Remove deprecated behaviour of passing encoding as third parameter in mb_strrpos()

Merged GH-5011

Author: Girgias

UPGRADING

@@ -211,6 +211,8 @@ PHP 8.0 UPGRADE NOTES
     restored with an explicit call to chr().
   . The $is_hex parameter, which was not used internally, has been removed from
     mb_decode_numericentity().
+  . The legacy behaviour of passing the encoding as the third argument instead of an offset for the mb_strrpos
+    function has been removed, provide an explicit 0 offset with the encoding as the fourth argument.
 
 - PCRE:
   . When passing invalid escape sequences they are no longer interpreted as

ext/mbstring/mbstring.c

@@ -2146,45 +2146,12 @@ PHP_FUNCTION(mb_strrpos)
 {
 	mbfl_string haystack, needle;
 	zend_string *enc_name = NULL;
-	zval *zoffset = NULL;
 	zend_long offset = 0, n;
 
-	if (zend_parse_parameters(ZEND_NUM_ARGS(), "ss|zS", (char **)&haystack.val, &haystack.len, (char **)&needle.val, &needle.len, &zoffset, &enc_name) == FAILURE) {
+	if (zend_parse_parameters(ZEND_NUM_ARGS(), "ss|lS", (char **)&haystack.val, &haystack.len, (char **)&needle.val, &needle.len, &offset, &enc_name) == FAILURE) {
 		return;
 	}
 
-	if (zoffset) {
-		if (Z_TYPE_P(zoffset) == IS_STRING) {
-			switch (Z_STRVAL_P(zoffset)[0]) {
-				case '0':
-				case '1':
-				case '2':
-				case '3':
-				case '4':
-				case '5':
-				case '6':
-				case '7':
-				case '8':
-				case '9':
-				case ' ':
-				case '-':
-				case '.':
-					convert_to_long_ex(zoffset);
-					offset = Z_LVAL_P(zoffset);
-					break;
-				default :
-					enc_name = Z_STR_P(zoffset);
-					php_error_docref(NULL, E_DEPRECATED,
-						"Passing the encoding as third parameter is deprecated. "
-						"Use an explicit zero offset");
-					break;
-			}
-		} else {
-			convert_to_long_ex(zoffset);
-			offset = Z_LVAL_P(zoffset);
-		}
-	}
-
 	haystack.no_language = needle.no_language = MBSTRG(language);
 	haystack.encoding = needle.encoding = php_mb_get_encoding(enc_name);
 	if (!haystack.encoding) {