add SCM_{PACK,UNPACK}_POINTER

* libguile/tags.h (SCM_UNPACK_POINTER, SCM_PACK_POINTER): New macros.
  The old SCM2PTR and PTR2SCM were defined in such a way that
  round-tripping through a pointer could lose precision, even in the
  case in which you weren't interested in actually dereferencing the
  pointer, it was simply that you needed to plumb a SCM through APIs
  that take pointers.  These new macros are more like SCM_PACK and
  SCM_UNPACK, but for pointer types.  The bit representation of the
  pointer should be the same as the scm_t_bits representation.

* libguile/gc.h (PTR2SCM, SCM2PTR): Remove support for (old) UNICOS
  pointers.  We are going to try tagging the SCM object itself in the
  future, and I don't think that keeping this support is worth its
  cost.  It probably doesn't work anyway.

* libguile/backtrace.c:
* libguile/bytevectors.c:
* libguile/continuations.c:
* libguile/fluids.c:
* libguile/foreign.c:
* libguile/gc.h:
* libguile/guardians.c:
* libguile/hashtab.c:
* libguile/load.c:
* libguile/numbers.c:
* libguile/ports.c:
* libguile/smob.c:
* libguile/strings.c:
* libguile/symbols.c:
* libguile/vm.c:
* libguile/weak-set.c:
* libguile/weak-table.c:
* libguile/weak-vector.c: Update many sites to use the new macros.

1 files changed, 2 insertions, 2 deletions

diff --git a/libguile/symbols.c b/libguile/symbols.c
index 1739ac04e..498e46ce8 100644
--- a/libguile/symbols.c
+++ b/libguile/symbols.c
@@ -147,7 +147,7 @@ lookup_interned_latin1_symbol (const char *str, size_t len,
 static int
 symbol_lookup_predicate_fn (SCM sym, void *closure)
 {
-  SCM other = PTR2SCM (closure);
+  SCM other = SCM_PACK_POINTER (closure);
 
   if (scm_i_symbol_hash (sym) == scm_i_symbol_hash (other)
       && scm_i_symbol_length (sym) == scm_i_symbol_length (other))
@@ -184,7 +184,7 @@ scm_i_str2symbol (SCM str)
          the same time.  */
       return scm_c_weak_set_add_x (symbols, raw_hash,
                                    symbol_lookup_predicate_fn,
-                                   SCM2PTR (symbol), symbol);
+                                   SCM_UNPACK_POINTER (symbol), symbol);
     }
 }