master a09619f2598 02/20: * src/print.c (print_object): Don't print empty hash-table data

[Mattias Engdegård]

branch: master
commit a09619f2598a1658feac6794e85bc61a07c4855f
Author: Mattias Engdegård <mattiase@acm.org>
Commit: Mattias Engdegård <mattiase@acm.org>

    * src/print.c (print_object): Don't print empty hash-table data
    
    Since no data is the default, this preserves bidirectional compatibility.
---
 src/print.c             | 37 +++++++++++++++++++++++--------------
 test/src/print-tests.el |  7 -------
 2 files changed, 23 insertions(+), 21 deletions(-)

diff --git a/src/print.c b/src/print.c
index 0a5f2ee48d4..d011962d85b 100644
--- a/src/print.c
+++ b/src/print.c
@@ -2603,21 +2603,30 @@ print_object (Lisp_Object obj, Lisp_Object 
printcharfun, bool escapeflag)
            if (h->purecopy)
              print_c_string (" purecopy t", printcharfun);
 
-           print_c_string (" data (", printcharfun);
-
            ptrdiff_t size = h->count;
-           /* Don't print more elements than the specified maximum.  */
-           if (FIXNATP (Vprint_length) && XFIXNAT (Vprint_length) < size)
-             size = XFIXNAT (Vprint_length);
-
-           print_stack_push ((struct print_stack_entry){
-               .type = PE_hash,
-               .u.hash.obj = obj,
-               .u.hash.nobjs = size * 2,
-               .u.hash.idx = 0,
-               .u.hash.printed = 0,
-               .u.hash.truncated = (size < h->count),
-             });
+           if (size > 0)
+             {
+               print_c_string (" data (", printcharfun);
+
+               /* Don't print more elements than the specified maximum.  */
+               if (FIXNATP (Vprint_length) && XFIXNAT (Vprint_length) < size)
+                 size = XFIXNAT (Vprint_length);
+
+               print_stack_push ((struct print_stack_entry){
+                   .type = PE_hash,
+                   .u.hash.obj = obj,
+                   .u.hash.nobjs = size * 2,
+                   .u.hash.idx = 0,
+                   .u.hash.printed = 0,
+                   .u.hash.truncated = (size < h->count),
+                 });
+             }
+           else
+             {
+               /* Empty table: we can omit the data entirely.  */
+               printchar (')', printcharfun);
+               --print_depth;   /* Done with this.  */
+             }
            goto next_obj;
          }
 
diff --git a/test/src/print-tests.el b/test/src/print-tests.el
index aedaa9a4e06..ff3a6fe7483 100644
--- a/test/src/print-tests.el
+++ b/test/src/print-tests.el
@@ -367,13 +367,6 @@ otherwise, use a different charset."
       (remhash 1 h)
       (format "%S" h))))
 
-  (should
-   (string-match
-    "data ()"
-    (let ((h (make-hash-table)))
-      (let ((print-length 0))
-        (format "%S" h)))))
-
   (should
    (string-match
     "data (99 99)"