Better support for future plugins

See the thread containing:
http://lists.gnu.org/archive/html/emacs-devel/2015-02/msg00720.html
* lib-src/make-docfile.c (write_globals): Generate code that #defines
Qxxx macros other than Qnil only if DEFINE_NONNIL_Q_SYMBOL_MACROS.
Qnil is safe to define even in plugins, since it must be zero for
other reasons.
* src/lisp.h (DEFINE_LISP_SYMBOL): New macro, replacing and simplifying
DEFINE_LISP_SYMBOL_BEGIN / DEFINE_LISP_SYMBOL_END.  All uses changed.
(DEFINE_NONNIL_Q_SYMBOL_MACROS): New macro, defaulting to true.

2 files changed, 24 insertions, 13 deletions

diff --git a/lib-src/ChangeLog b/lib-src/ChangeLog
index 8d2c95e671c..534d253cabb 100644
--- a/lib-src/ChangeLog
+++ b/lib-src/ChangeLog
@@ -1,3 +1,13 @@
+2015-02-13  Paul Eggert  <eggert@cs.ucla.edu>
+
+        Better support for future plugins
+        See the thread containing:
+        http://lists.gnu.org/archive/html/emacs-devel/2015-02/msg00720.html
+        * make-docfile.c (write_globals): Generate code that #defines
+        Qxxx macros other than Qnil only if DEFINE_NONNIL_Q_SYMBOL_MACROS.
+        Qnil is safe to define even in plugins, since it must be zero for
+        other reasons.
+
 2015-01-24  Paul Eggert  <eggert@cs.ucla.edu>
 
         Fix a couple of AM_V_GEN bugs
diff --git a/lib-src/make-docfile.c b/lib-src/make-docfile.c
index 79d421a0a8e..a7943e3118c 100644
--- a/lib-src/make-docfile.c
+++ b/lib-src/make-docfile.c
@@ -707,12 +707,9 @@ write_globals (void)
                   globals[i].name, globals[i].name);
         }
       else if (globals[i].type == SYMBOL)
-        printf (("DEFINE_LISP_SYMBOL_BEGIN (%s)\n"
-                 "#define i%s %d\n"
-                 "#define %s builtin_lisp_symbol (i%s)\n"
-                 "DEFINE_LISP_SYMBOL_END (%s)\n\n"),
-                globals[i].name, globals[i].name, symnum++,
-                globals[i].name, globals[i].name, globals[i].name);
+        printf (("#define i%s %d\n"
+                 "DEFINE_LISP_SYMBOL (%s)\n"),
+                globals[i].name, symnum++, globals[i].name);
       else
         {
           if (globals[i].flags & DEFUN_noreturn)
@@ -740,15 +737,19 @@ write_globals (void)
   puts ("#ifdef DEFINE_SYMBOLS");
   puts ("static char const *const defsym_name[] = {");
   for (int i = 0; i < num_globals; i++)
-    {
-      if (globals[i].type == SYMBOL)
-        printf ("\t\"%s\",\n", globals[i].v.svalue);
-      while (i + 1 < num_globals
-             && strcmp (globals[i].name, globals[i + 1].name) == 0)
-        i++;
-    }
+    if (globals[i].type == SYMBOL)
+      printf ("\t\"%s\",\n", globals[i].v.svalue);
   puts ("};");
   puts ("#endif");
+
+  puts ("#define Qnil builtin_lisp_symbol (0)");
+  puts ("#if DEFINE_NONNIL_Q_SYMBOL_MACROS");
+  num_symbols = 0;
+  for (int i = 0; i < num_globals; i++)
+    if (globals[i].type == SYMBOL && num_symbols++ != 0)
+      printf ("# define %s builtin_lisp_symbol (%d)\n",
+              globals[i].name, num_symbols - 1);
+  puts ("#endif");
 }