[PATCH] function to parse Perl statement sequence

[perl5.git] / regexec.c

diff --git a/regexec.c b/regexec.c
index 867965a..e569a91 100644 (file)
--- a/regexec.c
+++ b/regexec.c
@@ -3977,6 +3977,20 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                char *saved_regeol = PL_regeol;
                struct re_save_state saved_state;
 
+               /* To not corrupt the existing regex state while executing the
+                * eval we would normally put it on the save stack, like with
+                * save_re_context. However, re-evals have a weird scoping so we
+                * can't just add ENTER/LEAVE here. With that, things like
+                *
+                *    (?{$a=2})(a(?{local$a=$a+1}))*aak*c(?{$b=$a})
+                *
+                * would break, as they expect the localisation to be unwound
+                * only when the re-engine backtracks through the bit that
+                * localised it.
+                *
+                * What we do instead is just saving the state in a local c
+                * variable.
+                */
                Copy(&PL_reg_state, &saved_state, 1, struct re_save_state);
 
                n = ARG(scan);