Ah, I obviously did not read the error message close enough. Thanks for pointing out that problem was not in LibXML::XML.

Thanks to all who offered advice (upvotes all round). I took bits of information from various responses; this is a general reply to everyone. I determined a workaround, which I'll document below for anyone encountering the same problem. I suspect an actual solution would be to rebuild Perl and reinstall all modules (a fairly lengthy task which I really don't have time for right now).

Information regarding the missing xlocale.h: "glibc wiki: Removal of 'xlocale.h'".
Information about how this affects Perl: "glibc-2.26 removed xlocale.h".
Based on that information, I edited config.h (which is in the same directory as perl.h in the error message).

$ ls -al config.h*
-r--r--r-- 1 ken None 164422 Jun 23  2020 config.h
$ cp config.h config.h-20210102a
$ chmod +w config.h
$ vi config.h
$ chmod -w config.h
$ ls -al config.h*
-r--r--r-- 1 ken None 164425 Jan  2 10:55 config.h
-r--r--r-- 1 ken None 164422 Jan  2 10:51 config.h-20210102a
$ diff config.h config.h-20210102a
3096c3096
< /*#define     I_XLOCALE               / **/
---
> #define       I_XLOCALE               /**/
[download]

Now back to cpan:

cpan[1]> install XML::LibXML
...
  SHLOMIF/XML-LibXML-2.0206.tar.gz
  /usr/bin/make install  -- OK

cpan[2]>
[download]

And a very quick confirmation:

$ perl -E 'use XML::LibXML; say $XML::LibXML::VERSION'
2.0206
[download]

I don't have a solution or workaround.

As you are compiling C or C++ components, I would avoid any xlocale.h path which is not available on (Cygwin or MinGW) system-wide basis; that includes all the Perl & Wx specific ones.

Per Cygwin Package search, the file is in "cygwin-devel-3.0.7-1" (your older version) and 3 "libc++-devel" Clang packages (but GCC is being used per your output). Seems like either LibXML::XML has be to be updated for this (possibly things have moved to "locale.h"; in which case replace all "xlocale" with "locale") or downgrade to 3.0.7 Cygwin. :-(

As mentioned in the workaround post, "I suspect an actual solution would be to rebuild Perl and reinstall all modules ...". Doing that with 5.32.0 would have been very disruptive to other tasks I'm currently working on; so I decided to install the latest development version, 5.33.5 (https://metacpan.org/pod/release/CORION/perl-5.33.5/pod/perl.pod) — it's got "CORION" plastered all over it, so it has to be good; right? :-)

Installation worked. I checked for I_XLOCALE in config.h; it was commented out:

ken@titan ~/perl5/perlbrew/perls/perl-5.33.5/lib/5.33.5/cygwin-thread-
+multi/CORE
$ grep 'I_XLOCALE' config.h
/* I_XLOCALE:
/*#define       I_XLOCALE               / **/
[download]

I've now installed lots of modules — many with XS components, including XML::LibXML — and there's been no recurrence of the earlier problem.

It would seem this is a solid solution; although, the workaround is still working, and possibly a much faster solution for anyone encountering the same problem with xlocale.h.

Installation worked. I checked for I_XLOCALE in config.h; it was commented out

Did you build 5.33.5 in the same way as you had built 5.32.0 ?
If so, then we can say that the bug has been fixed.
Otherwise, the jury is still out.

Cheers,
Rob

"Did you build 5.33.5 in the same way as you had built 5.32.0 ?"

I built 5.33.5 using the basic instructions in Perlbrew:

perlbrew install perl-5.33.5
[download]

I built 5.32.0 over six months ago. I'm somewhat loathe to say I have perfect recollection; however, I'm almost 100% certain I built that in exactly the same way:

perlbrew install perl-5.32.0
[download]

I can say that I didn't use any options affecting compilation, such as -D (see "perlbrew: Options for install command" for a full list).

I can also say that I didn't use any wildly different method, such as downloading a tarball and installing manually.

All modules were installed in exactly the same way, for both versions, using the cpan utility. Just a very basic:

$ cpan
...
cpan[1]> install Some::Module
...
cpan[2]> install Other::Module
...
[download]

— Ken

"it's got "CORION" plastered all over it, so it has to be good; right? :-)

He's been helping people here for so very long now, perhaps he's gained the ability of reading Perlmonks questions in advance long before they're posted, so he can fix problems silently before they are run into, saving himself time from having to fix the problems *and* respond.

Heh, no - a Perl development release is "just" working through the steps of the Release Manager's Guide. There is very little creative input there, just some judgement on how bad errors are (if any). Maybe someday, all these steps will be automated.

Eventual bug fixes have likely been contributed by somebody other than me to Perl 5.33.x :)

hi

does upgrading update libc gcc etc under cygwin?

seems to me youre missing devel depends, and or need to rebrew to pickup new paths

xlocale.h site:https://www.nntp.perl.org/group/perl.perl5.porters/

perl5porters "xlocale.h"

https://github.com/msys2/MSYS2-packages/issues/1535

https://web.archive.org/web/20170625012813/http://ingar.satgnu.net/devenv/mingw32/base.html

Yup glibc-dev moved xlocale.... rebrew fixes https://github.com/Perl/perl5/issues/16684