move warning text to RExC_state (via RExC_warn_text)

This way we reuse the same AV each time, and avoid various refcount bookkeeping issues, all at a relatively modest cost (IMO)

Author: demerphq

regcomp.c

@@ -199,6 +199,7 @@ struct RExC_state_t {
     scan_frame *frame_head;
     scan_frame *frame_last;
     U32         frame_count;
+    AV         *warn_text;
 #ifdef ADD_TO_REGEXEC
     char 	*starttry;		/* -Dr: where regtry was called. */
 #define RExC_starttry	(pRExC_state->starttry)
@@ -290,6 +291,7 @@ struct RExC_state_t {
 #define RExC_frame_count (pRExC_state->frame_count)
 #define RExC_strict (pRExC_state->strict)
 #define RExC_study_started      (pRExC_state->study_started)
+#define RExC_warn_text (pRExC_state->warn_text)
 
 /* Heuristic check on the complexity of the pattern: if TOO_NAUGHTY, we set
  * a flag to disable back-off on the fixed/floating substrings - if it's
@@ -6764,6 +6766,7 @@ Perl_re_op_compile(pTHX_ SV ** const patternp, int pat_count,
 #endif
     }
 
+    pRExC_state->warn_text = NULL;
     pRExC_state->code_blocks = NULL;
     pRExC_state->num_code_blocks = 0;
 
@@ -13764,8 +13767,8 @@ S_populate_ANYOF_from_invlist(pTHX_ regnode *node, SV** invlist_ptr)
  * routine. q.v. */
 #define ADD_POSIX_WARNING(p, text)  STMT_START {                            \
         if (posix_warnings) {                                               \
-            if (! warn_text) warn_text = (AV *) sv_2mortal((SV *) newAV()); \
-            av_push(warn_text, Perl_newSVpvf(aTHX_                          \
+            if (! RExC_warn_text ) RExC_warn_text = (AV *) sv_2mortal((SV *) newAV()); \
+            av_push(RExC_warn_text, Perl_newSVpvf(aTHX_                          \
                                              WARNING_PREFIX                 \
                                              text                           \
                                              REPORT_LOCATION,               \
@@ -13896,7 +13899,6 @@ S_handle_possible_posix(pTHX_ RExC_state_t *pRExC_state,
     bool has_opening_colon    = FALSE;
     int class_number          = OOB_NAMEDCLASS; /* Out-of-bounds until find
                                                    valid class */
-    AV* warn_text             = NULL;   /* any warning messages */
     const char * possible_end = NULL;   /* used for a 2nd parse pass */
     const char* name_start;             /* ptr to class name first char */
 
@@ -13912,6 +13914,9 @@ S_handle_possible_posix(pTHX_ RExC_state_t *pRExC_state,
 
     PERL_ARGS_ASSERT_HANDLE_POSSIBLE_POSIX;
 
+    if (posix_warnings && RExC_warn_text)
+        av_clear(RExC_warn_text);
+
     if (p >= e) {
         return NOT_MEANT_TO_BE_A_POSIX_CLASS;
     }
@@ -14529,10 +14534,9 @@ S_handle_possible_posix(pTHX_ RExC_state_t *pRExC_state,
                 ADD_POSIX_WARNING(p, "there is no terminating ']'");
             }
 
-            if (warn_text) {
+            if (posix_warnings && av_top_index(RExC_warn_text) > -1) {
                 /* warn_text should only be true if posix_warnings is true */
-                assert(posix_warnings);
-                *posix_warnings = warn_text;
+                *posix_warnings = RExC_warn_text;
             }
         }
         else if (class_number != OOB_NAMEDCLASS) {