Fix bug 34297 (length of overloaded UTF-8 strings)

p4raw-id: //depot/perl@28006

3 files changed, 61 insertions, 1 deletions

diff --git a/MANIFEST b/MANIFEST
index d130e2e39d..7d34252a2c 100644
--- a/MANIFEST
+++ b/MANIFEST
@@ -3532,6 +3532,7 @@ t/uni/chomp.t			See if Unicode chomp works
 t/uni/class.t			See if Unicode classes work (\p)
 t/uni/fold.t			See if Unicode folding works
 t/uni/lower.t			See if Unicode casing works
+t/uni/overload.t		See if Unicode overloading works
 t/uni/sprintf.t			See if Unicode sprintf works
 t/uni/title.t			See if Unicode casing works
 t/uni/tr_7jis.t			See if Unicode tr/// works
diff --git a/pp.c b/pp.c
index 356bfec80c..718f0f0c83 100644
--- a/pp.c
+++ b/pp.c
@@ -2950,7 +2950,22 @@ PP(pp_length)
     dVAR; dSP; dTARGET;
     SV * const sv = TOPs;
 
-    if (DO_UTF8(sv))
+    if (SvAMAGIC(sv)) {
+	/* For an overloaded scalar, we can't know in advance if it's going to
+	   be UTF-8 or not. Also, we can't call sv_len_utf8 as it likes to
+	   cache the length. Maybe that should be a documented feature of it.
+	*/
+	STRLEN len;
+	const char *const p = SvPV_const(sv, len);
+
+	if (DO_UTF8(sv)) {
+	    SETi(Perl_utf8_length(aTHX_ p, p + len));
+	}
+	else
+	    SETi(len);
+
+    }
+    else if (DO_UTF8(sv))
 	SETi(sv_len_utf8(sv));
     else
 	SETi(sv_len(sv));
diff --git a/t/uni/overload.t b/t/uni/overload.t
new file mode 100644
index 0000000000..9338f75816
--- /dev/null
+++ b/t/uni/overload.t
@@ -0,0 +1,44 @@
+#!perl -w
+
+BEGIN {
+    if ($ENV{'PERL_CORE'}){
+        chdir 't';
+        @INC = '../lib';
+    }
+}
+
+use Test::More tests => 8;
+
+package UTF8Field;
+use strict;
+
+use overload '""' => 'stringify';
+
+sub new {
+    my $class = shift;
+    return bless [shift, 0], $class;
+}
+
+sub stringify {
+    my $self = shift;
+    $self->[1] = ! $self->[1];
+    if ($self->[1]) {
+	utf8::downgrade($self->[0]);
+    } else {
+	utf8::upgrade($self->[0]);
+    }
+    $self->[0];
+}
+
+package main;
+
+# Bug 34297
+foreach my $t ("ASCII", "B\366se") {
+    my $length = length $t;
+
+    my $u = UTF8Field->new($t);
+    is (length $u, $length, "length of '$t'");
+    is (length $u, $length, "length of '$t'");
+    is (length $u, $length, "length of '$t'");
+    is (length $u, $length, "length of '$t'");
+}