Perl_do_sv_dump: alert when skipping elements

When dumping an HV, we skip dumping the elements if the iterator is
already in use. Explain this in the dump output so people like me aren't
left wondering why the elements have vanished.

diff --git a/dump.c b/dump.c
index 843eb88..eeb43be 100644 (file)
--- a/dump.c
+++ b/dump.c
@@ -1884,29 +1884,34 @@ Perl_do_sv_dump(pTHX_ I32 level, PerlIO *file, SV *sv, I32 nest, I32 maxnest, bo
                }
            }
        }
-       if (nest < maxnest && !HvEITER_get(sv)) { /* Try to preserve iterator */
-           HE *he;
-           HV * const hv = MUTABLE_HV(sv);
-           int count = maxnest - nest;
-
-           hv_iterinit(hv);
-           while ((he = hv_iternext_flags(hv, HV_ITERNEXT_WANTPLACEHOLDERS))
-                   && count--) {
-               STRLEN len;
-               const U32 hash = HeHASH(he);
-               SV * const keysv = hv_iterkeysv(he);
-               const char * const keypv = SvPV_const(keysv, len);
-               SV * const elt = hv_iterval(hv, he);
-
-               Perl_dump_indent(aTHX_ level+1, file, "Elt %s ", pv_display(d, keypv, len, 0, pvlim));
-               if (SvUTF8(keysv))
-                   PerlIO_printf(file, "[UTF8 \"%s\"] ", sv_uni_display(d, keysv, 6 * SvCUR(keysv), UNI_DISPLAY_QQ));
-               if (HeKREHASH(he))
-                   PerlIO_printf(file, "[REHASH] ");
-               PerlIO_printf(file, "HASH = 0x%"UVxf"\n", (UV)hash);
-               do_sv_dump(level+1, file, elt, nest+1, maxnest, dumpops, pvlim);
+       if (nest < maxnest) {
+           if (HvEITER_get(sv)) /* preserve iterator */
+               Perl_dump_indent(aTHX_ level, file,
+                   "  (*** Active iterator; skipping element dump ***)\n");
+           else {
+               HE *he;
+               HV * const hv = MUTABLE_HV(sv);
+               int count = maxnest - nest;
+
+               hv_iterinit(hv);
+               while ((he = hv_iternext_flags(hv, HV_ITERNEXT_WANTPLACEHOLDERS))
+                      && count--) {
+                   STRLEN len;
+                   const U32 hash = HeHASH(he);
+                   SV * const keysv = hv_iterkeysv(he);
+                   const char * const keypv = SvPV_const(keysv, len);
+                   SV * const elt = hv_iterval(hv, he);
+
+                   Perl_dump_indent(aTHX_ level+1, file, "Elt %s ", pv_display(d, keypv, len, 0, pvlim));
+                   if (SvUTF8(keysv))
+                       PerlIO_printf(file, "[UTF8 \"%s\"] ", sv_uni_display(d, keysv, 6 * SvCUR(keysv), UNI_DISPLAY_QQ));
+                   if (HeKREHASH(he))
+                       PerlIO_printf(file, "[REHASH] ");
+                   PerlIO_printf(file, "HASH = 0x%"UVxf"\n", (UV)hash);
+                   do_sv_dump(level+1, file, elt, nest+1, maxnest, dumpops, pvlim);
+               }
+               hv_iterinit(hv);                /* Return to status quo */
            }
-           hv_iterinit(hv);            /* Return to status quo */
        }
        break;
     case SVt_PVCV: