t> &parms,
 				   unsigned int off)
 {
diff --git a/map_named_args.h b/map_named_args.h
index f0017198f..3196c1e2f 100644
--- a/map_named_args.h
+++ b/map_named_args.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2023 Lars-Peter Clausen <lars@metafoo.de>
+// SPDX-FileCopyrightText: 2023-2025 Lars-Peter Clausen <lars@metafoo.de>
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #ifndef MAP_NAMED_ARGS_H
@@ -15,7 +15,7 @@ std::vector<PExpr*> map_named_args(Design *des,
 			           const std::vector<perm_string> &names,
 			           const std::vector<named_pexpr_t> &parms);
 
-std::vector<PExpr*> map_named_args(Design *des, NetBaseDef *def,
+std::vector<PExpr*> map_named_args(Design *des, const NetBaseDef *def,
 			           const std::vector<named_pexpr_t> &parms,
 				   unsigned int off);
 
diff --git a/net_design.cc b/net_design.cc
index 771b7327e..f813751c2 100644
--- a/net_design.cc
+++ b/net_design.cc
@@ -214,7 +214,7 @@ NetScope* Design::find_scope(const hname_t&path) const
       return 0;
 }
 
-static bool is_design_unit(NetScope*scope)
+static bool is_design_unit(const NetScope*scope)
 {
       return (scope->type() == NetScope::MODULE && !scope->nested_module())
 	  || (scope->type() == NetScope::PACKAGE);
diff --git a/net_func_eval.cc b/net_func_eval.cc
index e986c4f2d..19327ea27 100644
--- a/net_func_eval.cc
+++ b/net_func_eval.cc
@@ -242,7 +242,7 @@ void NetAssign::eval_func_lval_op_real_(const LineInfo&loc,
 }
 
 void NetAssign::eval_func_lval_op_(const LineInfo&loc,
-				   verinum&lv, verinum&rv) const
+				   verinum&lv, const verinum&rv) const
 {
       unsigned lv_width = lv.len();
       bool lv_sign = lv.has_sign();
diff --git a/net_link.cc b/net_link.cc
index 1f782bd8b..ae638621f 100644
--- a/net_link.cc
+++ b/net_link.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000-2022 Stephen Williams (steve@icarus.com)
+ * Copyright (c) 2000-2025 Stephen Williams (steve@icarus.com)
  *
  *    This source code is free software; you can redistribute it
  *    and/or modify it in source code form under the terms of the GNU
@@ -164,7 +164,7 @@ Link::DIR Link::get_dir() const
       return dir_;
 }
 
-void Link::drivers_delays(NetExpr*rise, NetExpr*fall, NetExpr*decay)
+void Link::drivers_delays(const NetExpr*rise, const NetExpr*fall, const NetExpr*decay)
 {
       find_nexus_()->drivers_delays(rise, fall, decay);
 }
@@ -358,7 +358,7 @@ bool Nexus::drivers_present() const
       return false;
 }
 
-void Nexus::drivers_delays(NetExpr*rise, NetExpr*fall, NetExpr*decay)
+void Nexus::drivers_delays(const NetExpr*rise, const NetExpr*fall, const NetExpr*decay)
 {
       for (Link*cur = first_nlink() ; cur ; cur = cur->next_nlink()) {
 	    if (cur->get_dir() != Link::OUTPUT)
@@ -600,7 +600,7 @@ void NexusSet::add(Nexus*that, unsigned base, unsigned wid)
       items_.push_back(cur);
 }
 
-void NexusSet::add(NexusSet&that)
+void NexusSet::add(const NexusSet&that)
 {
       for (size_t idx = 0 ;  idx < that.items_.size() ;  idx += 1)
 	    add(that.items_[idx]->lnk.nexus(), that.items_[idx]->base, that.items_[idx]->wid);
diff --git a/net_scope.cc b/net_scope.cc
index 1380a7fef..1efc464e6 100644
--- a/net_scope.cc
+++ b/net_scope.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000-2024 Stephen Williams (steve@icarus.com)
+ * Copyright (c) 2000-2025 Stephen Williams (steve@icarus.com)
  * Copyright (c) 2016 CERN Michele Castellana (michele.castellana@cern.ch)
  *
  *    This source code is free software; you can redistribute it
@@ -52,7 +52,7 @@ void Definitions::add_enumeration_set(const enum_type_t*key, netenum_t*enum_set)
       tmp = enum_set;
 }
 
-bool Definitions::add_enumeration_name(netenum_t*enum_set, perm_string name)
+bool Definitions::add_enumeration_name(const netenum_t*enum_set, perm_string name)
 {
       netenum_t::iterator enum_val = enum_set->find_name(name);
       assert(enum_val != enum_set->end_name());
@@ -708,7 +708,7 @@ void NetScope::add_signal_placeholder(PWire*wire)
       signal_placeholders_[wire->basename()] = wire;
 }
 
-void NetScope::rem_signal_placeholder(PWire*wire)
+void NetScope::rem_signal_placeholder(const PWire*wire)
 {
       signal_placeholders_.erase(wire->basename());
 }
diff --git a/netlist.cc b/netlist.cc
index c2cf782cc..b63d142be 100644
--- a/netlist.cc
+++ b/netlist.cc
@@ -3271,7 +3271,7 @@ bool NetForever::check_synth(ivl_process_type_t pr_type,
  * structure for synthesis.
  */
 static void print_for_idx_warning(const NetProc*proc, const char*check,
-                                  ivl_process_type_t pr_type, NetNet*idx)
+                                  ivl_process_type_t pr_type, const NetNet*idx)
 {
       cerr << proc->get_fileline() << ": warning: A for statement must use "
               "the index (" << idx->name() << ") in the " << check
@@ -3293,7 +3293,7 @@ static void check_for_const_synth(const NetExpr*expr, const NetProc*proc,
 static void check_for_bin_synth(const NetExpr*left,const NetExpr*right,
                                 const char*str, const char*check,
                                 const NetProc*proc,
-                                ivl_process_type_t pr_type, NetNet*index)
+                                ivl_process_type_t pr_type, const NetNet*index)
 {
       const NetESignal*lsig = dynamic_cast<const NetESignal*>(left);
       const NetESignal*rsig = dynamic_cast<const NetESignal*>(right);
@@ -3327,7 +3327,7 @@ static void print_for_step_warning(const NetProc*proc,
 }
 
 static void print_for_step_warning(const NetProc*proc,
-                                   ivl_process_type_t pr_type, NetNet*idx)
+                                   ivl_process_type_t pr_type, const NetNet*idx)
 {
       cerr << proc->get_fileline() << ": warning: A for statement step must "
               "be an assignment to the index variable ("
@@ -3336,7 +3336,7 @@ static void print_for_step_warning(const NetProc*proc,
 }
 
 static void check_for_bstep_synth(const NetExpr*expr, const NetProc*proc,
-                                  ivl_process_type_t pr_type, NetNet*index)
+                                  ivl_process_type_t pr_type, const NetNet*index)
 {
       if (const NetECast*tmp = dynamic_cast<const NetECast*>(expr)) {
 	    expr = tmp->expr();
diff --git a/netlist.h b/netlist.h
index e04c8e42c..ab3b58485 100644
--- a/netlist.h
+++ b/netlist.h
@@ -125,7 +125,7 @@ class Link {
       DIR get_dir() const;
 
 	// Set the delay for all the drivers to this nexus.
-      void drivers_delays(NetExpr*rise, NetExpr*fall, NetExpr*decay);
+      void drivers_delays(const NetExpr*rise, const NetExpr*fall, const NetExpr*decay);
 
 	// A link has a drive strength for 0 and 1 values. The drive0
 	// strength is for when the link has the value 0, and drive1
@@ -373,7 +373,7 @@ class Nexus {
 
       const char* name() const;
 
-      void drivers_delays(NetExpr*rise, NetExpr*fall, NetExpr*decay);
+      void drivers_delays(const NetExpr*rise, const NetExpr*fall, const NetExpr*decay);
       void drivers_drive(ivl_drive_t d0, ivl_drive_t d1);
 
       Link*first_nlink();
@@ -475,7 +475,7 @@ class NexusSet {
 
 	// Add the nexus/part to the set, if it is not already present.
       void add(Nexus*that, unsigned base, unsigned wid);
-      void add(NexusSet&that);
+      void add(const NexusSet&that);
 
 	// Remove the nexus from the set, if it is present.
       void rem(const NexusSet&that);
@@ -911,7 +911,7 @@ class Definitions {
 	// up this enumeration based on the pform type.
       void add_enumeration_set(const enum_type_t*key, netenum_t*enum_set);
 
-      bool add_enumeration_name(netenum_t*enum_set, perm_string enum_name);
+      bool add_enumeration_name(const netenum_t*enum_set, perm_string enum_name);
 
 	// Look up the enumeration set that was added with the given
 	// key. This is used by enum_type_t::elaborate_type to locate
@@ -1020,7 +1020,7 @@ class NetScope : public Definitions, public Attrib {
 	   when using $bits in a range definition), regardless of the
 	   order in which the signals are elaborated. */
       void add_signal_placeholder(PWire*);
-      void rem_signal_placeholder(PWire*);
+      void rem_signal_placeholder(const PWire*);
       PWire* find_signal_placeholder(perm_string name);
 
 	/* These methods manage signals. The add_ and rem_signal
@@ -3019,7 +3019,7 @@ class NetAssign : public NetAssignBase {
 
     private:
       void eval_func_lval_op_real_(const LineInfo&loc, verireal&lv, const verireal&rv) const;
-      void eval_func_lval_op_(const LineInfo&loc, verinum&lv, verinum&rv) const;
+      void eval_func_lval_op_(const LineInfo&loc, verinum&lv, const verinum&rv) const;
       bool eval_func_lval_(const LineInfo&loc, std::map<perm_string,LocalVar>&ctx,
 			   const NetAssign_*lval, NetExpr*rval_result) const;
 
diff --git a/netmisc.cc b/netmisc.cc
index 5da5b143e..9e4162800 100644
--- a/netmisc.cc
+++ b/netmisc.cc
@@ -543,7 +543,7 @@ static void make_strides(const netranges_t&dims, vector<long>&stride)
  * word. If any of the indices are out of bounds, return nil instead
  * of an expression.
  */
-static NetExpr* normalize_variable_unpacked(const netranges_t&dims, list<long>&indices)
+static NetExpr* normalize_variable_unpacked(const netranges_t&dims, const list<long>&indices)
 {
 	// Make strides for each index. The stride is the distance (in
 	// words) to the next element in the canonical array.
@@ -574,19 +574,19 @@ static NetExpr* normalize_variable_unpacked(const netranges_t&dims, list<long>&i
       return canonical_expr;
 }
 
-NetExpr* normalize_variable_unpacked(const NetNet*net, list<long>&indices)
+NetExpr* normalize_variable_unpacked(const NetNet*net, const list<long>&indices)
 {
       const netranges_t&dims = net->unpacked_dims();
       return normalize_variable_unpacked(dims, indices);
 }
 
-NetExpr* normalize_variable_unpacked(const netsarray_t*stype, list<long>&indices)
+NetExpr* normalize_variable_unpacked(const netsarray_t*stype, const list<long>&indices)
 {
       const netranges_t&dims = stype->static_dimensions();
       return normalize_variable_unpacked(dims, indices);
 }
 
-NetExpr* normalize_variable_unpacked(const LineInfo&loc, const netranges_t&dims, list<NetExpr*>&indices)
+NetExpr* normalize_variable_unpacked(const LineInfo&loc, const netranges_t&dims, const list<NetExpr*>&indices)
 {
 	// Make strides for each index. The stride is the distance (in
 	// words) to the next element in the canonical array.
@@ -671,13 +671,13 @@ NetExpr* normalize_variable_unpacked(const LineInfo&loc, const netranges_t&dims,
       return canonical_expr;
 }
 
-NetExpr* normalize_variable_unpacked(const NetNet*net, list<NetExpr*>&indices)
+NetExpr* normalize_variable_unpacked(const NetNet*net, const list<NetExpr*>&indices)
 {
       const netranges_t&dims = net->unpacked_dims();
       return normalize_variable_unpacked(*net, dims, indices);
 }
 
-NetExpr* normalize_variable_unpacked(const LineInfo&loc, const netsarray_t*stype, list<NetExpr*>&indices)
+NetExpr* normalize_variable_unpacked(const LineInfo&loc, const netsarray_t*stype, const list<NetExpr*>&indices)
 {
       const netranges_t&dims = stype->static_dimensions();
       return normalize_variable_unpacked(loc, dims, indices);
@@ -1375,7 +1375,7 @@ const_bool const_logical(const NetExpr*expr)
       return C_NON;
 }
 
-uint64_t get_scaled_time_from_real(Design*des, NetScope*scope, NetECReal*val)
+uint64_t get_scaled_time_from_real(const Design*des, NetScope*scope, const NetECReal*val)
 {
       verireal fn = val->value();
 
@@ -1530,7 +1530,7 @@ bool evaluate_index_prefix(Design*des, NetScope*scope,
  * replace the exprs.
  */
 NetExpr*collapse_array_exprs(Design*des, NetScope*scope,
-			     const LineInfo*loc, NetNet*net,
+			     const LineInfo*loc, const NetNet*net,
 			     const list<index_component_t>&indices)
 {
 	// First elaborate all the expressions as far as possible.
@@ -1589,7 +1589,7 @@ NetExpr*collapse_array_exprs(Design*des, NetScope*scope,
  * them to an expression that normalizes the list to a single index
  * expression over a canonical equivalent 1-dimensional array.
  */
-NetExpr*collapse_array_indices(Design*des, NetScope*scope, NetNet*net,
+NetExpr*collapse_array_indices(Design*des, NetScope*scope, const NetNet*net,
 			       const list<index_component_t>&indices)
 {
       list<long>prefix_indices;
@@ -1787,7 +1787,7 @@ NetScope* find_method_containing_scope(const LineInfo&, NetScope*scope)
  * Print a warning if we find a mixture of default and explicit timescale
  * based delays in the design, since this is likely an error.
  */
-void check_for_inconsistent_delays(NetScope*scope)
+void check_for_inconsistent_delays(const NetScope*scope)
 {
       static bool used_implicit_timescale = false;
       static bool used_explicit_timescale = false;
diff --git a/netmisc.h b/netmisc.h
index 596033d1f..be460ad04 100644
--- a/netmisc.h
+++ b/netmisc.h
@@ -271,11 +271,11 @@ extern void indices_to_expressions(Design*des, NetScope*scope,
 				   indices_flags&flags,
 				   std::list<NetExpr*>&indices,std::list<long>&indices_const);
 
-extern NetExpr*normalize_variable_unpacked(const NetNet*net, std::list<long>&indices);
-extern NetExpr*normalize_variable_unpacked(const netsarray_t*net, std::list<long>&indices);
+extern NetExpr*normalize_variable_unpacked(const NetNet*net, const std::list<long>&indices);
+extern NetExpr*normalize_variable_unpacked(const netsarray_t*net, const std::list<long>&indices);
 
-extern NetExpr*normalize_variable_unpacked(const NetNet*net, std::list<NetExpr*>&indices);
-extern NetExpr*normalize_variable_unpacked(const LineInfo&loc, const netsarray_t*net, std::list<NetExpr*>&indices);
+extern NetExpr*normalize_variable_unpacked(const NetNet*net, const std::list<NetExpr*>&indices);
+extern NetExpr*normalize_variable_unpacked(const LineInfo&loc, const netsarray_t*net, const std::list<NetExpr*>&indices);
 
 extern NetExpr*make_canonical_index(Design*des, NetScope*scope,
 				      // loc for error messages
@@ -454,9 +454,9 @@ const_bool const_logical(const NetExpr*expr);
  * When scaling a real value to a time we need to do some standard
  * processing.
  */
-extern uint64_t get_scaled_time_from_real(Design*des,
+extern uint64_t get_scaled_time_from_real(const Design*des,
                                           NetScope*scope,
-                                          NetECReal*val);
+                                          const NetECReal*val);
 
 extern void collapse_partselect_pv_to_concat(Design*des, NetNet*sig);
 
@@ -464,11 +464,11 @@ extern bool evaluate_index_prefix(Design*des, NetScope*scope,
 				  std::list<long>&prefix_indices,
 				  const std::list<index_component_t>&indices);
 
-extern NetExpr*collapse_array_indices(Design*des, NetScope*scope, NetNet*net,
+extern NetExpr*collapse_array_indices(Design*des, NetScope*scope, const NetNet*net,
 				      const std::list<index_component_t>&indices);
 
 extern NetExpr*collapse_array_exprs(Design*des, NetScope*scope,
-				    const LineInfo*loc, NetNet*net,
+				    const LineInfo*loc, const NetNet*net,
 				    const std::list<index_component_t>&indices);
 
 extern void assign_unpacked_with_bufz(Design*des, NetScope*scope,
@@ -481,6 +481,6 @@ extern NetPartSelect* detect_partselect_lval(Link&pin);
  * Print a warning if we find a mixture of default and explicit timescale
  * based delays in the design, since this is likely an error.
  */
-extern void check_for_inconsistent_delays(NetScope*scope);
+extern void check_for_inconsistent_delays(const NetScope*scope);
 
 #endif /* IVL_netmisc_H */
diff --git a/parse.y b/parse.y
index d5f0e92eb..ee2b2404e 100644
--- a/parse.y
+++ b/parse.y
@@ -268,7 +268,7 @@ static std::list<named_pexpr_t>* make_named_number(const struct vlltype &loc,
       return lst;
 }
 
-static long check_enum_seq_value(const YYLTYPE&loc, verinum *arg, bool zero_ok)
+static long check_enum_seq_value(const YYLTYPE&loc, const verinum *arg, bool zero_ok)
 {
       long value = 1;
 	// We can never have an undefined value in an enumeration name
@@ -308,8 +308,8 @@ static void check_end_label(const struct vlltype&loc, const char *type,
       delete[] end;
 }
 
-static void check_for_loop(const struct vlltype&loc, PExpr*init,
-			   PExpr*cond, Statement*step)
+static void check_for_loop(const struct vlltype&loc, const PExpr*init,
+			   const PExpr*cond, const Statement*step)
 {
       if (generation_flag >= GN_VER2012)
 	    return;
diff --git a/pform.cc b/pform.cc
index dfc84e1d1..108dc1785 100644
--- a/pform.cc
+++ b/pform.cc
@@ -606,7 +606,7 @@ PPackage* pform_push_package_scope(const struct vlltype&loc, perm_string name,
       return pkg_scope;
 }
 
-PTask* pform_push_task_scope(const struct vlltype&loc, char*name,
+PTask* pform_push_task_scope(const struct vlltype&loc, const char*name,
 			     LexicalScope::lifetime_t lifetime)
 {
       perm_string task_name = lex_strings.make(name);
@@ -677,7 +677,7 @@ PFunction* pform_push_function_scope(const struct vlltype&loc, const char*name,
       return func;
 }
 
-PBlock* pform_push_block_scope(const struct vlltype&loc, char*name,
+PBlock* pform_push_block_scope(const struct vlltype&loc, const char*name,
 			       PBlock::BL_TYPE bt)
 {
       perm_string block_name;
@@ -1678,7 +1678,7 @@ void pform_generate_case_item(const struct vlltype&li, list<PExpr*>*expr_list)
       }
 }
 
-void pform_generate_block_name(char*name)
+void pform_generate_block_name(const char*name)
 {
       assert(pform_cur_generate != 0);
       assert(pform_cur_generate->scope_name == 0);
@@ -2638,7 +2638,7 @@ void pform_module_define_port(const struct vlltype&li,
  * this one to create the wire and stash it.
  */
 PWire *pform_makewire(const vlltype&li, const pform_ident_t&name,
-		      NetNet::Type type, std::list<pform_range_t> *indices)
+		      NetNet::Type type, const std::list<pform_range_t> *indices)
 {
       PWire*cur = pform_get_or_make_wire(li, name, type, NetNet::NOT_A_PORT, SR_NET);
       ivl_assert(li, cur);
@@ -2911,7 +2911,7 @@ static void pform_set_type_parameter(const struct vlltype&loc, perm_string name,
 
 void pform_set_parameter(const struct vlltype&loc,
 			 perm_string name, bool is_local, bool is_type,
-			 data_type_t*data_type, list<pform_range_t>*udims,
+			 data_type_t*data_type, const list<pform_range_t>*udims,
 			 PExpr*expr, LexicalScope::range_t*value_range)
 {
       LexicalScope*scope = lexical_scope;
diff --git a/pform.h b/pform.h
index d1335d8c5..3665da832 100644
--- a/pform.h
+++ b/pform.h
@@ -1,7 +1,7 @@
 #ifndef IVL_pform_H
 #define IVL_pform_H
 /*
- * Copyright (c) 1998-2024 Stephen Williams (steve@icarus.com)
+ * Copyright (c) 1998-2025 Stephen Williams (steve@icarus.com)
  *
  *    This source code is free software; you can redistribute it
  *    and/or modify it in source code form under the terms of the GNU
@@ -212,7 +212,7 @@ PPackage *pform_find_potential_import(const struct vlltype&loc, LexicalScope*sco
 
 
 extern PExpr* pform_package_ident(const struct vlltype&loc,
-				  PPackage*pkg, pform_name_t*ident);
+				  PPackage*pkg, const pform_name_t*ident);
 
 /*
  * Interface related functions.
@@ -255,13 +255,13 @@ extern PFunction*pform_push_constructor_scope(const struct vlltype&loc);
 extern PPackage* pform_push_package_scope(const struct vlltype&loc, perm_string name,
 					  LexicalScope::lifetime_t lifetime);
 
-extern PTask*pform_push_task_scope(const struct vlltype&loc, char*name,
+extern PTask*pform_push_task_scope(const struct vlltype&loc, const char*name,
 				   LexicalScope::lifetime_t lifetime);
 
 extern PFunction*pform_push_function_scope(const struct vlltype&loc, const char*name,
 					   LexicalScope::lifetime_t lifetime);
 
-extern PBlock*pform_push_block_scope(const struct vlltype&loc, char*name,
+extern PBlock*pform_push_block_scope(const struct vlltype&loc, const char*name,
 				     PBlock::BL_TYPE tt);
 
 extern void pform_put_behavior_in_scope(AProcess*proc);
@@ -294,7 +294,7 @@ extern void pform_start_generate_else(const struct vlltype&li);
 extern void pform_start_generate_case(const struct vlltype&lp, PExpr*test);
 extern void pform_start_generate_nblock(const struct vlltype&lp, char*name);
 extern void pform_generate_case_item(const struct vlltype&lp, std::list<PExpr*>*test);
-extern void pform_generate_block_name(char*name);
+extern void pform_generate_block_name(const char*name);
 extern void pform_endgenerate(bool end_conditional);
 
 /*
@@ -342,7 +342,7 @@ extern PForeach* pform_make_foreach(const struct vlltype&loc,
 extern PWire *pform_makewire(const struct vlltype&li,
                              const pform_ident_t&name,
 			     NetNet::Type type,
-			     std::list<pform_range_t> *indices);
+			     const std::list<pform_range_t> *indices);
 
 /* This form handles assignment declarations. */
 
@@ -401,10 +401,10 @@ extern LexicalScope::range_t* pform_parameter_value_range(bool exclude_flag,
 						    bool hig_open, PExpr*hig_expr);
 
 extern void pform_set_parameter(const struct vlltype&loc,
-				perm_string name,
-				bool is_local, bool is_type,
-				data_type_t*data_type, std::list<pform_range_t>*udims,
-				PExpr*expr, LexicalScope::range_t*value_range);
+                                perm_string name,
+                                bool is_local, bool is_type,
+                                data_type_t*data_type, const std::list<pform_range_t>*udims,
+                                PExpr*expr, LexicalScope::range_t*value_range);
 extern void pform_set_specparam(const struct vlltype&loc,
 				 perm_string name,
 				 std::list<pform_range_t>*range,
@@ -520,7 +520,7 @@ extern PExpr* pform_genvar_compressed(const struct vlltype &loc,
  * parses the source file and places all the modules it finds into the
  * mod list. The dump function dumps a module to the output stream.
  */
-extern void pform_dump(std::ostream&out, Module*mod);
+extern void pform_dump(std::ostream&out, const Module*mod);
 
 /* ** pform_discipline.cc
  * Functions for handling the parse of natures and disciplines. These
@@ -554,10 +554,10 @@ extern AContrib*pform_contribution_statement(const struct vlltype&loc,
 					     PExpr*lval, PExpr*rval);
 
 extern PExpr* pform_make_branch_probe_expression(const struct vlltype&loc,
-						 char*name, char*n1, char*n2);
+                                                 const char*name, const char*n1, const char*n2);
 
 extern PExpr* pform_make_branch_probe_expression(const struct vlltype&loc,
-						 char*name, char*branch);
+                                                 const char*name, const char*branch);
 
 /*
  * Parse configuration file with format <key>=<value>, where key
diff --git a/pform_analog.cc b/pform_analog.cc
index b5058d655..c1e0c1775 100644
--- a/pform_analog.cc
+++ b/pform_analog.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008-2024 Stephen Williams (steve@icarus.com)
+ * Copyright (c) 2008-2025 Stephen Williams (steve@icarus.com)
  *
  *    This source code is free software; you can redistribute it
  *    and/or modify it in source code form under the terms of the GNU
@@ -44,7 +44,7 @@ void pform_make_analog_behavior(const struct vlltype&loc, ivl_process_type_t pt,
 }
 
 PExpr* pform_make_branch_probe_expression(const struct vlltype&loc,
-					  char*name, char*n1, char*n2)
+					  const char*name, const char*n1, const char*n2)
 {
       vector<named_pexpr_t> parms (2);
       parms[0].parm = new PEIdent(lex_strings.make(n1), loc.lexical_pos);
@@ -59,7 +59,7 @@ PExpr* pform_make_branch_probe_expression(const struct vlltype&loc,
 }
 
 PExpr* pform_make_branch_probe_expression(const struct vlltype&loc,
-					  char*name, char*branch_name)
+					  const char*name, const char*branch_name)
 {
       vector<named_pexpr_t> parms (1);
       parms[0].parm = new PEIdent(lex_strings.make(branch_name), loc.lexical_pos);
diff --git a/pform_dump.cc b/pform_dump.cc
index 13883775b..6dc130687 100644
--- a/pform_dump.cc
+++ b/pform_dump.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998-2024 Stephen Williams (steve@icarus.com)
+ * Copyright (c) 1998-2025 Stephen Williams (steve@icarus.com)
  *
  *    This source code is free software; you can redistribute it
  *    and/or modify it in source code form under the terms of the GNU
@@ -1811,7 +1811,7 @@ void Module::dump(ostream&out) const
       out << "endmodule" << endl;
 }
 
-void pform_dump(ostream&out, Module*mod)
+void pform_dump(ostream&out, const Module*mod)
 {
       mod->dump(out);
 }
diff --git a/pform_package.cc b/pform_package.cc
index 7e949f391..05c440751 100644
--- a/pform_package.cc
+++ b/pform_package.cc
@@ -229,7 +229,7 @@ void pform_package_export(const struct vlltype &loc, PPackage *pkg, const char *
 }
 
 PExpr* pform_package_ident(const struct vlltype&loc,
-			   PPackage*pkg, pform_name_t*ident_name)
+			   PPackage*pkg, const pform_name_t*ident_name)
 {
       ivl_assert(loc, ident_name);
       PEIdent*tmp = new PEIdent(pkg, *ident_name, loc.lexical_pos);
diff --git a/syn-rules.y b/syn-rules.y
index 201db1b63..3ce56c833 100644
--- a/syn-rules.y
+++ b/syn-rules.y
@@ -1,7 +1,7 @@
 
 %{
 /*
- * Copyright (c) 2000-2021 Stephen Williams (steve@icarus.com)
+ * Copyright (c) 2000-2025 Stephen Williams (steve@icarus.com)
  *
  *    This source code is free software; you can redistribute it
  *    and/or modify it in source code form under the terms of the GNU
@@ -185,9 +185,9 @@ static syn_token_t*ptr_ = 0;
  */
 struct tokenize : public proc_match_t {
       tokenize() { }
-      ~tokenize() { }
+      ~tokenize() override { }
 
-      int assign(NetAssign*dev)
+      int assign(NetAssign*dev) override
       {
 	    syn_token_t*cur;
 	    cur = new syn_token_t;
@@ -202,7 +202,7 @@ struct tokenize : public proc_match_t {
 	    return 0;
       }
 
-      int assign_nb(NetAssignNB*dev)
+      int assign_nb(NetAssignNB*dev) override
       {
 	    syn_token_t*cur;
 	    cur = new syn_token_t;
@@ -217,7 +217,7 @@ struct tokenize : public proc_match_t {
 	    return 0;
       }
 
-      int condit(NetCondit*dev)
+      int condit(NetCondit*dev) override
       {
 	    syn_token_t*cur;
 
@@ -257,7 +257,7 @@ struct tokenize : public proc_match_t {
 	    return 0;
       }
 
-      int event_wait(NetEvWait*dev)
+      int event_wait(NetEvWait*dev) override
       {
 	    syn_token_t*cur;
 
@@ -345,9 +345,9 @@ static int yylex()
 }
 
 struct syn_rules_f  : public functor_t {
-      ~syn_rules_f() { }
+      ~syn_rules_f() override { }
 
-      void process(class Design*, class NetProcTop*top)
+      void process(class Design*, class NetProcTop*top) override
       {
 	      /* If the scope that contains this process as a cell
 		 attribute attached to it, then skip synthesis. */