Update Filter::Util::Call to CPAN version 1.51

  [DELTA]

1.50 2014-06-04 rurban
----

  * Do not re-bless already blessed filter_add arguments into the callers package.
    Fixes RT #54452
  * t/z_pod-coverage.t: omit empty Filter::decrypt (also fixes RT #84405)
  * Fix Perl Compiler detection in Filter::decrypt

1.51 2014-12-09 rurban
----

  * Minor -Wall -Wextra cleanups by jhi and me. Fixes RT #100742
  * Updated Copyright years
  * Document and warn about its limitations

1 files changed, 22 insertions, 0 deletions

diff --git a/pod/perlfilter.pod b/pod/perlfilter.pod
index 27061883c1..21df352c9c 100644
--- a/pod/perlfilter.pod
+++ b/pod/perlfilter.pod
@@ -550,6 +550,28 @@ useful features from the C preprocessor and any other macro processors
 you know. The tricky bit will be choosing how much knowledge of Perl's
 syntax you want your filter to have.
 
+=head1 LIMITATIONS
+
+Source filters only work on the string level, thus are highly limited
+in its ability to change source code on the fly. It cannot detect
+comments, quoted strings, heredocs, it is no replacement for a real
+parser.
+The only stable usage for source filters are encryption, compression,
+or the byteloader, to translate binary code back to source code.
+
+See for example the limitations in Switch, which uses source filters,
+and thus is does not work inside a string eval, the presence of
+regexes with embedded newlines that are specified with raw /.../
+delimiters and don't have a modifier //x are indistinguishable from
+code chunks beginning with the division operator /. As a workaround
+you must use m/.../ or m?...? for such patterns. Also, the presence of
+regexes specified with raw ?...? delimiters may cause mysterious
+errors. The workaround is to use m?...? instead.  See
+http://search.cpan.org/perldoc?Switch#LIMITATIONS
+
+Currently internal buffer lengths are limited to 32-bit only.
+
+
 =head1 THINGS TO LOOK OUT FOR
 
 =over 5