Changes to m4/modules/gnu.c,v

[Eric Blake]

CVSROOT:        /sources/m4
Module name:    m4
Changes by:     Eric Blake <ericb>      06/10/27 17:03:51

Index: modules/gnu.c
===================================================================
RCS file: /sources/m4/m4/modules/gnu.c,v
retrieving revision 1.65
retrieving revision 1.66
diff -u -b -r1.65 -r1.66
--- modules/gnu.c       21 Oct 2006 22:15:52 -0000      1.65
+++ modules/gnu.c       27 Oct 2006 17:03:51 -0000      1.66
@@ -323,23 +323,57 @@
 
 /* The builtin "builtin" allows calls to builtin macros, even if their
    definition has been overridden or shadowed.  It is thus possible to
-   redefine builtins, and still access their original definition.  */
+   redefine builtins, and still access their original definition.  A
+   special form allows one to retrieve the special token that defn
+   would normally return, even if that builtin is not currently
+   defined and hence can't be passed to defn.  */
 
 /**
  * builtin(MACRO, [...])
+ * builtin(defn(`builtin'), MACRO)
  **/
 M4BUILTIN_HANDLER (builtin)
 {
+  const char *name;
+  m4_symbol_value *value;
+
   if (! m4_is_symbol_value_text (argv[1]))
+    {
+      if (m4_is_symbol_value_func (argv[1])
+        && m4_get_symbol_value_func (argv[1]) == builtin_builtin)
+       {
+        if (m4_bad_argc (context, argc, argv, 2, 2, false))
+          return;
+        if (! m4_is_symbol_value_text (argv[2]))
+          {
+            m4_warn (context, 0, _("%s: invalid macro name ignored"),
+                     M4ARG (0));
+            return;
+          }
+        name = M4ARG (2);
+        value = m4_builtin_find_by_name (NULL, name);
+        if (value == NULL)
+          m4_warn (context, 0, _("%s: undefined builtin `%s'"), M4ARG (0),
+                   name);
+        else
+          {
+            m4_push_builtin (context, value);
+            free (value);
+          }
+       }
+      else
     m4_warn (context, 0, _("%s: invalid macro name ignored"), M4ARG (0));
+    }
   else
     {
-      const char *name = M4ARG (1);
-      const m4_builtin *bp = m4_builtin_find_by_name (NULL, name);
-
-      if (bp == NULL)
+      name = M4ARG (1);
+      value = m4_builtin_find_by_name (NULL, name);
+      if (value == NULL)
        m4_warn (context, 0, _("%s: undefined builtin `%s'"), M4ARG (0), name);
-      else if (!m4_bad_argc (context, argc - 1, argv + 1,
+      else
+       {
+         const m4_builtin *bp = m4_get_symbol_value_builtin (value);
+         if (!m4_bad_argc (context, argc - 1, argv + 1,
                             bp->min_args, bp->max_args,
                             (bp->flags & M4_BUILTIN_SIDE_EFFECT) != 0))
        {
@@ -350,6 +384,8 @@
                m4_set_symbol_value_text (argv[i], "");
          bp->func (context, obs, argc - 1, argv + 1);
        }
+         free (value);
+       }
     }
 }