diff --git a/.travis.yml b/.travis.yml
index 52d548e3de2..6987a0b55d7 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -38,6 +38,13 @@ jobs:
       script: scripts/travis_lint.sh
       before_cache:
 
+    - &string-table-check
+      stage: Linter + Doxygen + non-debug Ubuntu/gcc-5 test
+      env: NAME="string-table"
+      install:
+      script: scripts/string_table_check.sh
+      before_cache:
+
     - stage: Linter + Doxygen + non-debug Ubuntu/gcc-5 test
       env: NAME="DOXYGEN-CHECK"
       addons:
diff --git a/scripts/string_table_check.sh b/scripts/string_table_check.sh
new file mode 100755
index 00000000000..5bf6d4b2dd2
--- /dev/null
+++ b/scripts/string_table_check.sh
@@ -0,0 +1,30 @@
+#!/bin/bash
+
+whitelist=" \
+"
+
+cleanup()
+{
+  rm -f "$ids_file"
+}
+
+ids_file=$(mktemp)
+
+trap cleanup EXIT
+
+gcc -E -P -x c src/util/irep_ids.def \
+  -D'IREP_ID_ONE(x)=ID_ ## x' -D'IREP_ID_TWO(x,y)=ID_ ## x' > $ids_file
+
+for w in $whitelist
+do
+  perl -p -i -e "s/^$w\n//" $ids_file
+done
+
+for i in $(<$ids_file)
+do
+  if ! git grep -w -q -c -F $i
+  then
+    echo "$i is never used"
+    exit  1
+  fi
+done
diff --git a/src/cpp/cpp_typecheck_resolve.cpp b/src/cpp/cpp_typecheck_resolve.cpp
index afc841da20b..647e1e14e46 100644
--- a/src/cpp/cpp_typecheck_resolve.cpp
+++ b/src/cpp/cpp_typecheck_resolve.cpp
@@ -839,11 +839,11 @@ exprt cpp_typecheck_resolvet::do_builtin(
                             << ": " << original_scope->prefix
                             << messaget::eom;
   }
-  else if(base_name=="size_t")
+  else if(base_name == ID_size_t)
   {
     dest=type_exprt(size_type());
   }
-  else if(base_name=="ssize_t")
+  else if(base_name == ID_ssize_t)
   {
     dest=type_exprt(signed_size_type());
   }
diff --git a/src/goto-programs/remove_asm.cpp b/src/goto-programs/remove_asm.cpp
index 0a514d04487..d93032a33aa 100644
--- a/src/goto-programs/remove_asm.cpp
+++ b/src/goto-programs/remove_asm.cpp
@@ -195,7 +195,7 @@ void remove_asmt::process_instruction(
       {
         gcc_asm_function_call("__asm_"+id2string(command), code, tmp_dest);
       }
-      else if(command=="sync") // Power
+      else if(command == ID_sync) // Power
       {
         goto_programt::targett t=tmp_dest.add_instruction(OTHER);
         t->source_location=code.source_location();
@@ -210,7 +210,7 @@ void remove_asmt::process_instruction(
         t->code.set(ID_RRcumul, true);
         t->code.set(ID_WRcumul, true);
       }
-      else if(command=="lwsync") // Power
+      else if(command == ID_lwsync) // Power
       {
         goto_programt::targett t=tmp_dest.add_instruction(OTHER);
         t->source_location=code.source_location();
@@ -223,7 +223,7 @@ void remove_asmt::process_instruction(
         t->code.set(ID_RWcumul, true);
         t->code.set(ID_RRcumul, true);
       }
-      else if(command=="isync") // Power
+      else if(command == ID_isync) // Power
       {
         goto_programt::targett t=tmp_dest.add_instruction(OTHER);
         t->source_location=code.source_location();
diff --git a/src/goto-symex/slice_by_trace.cpp b/src/goto-symex/slice_by_trace.cpp
index 5218870e96f..9fe0036911d 100644
--- a/src/goto-symex/slice_by_trace.cpp
+++ b/src/goto-symex/slice_by_trace.cpp
@@ -244,7 +244,7 @@ void symex_slice_by_tracet::compute_ts_back(
        !i->io_args.empty() &&
        i->io_args.front().id()=="trace_event")
     {
-      irep_idt event=i->io_args.front().get("event");
+      irep_idt event = i->io_args.front().get(ID_event);
 
       if(!alphabet.empty())
       {
diff --git a/src/solvers/smt2/smt2_parser.cpp b/src/solvers/smt2/smt2_parser.cpp
index 39bb7c0d519..d52bb8eafa1 100644
--- a/src/solvers/smt2/smt2_parser.cpp
+++ b/src/solvers/smt2/smt2_parser.cpp
@@ -774,7 +774,7 @@ exprt smt2_parsert::function_application()
         }
         else if(id=="rotate_left" ||
                 id=="rotate_right" ||
-                id=="repeat" ||
+                id == ID_repeat ||
                 id=="sign_extend" ||
                 id=="zero_extend")
         {
@@ -826,7 +826,7 @@ exprt smt2_parsert::function_application()
 
             return typecast_exprt(op[0], unsigned_type);
           }
-          else if(id=="repeat")
+          else if(id == ID_repeat)
           {
             return nil_exprt();
           }
diff --git a/src/util/irep_ids.cpp b/src/util/irep_ids.cpp
index 5151cd92fed..5a6bc4e525d 100644
--- a/src/util/irep_ids.cpp
+++ b/src/util/irep_ids.cpp
@@ -27,6 +27,14 @@ const char *irep_ids_table[]=
 
 #ifdef USE_DSTRING
 
+enum class idt:unsigned
+{
+#define IREP_ID_ONE(the_id) id_##the_id,
+#define IREP_ID_TWO(the_id, str) id_##the_id,
+
+#include "irep_ids.def" // NOLINT(build/include)
+};
+
 #define IREP_ID_ONE(the_id)                                                    \
   const dstringt ID_##the_id=dstringt::make_from_table_index(                  \
       static_cast<unsigned>(idt::id_##the_id));
diff --git a/src/util/irep_ids.def b/src/util/irep_ids.def
index 4f68f78051c..78ff9b00e16 100644
--- a/src/util/irep_ids.def
+++ b/src/util/irep_ids.def
@@ -1,4 +1,5 @@
-/// \file List of irep id names and values.
+/// \file
+/// List of irep id names and values.
 /// For an explanation of how this works, see irep_ids.h.
 
 IREP_ID_TWO(empty_string, )
@@ -34,7 +35,6 @@ IREP_ID_ONE(dynamic_cast)
 IREP_ID_ONE(const_cast)
 IREP_ID_ONE(reinterpret_cast)
 IREP_ID_ONE(index)
-IREP_ID_ONE(index_range)
 IREP_ID_ONE(ptrmember)
 IREP_ID_ONE(member)
 IREP_ID_ONE(member_name)
@@ -47,7 +47,6 @@ IREP_ID_ONE(nand)
 IREP_ID_ONE(or)
 IREP_ID_ONE(nor)
 IREP_ID_ONE(xor)
-IREP_ID_ONE(xnor)
 IREP_ID_ONE(not)
 IREP_ID_ONE(bitand)
 IREP_ID_ONE(bitor)
@@ -61,7 +60,6 @@ IREP_ID_ONE(if)
 IREP_ID_ONE(symbol)
 IREP_ID_ONE(next_symbol)
 IREP_ID_ONE(nondet_symbol)
-IREP_ID_ONE(predicate)
 IREP_ID_ONE(predicate_symbol)
 IREP_ID_ONE(predicate_next_symbol)
 IREP_ID_ONE(nondet_bool)
@@ -148,13 +146,6 @@ IREP_ID_ONE(range)
 IREP_ID_ONE(from)
 IREP_ID_ONE(to)
 IREP_ID_ONE(module)
-IREP_ID_ONE(module_instance)
-IREP_ID_ONE(macromodule)
-IREP_ID_ONE(primitive_module_instance)
-IREP_ID_ONE(module_items)
-IREP_ID_ONE(module_source)
-IREP_ID_ONE(parameter_decl)
-IREP_ID_ONE(local_parameter_decl)
 IREP_ID_ONE(parameter)
 IREP_ID_ONE(component_name)
 IREP_ID_ONE(component_number)
@@ -170,13 +161,9 @@ IREP_ID_ONE(width)
 IREP_ID_ONE(components)
 IREP_ID_ONE(bv)
 IREP_ID_ONE(f)
-IREP_ID_ONE(ports)
-IREP_ID_ONE(port)
-IREP_ID_ONE(offset)
 IREP_ID_ONE(with)
 IREP_ID_ONE(trans)
 IREP_ID_ONE(throw)
-IREP_ID_ONE(catch)
 IREP_ID_ONE(try_catch)
 IREP_ID_ONE(noexcept)
 IREP_ID_ONE(CPROVER_throw)
@@ -193,7 +180,6 @@ IREP_ID_ONE(constexpr)
 IREP_ID_ONE(inline)
 IREP_ID_ONE(forall)
 IREP_ID_ONE(exists)
-IREP_ID_ONE(forever)
 IREP_ID_ONE(repeat)
 IREP_ID_ONE(extractbit)
 IREP_ID_ONE(extractbits)
@@ -222,8 +208,6 @@ IREP_ID_ONE(java_string_literal)
 IREP_ID_ONE(printf)
 IREP_ID_ONE(input)
 IREP_ID_ONE(output)
-IREP_ID_ONE(output_register)
-IREP_ID_ONE(inout)
 IREP_ID_ONE(nondet)
 IREP_ID_ONE(NULL)
 IREP_ID_ONE(null)
@@ -280,7 +264,6 @@ IREP_ID_ONE(ptr64)
 IREP_ID_ONE(char)
 IREP_ID_ONE(short)
 IREP_ID_ONE(long)
-IREP_ID_ONE(longlong)
 IREP_ID_ONE(float)
 IREP_ID_ONE(double)
 IREP_ID_ONE(byte)
@@ -299,9 +282,6 @@ IREP_ID_ONE(unsigned_long_long_int)
 IREP_ID_ONE(signed_int128)
 IREP_ID_ONE(unsigned_int128)
 IREP_ID_ONE(case)
-IREP_ID_ONE(casex)
-IREP_ID_ONE(casez)
-IREP_ID_ONE(case_item)
 IREP_ID_TWO(C_inlined, #inlined)
 IREP_ID_TWO(C_hide, #hide)
 IREP_ID_ONE(hide)
@@ -322,22 +302,6 @@ IREP_ID_ONE(bv_literals)
 IREP_ID_ONE(isfinite)
 IREP_ID_ONE(isinf)
 IREP_ID_ONE(isnormal)
-IREP_ID_ONE(AG)
-IREP_ID_ONE(AF)
-IREP_ID_ONE(AX)
-IREP_ID_ONE(EG)
-IREP_ID_ONE(EF)
-IREP_ID_ONE(EX)
-IREP_ID_ONE(U)
-IREP_ID_ONE(R)
-IREP_ID_ONE(A)
-IREP_ID_ONE(F)
-IREP_ID_ONE(E)
-IREP_ID_ONE(G)
-IREP_ID_ONE(X)
-IREP_ID_ONE(continuous_assign)
-IREP_ID_ONE(blocking_assign)
-IREP_ID_ONE(non_blocking_assign)
 IREP_ID_ONE(alignof)
 IREP_ID_ONE(clang_builtin_convertvector)
 IREP_ID_ONE(gcc_builtin_va_arg)
@@ -353,11 +317,6 @@ IREP_ID_ONE(gcc_decimal128)
 IREP_ID_ONE(builtin_offsetof)
 IREP_ID_ONE(0)
 IREP_ID_ONE(1)
-IREP_ID_ONE(8)
-IREP_ID_ONE(16)
-IREP_ID_ONE(32)
-IREP_ID_ONE(64)
-IREP_ID_ONE(128)
 IREP_ID_ONE(sizeof)
 IREP_ID_ONE(type_arg)
 IREP_ID_ONE(expr_arg)
@@ -382,11 +341,9 @@ IREP_ID_TWO(mult, *)
 IREP_ID_TWO(div, /)
 IREP_ID_TWO(power, **)
 IREP_ID_ONE(factorial_power)
-IREP_ID_ONE(component)
 IREP_ID_ONE(pretty_name)
 IREP_ID_TWO(C_class, #class)
 IREP_ID_TWO(C_interface, #interface)
-IREP_ID_ONE(interface)
 IREP_ID_ONE(targets)
 IREP_ID_ONE(location)
 IREP_ID_ONE(labels)
@@ -396,7 +353,6 @@ IREP_ID_ONE(designated_initializer)
 IREP_ID_ONE(designator)
 IREP_ID_ONE(member_designator)
 IREP_ID_ONE(index_designator)
-IREP_ID_ONE(offset_designator)
 IREP_ID_TWO(C_constant, #constant)
 IREP_ID_TWO(C_volatile, #volatile)
 IREP_ID_TWO(C_restricted, #restricted)
@@ -411,7 +367,6 @@ IREP_ID_ONE(byte_extract_little_endian)
 IREP_ID_ONE(byte_update_big_endian)
 IREP_ID_ONE(byte_update_little_endian)
 IREP_ID_ONE(replication)
-IREP_ID_ONE(dummy)
 IREP_ID_ONE(init)
 IREP_ID_ONE(cprover_atomic)
 IREP_ID_ONE(atomic)
@@ -424,18 +379,10 @@ IREP_ID_ONE(specc_notify)
 IREP_ID_ONE(specc_par)
 IREP_ID_ONE(specc_wait)
 IREP_ID_ONE(specc_event)
-IREP_ID_ONE(bp_enforce)
-IREP_ID_ONE(bp_abortif)
-IREP_ID_ONE(bp_constrain)
-IREP_ID_ONE(bp_schoose)
-IREP_ID_ONE(bp_dead)
-IREP_ID_ONE(instance)
-IREP_ID_ONE(cover)
 IREP_ID_ONE(coverage_criterion)
 IREP_ID_ONE(initializer)
 IREP_ID_ONE(anonymous)
 IREP_ID_TWO(C_is_anonymous, #is_anonymous)
-IREP_ID_ONE(is_macro)
 IREP_ID_ONE(is_enum_constant)
 IREP_ID_ONE(is_inline)
 IREP_ID_ONE(is_extern)
@@ -475,34 +422,14 @@ IREP_ID_ONE(typename)
 IREP_ID_ONE(C)
 IREP_ID_ONE(cpp)
 IREP_ID_ONE(java)
-IREP_ID_ONE(SpecC)
-IREP_ID_ONE(SystemC)
 IREP_ID_ONE(decl_block)
 IREP_ID_ONE(decl_type)
-IREP_ID_ONE(genvar)
-IREP_ID_ONE(realtime)
 IREP_ID_ONE(parameters)
-IREP_ID_ONE(parameter_assignments)
-IREP_ID_ONE(named_parameter_assignment)
-IREP_ID_ONE(specify)
-IREP_ID_ONE(pullup)
-IREP_ID_ONE(pulldown)
-IREP_ID_ONE(automatic)
-IREP_ID_ONE(rcmos)
-IREP_ID_ONE(cmos)
-IREP_ID_ONE(nmos)
-IREP_ID_ONE(pmos)
-IREP_ID_ONE(rnmos)
-IREP_ID_ONE(rpmos)
 IREP_ID_ONE(wchar_t)
 IREP_ID_ONE(char16_t)
 IREP_ID_ONE(char32_t)
 IREP_ID_ONE(size_t)
 IREP_ID_ONE(ssize_t)
-IREP_ID_ONE(inst)
-IREP_ID_ONE(inst_builtin)
-IREP_ID_ONE(always)
-IREP_ID_ONE(initial)
 IREP_ID_ONE(mode)
 IREP_ID_ONE(this)
 IREP_ID_TWO(C_this, #this)
@@ -514,7 +441,6 @@ IREP_ID_ONE(reduction_xor)
 IREP_ID_ONE(reduction_xnor)
 IREP_ID_TWO(C_zero_initializer, #zero_initializer)
 IREP_ID_ONE(body)
-IREP_ID_ONE(entity)
 IREP_ID_ONE(temporary_object)
 IREP_ID_TWO(overflow_plus, overflow-+)
 IREP_ID_TWO(overflow_minus, overflow--)
@@ -531,10 +457,7 @@ IREP_ID_ONE(static_object)
 IREP_ID_ONE(stack_object)
 IREP_ID_TWO(C_is_failed_symbol, #is_failed_symbol)
 IREP_ID_TWO(C_failed_symbol, #failed_symbol)
-IREP_ID_ONE(list)
-IREP_ID_ONE(map)
 IREP_ID_ONE(set)
-IREP_ID_ONE(storage)
 IREP_ID_ONE(friend)
 IREP_ID_ONE(explicit)
 IREP_ID_ONE(storage_spec)
@@ -548,21 +471,6 @@ IREP_ID_ONE(aligned)
 IREP_ID_TWO(C_alignment, #alignment)
 IREP_ID_ONE(vector)
 IREP_ID_ONE(abstract)
-IREP_ID_ONE(bit)
-IREP_ID_ONE(logic)
-IREP_ID_ONE(chandle)
-IREP_ID_ONE(reg)
-IREP_ID_ONE(wire)
-IREP_ID_ONE(tri)
-IREP_ID_ONE(tri1)
-IREP_ID_ONE(supply0)
-IREP_ID_ONE(wand)
-IREP_ID_ONE(triand)
-IREP_ID_ONE(tri0)
-IREP_ID_ONE(supply1)
-IREP_ID_ONE(wor)
-IREP_ID_ONE(trior)
-IREP_ID_ONE(trireg)
 IREP_ID_ONE(function_application)
 IREP_ID_ONE(cpp_declarator)
 IREP_ID_ONE(cpp_linkage_spec)
@@ -576,57 +484,12 @@ IREP_ID_TWO(C_c_type, #c_type)
 IREP_ID_ONE(namespace)
 IREP_ID_ONE(linkage)
 IREP_ID_ONE(decltype)
-IREP_ID_ONE(buf)
-IREP_ID_ONE(bufif0)
-IREP_ID_ONE(bufif1)
-IREP_ID_ONE(notif0)
-IREP_ID_ONE(notif1)
-IREP_ID_ONE(task)
-IREP_ID_TWO(C_little_endian, #little_endian)
-IREP_ID_TWO(C_offset, #offset)
 IREP_ID_TWO(C_tag_only_declaration, #tag_only_declaration)
 IREP_ID_ONE(struct_tag)
 IREP_ID_ONE(union_tag)
 IREP_ID_ONE(c_enum_tag)
-IREP_ID_ONE(enum_constant)
-IREP_ID_ONE(bit_select)
-IREP_ID_ONE(part_select)
-IREP_ID_ONE(indexed_part_select_plus)
-IREP_ID_ONE(indexed_part_select_minus)
-IREP_ID_ONE(generate_block)
-IREP_ID_ONE(generate_assign)
-IREP_ID_ONE(generate_skip)
-IREP_ID_ONE(generate_case)
-IREP_ID_ONE(generate_if)
-IREP_ID_ONE(generate_for)
-IREP_ID_ONE(delay)
-IREP_ID_ONE(verilog_cycle_delay)
-IREP_ID_ONE(sva_cycle_delay)
-IREP_ID_ONE(sva_sequence_throughout)
-IREP_ID_ONE(sva_sequence_concatenation)
-IREP_ID_ONE(sva_sequence_first_match)
-IREP_ID_ONE(sva_always)
-IREP_ID_ONE(sva_nexttime)
-IREP_ID_ONE(sva_s_nexttime)
-IREP_ID_ONE(sva_eventually)
-IREP_ID_ONE(sva_s_eventually)
-IREP_ID_ONE(sva_until)
-IREP_ID_ONE(sva_s_until)
-IREP_ID_ONE(sva_until_with)
-IREP_ID_ONE(sva_s_until_with)
-IREP_ID_ONE(sva_overlapped_implication)
-IREP_ID_ONE(sva_non_overlapped_implication)
-IREP_ID_ONE(hierarchical_identifier)
-IREP_ID_ONE(named_port_connection)
-IREP_ID_ONE(named_block)
-IREP_ID_ONE(verilog_primitive_module)
-IREP_ID_ONE(verilog_module)
 IREP_ID_ONE(verilog_case_equality)
 IREP_ID_ONE(verilog_case_inequality)
-IREP_ID_ONE(event_guard)
-IREP_ID_ONE(posedge)
-IREP_ID_ONE(negedge)
-IREP_ID_ONE(pointer_and_address_pair)
 IREP_ID_ONE(user_specified_predicate)
 IREP_ID_ONE(user_specified_parameter_predicates)
 IREP_ID_ONE(user_specified_return_predicates)
@@ -644,13 +507,9 @@ IREP_ID_ONE(msc_if_not_exists)
 IREP_ID_ONE(msc_underlying_type)
 IREP_ID_ONE(msc_based)
 IREP_ID_ONE(alias)
-IREP_ID_ONE(auto_object)
-IREP_ID_ONE(ssa_object)
 IREP_ID_ONE(ptr_object)
 IREP_ID_TWO(C_c_sizeof_type, #c_sizeof_type)
 IREP_ID_ONE(array_update)
-IREP_ID_ONE(struct_update)
-IREP_ID_ONE(union_update)
 IREP_ID_ONE(update)
 IREP_ID_ONE(float_debug1)
 IREP_ID_ONE(float_debug2)
@@ -659,10 +518,7 @@ IREP_ID_ONE(gcc_attribute_mode)
 IREP_ID_TWO(built_in, <built-in>)
 IREP_ID_ONE(exception_list)
 IREP_ID_ONE(exception_id)
-IREP_ID_ONE(priority)
 IREP_ID_ONE(predicate_passive_symbol)
-IREP_ID_ONE(all)
-IREP_ID_ONE(when)
 IREP_ID_ONE(cw_va_arg_typeof)
 IREP_ID_ONE(fence)
 IREP_ID_ONE(sync)
@@ -676,7 +532,6 @@ IREP_ID_ONE(RRcumul)
 IREP_ID_ONE(RWcumul)
 IREP_ID_ONE(WWcumul)
 IREP_ID_ONE(WRcumul)
-IREP_ID_ONE(claim)
 IREP_ID_ONE(generic_selection)
 IREP_ID_ONE(generic_associations)
 IREP_ID_ONE(generic_association)
@@ -685,13 +540,7 @@ IREP_ID_ONE(floatbv_minus)
 IREP_ID_ONE(floatbv_mult)
 IREP_ID_ONE(floatbv_div)
 IREP_ID_ONE(floatbv_rem)
-IREP_ID_ONE(floatbv_sin)
-IREP_ID_ONE(floatbv_cos)
 IREP_ID_ONE(floatbv_typecast)
-IREP_ID_ONE(read)
-IREP_ID_ONE(write)
-IREP_ID_ONE(native)
-IREP_ID_ONE(final)
 IREP_ID_ONE(compound_literal)
 IREP_ID_ONE(custom_bv)
 IREP_ID_ONE(custom_unsignedbv)
@@ -699,7 +548,6 @@ IREP_ID_ONE(custom_signedbv)
 IREP_ID_ONE(custom_fixedbv)
 IREP_ID_ONE(custom_floatbv)
 IREP_ID_TWO(C_SSA_symbol, #SSA_symbol)
-IREP_ID_TWO(C_full_identifier, #full_identifier)
 IREP_ID_ONE(L0)
 IREP_ID_ONE(L1)
 IREP_ID_ONE(L2)
@@ -707,26 +555,12 @@ IREP_ID_ONE(L1_object_identifier)
 IREP_ID_ONE(already_typechecked)
 IREP_ID_TWO(C_va_arg_type, #va_arg_type)
 IREP_ID_ONE(smt2_symbol)
-IREP_ID_ONE(VHDL)
-IREP_ID_ONE(Verilog)
-IREP_ID_ONE(verilog_realtime)
 IREP_ID_ONE(onehot)
 IREP_ID_ONE(onehot0)
-IREP_ID_ONE(verilog_star_event)
-IREP_ID_ONE(verilog_attribute)
-IREP_ID_ONE(time)
-IREP_ID_ONE(fork)
-IREP_ID_ONE(disable)
-IREP_ID_ONE(wait)
-IREP_ID_ONE(deassign)
-IREP_ID_ONE(force)
-IREP_ID_ONE(release)
 IREP_ID_ONE(popcount)
 IREP_ID_ONE(function_type)
 IREP_ID_ONE(noreturn)
 IREP_ID_TWO(C_noreturn, #noreturn)
-IREP_ID_ONE(process)
-IREP_ID_ONE(signal)
 IREP_ID_ONE(weak)
 IREP_ID_ONE(is_weak)
 IREP_ID_TWO(C_spec_loop_invariant, #spec_loop_invariant)
@@ -736,13 +570,6 @@ IREP_ID_ONE(virtual_function)
 IREP_ID_TWO(C_element_type, #element_type)
 IREP_ID_ONE(working_directory)
 IREP_ID_ONE(section)
-IREP_ID_ONE(msb)
-IREP_ID_ONE(lsb)
-IREP_ID_ONE(verilog_signed_vector)
-IREP_ID_ONE(verilog_unsigned_vector)
-IREP_ID_ONE(verilog_array)
-IREP_ID_ONE(low)
-IREP_ID_ONE(high)
 IREP_ID_ONE(bswap)
 IREP_ID_ONE(java_bytecode_index)
 IREP_ID_ONE(java_instanceof)
@@ -758,7 +585,6 @@ IREP_ID_ONE(cprover_associate_array_to_pointer_func)
 IREP_ID_ONE(cprover_associate_length_to_array_func)
 IREP_ID_ONE(cprover_char_literal_func)
 IREP_ID_ONE(cprover_string_literal_func)
-IREP_ID_ONE(cprover_string_array_of_char_pointer_func)
 IREP_ID_ONE(cprover_string_char_at_func)
 IREP_ID_ONE(cprover_string_char_set_func)
 IREP_ID_ONE(cprover_string_code_point_at_func)
@@ -794,13 +620,11 @@ IREP_ID_ONE(cprover_string_insert_bool_func)
 IREP_ID_ONE(cprover_string_insert_char_func)
 IREP_ID_ONE(cprover_string_insert_float_func)
 IREP_ID_ONE(cprover_string_insert_double_func)
-IREP_ID_ONE(cprover_string_insert_char_array_func)
 IREP_ID_ONE(cprover_string_is_prefix_func)
 IREP_ID_ONE(cprover_string_is_suffix_func)
 IREP_ID_ONE(cprover_string_is_empty_func)
 IREP_ID_ONE(cprover_string_last_index_of_func)
 IREP_ID_ONE(cprover_string_length_func)
-IREP_ID_ONE(cprover_string_data_func)
 IREP_ID_ONE(cprover_string_of_int_func)
 IREP_ID_ONE(cprover_string_of_int_hex_func)
 IREP_ID_ONE(cprover_string_of_long_func)
@@ -809,17 +633,14 @@ IREP_ID_ONE(cprover_string_of_float_func)
 IREP_ID_ONE(cprover_string_of_float_scientific_notation_func)
 IREP_ID_ONE(cprover_string_of_double_func)
 IREP_ID_ONE(cprover_string_of_char_func)
-IREP_ID_ONE(cprover_string_of_char_array_func)
 IREP_ID_ONE(cprover_string_parse_int_func)
 IREP_ID_ONE(cprover_string_replace_func)
 IREP_ID_ONE(cprover_string_set_length_func)
 IREP_ID_ONE(cprover_string_startswith_func)
 IREP_ID_ONE(cprover_string_substring_func)
-IREP_ID_ONE(cprover_string_to_char_array_func)
 IREP_ID_ONE(cprover_string_to_lower_case_func)
 IREP_ID_ONE(cprover_string_to_upper_case_func)
 IREP_ID_ONE(cprover_string_trim_func)
-IREP_ID_ONE(cprover_string_value_of_func)
 IREP_ID_ONE(skip_initialize)
 IREP_ID_ONE(basic_block_covered_lines)
 IREP_ID_ONE(is_nondet_nullable)
@@ -831,7 +652,6 @@ IREP_ID_ONE(integer_dereference)
 IREP_ID_TWO(C_java_generic_parameter, #java_generic_parameter)
 IREP_ID_TWO(C_java_generic_type, #java_generic_type)
 IREP_ID_TWO(C_java_generics_class_type, #java_generics_class_type)
-IREP_ID_TWO(C_specialized_generic_java_class, #specialized_generic_java_class)
 IREP_ID_TWO(C_java_implicitly_generic_class_type, #java_implicitly_generic_class_type)
 IREP_ID_TWO(C_java_generic_symbol, #java_generic_symbol)
 IREP_ID_TWO(generic_types, #generic_types)
@@ -846,5 +666,13 @@ IREP_ID_TWO(overlay_class, java::com.diffblue.OverlayClassImplementation)
 IREP_ID_TWO(overlay_method, java::com.diffblue.OverlayMethodImplementation)
 IREP_ID_ONE(annotations)
 
+// Projects depending on this code base that wish to extend the list of
+// available ids should provide a file local_irep_ids.h in their source tree and
+// add -D'LOCAL_IREP_IDS=<project/local_irep_ids.h>' to their compiler command
+// line.
+#ifdef LOCAL_IREP_IDS
+#include LOCAL_IREP_IDS
+#endif
+
 #undef IREP_ID_ONE
 #undef IREP_ID_TWO
diff --git a/src/util/irep_ids.h b/src/util/irep_ids.h
index 2fec6ff4114..7d946bed305 100644
--- a/src/util/irep_ids.h
+++ b/src/util/irep_ids.h
@@ -33,14 +33,6 @@ Author: Reuben Thomas, reuben.thomas@me.com
 /// into a const extern irep_idt with the variable name `ID_param` and the
 /// string value `"contents"`.
 
-enum class idt:unsigned
-{
-#define IREP_ID_ONE(the_id) id_##the_id,
-#define IREP_ID_TWO(the_id, str) id_##the_id,
-
-#include "irep_ids.def"
-};
-
 #ifdef USE_DSTRING
 
 #define IREP_ID_ONE(the_id) extern const dstringt ID_##the_id;
@@ -53,6 +45,6 @@ enum class idt:unsigned
 
 #endif
 
-#include "irep_ids.def" // NOLINT(build/include)
+#include "irep_ids.def"
 
 #endif
diff --git a/src/util/symbol.cpp b/src/util/symbol.cpp
index 652fe422c56..95676c17dfc 100644
--- a/src/util/symbol.cpp
+++ b/src/util/symbol.cpp
@@ -73,86 +73,6 @@ std::ostream &operator<<(std::ostream &out,
   return out;
 }
 
-irept symbolt::to_irep() const
-{
-  irept dest;
-
-  dest.clear();
-  dest.add(ID_type)=type;
-  dest.add(ID_value)=value;
-  dest.add(ID_location)=location;
-  dest.set(ID_name, name);
-  dest.set(ID_module, module);
-  dest.set(ID_base_name, base_name);
-  dest.set(ID_mode, mode);
-  dest.set(ID_pretty_name, pretty_name);
-
-  if(is_type)
-    dest.set("is_type", true);
-  if(is_macro)
-    dest.set("is_macro", true);
-  if(is_exported)
-    dest.set("is_exported", true);
-  if(is_input)
-    dest.set("is_input", true);
-  if(is_output)
-    dest.set("is_output", true);
-  if(is_state_var)
-    dest.set("is_statevar", true);
-  if(is_parameter)
-    dest.set("is_parameter", true);
-  if(is_auxiliary)
-    dest.set("is_auxiliary", true);
-  if(is_weak)
-    dest.set("is_weak", true);
-  if(is_property)
-    dest.set("is_property", true);
-  if(is_lvalue)
-    dest.set("is_lvalue", true);
-  if(is_static_lifetime)
-    dest.set("is_static_lifetime", true);
-  if(is_thread_local)
-    dest.set("is_thread_local", true);
-  if(is_file_local)
-    dest.set("is_file_local", true);
-  if(is_extern)
-    dest.set("is_extern", true);
-  if(is_volatile)
-    dest.set("is_volatile", true);
-
-  return dest;
-}
-
-void symbolt::from_irep(const irept &src)
-{
-  type=static_cast<const typet &>(src.find(ID_type));
-  value=static_cast<const exprt &>(src.find(ID_value));
-  location=static_cast<const source_locationt &>(src.find(ID_location));
-
-  name=src.get(ID_name);
-  module=src.get(ID_module);
-  base_name=src.get(ID_base_name);
-  mode=src.get(ID_mode);
-  pretty_name=src.get(ID_pretty_name);
-
-  is_type=src.get_bool("is_type");
-  is_macro=src.get_bool("is_macro");
-  is_exported=src.get_bool("is_exported");
-  is_input=src.get_bool("is_input");
-  is_output=src.get_bool("is_output");
-  is_state_var=src.get_bool("is_state_var");
-  is_parameter=src.get_bool("is_parameter");
-  is_auxiliary=src.get_bool("is_auxiliary");
-  is_weak=src.get_bool("is_weak");
-  is_property=src.get_bool("property");
-  is_lvalue=src.get_bool("lvalue");
-  is_static_lifetime=src.get_bool("static_lifetime");
-  is_thread_local=src.get_bool("thread_local");
-  is_file_local=src.get_bool("file_local");
-  is_extern=src.get_bool("is_extern");
-  is_volatile=src.get_bool("is_volatile");
-}
-
 void symbolt::swap(symbolt &b)
 {
   #define SYM_SWAP1(x) x.swap(b.x)
diff --git a/src/util/symbol.h b/src/util/symbol.h
index ca26306d6bf..078f80ad7b2 100644
--- a/src/util/symbol.h
+++ b/src/util/symbol.h
@@ -91,10 +91,6 @@ class symbolt
   void swap(symbolt &b);
   void show(std::ostream &out) const;
 
-  // serialization
-  irept to_irep() const;
-  void from_irep(const irept &src);
-
   class symbol_exprt symbol_expr() const;
 
   bool is_shared() const