[regexp] back refs must not start/end in the middle of a surrogate pair

test/mjsunit/harmony/unicode-regexp-backrefs.js

+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --harmony-unicode-regexps --harmony-regexp-lookbehind
+
+// Back reference does not end in the middle of a surrogate pair.
+function replace(string) {
+  return string.replace(/L/g, "\ud800")
+               .replace(/l/g, "\ud801")
+               .replace(/T/g, "\udc00")
+               .replace(/\./g, "[^]");
+}
+
+function test(expectation, regexp_source, subject) {
+  if (expectation !== null) expectation = expectation.map(replace);
+  subject = replace(subject);
+  regexp_source = replace(regexp_source);
+  assertEquals(expectation, new RegExp(regexp_source, "u").exec(subject));
+}
+
+// Back reference does not end in the middle of a surrogate pair.
+test(null, "(L)\\1", "LLT");
+test(["LLTLl", "L", "l"], "(L).*\\1(.)", "LLTLl");
+test(null, "(aL).*\\1", "aLaLT");
+test(["aLaLTaLl", "aL", "l"], "(aL).*\\1(.)", "aLaLTaLl");
+
+var s = "TabcLxLTabcLxTabcLTyTabcLz";
+test([s, "TabcL", "z"], "([^x]+).*\\1(.)", s);
+
+// Back reference does not start in the middle of a surrogate pair.
+test(["TLTabTc", "T", "c"], "(T).*\\1(.)", "TLTabTc");
+
+// Lookbehinds.
+test(null, "(?<=\\1(T)x)", "LTTx");
+test(["", "b", "T"], "(?<=(.)\\2.*(T)x)", "bTaLTTx");
+test(null, "(?<=\\1.*(L)x)", "LTLx");
+test(["", "b", "L"], "(?<=(.)\\2.*(L)x)", "bLaLTLx");
+
+
+test(null, "([^x]+)x*\\1", "LxLT");
+test(null, "([^x]+)x*\\1", "TxLT");
+test(null, "([^x]+)x*\\1", "LTxL");
+test(null, "([^x]+)x*\\1", "LTxT");
+test(null, "([^x]+)x*\\1", "xLxLT");
+test(null, "([^x]+)x*\\1", "xTxLT");
+test(null, "([^x]+)x*\\1", "xLTxL");
+test(null, "([^x]+)x*\\1", "xLTxT");
+test(null, "([^x]+)x*\\1", "xxxLxxLTxx");
+test(null, "([^x]+)x*\\1", "xxxTxxLTxx");
+test(null, "([^x]+)x*\\1", "xxxLTxxLxx");
+test(null, "([^x]+)x*\\1", "xxxLTxxTxx");
+test(["LTTxxLTT", "LTT"], "([^x]+)x*\\1", "xxxLTTxxLTTxx");