count-only transliteration needlessly makes copy-on-write

From: "Yitzchak Scott-Thoennes" <sthoenna@efn.org>
Message-ID: <47935.71.32.86.11.1204678469.squirrel@webmail.efn.org>

p4raw-id: //depot/perl@33457

2 files changed, 10 insertions, 3 deletions

diff --git a/doop.c b/doop.c
index 1a5c829a6f..8bd7c0f414 100644
--- a/doop.c
+++ b/doop.c
@@ -633,10 +633,10 @@ Perl_do_trans(pTHX_ SV *sv)
 
     PERL_ARGS_ASSERT_DO_TRANS;
 
-    if (SvREADONLY(sv)) {
+    if (SvREADONLY(sv) && !(PL_op->op_private & OPpTRANS_IDENTICAL)) {
         if (SvIsCOW(sv))
             sv_force_normal_flags(sv, 0);
-        if (SvREADONLY(sv) && !(PL_op->op_private & OPpTRANS_IDENTICAL))
+        if (SvREADONLY(sv))
             Perl_croak(aTHX_ PL_no_modify);
     }
     (void)SvPV_const(sv, len);
diff --git a/t/op/tr.t b/t/op/tr.t
index 279470c0eb..9273e09d19 100755
--- a/t/op/tr.t
+++ b/t/op/tr.t
@@ -6,7 +6,7 @@ BEGIN {
     require './test.pl';
 }
 
-plan tests => 117;
+plan tests => 118;
 
 my $Is_EBCDIC = (ord('i') == 0x89 & ord('J') == 0xd1);
 
@@ -461,3 +461,10 @@ is($s, "AxBC", "utf8, DELETE");
     is($c, "\x20\x30\x40\x50\x60", "tr/\\x00-\\x1f//d");
 }
 
+($s) = keys %{{pie => 3}};
+my $wasro = Internals::SvREADONLY($s);
+{
+    $wasro or local $TODO = "didn't have a COW";
+    $s =~ tr/i//;
+    ok( Internals::SvREADONLY($s), "count-only tr doesn't deCOW COWs" );
+}