Issue 4459/1: Mark mark_smob () member functions as const

58 files changed, 63 insertions, 63 deletions

diff --git a/lily/all-font-metrics.cc b/lily/all-font-metrics.cc
index 0c855fd4d0..ca3703369a 100644
--- a/lily/all-font-metrics.cc
+++ b/lily/all-font-metrics.cc
@@ -72,7 +72,7 @@ All_font_metrics::~All_font_metrics ()
 }
 
 SCM
-All_font_metrics::mark_smob ()
+All_font_metrics::mark_smob () const
 {
 #if HAVE_PANGO_FT2
   if (pango_dict_)
diff --git a/lily/book.cc b/lily/book.cc
index 8ba2aac908..bf32409104 100644
--- a/lily/book.cc
+++ b/lily/book.cc
@@ -107,7 +107,7 @@ Book::~Book ()
 
 
 SCM
-Book::mark_smob ()
+Book::mark_smob () const
 {
   if (paper_)
     scm_gc_mark (paper_->self_scm ());
diff --git a/lily/context-def.cc b/lily/context-def.cc
index 7e391740a6..6289596603 100644
--- a/lily/context-def.cc
+++ b/lily/context-def.cc
@@ -97,7 +97,7 @@ Context_def::print_smob (SCM port, scm_print_state *)
 }
 
 SCM
-Context_def::mark_smob ()
+Context_def::mark_smob () const
 {
   ASSERT_LIVE_IS_ALLOWED (self_scm ());
 
diff --git a/lily/context-mod.cc b/lily/context-mod.cc
index fd2a25d2fe..c45e4f4d1a 100644
--- a/lily/context-mod.cc
+++ b/lily/context-mod.cc
@@ -46,7 +46,7 @@ Context_mod::print_smob (SCM port, scm_print_state *)
 }
 
 SCM
-Context_mod::mark_smob ()
+Context_mod::mark_smob () const
 {
   return mods_;
 }
diff --git a/lily/context-property.cc b/lily/context-property.cc
index 5904254d7d..99b16f669b 100644
--- a/lily/context-property.cc
+++ b/lily/context-property.cc
@@ -66,7 +66,7 @@ typecheck_grob (SCM symbol, SCM value)
 class Grob_properties : public Simple_smob<Grob_properties>
 {
 public:
-  SCM mark_smob ();
+  SCM mark_smob () const;
   static const char type_p_name_[];
 private:
   friend class Grob_property_info;
@@ -97,7 +97,7 @@ private:
 const char Grob_properties::type_p_name_[] = "ly:grob-properties?";
 
 SCM
-Grob_properties::mark_smob ()
+Grob_properties::mark_smob () const
 {
   scm_gc_mark (alist_);
   scm_gc_mark (based_on_);
diff --git a/lily/context.cc b/lily/context.cc
index 51aa8f024e..da92c0748c 100644
--- a/lily/context.cc
+++ b/lily/context.cc
@@ -717,7 +717,7 @@ Context::print_smob (SCM port, scm_print_state *)
 }
 
 SCM
-Context::mark_smob ()
+Context::mark_smob () const
 {
   scm_gc_mark (context_list_);
   scm_gc_mark (aliases_);
diff --git a/lily/dispatcher.cc b/lily/dispatcher.cc
index 2b80c3358e..1cb7dfaa87 100644
--- a/lily/dispatcher.cc
+++ b/lily/dispatcher.cc
@@ -41,7 +41,7 @@ Dispatcher::Dispatcher ()
 }
 
 SCM
-Dispatcher::mark_smob ()
+Dispatcher::mark_smob () const
 {
   scm_gc_mark (dispatchers_);
   scm_gc_mark (listen_classes_);
diff --git a/lily/font-metric.cc b/lily/font-metric.cc
index f18b2d7256..674aef76a9 100644
--- a/lily/font-metric.cc
+++ b/lily/font-metric.cc
@@ -95,7 +95,7 @@ Font_metric::derived_mark () const
 }
 
 SCM
-Font_metric::mark_smob ()
+Font_metric::mark_smob () const
 {
   derived_mark ();
   return description_;
diff --git a/lily/grob-array.cc b/lily/grob-array.cc
index 27f05076f2..1cabe136ed 100644
--- a/lily/grob-array.cc
+++ b/lily/grob-array.cc
@@ -52,7 +52,7 @@ Grob_array::array () const
 }
 
 SCM
-Grob_array::mark_smob ()
+Grob_array::mark_smob () const
 {
 #if 0  /* see System::derived_mark () const */
   for (vsize i = 0; i < grobs_.size (); i++)
diff --git a/lily/grob-smob.cc b/lily/grob-smob.cc
index f3383e77fd..d038f9b840 100644
--- a/lily/grob-smob.cc
+++ b/lily/grob-smob.cc
@@ -26,7 +26,7 @@
 const char Grob::type_p_name_[] = "ly:grob?";
 
 SCM
-Grob::mark_smob ()
+Grob::mark_smob () const
 {
   ASSERT_LIVE_IS_ALLOWED (self_scm ());
 
diff --git a/lily/include/all-font-metrics.hh b/lily/include/all-font-metrics.hh
index 88820ea363..a2d090a6df 100644
--- a/lily/include/all-font-metrics.hh
+++ b/lily/include/all-font-metrics.hh
@@ -48,7 +48,7 @@ class All_font_metrics : public Smob<All_font_metrics>
 
   All_font_metrics (All_font_metrics const &);
 public:
-  SCM mark_smob ();
+  SCM mark_smob () const;
 
   Index_to_charcode_map const *get_index_to_charcode_map (const string &filename,
                                                           int face_index,
diff --git a/lily/include/book.hh b/lily/include/book.hh
index 6b1c2bfb14..3ea6c2c550 100644
--- a/lily/include/book.hh
+++ b/lily/include/book.hh
@@ -29,7 +29,7 @@
 class Book : public Smob<Book>
 {
 public:
-  SCM mark_smob ();
+  SCM mark_smob () const;
   static const char type_p_name_[];
   virtual ~Book ();
   SCM header_;
diff --git a/lily/include/context-def.hh b/lily/include/context-def.hh
index 9a7db15b6d..e8e8d3b68e 100644
--- a/lily/include/context-def.hh
+++ b/lily/include/context-def.hh
@@ -33,7 +33,7 @@
 */
 struct Context_def : public Smob<Context_def>
 {
-  SCM mark_smob ();
+  SCM mark_smob () const;
   int print_smob (SCM, scm_print_state *);
   static const char type_p_name_[];
   virtual ~Context_def ();
diff --git a/lily/include/context-mod.hh b/lily/include/context-mod.hh
index a42ec91433..cef084c87e 100644
--- a/lily/include/context-mod.hh
+++ b/lily/include/context-mod.hh
@@ -36,7 +36,7 @@
 */
 struct Context_mod : public Simple_smob<Context_mod>
 {
-  SCM mark_smob ();
+  SCM mark_smob () const;
   int print_smob (SCM, scm_print_state *);
   static const char type_p_name_[];
 private:
diff --git a/lily/include/context.hh b/lily/include/context.hh
index 048bbd6dd4..85e2d1f44c 100644
--- a/lily/include/context.hh
+++ b/lily/include/context.hh
@@ -31,7 +31,7 @@
 class Context : public Smob<Context>
 {
 public:
-  SCM mark_smob ();
+  SCM mark_smob () const;
   int print_smob (SCM, scm_print_state *);
   static const char type_p_name_[];
   virtual ~Context ();
diff --git a/lily/include/dispatcher.hh b/lily/include/dispatcher.hh
index f7efad8214..a7c96f9201 100644
--- a/lily/include/dispatcher.hh
+++ b/lily/include/dispatcher.hh
@@ -28,7 +28,7 @@ class Dispatcher : public Smob<Dispatcher>
 {
 public:
   int print_smob (SCM, scm_print_state *);
-  SCM mark_smob ();
+  SCM mark_smob () const;
   static const char type_p_name_[];
   virtual ~Dispatcher ();
 private:
diff --git a/lily/include/font-metric.hh b/lily/include/font-metric.hh
index b1016b65c6..f1917b0c4a 100644
--- a/lily/include/font-metric.hh
+++ b/lily/include/font-metric.hh
@@ -34,7 +34,7 @@ class Font_metric : public Smob<Font_metric>
 {
 public:
   int print_smob (SCM, scm_print_state *);
-  SCM mark_smob ();
+  SCM mark_smob () const;
   static const char type_p_name_[];
   virtual ~Font_metric ();
 private:
diff --git a/lily/include/grob-array.hh b/lily/include/grob-array.hh
index 87cb19e23d..e3631c8ea9 100644
--- a/lily/include/grob-array.hh
+++ b/lily/include/grob-array.hh
@@ -28,7 +28,7 @@ class Grob_array : public Simple_smob<Grob_array>
 {
 public:
   int print_smob (SCM, scm_print_state *);
-  SCM mark_smob ();
+  SCM mark_smob () const;
   static const char type_p_name_[];
 private:
   vector<Grob *> grobs_;
diff --git a/lily/include/grob.hh b/lily/include/grob.hh
index 4748b17273..5dea5a948c 100644
--- a/lily/include/grob.hh
+++ b/lily/include/grob.hh
@@ -31,7 +31,7 @@ class Grob : public Smob<Grob>
 {
 public:
   int print_smob (SCM, scm_print_state *);
-  SCM mark_smob ();
+  SCM mark_smob () const;
   static const char type_p_name_[];
   virtual ~Grob ();
 private:
diff --git a/lily/include/input.hh b/lily/include/input.hh
index b33b506730..cde9b87893 100644
--- a/lily/include/input.hh
+++ b/lily/include/input.hh
@@ -35,7 +35,7 @@ public:
   static const char type_p_name_[];
   int print_smob (SCM, scm_print_state *);
   static SCM equal_p (SCM, SCM);
-  SCM mark_smob ();
+  SCM mark_smob () const;
   Source_file *get_source_file () const;
   char const *start () const;
   char const *end () const;
diff --git a/lily/include/lily-lexer.hh b/lily/include/lily-lexer.hh
index 5a622c9317..7a4bc15de5 100644
--- a/lily/include/lily-lexer.hh
+++ b/lily/include/lily-lexer.hh
@@ -35,7 +35,7 @@ class Lily_lexer : public Smob<Lily_lexer>, public Includable_lexer
 {
 public:
   int print_smob (SCM, scm_print_state *);
-  SCM mark_smob ();
+  SCM mark_smob () const;
   static const char type_p_name_[];
   virtual ~Lily_lexer ();
 private:
diff --git a/lily/include/lily-parser.hh b/lily/include/lily-parser.hh
index 6d299d48b4..cb36382b3b 100644
--- a/lily/include/lily-parser.hh
+++ b/lily/include/lily-parser.hh
@@ -35,7 +35,7 @@ class Lily_parser : public Smob<Lily_parser>
   static SCM do_yyparse_trampoline (void *parser);
 public:
   int print_smob (SCM, scm_print_state *);
-  SCM mark_smob ();
+  SCM mark_smob () const;
   static const char type_p_name_[];
   virtual ~Lily_parser ();
   Lily_lexer *lexer_;
diff --git a/lily/include/listener.hh b/lily/include/listener.hh
index 6f8995c64e..00a64eebb8 100644
--- a/lily/include/listener.hh
+++ b/lily/include/listener.hh
@@ -108,7 +108,7 @@ public:
     return SCM_UNSPECIFIED;
   }
 
-  SCM mark_smob ()
+  SCM mark_smob () const
   {
     scm_gc_mark (callback_);
     return target_;
diff --git a/lily/include/music-iterator.hh b/lily/include/music-iterator.hh
index 2afa31941a..30f27ba894 100644
--- a/lily/include/music-iterator.hh
+++ b/lily/include/music-iterator.hh
@@ -62,7 +62,7 @@ class Music_iterator : public Smob<Music_iterator>
 {
 public:
   int print_smob (SCM, scm_print_state *);
-  SCM mark_smob ();
+  SCM mark_smob () const;
   static const char type_p_name_[];
   virtual ~Music_iterator ();
 protected:
diff --git a/lily/include/music-output.hh b/lily/include/music-output.hh
index 37437fbcac..3d1d25728a 100644
--- a/lily/include/music-output.hh
+++ b/lily/include/music-output.hh
@@ -30,7 +30,7 @@ class Music_output : public Smob<Music_output>
 {
 public:
   int print_smob (SCM, scm_print_state *);
-  SCM mark_smob ();
+  SCM mark_smob () const;
   static const char type_p_name_[];
   virtual ~Music_output ();
 private:
diff --git a/lily/include/output-def.hh b/lily/include/output-def.hh
index 1364b64666..5712639cb0 100644
--- a/lily/include/output-def.hh
+++ b/lily/include/output-def.hh
@@ -50,7 +50,7 @@ class Output_def : public Smob<Output_def>
 {
 public:
   int print_smob (SCM, scm_print_state *);
-  SCM mark_smob ();
+  SCM mark_smob () const;
   static const char type_p_name_[];
   virtual ~Output_def ();
   VIRTUAL_COPY_CONSTRUCTOR (Output_def, Output_def);
diff --git a/lily/include/page-marker.hh b/lily/include/page-marker.hh
index cb823d0f0d..02233d30a6 100644
--- a/lily/include/page-marker.hh
+++ b/lily/include/page-marker.hh
@@ -26,7 +26,7 @@
 class Page_marker : public Smob<Page_marker>
 {
 public:
-  SCM mark_smob ();
+  SCM mark_smob () const;
   static const char type_p_name_[];
   virtual ~Page_marker ();
 private:
diff --git a/lily/include/paper-book.hh b/lily/include/paper-book.hh
index 40a40a39b6..b105cdb3de 100644
--- a/lily/include/paper-book.hh
+++ b/lily/include/paper-book.hh
@@ -30,7 +30,7 @@
 class Paper_book : public Smob<Paper_book>
 {
 public:
-  SCM mark_smob ();
+  SCM mark_smob () const;
   static const char type_p_name_[];
   virtual ~Paper_book ();
 private:
diff --git a/lily/include/paper-outputter.hh b/lily/include/paper-outputter.hh
index 73daf148b4..cd1a5e2c92 100644
--- a/lily/include/paper-outputter.hh
+++ b/lily/include/paper-outputter.hh
@@ -33,7 +33,7 @@
 class Paper_outputter : public Smob<Paper_outputter>
 {
 public:
-  SCM mark_smob ();
+  SCM mark_smob () const;
   virtual ~Paper_outputter ();
 private:
   SCM output_module_;
diff --git a/lily/include/pitch.hh b/lily/include/pitch.hh
index 90b4317f68..3e78b79952 100644
--- a/lily/include/pitch.hh
+++ b/lily/include/pitch.hh
@@ -37,7 +37,7 @@ class Pitch : public Simple_smob<Pitch>
 public:
   static SCM equal_p (SCM, SCM);
   int print_smob (SCM, scm_print_state *);
-  SCM mark_smob ();
+  SCM mark_smob () const;
   static const char type_p_name_[];
 private:
   int octave_;
diff --git a/lily/include/prob.hh b/lily/include/prob.hh
index 9f6ad9609a..1f437ac5ef 100644
--- a/lily/include/prob.hh
+++ b/lily/include/prob.hh
@@ -35,7 +35,7 @@ class Prob : public Smob<Prob>
 {
 public:
   int print_smob (SCM, scm_print_state *);
-  SCM mark_smob ();
+  SCM mark_smob () const;
   static SCM equal_p (SCM, SCM);
   static const char type_p_name_[];
   virtual ~Prob ();
diff --git a/lily/include/scm-hash.hh b/lily/include/scm-hash.hh
index d14997676a..8a1922d3c3 100644
--- a/lily/include/scm-hash.hh
+++ b/lily/include/scm-hash.hh
@@ -47,7 +47,7 @@ class Scheme_hash_table : public Smob<Scheme_hash_table>
 {
 public:
   int print_smob (SCM, scm_print_state *);
-  SCM mark_smob ();
+  SCM mark_smob () const;
   virtual ~Scheme_hash_table ();
   bool try_retrieve (SCM key, SCM *val);
   bool contains (SCM key) const;
diff --git a/lily/include/score.hh b/lily/include/score.hh
index 0baf198fa3..b3ece8960a 100644
--- a/lily/include/score.hh
+++ b/lily/include/score.hh
@@ -30,7 +30,7 @@
 class Score : public Smob<Score>
 {
 public:
-  SCM mark_smob ();
+  SCM mark_smob () const;
   static const char type_p_name_[];
   virtual ~Score ();
 private:
diff --git a/lily/include/small-smobs.hh b/lily/include/small-smobs.hh
index 41171b4881..07fd4ef341 100644
--- a/lily/include/small-smobs.hh
+++ b/lily/include/small-smobs.hh
@@ -32,7 +32,7 @@ public:
   static SCM make_smob (SCM arg1 = SCM_UNDEFINED) {
     SCM_RETURN_NEWSMOB (Smob_base<Super>::smob_tag (), SCM_UNPACK (arg1));
   }
-  SCM mark_smob () { return scm1 (); };
+  SCM mark_smob () const { return scm1 (); };
   static Super *unchecked_unsmob (SCM s) {
     return reinterpret_cast<Super *> (SCM_UNPACK (s));
   }
@@ -52,7 +52,7 @@ public:
                          SCM_UNPACK (arg1),
                          SCM_UNPACK (arg2));
   }
-  SCM mark_smob ()
+  SCM mark_smob () const
   {
     scm_gc_mark (scm2 ());
     return scm1 ();
@@ -80,7 +80,7 @@ public:
                          SCM_UNPACK (arg2),
                          SCM_UNPACK (arg3));
   }
-  SCM mark_smob ()
+  SCM mark_smob () const
   {
     scm_gc_mark (scm3 ());
     scm_gc_mark (scm2 ());
diff --git a/lily/include/smobs.hh b/lily/include/smobs.hh
index 3bcec9931e..c5edc4b01f 100644
--- a/lily/include/smobs.hh
+++ b/lily/include/smobs.hh
@@ -177,7 +177,7 @@ private:
   // Most default functions are do-nothings.  void init() will
   // recognize their address when not overriden and will then refrain
   // altogether from passing the the respective callbacks to GUILE.
-  SCM mark_smob (void);
+  SCM mark_smob (void) const;
   static SCM mark_trampoline (SCM); // Used for calling mark_smob
   static size_t free_smob (SCM obj);
   static SCM equal_p (SCM, SCM);
diff --git a/lily/include/smobs.tcc b/lily/include/smobs.tcc
index f76609bf5b..c063da2f93 100644
--- a/lily/include/smobs.tcc
+++ b/lily/include/smobs.tcc
@@ -65,7 +65,7 @@ Smob_base<Super>::register_ptr (Super *p)
 // Defaults, should not actually get called
 template <class Super>
 SCM
-Smob_base<Super>::mark_smob ()
+Smob_base<Super>::mark_smob () const
 {
   return SCM_UNSPECIFIED;
 }
diff --git a/lily/include/source-file.hh b/lily/include/source-file.hh
index 223725f462..8c67cd9be5 100644
--- a/lily/include/source-file.hh
+++ b/lily/include/source-file.hh
@@ -39,7 +39,7 @@ class Source_file : public Smob<Source_file>
 {
 public:
   int print_smob (SCM, scm_print_state *);
-  SCM mark_smob ();
+  SCM mark_smob () const;
   static const char type_p_name_[];
   virtual ~Source_file ();
 private:
diff --git a/lily/include/stencil.hh b/lily/include/stencil.hh
index 23a5be7fbc..6ccb9252bb 100644
--- a/lily/include/stencil.hh
+++ b/lily/include/stencil.hh
@@ -58,7 +58,7 @@ using namespace std;
 class Stencil : public Simple_smob<Stencil>
 {
 public:
-  SCM mark_smob ();
+  SCM mark_smob () const;
   static const char type_p_name_[];
 private:
   Box dim_;
diff --git a/lily/include/translator-group.hh b/lily/include/translator-group.hh
index 97906c1602..a7d3a4da1b 100644
--- a/lily/include/translator-group.hh
+++ b/lily/include/translator-group.hh
@@ -50,7 +50,7 @@ struct Translator_method_binding
 class Translator_group : public Smob<Translator_group>
 {
 public:
-  SCM mark_smob ();
+  SCM mark_smob () const;
   int print_smob (SCM, scm_print_state *);
   static const char type_p_name_[];
   virtual ~Translator_group ();
diff --git a/lily/include/translator.hh b/lily/include/translator.hh
index 22e656ceb8..74f9ecb146 100644
--- a/lily/include/translator.hh
+++ b/lily/include/translator.hh
@@ -97,7 +97,7 @@ public:
   typedef void (Translator::*Grob_info_callback) (Grob_info);
   typedef void (Translator::*Callback) (void);
   int print_smob (SCM, scm_print_state *);
-  SCM mark_smob ();
+  SCM mark_smob () const;
   static const char type_p_name_[];
   virtual ~Translator ();
 private:
diff --git a/lily/input-smob.cc b/lily/input-smob.cc
index 605b790a68..830f946612 100644
--- a/lily/input-smob.cc
+++ b/lily/input-smob.cc
@@ -28,7 +28,7 @@ Input dummy_input_global;
 const char Input::type_p_name_[] = "ly:input-location?";
 
 SCM
-Input::mark_smob ()
+Input::mark_smob () const
 {
   if (Source_file *sf = get_source_file ())
     return sf->self_scm ();
diff --git a/lily/lily-lexer.cc b/lily/lily-lexer.cc
index d9d284864f..6d4de7f7fe 100644
--- a/lily/lily-lexer.cc
+++ b/lily/lily-lexer.cc
@@ -368,7 +368,7 @@ Lily_lexer::add_lexed_char (int count)
 const char Lily_lexer::type_p_name_[] = "ly:lily-lexer?";
 
 SCM
-Lily_lexer::mark_smob ()
+Lily_lexer::mark_smob () const
 {
   ASSERT_LIVE_IS_ALLOWED (self_scm ());
 
diff --git a/lily/lily-parser.cc b/lily/lily-parser.cc
index 170a5e77e4..54b0211d15 100644
--- a/lily/lily-parser.cc
+++ b/lily/lily-parser.cc
@@ -77,7 +77,7 @@ Lily_parser::~Lily_parser ()
 }
 
 SCM
-Lily_parser::mark_smob ()
+Lily_parser::mark_smob () const
 {
   scm_gc_mark (closures_);
   return (lexer_) ? lexer_->self_scm () : SCM_EOL;
diff --git a/lily/music-iterator.cc b/lily/music-iterator.cc
index a9098bcba3..ced7fa7952 100644
--- a/lily/music-iterator.cc
+++ b/lily/music-iterator.cc
@@ -193,7 +193,7 @@ Music_iterator::get_music () const
 const char Music_iterator::type_p_name_[] = "ly:iterator?";
 
 SCM
-Music_iterator::mark_smob ()
+Music_iterator::mark_smob () const
 {
   derived_mark ();
   /*
diff --git a/lily/music-output.cc b/lily/music-output.cc
index 0907bf38f4..dbbf606083 100644
--- a/lily/music-output.cc
+++ b/lily/music-output.cc
@@ -42,7 +42,7 @@ Music_output::derived_mark () const
 const char Music_output::type_p_name_[] = "ly:music-output?";
 
 SCM
-Music_output::mark_smob ()
+Music_output::mark_smob () const
 {
   derived_mark ();
   return SCM_EOL;
diff --git a/lily/output-def.cc b/lily/output-def.cc
index b58feaea6c..4415f83f9d 100644
--- a/lily/output-def.cc
+++ b/lily/output-def.cc
@@ -63,7 +63,7 @@ Output_def::~Output_def ()
 
 
 SCM
-Output_def::mark_smob ()
+Output_def::mark_smob () const
 {
   /* FIXME: why is this necessary?
      all paper_ should be protected by themselves. */
diff --git a/lily/page-marker.cc b/lily/page-marker.cc
index 1e393862e6..02b9c4ad19 100644
--- a/lily/page-marker.cc
+++ b/lily/page-marker.cc
@@ -43,7 +43,7 @@ Page_marker::~Page_marker ()
 const char Page_marker::type_p_name_[] = "ly:page-marker?";
 
 SCM
-Page_marker::mark_smob ()
+Page_marker::mark_smob () const
 {
   scm_gc_mark (symbol_);
   scm_gc_mark (permission_);
diff --git a/lily/paper-book.cc b/lily/paper-book.cc
index b79041bb7b..dfa52f4f79 100644
--- a/lily/paper-book.cc
+++ b/lily/paper-book.cc
@@ -54,7 +54,7 @@ Paper_book::~Paper_book ()
 const char Paper_book::type_p_name_[] = "ly:paper-book?";
 
 SCM
-Paper_book::mark_smob ()
+Paper_book::mark_smob () const
 {
   if (paper_)
     scm_gc_mark (paper_->self_scm ());
diff --git a/lily/paper-outputter.cc b/lily/paper-outputter.cc
index 269e1e294c..5da493ba48 100644
--- a/lily/paper-outputter.cc
+++ b/lily/paper-outputter.cc
@@ -62,7 +62,7 @@ Paper_outputter::~Paper_outputter ()
 
 
 SCM
-Paper_outputter::mark_smob ()
+Paper_outputter::mark_smob () const
 {
   scm_gc_mark (output_module_);
   return file_;
diff --git a/lily/pitch.cc b/lily/pitch.cc
index 1415178372..7772651525 100644
--- a/lily/pitch.cc
+++ b/lily/pitch.cc
@@ -221,7 +221,7 @@ Pitch::down_to (int notename)
 const char Pitch::type_p_name_[] = "ly:pitch?";
 
 SCM
-Pitch::mark_smob ()
+Pitch::mark_smob () const
 {
   return scale_->self_scm ();
 }
diff --git a/lily/prob.cc b/lily/prob.cc
index 24ce604db9..3f6ba2fef1 100644
--- a/lily/prob.cc
+++ b/lily/prob.cc
@@ -113,7 +113,7 @@ Prob::derived_mark () const
 }
 
 SCM
-Prob::mark_smob ()
+Prob::mark_smob () const
 {
   ASSERT_LIVE_IS_ALLOWED (self_scm ());
 
diff --git a/lily/scm-hash.cc b/lily/scm-hash.cc
index 5eb048f6d1..a9c26c620d 100644
--- a/lily/scm-hash.cc
+++ b/lily/scm-hash.cc
@@ -72,7 +72,7 @@ Scheme_hash_table::~Scheme_hash_table ()
 }
 
 SCM
-Scheme_hash_table::mark_smob ()
+Scheme_hash_table::mark_smob () const
 {
   scm_gc_mark (hash_tab_);
   return SCM_EOL;
diff --git a/lily/score.cc b/lily/score.cc
index 895954a01a..52f9d2ac53 100644
--- a/lily/score.cc
+++ b/lily/score.cc
@@ -62,7 +62,7 @@ Score::~Score ()
 const char Score::type_p_name_[] = "ly:score?";
 
 SCM
-Score::mark_smob ()
+Score::mark_smob () const
 {
   scm_gc_mark (header_);
   for (vsize i = defs_.size (); i--;)
diff --git a/lily/source-file.cc b/lily/source-file.cc
index 1118b9d286..b06edbf0b3 100644
--- a/lily/source-file.cc
+++ b/lily/source-file.cc
@@ -365,7 +365,7 @@ Source_file::get_port () const
 const char Source_file::type_p_name_[] = "ly:source-file?";
 
 SCM
-Source_file::mark_smob ()
+Source_file::mark_smob () const
 {
   return str_port_;
 }
diff --git a/lily/stencil.cc b/lily/stencil.cc
index 980618ceaa..987a879053 100644
--- a/lily/stencil.cc
+++ b/lily/stencil.cc
@@ -39,7 +39,7 @@ Stencil::Stencil (Box b, SCM func)
 }
 
 SCM
-Stencil::mark_smob ()
+Stencil::mark_smob () const
 {
   return expr_;
 }
diff --git a/lily/translator-group.cc b/lily/translator-group.cc
index 73a9c602e0..fc1c2a8a7b 100644
--- a/lily/translator-group.cc
+++ b/lily/translator-group.cc
@@ -356,7 +356,7 @@ Translator_group::print_smob (SCM port, scm_print_state *)
 }
 
 SCM
-Translator_group::mark_smob ()
+Translator_group::mark_smob () const
 {
   derived_mark ();
   scm_gc_mark (protected_events_);
diff --git a/lily/translator.cc b/lily/translator.cc
index b20e2aa4ed..54d97c3c19 100644
--- a/lily/translator.cc
+++ b/lily/translator.cc
@@ -189,7 +189,7 @@ Translator::static_translator_description (const char *grobs,
   SMOBS
 */
 SCM
-Translator::mark_smob ()
+Translator::mark_smob () const
 {
   derived_mark ();
   return SCM_EOL;
diff --git a/lily/undead.cc b/lily/undead.cc
index 40d8316157..db2d6f19e0 100644
--- a/lily/undead.cc
+++ b/lily/undead.cc
@@ -23,17 +23,17 @@ class Undead : public Simple_smob<Undead>
 {
 public:
   int print_smob (SCM, scm_print_state *);
-  SCM mark_smob ();
+  SCM mark_smob () const;
   static const char type_p_name_[];
 private:
   SCM object_;
 public:
-  SCM object () { return object_; }
+  SCM object () const { return object_; }
   Undead (SCM object = SCM_UNDEFINED) : object_ (object) { };
 };
 
 SCM
-Undead::mark_smob ()
+Undead::mark_smob () const
 {
   bool saved = parsed_objects_should_be_dead;
   parsed_objects_should_be_dead = false;