regrepeat: Use new utf8_to_uv_or_die; not utf8_to_uvchr_buf

This is a subtle bug fix when the input is malformed UTF-8.  We say we
don't support malformed, but this commit is a step towards better
protecting against that eventuality.

Prior to this commit, some patterns that use regrepeat() would exhibit
different matching behavior of malformed input depending on if utf8
warnings were enabled or not.

This is because utf8_to_uvchr_buf() returns NUL if utf8 warnings are on;
and the REPLACEMENT CHARACTER if they are off.  If the match criteria
accepts one but not the other, the behavior would differ.

Now, malformed input is treated as a runtime error, like division by 0.

Author: khwilliamson

regexec.c

@@ -10566,9 +10566,9 @@ S_regrepeat(pTHX_ regexp *prog, char **startposp, const regnode *p,
                && scan < this_eol
                && NATIVE_UTF8_TO_I8(*scan) >= ANYOF_FLAGS(p)
                && _invlist_contains_cp(anyofh_list,
-                                             utf8_to_uvchr_buf((U8 *) scan,
-                                                               (U8 *) this_eol,
-                                                               NULL)))
+                                       utf8_to_uv_or_die((U8 *) scan,
+                                                         (U8 *) this_eol,
+                                                         NULL)))
         {
             scan += UTF8SKIP(scan);
             hardcount++;
@@ -10582,9 +10582,9 @@ S_regrepeat(pTHX_ regexp *prog, char **startposp, const regnode *p,
                && scan < this_eol
                && (U8) *scan == ANYOF_FLAGS(p)
                && _invlist_contains_cp(anyofh_list,
-                                             utf8_to_uvchr_buf((U8 *) scan,
-                                                               (U8 *) this_eol,
-                                                               NULL)))
+                                       utf8_to_uv_or_die((U8 *) scan,
+                                                         (U8 *) this_eol,
+                                                         NULL)))
         {
             scan += UTF8SKIP(scan);
             hardcount++;
@@ -10612,9 +10612,9 @@ S_regrepeat(pTHX_ regexp *prog, char **startposp, const regnode *p,
                           HIGHEST_ANYOF_HRx_BYTE(ANYOF_FLAGS(p)))
                && NATIVE_UTF8_TO_I8(*scan) >= ANYOF_FLAGS(p)
                && _invlist_contains_cp(anyofh_list,
-                                             utf8_to_uvchr_buf((U8 *) scan,
-                                                               (U8 *) this_eol,
-                                                               NULL)))
+                                       utf8_to_uv_or_die((U8 *) scan,
+                                                         (U8 *) this_eol,
+                                                         NULL)))
         {
             scan += UTF8SKIP(scan);
             hardcount++;
@@ -10627,9 +10627,9 @@ S_regrepeat(pTHX_ regexp *prog, char **startposp, const regnode *p,
                && scan + FLAGS(p) < this_eol
                && memEQ(scan, ((struct regnode_anyofhs *) p)->string, FLAGS(p))
                && _invlist_contains_cp(anyofh_list,
-                                             utf8_to_uvchr_buf((U8 *) scan,
-                                                               (U8 *) this_eol,
-                                                               NULL)))
+                                       utf8_to_uv_or_die((U8 *) scan,
+                                                         (U8 *) this_eol,
+                                                         NULL)))
         {
             scan += UTF8SKIP(scan);
             hardcount++;
@@ -10640,9 +10640,9 @@ S_regrepeat(pTHX_ regexp *prog, char **startposp, const regnode *p,
         while (   hardcount < max
                && scan < this_eol
                && NATIVE_UTF8_TO_I8(*scan) >= ANYOF_FLAGS(p)
-               && withinCOUNT(utf8_to_uvchr_buf((U8 *) scan,
-                                            (U8 *) this_eol,
-                                            NULL),
+               && withinCOUNT(utf8_to_uv_or_die((U8 *) scan,
+                                                (U8 *) this_eol,
+                                                NULL),
                               ANYOFRbase(p), ANYOFRdelta(p)))
         {
             scan += UTF8SKIP(scan);
@@ -10664,9 +10664,9 @@ S_regrepeat(pTHX_ regexp *prog, char **startposp, const regnode *p,
         while (   hardcount < max
                && scan < this_eol
                && (U8) *scan == ANYOF_FLAGS(p)
-               && withinCOUNT(utf8_to_uvchr_buf((U8 *) scan,
-                                            (U8 *) this_eol,
-                                            NULL),
+               && withinCOUNT(utf8_to_uv_or_die((U8 *) scan,
+                                                (U8 *) this_eol,
+                                                NULL),
                               ANYOFRbase(p), ANYOFRdelta(p)))
         {
             scan += UTF8SKIP(scan);
@@ -10780,7 +10780,7 @@ S_regrepeat(pTHX_ regexp *prog, char **startposp, const regnode *p,
             while (   hardcount < max && scan < this_eol
                    && to_complement
                     ^ cBOOL(_invlist_contains_cp(PL_XPosix_ptrs[classnum],
-                       utf8_to_uvchr_buf((U8 *) scan, (U8 *) this_eol, NULL))))
+                       utf8_to_uv_or_die((U8 *) scan, (U8 *) this_eol, NULL))))
             {
                 scan += UTF8SKIP(scan);
                 hardcount++;