Update RExC_npar and after_freeze correctly after the first branch of a (?| ... )

This fixes RT #59734 : Segfault when using (?|) in regexp.

(cherry-picked from commit ee91d26e067c78d37242b4b2ccf3d5d8d3c85b5f)

1 files changed, 7 insertions, 0 deletions

diff --git a/regcomp.c b/regcomp.c
index 299f925b01..ccbe98257d 100644
--- a/regcomp.c
+++ b/regcomp.c
@@ -6119,6 +6119,13 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp,U32 depth)
     /* Pick up the branches, linking them together. */
     parse_start = RExC_parse;   /* MJD */
     br = regbranch(pRExC_state, &flags, 1,depth+1);
+
+    if (freeze_paren) {
+        if (RExC_npar > after_freeze)
+            after_freeze = RExC_npar;
+        RExC_npar = freeze_paren;
+    }
+
     /*     branch_len = (paren != 0); */
 
     if (br == NULL)