[perl #58608] Fix DD’s dumping of qr|\/|

By trying to escape / as \/, DD was turning \/ into \\/, producing
invalid qr//’s like qr/ \\/ /.  You can’t (and don’t need to) escape a
/ preceded by a backslash.  But you have to make sure \\/ gets escaped
properly as \\\/.  Counting forward from the beginning of the string
and ignoring escaped characters is the proper way to do it.

3 files changed, 8 insertions, 6 deletions

diff --git a/dist/Data-Dumper/Dumper.pm b/dist/Data-Dumper/Dumper.pm
index fcf06ad5d9..06b5eebb49 100644
--- a/dist/Data-Dumper/Dumper.pm
+++ b/dist/Data-Dumper/Dumper.pm
@@ -373,7 +373,7 @@ sub _dump {
         } else {
             $pat = "$val";
         }
-        $pat =~ s,/,\\/,g;
+        $pat =~ s <(\\.)|/> { $1 || '\\/' }ge;
         $out .= "qr/$pat/";
     }
     elsif ($realtype eq 'SCALAR' || $realtype eq 'REF'
diff --git a/dist/Data-Dumper/Dumper.xs b/dist/Data-Dumper/Dumper.xs
index 2ad53a15c3..afb282698a 100644
--- a/dist/Data-Dumper/Dumper.xs
+++ b/dist/Data-Dumper/Dumper.xs
@@ -463,14 +463,17 @@ DD_dump(pTHX_ SV *val, const char *name, STRLEN namelen, SV *retval, HV *seenhv,
         {
             STRLEN rlen;
 	    const char *rval = SvPV(val, rlen);
-	    const char *slash = strchr(rval, '/');
+	    const char * const rend = rval+rlen;
+	    const char *slash = rval;
 	    sv_catpvn(retval, "qr/", 3);
-	    while (slash) {
+	    for (;slash < rend; slash++) {
+	      if (*slash == '\\') { ++slash; continue; }
+	      if (*slash == '/') {    
 		sv_catpvn(retval, rval, slash-rval);
 		sv_catpvn(retval, "\\/", 2);
 		rlen -= slash-rval+1;
 		rval = slash+1;
-		slash = strchr(rval, '/');
+	      }
 	    }
 	    sv_catpvn(retval, rval, rlen);
 	    sv_catpvn(retval, "/", 1);
diff --git a/dist/Data-Dumper/t/qr.t b/dist/Data-Dumper/t/qr.t
index 668bc82ace..43a3c19b98 100644
--- a/dist/Data-Dumper/t/qr.t
+++ b/dist/Data-Dumper/t/qr.t
@@ -12,8 +12,7 @@ BEGIN {
 use Test::More tests => 2;
 use Data::Dumper;
 
-TODO: {
-    local $TODO = "RT#58608: Data::Dumper and slashes within qr";
+{
     my $q = q| \/ |;
     use Data::Dumper;
     my $qr = qr{$q};