perldelta: Rmv reference to internal flag

SCF_DO_SUBSTR is a flag internal to the current implementation of the
regular expression optimizer.  There is no need to proclaim its
existence to the outside world, and is just extraneous noise.

I myself do not understand this flag, and I've spent more time looking
at this code than all but a few people likely to be reading this
perldelta.  If someone who does understand it could explain it to me, I
would add comments to the code (after the freeze) to aid future readers.

diff --git a/pod/perldelta.pod b/pod/perldelta.pod
index a261f88..76aec1d 100644 (file)
--- a/pod/perldelta.pod
+++ b/pod/perldelta.pod
@@ -3029,10 +3029,8 @@ L<[cpan #85570]|https://rt.cpan.org/Ticket/Display.html?id=85570>.
 
 =item *
 
-During the optimization phase of a regexp compilation, we no longer
-recurse into C<GOSUB>/C<GOSTART> when the internal C<SCF_DO_SUBSTR> flag
-is false. This prevents the optimizer from running "forever" and
-exhausting all memory.
+The optimization phase of a regexp compilation could run "forever" and
+exhaust all memory under certain circumstances; now fixed.
 L<[perl #122283]|https://rt.perl.org/Ticket/Display.html?id=122283>.
 
 =item *