Resolve Abe's failing is.t, diagnosed by Sarathy

(setlocale(LC_ALL, 'C') was the key).  Document that
locale settings may be hazardous to your isxxxx() health.
(Surgeon General warning).

p4raw-id: //depot/maint-5.8/perl@18294

diff --git a/ext/POSIX/POSIX.pod b/ext/POSIX/POSIX.pod
index a455085..a569dd4 100644 (file)
--- a/ext/POSIX/POSIX.pod
+++ b/ext/POSIX/POSIX.pod
@@ -580,15 +580,20 @@ see L<perlfunc/gmtime>.
 
 =item isalnum
 
-This is identical to the C function, except that it can apply to a single
-character or to a whole string.  Consider using regular expressions and the
-C</[[:alnum:]]/> construct instead, or possibly the C</\w/> construct.
+This is identical to the C function, except that it can apply to a
+single character or to a whole string.  Note that locale settings may
+affect what characters are considered C<isalnum>.  Does not work on
+Unicode characters code point 256 or higher.  Consider using regular
+expressions and the C</[[:alnum:]]/> construct instead, or possibly
+the C</\w/> construct.
 
 =item isalpha
 
-This is identical to the C function, except that it can apply to a single
-character or to a whole string.  Consider using regular expressions and the
-C</[[:alpha:]]/> construct instead.
+This is identical to the C function, except that it can apply to
+a single character or to a whole string.  Note that locale settings
+may affect what characters are considered C<isalpha>.  Does not work
+on Unicode characters code point 256 or higher.  Consider using regular
+expressions and the C</[[:alpha:]]/> construct instead.
 
 =item isatty
 
@@ -597,60 +602,82 @@ to a tty.  Similar to the C<-t> operator, see L<perlfunc/-X>.
 
 =item iscntrl
 
-This is identical to the C function, except that it can apply to a single
-character or to a whole string.  Consider using regular expressions and the
-C</[[:cntrl:]]/> construct instead.
+This is identical to the C function, except that it can apply to
+a single character or to a whole string.  Note that locale settings
+may affect what characters are considered C<iscntrl>.  Does not work
+on Unicode characters code point 256 or higher.  Consider using regular
+expressions and the C</[[:cntrl:]]/> construct instead.
 
 =item isdigit
 
-This is identical to the C function, except that it can apply to a single
-character or to a whole string.  Consider using regular expressions and the
-C</[[:digit:]]/> construct instead, or the C</\d/> construct.
+This is identical to the C function, except that it can apply to
+a single character or to a whole string.  Note that locale settings
+may affect what characters are considered C<isdigit> (unlikely, but
+still possible). Does not work on Unicode characters code point 256
+or higher.  Consider using regular expressions and the C</[[:digit:]]/>
+construct instead, or the C</\d/> construct.
 
 =item isgraph
 
-This is identical to the C function, except that it can apply to a single
-character or to a whole string.  Consider using regular expressions and the
-C</[[:graph:]]/> construct instead.
+This is identical to the C function, except that it can apply to
+a single character or to a whole string.  Note that locale settings
+may affect what characters are considered C<isgraph>.  Does not work
+on Unicode characters code point 256 or higher.  Consider using regular
+expressions and the C</[[:graph:]]/> construct instead.
 
 =item islower
 
-This is identical to the C function, except that it can apply to a single
-character or to a whole string.  Consider using regular expressions and the
-C</[[:lower:]]/> construct instead.  Do B<not> use C</[a-z]/>.
+This is identical to the C function, except that it can apply to
+a single character or to a whole string.  Note that locale settings
+may affect what characters are considered C<islower>.  Does not work
+on Unicode characters code point 256 or higher.  Consider using regular
+expressions and the C</[[:lower:]]/> construct instead.  Do B<not> use
+C</[a-z]/>.
 
 =item isprint
 
-This is identical to the C function, except that it can apply to a single
-character or to a whole string.  Consider using regular expressions and the
-C</[[:print:]]/> construct instead.
+This is identical to the C function, except that it can apply to
+a single character or to a whole string.  Note that locale settings
+may affect what characters are considered C<isprint>.  Does not work
+on Unicode characters code point 256 or higher.  Consider using regular
+expressions and the C</[[:print:]]/> construct instead.
 
 =item ispunct
 
-This is identical to the C function, except that it can apply to a single
-character or to a whole string.  Consider using regular expressions and the
-C</[[:punct:]]/> construct instead.
+This is identical to the C function, except that it can apply to
+a single character or to a whole string.  Note that locale settings
+may affect what characters are considered C<ispunct>.  Does not work
+on Unicode characters code point 256 or higher.  Consider using regular
+expressions and the C</[[:punct:]]/> construct instead.
 
 =item isspace
 
-This is identical to the C function, except that it can apply to a single
-character or to a whole string.  Consider using regular expressions and the
-C</[[:space:]]/> construct instead, or the C</\s/> construct.
-(Note that C</\s/> and C</[[:space:]]/> are slightly different in that
-C</[[:space:]]/> can normally match a vertical tab, while C</\s/> does
-not.)
+This is identical to the C function, except that it can apply to
+a single character or to a whole string.  Note that locale settings
+may affect what characters are considered C<isspace>.  Does not work
+on Unicode characters code point 256 or higher.  Consider using regular
+expressions and the C</[[:space:]]/> construct instead, or the C</\s/>
+construct.  (Note that C</\s/> and C</[[:space:]]/> are slightly
+different in that C</[[:space:]]/> can normally match a vertical tab,
+while C</\s/> does not.)
 
 =item isupper
 
-This is identical to the C function, except that it can apply to a single
-character or to a whole string.  Consider using regular expressions and the
-C</[[:upper:]]/> construct instead.  Do B<not> use C</[A-Z]/>.
+This is identical to the C function, except that it can apply to
+a single character or to a whole string.  Note that locale settings
+may affect what characters are considered C<isupper>.  Does not work
+on Unicode characters code point 256 or higher.  Consider using regular
+expressions and the C</[[:upper:]]/> construct instead.  Do B<not> use
+C</[A-Z]/>.
 
 =item isxdigit
 
 This is identical to the C function, except that it can apply to a single
-character or to a whole string.  Consider using regular expressions and the
-C</[[:xdigit:]]/> construct instead, or simply C</[0-9a-f]/i>.
+character or to a whole string.  Note that locale settings may affect what
+characters are considered C<isxdigit> (unlikely, but still possible).
+Does not work on Unicode characters code point 256 or higher.
+Consider using regular expressions and the C</[[:xdigit:]]/>
+construct instead, or simply C</[0-9a-f]/i>.
 
 =item kill
 

diff --git a/ext/POSIX/t/is.t b/ext/POSIX/t/is.t
index 6aa96f0..9ab851c 100644 (file)
--- a/ext/POSIX/t/is.t
+++ b/ext/POSIX/t/is.t
@@ -10,12 +10,14 @@ BEGIN {
     }
 }
 
-
 use POSIX;
 use strict ;
 
-$| = 1;
+# E.g. \t might or might not be isprint() depending on the locale,
+# so let's reset to the default.
+setlocale(LC_ALL, 'C') if $Config{d_setlocale};
 
+$| = 1;
 
 # List of characters (and strings) to feed to the is<xxx> functions.
 #