I'll see if I can patch the XS file so that the tests pass

UPDATE: The correct patch to apply is at https://rt.cpan.org/Ticket/Attachment/564402/285045/LibIDN_xs.diff . See Re: [Win32] "Free to wrong pool ..." error.

Not necessarily the right way to correct it. It may well lead to memory leaks, but at least it renders the module usable on Win32 (in that it enables all of the tests to pass without warning or error):

C:\> diff -u LibIDN.xs_orig LibIDN.xs
--- LibIDN.xs_orig      Fri Feb  6 11:48:52 2009
+++ LibIDN.xs   Fri Feb  6 11:53:00 2009
@@ -27,13 +27,13 @@
                return NULL;

        res = stringprep_profile(utf8, &output, profile, 0);
-       free(utf8);
+       /* free(utf8); */

        if( (res != STRINGPREP_OK) || !output)
                return NULL;

        res_str = stringprep_convert(output, charset, "UTF-8");
-       free(output);
+       /* free(output); */

        return res_str;
 }
@@ -96,7 +96,7 @@
                if (utf8_str)
                {
                        res = idna_to_ascii_8z(utf8_str, &tmp_str, fla
+gs);
-                       free(utf8_str);
+                       /* free(utf8_str); */
                }
                else
                {
@@ -110,8 +110,8 @@
        OUTPUT:
                RETVAL
        CLEANUP:
-               if (tmp_str)
-                       free(tmp_str);
+               if (tmp_str){}
+                       /* free(tmp_str); */


 char *
@@ -133,7 +133,7 @@
                if (tmp_str)
                {
                        res_str = stringprep_convert(tmp_str, charset,
+ "UTF-8");

-                       free(tmp_str);
+                       /* free(tmp_str); */
                }
                else
                {
@@ -147,7 +147,7 @@
        OUTPUT:
                RETVAL
        CLEANUP:
-               free(res_str);
+               /* free(res_str); */


 char *
@@ -167,7 +167,7 @@
                if (utf8_str)
                {
                        q = stringprep_utf8_to_ucs4(utf8_str, -1, &len
+);
-                       free(utf8_str);
+                       /* free(utf8_str); */
                }
                else
                {
@@ -182,7 +182,7 @@
                tmp_str = malloc(MAX_DNSLEN*sizeof(char));
                len2 = MAX_DNSLEN-1;
                res = punycode_encode(len, q, NULL, &len2, tmp_str);
-               free(q);
+               /* free(q); */

                if (res != PUNYCODE_SUCCESS)
                {
@@ -201,7 +201,7 @@
        OUTPUT:
                RETVAL
        CLEANUP:
-               free(res_str);
+               /* free(res_str); */


 char *
@@ -239,7 +239,7 @@
                if (utf8_str)
                {
                        res_str = stringprep_convert(utf8_str, charset
+, "UTF-8")
;
-                       free(utf8_str);
+                       /* free(utf8_str); */
                }
                else
                {
@@ -254,7 +254,7 @@
        OUTPUT:
                RETVAL
        CLEANUP:
-               free(res_str);
+               /* free(res_str); */


 char *
@@ -274,7 +274,7 @@
        OUTPUT:
                RETVAL
        CLEANUP:
-               free(res_str);
+               /* free(res_str); */


 char *
@@ -450,7 +450,7 @@
                        XSRETURN_UNDEF;
                }
                res = stringprep_profile(utf8_str, &tmp_str, "Nameprep
+", 0);
-               free(utf8_str);
+               /* free(utf8_str); */
                if (res != STRINGPREP_OK)
                {
                        XSRETURN_UNDEF;
@@ -458,18 +458,18 @@
                if (tld)
                {
                        q = stringprep_utf8_to_ucs4(tmp_str, -1, &len)
+;
-                       free(tmp_str);
+                       /* free(tmp_str); */
                        if (!q)
                        {
                                XSRETURN_UNDEF;
                        }
                        res = tld_check_4t(q, len, &errpos, tld_table)
+;
-                       free(q);
+                       /* free(q); */
                }
                else
                {
                        res = tld_check_8z(tmp_str, &errpos, NULL);
-                       free(tmp_str);
+                       /* free(tmp_str); */
                }
                if (res == TLD_SUCCESS)
                {
@@ -507,7 +507,7 @@
        OUTPUT:
                RETVAL
        CLEANUP:
-               free(res_str);
+               /* free(res_str); */


 SV *
[download]

As you can see, all I've done is remove many of the free() calls. The are possibly other free() calls (not tested by the test suite) that also produce the "Free to wrong pool ..." error.

UPDATE: The correct patch to apply is at https://rt.cpan.org/Ticket/Attachment/564402/285045/LibIDN_xs.diff . See Re: [Win32] "Free to wrong pool ..." error.

Cheers,
Rob