From: Jarkko Hietaniemi <jhi@iki.fi>
Date: Sat, 21 Oct 2000 00:44:18 +0000 (+0000)
Subject: Fix for ID 20001020.006, concatenating an unset submatch
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=689440ec6112b0ad8e13a518cfe8f7c6b95df346;p=p5sagit%2Fp5-mst-13.2.git

Fix for ID 20001020.006, concatenating an unset submatch
with utf8 resulted in "Modification of a read-only value".

p4raw-id: //depot/perl@7383
---

diff --git a/pp_hot.c b/pp_hot.c
index 9b0573b..d6a7f04 100644
--- a/pp_hot.c
+++ b/pp_hot.c
@@ -172,8 +172,14 @@ PP(pp_concat)
 		/* Take a copy since we're about to overwrite TARG */
 		olds = s = (U8*)savepvn((char*)s, len);
 	    }
-	    if (!SvOK(left) && SvTYPE(left) <= SVt_PVMG)
-		sv_setpv(left, "");	/* Suppress warning. */
+	    if (!SvOK(left) && SvTYPE(left) <= SVt_PVMG) {
+	        if (SvREADONLY(left)) {
+		    left = sv_2mortal(newSVpvn("", 0));
+		    left_utf = FALSE;
+		}
+		else
+		    sv_setpv(left, "");	/* Suppress warning. */
+	    }
             l = (U8*)SvPV(left, targlen);
 	    left_utf |= DO_UTF8(left);
             if (TARG != left)
diff --git a/t/pragma/utf8.t b/t/pragma/utf8.t
index c3538c0..75f607d 100755
--- a/t/pragma/utf8.t
+++ b/t/pragma/utf8.t
@@ -10,7 +10,7 @@ BEGIN {
     }
 }
 
-print "1..99\n";
+print "1..101\n";
 
 my $test = 1;
 
@@ -525,3 +525,22 @@ sub nok_bytes {
 	$test++;
     }
 }
+
+{
+    # ID 20001020.006
+
+    "x" =~ /(.)/; # unset $2
+
+    # Without the fix this will croak:
+    # Modification of a read-only value attempted at ...
+    "$2\x{1234}";
+
+    print "ok $test\n";
+    $test++;
+
+    # For symmetry with the above.
+    "\x{1234}$2";
+
+    print "ok $test\n";
+    $test++;
+}