PATCH: [perl #124091] PP Data::Dumper fails on \n isolate

Commit 31ac59b61698e704b64192de74793793f4b5b0c0 inadvertently changed
the behavior of the pure perl version of Data::Dumper.  If a newline is
the sole character in something being dumped with useqq, it no longer
got translated into a \n sequence and was output raw.  This was due to
the regex matching of \n at beginning and ends of strings.

2 files changed, 11 insertions, 2 deletions

diff --git a/dist/Data-Dumper/Dumper.pm b/dist/Data-Dumper/Dumper.pm
index 0ea2e77d43..e884298d74 100644
--- a/dist/Data-Dumper/Dumper.pm
+++ b/dist/Data-Dumper/Dumper.pm
@@ -761,7 +761,7 @@ sub qquote {
        # this.
        || (! $IS_ASCII && $] ge 5.008_001 && utf8::is_utf8($_));
 
-  return qq("$_") if / ^ [[:print:]]* $ /x;    # fast exit
+  return qq("$_") unless /[[:^print:]]/;  # fast exit if only printables
 
   # Here, there is at least one non-printable to output.  First, translate the
   # escapes.
diff --git a/dist/Data-Dumper/t/dumper.t b/dist/Data-Dumper/t/dumper.t
index fa3ce97f5b..14f92dd949 100644
--- a/dist/Data-Dumper/t/dumper.t
+++ b/dist/Data-Dumper/t/dumper.t
@@ -108,7 +108,7 @@ sub SKIP_TEST {
   ++$TNUM; print "ok $TNUM # skip $reason\n";
 }
 
-$TMAX = 444;
+$TMAX = 450;
 
 # Force Data::Dumper::Dump to use perl. We test Dumpxs explicitly by calling
 # it direct. Out here it lets us knobble the next if to test that the perl
@@ -1746,3 +1746,12 @@ EOT
         TEST (q(Data::Dumper::DumperX($foo)), 'EBCDIC outlier control: DumperX') if $XS;
     }
 }
+############# [perl #124091]
+{
+        $WANT = <<'EOT';
+#$VAR1 = "\n";
+EOT
+        local $Data::Dumper::Useqq = 1;
+        TEST (qq(Dumper("\n")), '\n alone');
+        TEST (qq(Data::Dumper::DumperX("\n")), '\n alone') if $XS;
+}