fix bug #24605.

substr() wasn't working when used repeatedly on the same utf-8
string.

p4raw-id: //depot/perl@21875

diff --git a/sv.c b/sv.c
index 6f53c58..40d99cb 100644 (file)
--- a/sv.c
+++ b/sv.c
@@ -5735,10 +5735,8 @@ S_utf8_mg_pos_init(pTHX_ SV *sv, MAGIC **mgp, STRLEN **cachep, I32 i, I32 *offse
     bool found = FALSE; 
 
     if (SvMAGICAL(sv) && !SvREADONLY(sv)) {
-       if (!*mgp) {
-           sv_magic(sv, 0, PERL_MAGIC_utf8, 0, 0);
-           *mgp = mg_find(sv, PERL_MAGIC_utf8);
-       }
+       if (!*mgp)
+           *mgp = sv_magicext(sv, 0, PERL_MAGIC_utf8, &PL_vtbl_utf8, 0, 0);
        assert(*mgp);
 
        if ((*mgp)->mg_ptr)
@@ -5831,6 +5829,12 @@ S_utf8_mg_pos(pTHX_ SV *sv, MAGIC **mgp, STRLEN **cachep, I32 i, I32 *offsetp, I
                      /* Update the cache. */
                      (*cachep)[i]   = (STRLEN)uoff;
                      (*cachep)[i+1] = p - start;
+
+                     /* Drop the stale "length" cache */
+                     if (i == 0) {
+                         (*cachep)[2] = 0;
+                         (*cachep)[3] = 0;
+                     }
  
                      found = TRUE;
                 }

diff --git a/t/op/substr.t b/t/op/substr.t
index 533f1a5..dfb483a 100755 (executable)
--- a/t/op/substr.t
+++ b/t/op/substr.t
@@ -1,6 +1,6 @@
 #!./perl
 
-print "1..176\n";
+print "1..177\n";
 
 #P = start of string  Q = start of substr  R = end of substr  S = end of string
 
@@ -602,3 +602,10 @@ ok 174, $x eq "\x{100}\x{200}\xFFb";
     my $x = my $y = 'AB'; ss $x; ss $y;
     ok 176, $x eq $y;
 }
+
+# [perl #24605]
+{
+    my $x = "0123456789\x{500}";
+    my $y = substr $x, 4;
+    ok 177, substr($x, 7, 1) eq "7";
+}