Merge branch 'PHP-7.3'

Author: nikic

ext/mbstring/php_mbregex.c

@@ -713,8 +713,7 @@ static inline void mb_regex_substitute(
 		sp = p; /* save position */
 		clen = (int) php_mb_mbchar_bytes_ex(++p, enc);
 		if (clen != 1 || p == eos) {
-			/* skip escaped multibyte char */
-			p += clen;
+			/* skip backslash followed by multibyte char */
 			smart_str_appendl(pbuf, sp, p - sp);
 			continue;
 		}

ext/mbstring/tests/bug77514.phpt

@@ -0,0 +1,11 @@
+--TEST--
+Bug #77514: mb_ereg_replace() with trailing backslash adds null byte
+--FILE--
+<?php
+
+$a="abc123";
+var_dump(mb_ereg_replace("123","def\\",$a));
+
+?>
+--EXPECT--
+string(7) "abcdef\"