(print): When backquote form is the car of a list,

output in old style.  Use old_backquote_output to output all
comma forms inside it in old style too.

diff --git a/src/print.c b/src/print.c
index 038a9aaeaa4b1ae7d6e3312f5175d3de139604be..6c85c24cbe538d21768dd656af071ad44046d9b8 100644 (file)
--- a/src/print.c
+++ b/src/print.c
@@ -91,6 +91,9 @@ Lisp_Object Vfloat_output_format, Qfloat_output_format;
 /* Avoid actual stack overflow in print.  */
 int print_depth;
 
+/* Nonzero if inside outputting backquote in old style.  */
+int old_backquote_output;
+
 /* Detect most circularities to print finite output.  */
 #define PRINT_CIRCLE 200
 Lisp_Object being_printed[PRINT_CIRCLE];
@@ -1154,6 +1157,7 @@ print (obj, printcharfun, escapeflag)
      int escapeflag;
 {
   print_depth = 0;
+  old_backquote_output = 0;
 
   /* Reset print_number_index and Vprint_number_table only when
      the variable Vprint_continuous_numbering is nil.  Otherwise,
@@ -1582,6 +1586,7 @@ print_object (obj, printcharfun, escapeflag)
          print_object (XCAR (XCDR (obj)), printcharfun, escapeflag);
        }
       else if (print_quoted && CONSP (XCDR (obj)) && NILP (XCDR (XCDR (obj)))
+              && ! old_backquote_output
               && ((EQ (XCAR (obj), Qbackquote)
                    || EQ (XCAR (obj), Qcomma)
                    || EQ (XCAR (obj), Qcomma_at)
@@ -1593,6 +1598,29 @@ print_object (obj, printcharfun, escapeflag)
       else
        {
          PRINTCHAR ('(');
+         
+         /* If the first element is a backquote form,
+            print it old-style so it won't be misunderstood.  */
+         if (print_quoted && CONSP (XCAR (obj))
+             && CONSP (XCDR (XCAR (obj)))
+             && NILP (XCDR (XCDR (XCAR (obj))))
+             && EQ (XCAR (XCAR (obj)), Qbackquote))
+           {
+             Lisp_Object tem;
+             tem = XCAR (obj);
+             PRINTCHAR ('(');
+
+             print_object (Qbackquote, printcharfun, 0);
+             PRINTCHAR (' ');
+
+             ++old_backquote_output;
+             print_object (XCAR (XCDR (tem)), printcharfun, 0);
+             --old_backquote_output;
+             PRINTCHAR (')');
+
+             obj = XCDR (obj);
+           }
+
          {
            int print_length, i;
            Lisp_Object halftail = obj;