From: Gerard Goossen <gerard@tty.nl>
Date: Tue, 27 Oct 2009 20:59:34 +0000 (+0100)
Subject: Improve warnings about known issues in (?{...}) blocks in the regex engine
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=e95d73140218cc53e63e359a04270e05457c786f;p=p5sagit%2Fp5-mst-13.2.git

Improve warnings about known issues in (?{...}) blocks in the regex engine
---

diff --git a/pod/perlre.pod b/pod/perlre.pod
index 58c3dc7..df627ff 100644
--- a/pod/perlre.pod
+++ b/pod/perlre.pod
@@ -946,13 +946,6 @@ The assignment to C<$^R> above is properly localized, so the old
 value of C<$^R> is restored if the assertion is backtracked; compare
 L<"Backtracking">.
 
-Due to an unfortunate implementation issue, the Perl code contained in these
-blocks is treated as a compile time closure that can have seemingly bizarre
-consequences when used with lexically scoped variables inside of subroutines
-or loops.  There are various workarounds for this, including simply using
-global variables instead.  If you are using this construct and strange results
-occur then check for the use of lexically scoped variables.
-
 For reasons of security, this construct is forbidden if the regular
 expression involves run-time interpolation of variables, unless the
 perilous C<use re 'eval'> pragma has been used (see L<re>), or the
@@ -974,9 +967,15 @@ so you should only do so if you are also using taint checking.
 Better yet, use the carefully constrained evaluation within a Safe
 compartment.  See L<perlsec> for details about both these mechanisms.
 
-Because Perl's regex engine is currently not re-entrant, interpolated
-code may not invoke the regex engine either directly with C<m//> or C<s///>),
-or indirectly with functions such as C<split>.
+B<WARNING>: Use of lexical (C<my>) variables in these blocks is
+broken. The result is unpredictable and will make perl unstable. The
+workaround is to use global (C<our>) variables.
+
+B<WARNING>: Because Perl's regex engine is currently not re-entrant,
+interpolated code may not invoke the regex engine either directly with
+C<m//> or C<s///>), or indirectly with functions such as
+C<split>. Invoking the regex engine in these blocks will make perl
+unstable.
 
 =item C<(??{ code })>
 X<(??{})>