(print_object): Treat print-length < 0 as nil.

1 files changed, 27 insertions, 12 deletions

diff --git a/src/print.c b/src/print.c
index be2eee4e5cf..80a897fdb22 100644
--- a/src/print.c
+++ b/src/print.c
@@ -1487,12 +1487,17 @@ print_object (obj, printcharfun, escapeflag)
         {
           PRINTCHAR ('(');
           {
-            register int i = 0;
-            register int print_length = 0;
+            int print_length, i;
             Lisp_Object halftail = obj;
 
-            if (INTEGERP (Vprint_length))
-              print_length = XINT (Vprint_length);
+            /* Negative values of print-length are illegal in CL.
+               Treat them like nil, as CMUCL does.  */
+            if (NATNUMP (Vprint_length))
+              print_length = XFASTINT (Vprint_length);
+            else
+              print_length = 0;
+
+            i = 0;
             while (CONSP (obj))
               {
                 /* Detect circular list.  */
@@ -1513,7 +1518,8 @@ print_object (obj, printcharfun, escapeflag)
                       {
                         int i;
                         for (i = 0; i < print_number_index; i++)
-                          if (EQ (PRINT_NUMBER_OBJECT (Vprint_number_table, i), obj))
+                          if (EQ (PRINT_NUMBER_OBJECT (Vprint_number_table, i),
+                                  obj))
                             {
                               if (NILP (PRINT_NUMBER_STATUS (Vprint_number_table, i)))
                                 {
@@ -1529,24 +1535,31 @@ print_object (obj, printcharfun, escapeflag)
                             }
                       }
                   }
+                
                 if (i++)
                   PRINTCHAR (' ');
+                
                 if (print_length && i > print_length)
                   {
                     strout ("...", 3, 3, printcharfun, 0);
                     goto end_of_list;
                   }
+                
                 print_object (XCAR (obj), printcharfun, escapeflag);
+                
                 obj = XCDR (obj);
                 if (!(i & 1))
                   halftail = XCDR (halftail);
               }
           }
+
+          /* OBJ non-nil here means it's the end of a dotted list.  */
           if (!NILP (obj))
             {
               strout (" . ", 3, 3, printcharfun, 0);
               print_object (obj, printcharfun, escapeflag);
             }
+          
         end_of_list:
           PRINTCHAR (')');
         }
@@ -1580,10 +1593,12 @@ print_object (obj, printcharfun, escapeflag)
           strout (buf, -1, -1, printcharfun, 0);
           PRINTCHAR ('\"');
 
-          /* Don't print more characters than the specified maximum.  */
-          if (INTEGERP (Vprint_length)
-              && XINT (Vprint_length) < size_in_chars)
-            size_in_chars = XINT (Vprint_length);
+          /* Don't print more characters than the specified maximum.
+             Negative values of print-length are illegal.  Treat them
+             like a print-length of nil.  */
+          if (NATNUMP (Vprint_length)
+              && XFASTINT (Vprint_length) < size_in_chars)
+            size_in_chars = XFASTINT (Vprint_length);
 
           for (i = 0; i < size_in_chars; i++)
             {
@@ -1703,9 +1718,9 @@ print_object (obj, printcharfun, escapeflag)
             register Lisp_Object tem;
 
             /* Don't print more elements than the specified maximum.  */
-            if (INTEGERP (Vprint_length)
-                && XINT (Vprint_length) < size)
-              size = XINT (Vprint_length);
+            if (NATNUMP (Vprint_length)
+                && XFASTINT (Vprint_length) < size)
+              size = XFASTINT (Vprint_length);
 
             for (i = 0; i < size; i++)
               {