Actually make I18N::Langinfo avail on all platforms

I thought I had done this earlier, but testing on Windows demonstrated
that I hadn't.

While at it, move the details in the docs for Perl_langinfo to the
module's pod.

This doesn't follow the paradigm for putting the Configure stuff in all
the related configure files, but I saw no point to doing so.  If you are
reading this because I was wrong, feel free to ticket it or fix it.

2 files changed, 76 insertions, 16 deletions

diff --git a/ext/I18N-Langinfo/Langinfo.pm b/ext/I18N-Langinfo/Langinfo.pm
index 7a7005f7ab..bbbc4d1766 100644
--- a/ext/I18N-Langinfo/Langinfo.pm
+++ b/ext/I18N-Langinfo/Langinfo.pm
@@ -72,7 +72,7 @@ our @EXPORT_OK = qw(
 	YESSTR
 );
 
-our $VERSION = '0.15';
+our $VERSION = '0.16';
 
 XSLoader::load();
 
@@ -140,12 +140,17 @@ for the date-time, date, and time formats used by the strftime() function
 for the locales for which it makes sense to have ante meridiem and post
 meridiem time formats,
 
-    CODESET CRNCYSTR RADIXCHAR
+    CODESET CRNCYSTR
 
 for the character code set being used (such as "ISO8859-1", "cp850",
-"koi8-r", "sjis", "utf8", etc.), for the currency string, for the
+"koi8-r", "sjis", "utf8", etc.), for the currency string
+
+    ALT_DIGITS RADIXCHAR THOUSEP
+
+for an alternate representation of digits, for the
 radix character used between the integer and the fractional part
-of decimal numbers (yes, this is redundant with POSIX::localeconv())
+of decimal numbers, the group separator string for large-ish floating point
+numbers  (yes, the final two are redundant with POSIX::localeconv())
 
     YESSTR YESEXPR NOSTR NOEXPR
 
@@ -155,21 +160,74 @@ for the affirmative and negative responses and expressions, and
 
 for the Japanese Emperor eras (naturally only defined under Japanese locales).
 
+Starting in Perl 5.28, this module is available even on systems that lack a
+nativeC<nl_langinfo>.  On such systems, it uses various methods to construct
+what that function, if present, would return.  But there are potential
+glitches.  These are the items that could be different:
+
+=over
+
+=item C<CODESET>
+
+=item C<ERA>
+
+Unimplemented, so returns C<"">.
+
+=item C<YESEXPR>
+
+=item C<YESSTR>
+
+=item C<NOEXPR>
+
+=item C<NOSTR>
+
+Only the values for English are returned.  C<YESSTR> and C<NOSTR> have been
+removed from POSIX 2008, and are retained here for backwards compatibility.
+Your platform's C<nl_langinfo> may not support them.
+
+=item C<D_FMT>
+
+Always evaluates to C<%x>, the locale's appropriate date representation.
+
+=item C<T_FMT>
+
+Always evaluates to C<%X>, the locale's appropriate time representation.
+
+=item C<D_T_FMT>
+
+Always evaluates to C<%c>, the locale's appropriate date and time
+representation.
+
+=item C<CRNCYSTR>
+
+The return may be incorrect for those rare locales where the currency symbol
+replaces the radix character.
+Send email to L<mailto:perlbug@perl.org> if you have examples of it needing
+to work differently.
+
+=item C<ALT_DIGITS>
+
+Currently this gives the same results as Linux does.
+Send email to L<mailto:perlbug@perl.org> if you have examples of it needing
+to work differently.
+
+=item C<ERA_D_FMT>
+
+=item C<ERA_T_FMT>
+
+=item C<ERA_D_T_FMT>
+
+=item C<T_FMT_AMPM>
+
+These are derived by using C<strftime()>, and not all versions of that function
+know about them.  C<""> is returned for these on such systems.
+
+=back
+
 See your L<langinfo(3)> for more information about the available
 constants.  (Often this means having to look directly at the
 F<langinfo.h> C header file.)
 
-Note that unfortunately none of the above constants are guaranteed
-to be available on a particular platform.  To be on the safe side
-you can wrap the import in an eval like this:
-
-    eval {
-        require I18N::Langinfo;
-        I18N::Langinfo->import(qw(langinfo CODESET));
-        $codeset = langinfo(CODESET()); # note the ()
-    };
-    if ($@) { ... failed ... }
-
 =head2 EXPORT
 
 By default only the C<langinfo()> function is exported.
diff --git a/ext/I18N-Langinfo/Langinfo.xs b/ext/I18N-Langinfo/Langinfo.xs
index aae48c2b28..663cb2a665 100644
--- a/ext/I18N-Langinfo/Langinfo.xs
+++ b/ext/I18N-Langinfo/Langinfo.xs
@@ -7,6 +7,8 @@
 #ifdef I_LANGINFO
 #   define __USE_GNU 1 /* Enables YESSTR, otherwise only __YESSTR. */
 #   include <langinfo.h>
+#else
+#   include <perl_langinfo.h>
 #endif
 
 #include "const-c.inc"
@@ -30,7 +32,7 @@ langinfo(code)
             RETVAL = newSVpv(Perl_langinfo(code), 0);
         }
 #else
-	croak("nl_langinfo() not implemented on this architecture");
+        RETVAL = newSVpv(Perl_langinfo(code), 0);
 #endif
   OUTPUT:
 	RETVAL