Add s///r (non-destructive substitution).

This changes s/// so that it doesn't act destructively on its target.
Instead it returns the result of the substitution (or the original string if
there was no match).

In addition this patch:

  * Adds a new warning when s///r happens in void context.
  * Adds a error when you try to use s///r with !~
  * Makes it so constant strings can be bound to s///r with =~
  * Adds documentation.
  * Adds some tests.
  * Updates various debug code so it knows about the /r flag.
  * Adds some new 'r' words to B::Deparse.

1 files changed, 2 insertions, 0 deletions

diff --git a/dump.c b/dump.c
index 6bfe5f4015..631f37cbb2 100644
--- a/dump.c
+++ b/dump.c
@@ -645,6 +645,8 @@ S_pm_description(pTHX_ const PMOP *pm)
 	sv_catpv(desc, ",RETAINT");
     if (pmflags & PMf_EVAL)
 	sv_catpv(desc, ",EVAL");
+    if (pmflags & PMf_NONDESTRUCT)
+	sv_catpv(desc, ",NONDESTRUCT");
     return desc;
 }