regcomp.c: Remove memory leak

This fixes GH #18604.  There was a path through the code where a
particular SV did not get its reference count decremented.

I did an audit of the function and came up with several other
possiblities that are included in this commit.

Further, there would be leaks for some instances of finding syntax
errors in the input pattern, or when warnings are fatalized.  Those
would require mortalizing some SVs, but that is beyond the scope of this
commit.

1 files changed, 7 insertions, 0 deletions

diff --git a/regcomp.c b/regcomp.c
index e44c7a37e5..f5e5f581dc 100644
--- a/regcomp.c
+++ b/regcomp.c
@@ -18765,6 +18765,12 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth,
 	RExC_end = save_end;
 	RExC_in_multi_char_class = 0;
         SvREFCNT_dec_NN(multi_char_matches);
+        SvREFCNT_dec(properties);
+        SvREFCNT_dec(cp_list);
+        SvREFCNT_dec(simple_posixes);
+        SvREFCNT_dec(posixes);
+        SvREFCNT_dec(nposixes);
+        SvREFCNT_dec(cp_foldable_list);
         return ret;
     }
 
@@ -20122,6 +20128,7 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth,
                                            RExC_parse - orig_parse);;
     SvREFCNT_dec(cp_list);;
     SvREFCNT_dec(only_utf8_locale_list);
+    SvREFCNT_dec(upper_latin1_only_utf8_matches);
     return ret;
 }