Add disjoint syntax object type

* libguile/Makefile.am (libguile_@GUILE_EFFECTIVE_VERSION@_la_SOURCES):
  (DOT_X_FILES, DOT_DOC_FILES, noinst_HEADERS): Add syntax.c and
  syntax.h.
* libguile/evalext.c (scm_self_evaluating_p):
* libguile/goops.c (class_syntax, scm_class_of, scm_goops_early_init):
* libguile/init.c (scm_init_guile):
* libguile/print.c (iprin1):
* libguile/tags.h (scm_tc7_syntax):
* module/oop/goops.scm (<syntax>):
* module/system/base/types.scm (%tc7-syntax, cell->object):
* module/system/vm/disassembler.scm (code-annotation): Wire up the new
  data type.
* libguile/syntax.c:
* libguile/syntax.h: New files.
* module/ice-9/boot-9.scm: Move new definitions to (system syntax
  internal).
* module/system/syntax.scm (print-syntax): New helper.
* module/system/vm/assembler.scm (statically-allocatable?)
  (intern-constant, link-data): Arrange to be able to write syntax
  objects into images.
* module/language/cps/types.scm (&syntax): New type.  Remove
  &hash-table; it was never detected, an internal binding, and we need
  the bit to avoid going into bignum territory.

libguile/syntax.c

@@ -0,0 +1,120 @@
+/* Copyright (C) 2017 Free Software Foundation, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+
+
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "libguile/_scm.h"
+#include "libguile/keywords.h"
+#include "libguile/ports.h"
+#include "libguile/syntax.h"
+#include "libguile/validate.h"
+
+
+
+static int
+scm_is_syntax (SCM x)
+{
+  return SCM_HAS_TYP7 (x, scm_tc7_syntax);
+}
+
+#define SCM_VALIDATE_SYNTAX(pos, scm) \
+  SCM_I_MAKE_VALIDATE_MSG2 (pos, scm, scm_is_syntax, "syntax object")
+
+SCM_DEFINE (scm_syntax_p, "syntax?", 1, 0, 0,
+            (SCM obj),
+	    "Return @code{#t} if the argument @var{obj} is a syntax object,\n"
+            "else @code{#f}.")
+#define FUNC_NAME s_scm_syntax_p
+{
+  return scm_from_bool (scm_is_syntax (obj));
+}
+#undef FUNC_NAME
+
+SCM_DEFINE (scm_make_syntax, "make-syntax", 3, 0, 0,
+	    (SCM exp, SCM wrap, SCM module),
+	    "Make a new syntax object.")
+#define FUNC_NAME s_scm_make_syntax
+{
+  return scm_double_cell (scm_tc7_syntax, SCM_UNPACK (exp),
+                          SCM_UNPACK (wrap), SCM_UNPACK (module));
+}
+#undef FUNC_NAME
+
+SCM_DEFINE (scm_syntax_expression, "syntax-expression", 1, 0, 0,
+	    (SCM obj),
+	    "Return the expression contained in the syntax object @var{obj}.")
+#define FUNC_NAME s_scm_syntax_expression
+{
+  SCM_VALIDATE_SYNTAX (1, obj);
+  return SCM_CELL_OBJECT_1 (obj);
+}
+#undef FUNC_NAME
+
+SCM_DEFINE (scm_syntax_wrap, "syntax-wrap", 1, 0, 0,
+	    (SCM obj),
+	    "Return the wrap contained in the syntax object @var{obj}.")
+#define FUNC_NAME s_scm_syntax_wrap
+{
+  SCM_VALIDATE_SYNTAX (1, obj);
+  return SCM_CELL_OBJECT_2 (obj);
+}
+#undef FUNC_NAME
+
+SCM_DEFINE (scm_syntax_module, "syntax-module", 1, 0, 0,
+	    (SCM obj),
+	    "Return the module info contained in the syntax object @var{obj}.")
+#define FUNC_NAME s_scm_syntax_module
+{
+  SCM_VALIDATE_SYNTAX (1, obj);
+  return SCM_CELL_OBJECT_3 (obj);
+}
+#undef FUNC_NAME
+
+static SCM print_syntax_var;
+
+static void
+init_print_syntax_var (void)
+{
+  print_syntax_var =
+    scm_c_private_variable ("system syntax", "print-syntax");
+}
+
+void
+scm_i_syntax_print (SCM obj, SCM port, scm_print_state *pstate)
+{
+  static scm_i_pthread_once_t once = SCM_I_PTHREAD_ONCE_INIT;
+  scm_i_pthread_once (&once, init_print_syntax_var);
+  scm_call_2 (scm_variable_ref (print_syntax_var), obj, port);
+}
+
+void
+scm_init_syntax ()
+{
+#include "libguile/syntax.x"
+}
+
+
+/*
+  Local Variables:
+  c-file-style: "gnu"
+  End:
+*/