summaryrefslogtreecommitdiffstats
path: root/js/src/jsfun.cpp
blob: bcb0da80b27b8280dd22fe0b68d87d20f86825d4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set ts=8 sts=4 et sw=4 tw=99:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/*
 * JS function support.
 */

#include "jsfuninlines.h"

#include "mozilla/ArrayUtils.h"
#include "mozilla/CheckedInt.h"
#include "mozilla/Maybe.h"
#include "mozilla/PodOperations.h"
#include "mozilla/Range.h"

#include <string.h>

#include "jsapi.h"
#include "jsarray.h"
#include "jsatom.h"
#include "jscntxt.h"
#include "jsobj.h"
#include "jsscript.h"
#include "jsstr.h"
#include "jstypes.h"
#include "jswrapper.h"

#include "builtin/Eval.h"
#include "builtin/Object.h"
#include "builtin/SelfHostingDefines.h"
#include "frontend/BytecodeCompiler.h"
#include "frontend/TokenStream.h"
#include "gc/Marking.h"
#include "gc/Policy.h"
#include "jit/InlinableNatives.h"
#include "jit/Ion.h"
#include "jit/JitFrameIterator.h"
#include "js/CallNonGenericMethod.h"
#include "js/Proxy.h"
#include "vm/AsyncFunction.h"
#include "vm/Debugger.h"
#include "vm/GlobalObject.h"
#include "vm/Interpreter.h"
#include "vm/SelfHosting.h"
#include "vm/Shape.h"
#include "vm/SharedImmutableStringsCache.h"
#include "vm/StringBuffer.h"
#include "vm/WrapperObject.h"
#include "vm/Xdr.h"

#include "jsscriptinlines.h"

#include "vm/Interpreter-inl.h"
#include "vm/Stack-inl.h"

using namespace js;
using namespace js::gc;
using namespace js::frontend;

using mozilla::ArrayLength;
using mozilla::Maybe;
using mozilla::PodCopy;
using mozilla::RangedPtr;
using mozilla::Some;

static bool
fun_enumerate(JSContext* cx, HandleObject obj)
{
    MOZ_ASSERT(obj->is<JSFunction>());

    RootedId id(cx);
    bool found;

    if (!obj->isBoundFunction() && !obj->as<JSFunction>().isArrow()) {
        id = NameToId(cx->names().prototype);
        if (!HasProperty(cx, obj, id, &found))
            return false;
    }

    id = NameToId(cx->names().length);
    if (!HasProperty(cx, obj, id, &found))
        return false;

    id = NameToId(cx->names().name);
    if (!HasProperty(cx, obj, id, &found))
        return false;

    return true;
}

bool
IsFunction(HandleValue v)
{
    return v.isObject() && v.toObject().is<JSFunction>();
}

static bool
AdvanceToActiveCallLinear(JSContext* cx, NonBuiltinScriptFrameIter& iter, HandleFunction fun)
{
    MOZ_ASSERT(!fun->isBuiltin());

    for (; !iter.done(); ++iter) {
        if (!iter.isFunctionFrame())
            continue;
        if (iter.matchCallee(cx, fun))
            return true;
    }
    return false;
}

static void
ThrowTypeErrorBehavior(JSContext* cx)
{
    JS_ReportErrorFlagsAndNumberASCII(cx, JSREPORT_ERROR, GetErrorMessage, nullptr,
                                     JSMSG_THROW_TYPE_ERROR);
}

static bool
IsFunctionInStrictMode(JSFunction* fun)
{
    // Interpreted functions have a strict flag.
    if (fun->isInterpreted() && fun->strict())
        return true;

    // Only asm.js functions can also be strict.
    return IsAsmJSStrictModeModuleOrFunction(fun);
}

// Beware: this function can be invoked on *any* function! That includes
// natives, strict mode functions, bound functions, arrow functions,
// self-hosted functions and constructors, asm.js functions, functions with
// destructuring arguments and/or a rest argument, and probably a few more I
// forgot. Turn back and save yourself while you still can. It's too late for
// me.
static bool
ArgumentsRestrictions(JSContext* cx, HandleFunction fun)
{
    // Throw if the function is a builtin (note: this doesn't include asm.js),
    // a strict mode function, or a bound function.
    // TODO (bug 1057208): ensure semantics are correct for all possible
    // pairings of callee/caller.
    if (fun->isBuiltin() || IsFunctionInStrictMode(fun) || fun->isBoundFunction()) {
        ThrowTypeErrorBehavior(cx);
        return false;
    }

    // Otherwise emit a strict warning about |f.arguments| to discourage use of
    // this non-standard, performance-harmful feature.
    if (!JS_ReportErrorFlagsAndNumberASCII(cx, JSREPORT_WARNING | JSREPORT_STRICT, GetErrorMessage,
                                           nullptr, JSMSG_DEPRECATED_USAGE, js_arguments_str))
    {
        return false;
    }

    return true;
}

bool
ArgumentsGetterImpl(JSContext* cx, const CallArgs& args)
{
    MOZ_ASSERT(IsFunction(args.thisv()));

    RootedFunction fun(cx, &args.thisv().toObject().as<JSFunction>());
    if (!ArgumentsRestrictions(cx, fun))
        return false;

    // Return null if this function wasn't found on the stack.
    NonBuiltinScriptFrameIter iter(cx);
    if (!AdvanceToActiveCallLinear(cx, iter, fun)) {
        args.rval().setNull();
        return true;
    }

    Rooted<ArgumentsObject*> argsobj(cx, ArgumentsObject::createUnexpected(cx, iter));
    if (!argsobj)
        return false;

    // Disabling compiling of this script in IonMonkey.  IonMonkey doesn't
    // guarantee |f.arguments| can be fully recovered, so we try to mitigate
    // observing this behavior by detecting its use early.
    JSScript* script = iter.script();
    jit::ForbidCompilation(cx, script);

    args.rval().setObject(*argsobj);
    return true;
}

static bool
ArgumentsGetter(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    return CallNonGenericMethod<IsFunction, ArgumentsGetterImpl>(cx, args);
}

bool
ArgumentsSetterImpl(JSContext* cx, const CallArgs& args)
{
    MOZ_ASSERT(IsFunction(args.thisv()));

    RootedFunction fun(cx, &args.thisv().toObject().as<JSFunction>());
    if (!ArgumentsRestrictions(cx, fun))
        return false;

    // If the function passes the gauntlet, return |undefined|.
    args.rval().setUndefined();
    return true;
}

static bool
ArgumentsSetter(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    return CallNonGenericMethod<IsFunction, ArgumentsSetterImpl>(cx, args);
}

// Beware: this function can be invoked on *any* function! That includes
// natives, strict mode functions, bound functions, arrow functions,
// self-hosted functions and constructors, asm.js functions, functions with
// destructuring arguments and/or a rest argument, and probably a few more I
// forgot. Turn back and save yourself while you still can. It's too late for
// me.
static bool
CallerRestrictions(JSContext* cx, HandleFunction fun)
{
    // Throw if the function is a builtin (note: this doesn't include asm.js),
    // a strict mode function, or a bound function.
    // TODO (bug 1057208): ensure semantics are correct for all possible
    // pairings of callee/caller.
    if (fun->isBuiltin() || IsFunctionInStrictMode(fun) || fun->isBoundFunction()) {
        ThrowTypeErrorBehavior(cx);
        return false;
    }

    // Otherwise emit a strict warning about |f.caller| to discourage use of
    // this non-standard, performance-harmful feature.
    if (!JS_ReportErrorFlagsAndNumberASCII(cx, JSREPORT_WARNING | JSREPORT_STRICT, GetErrorMessage,
                                           nullptr, JSMSG_DEPRECATED_USAGE, js_caller_str))
    {
        return false;
    }

    return true;
}

bool
CallerGetterImpl(JSContext* cx, const CallArgs& args)
{
    MOZ_ASSERT(IsFunction(args.thisv()));

    // Beware!  This function can be invoked on *any* function!  It can't
    // assume it'll never be invoked on natives, strict mode functions, bound
    // functions, or anything else that ordinarily has immutable .caller
    // defined with [[ThrowTypeError]].
    RootedFunction fun(cx, &args.thisv().toObject().as<JSFunction>());
    if (!CallerRestrictions(cx, fun))
        return false;

    // Also return null if this function wasn't found on the stack.
    NonBuiltinScriptFrameIter iter(cx);
    if (!AdvanceToActiveCallLinear(cx, iter, fun)) {
        args.rval().setNull();
        return true;
    }

    ++iter;
    while (!iter.done() && iter.isEvalFrame())
        ++iter;

    if (iter.done() || !iter.isFunctionFrame()) {
        args.rval().setNull();
        return true;
    }

    RootedObject caller(cx, iter.callee(cx));
    if (!cx->compartment()->wrap(cx, &caller))
        return false;

    // Censor the caller if we don't have full access to it.  If we do, but the
    // caller is a function with strict mode code, throw a TypeError per ES5.
    // If we pass these checks, we can return the computed caller.
    {
        JSObject* callerObj = CheckedUnwrap(caller);
        if (!callerObj) {
            args.rval().setNull();
            return true;
        }

        JSFunction* callerFun = &callerObj->as<JSFunction>();
        MOZ_ASSERT(!callerFun->isBuiltin(), "non-builtin iterator returned a builtin?");

        if (callerFun->strict()) {
            JS_ReportErrorFlagsAndNumberASCII(cx, JSREPORT_ERROR, GetErrorMessage, nullptr,
                                              JSMSG_CALLER_IS_STRICT);
            return false;
        }
    }

    args.rval().setObject(*caller);
    return true;
}

static bool
CallerGetter(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    return CallNonGenericMethod<IsFunction, CallerGetterImpl>(cx, args);
}

bool
CallerSetterImpl(JSContext* cx, const CallArgs& args)
{
    MOZ_ASSERT(IsFunction(args.thisv()));

    // Beware!  This function can be invoked on *any* function!  It can't
    // assume it'll never be invoked on natives, strict mode functions, bound
    // functions, or anything else that ordinarily has immutable .caller
    // defined with [[ThrowTypeError]].
    RootedFunction fun(cx, &args.thisv().toObject().as<JSFunction>());
    if (!CallerRestrictions(cx, fun))
        return false;

    // Return |undefined| unless an error must be thrown.
    args.rval().setUndefined();

    // We can almost just return |undefined| here -- but if the caller function
    // was strict mode code, we still have to throw a TypeError.  This requires
    // computing the caller, checking that no security boundaries are crossed,
    // and throwing a TypeError if the resulting caller is strict.

    NonBuiltinScriptFrameIter iter(cx);
    if (!AdvanceToActiveCallLinear(cx, iter, fun))
        return true;

    ++iter;
    while (!iter.done() && iter.isEvalFrame())
        ++iter;

    if (iter.done() || !iter.isFunctionFrame())
        return true;

    RootedObject caller(cx, iter.callee(cx));
    if (!cx->compartment()->wrap(cx, &caller)) {
        cx->clearPendingException();
        return true;
    }

    // If we don't have full access to the caller, or the caller is not strict,
    // return undefined.  Otherwise throw a TypeError.
    JSObject* callerObj = CheckedUnwrap(caller);
    if (!callerObj)
        return true;

    JSFunction* callerFun = &callerObj->as<JSFunction>();
    MOZ_ASSERT(!callerFun->isBuiltin(), "non-builtin iterator returned a builtin?");

    if (callerFun->strict()) {
        JS_ReportErrorFlagsAndNumberASCII(cx, JSREPORT_ERROR, GetErrorMessage, nullptr,
                                          JSMSG_CALLER_IS_STRICT);
        return false;
    }

    return true;
}

static bool
CallerSetter(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    return CallNonGenericMethod<IsFunction, CallerSetterImpl>(cx, args);
}

static const JSPropertySpec function_properties[] = {
    JS_PSGS("arguments", ArgumentsGetter, ArgumentsSetter, 0),
    JS_PSGS("caller", CallerGetter, CallerSetter, 0),
    JS_PS_END
};

static bool
ResolveInterpretedFunctionPrototype(JSContext* cx, HandleFunction fun, HandleId id)
{
    MOZ_ASSERT(fun->isInterpreted() || fun->isAsmJSNative());
    MOZ_ASSERT(id == NameToId(cx->names().prototype));

    // Assert that fun is not a compiler-created function object, which
    // must never leak to script or embedding code and then be mutated.
    // Also assert that fun is not bound, per the ES5 15.3.4.5 ref above.
    MOZ_ASSERT(!IsInternalFunctionObject(*fun));
    MOZ_ASSERT(!fun->isBoundFunction());

    // Make the prototype object an instance of Object with the same parent as
    // the function object itself, unless the function is an ES6 generator.  In
    // that case, per the 15 July 2013 ES6 draft, section 15.19.3, its parent is
    // the GeneratorObjectPrototype singleton.
    bool isStarGenerator = fun->isStarGenerator();
    Rooted<GlobalObject*> global(cx, &fun->global());
    RootedObject objProto(cx);
    if (isStarGenerator)
        objProto = GlobalObject::getOrCreateStarGeneratorObjectPrototype(cx, global);
    else
        objProto = fun->global().getOrCreateObjectPrototype(cx);
    if (!objProto)
        return false;

    RootedPlainObject proto(cx, NewObjectWithGivenProto<PlainObject>(cx, objProto,
                                                                     SingletonObject));
    if (!proto)
        return false;

    // Per ES5 13.2 the prototype's .constructor property is configurable,
    // non-enumerable, and writable.  However, per the 15 July 2013 ES6 draft,
    // section 15.19.3, the .prototype of a generator function does not link
    // back with a .constructor.
    if (!isStarGenerator) {
        RootedValue objVal(cx, ObjectValue(*fun));
        if (!DefineProperty(cx, proto, cx->names().constructor, objVal, nullptr, nullptr, 0))
            return false;
    }

    // Per ES5 15.3.5.2 a user-defined function's .prototype property is
    // initially non-configurable, non-enumerable, and writable.
    RootedValue protoVal(cx, ObjectValue(*proto));
    return DefineProperty(cx, fun, id, protoVal, nullptr, nullptr,
                          JSPROP_PERMANENT | JSPROP_RESOLVING);
}

static bool
fun_mayResolve(const JSAtomState& names, jsid id, JSObject*)
{
    if (!JSID_IS_ATOM(id))
        return false;

    JSAtom* atom = JSID_TO_ATOM(id);
    return atom == names.prototype || atom == names.length || atom == names.name;
}

static bool
fun_resolve(JSContext* cx, HandleObject obj, HandleId id, bool* resolvedp)
{
    if (!JSID_IS_ATOM(id))
        return true;

    RootedFunction fun(cx, &obj->as<JSFunction>());

    if (JSID_IS_ATOM(id, cx->names().prototype)) {
        /*
         * Built-in functions do not have a .prototype property per ECMA-262,
         * or (Object.prototype, Function.prototype, etc.) have that property
         * created eagerly.
         *
         * ES5 15.3.4.5: bound functions don't have a prototype property. The
         * isBuiltin() test covers this case because bound functions are native
         * (and thus built-in) functions by definition/construction.
         *
         * ES6 9.2.8 MakeConstructor defines the .prototype property on constructors.
         * Generators are not constructors, but they have a .prototype property anyway,
         * according to errata to ES6. See bug 1191486.
         *
         * Thus all of the following don't get a .prototype property:
         * - Methods (that are not class-constructors or generators)
         * - Arrow functions
         * - Function.prototype
         */
        if (fun->isBuiltin() || (!fun->isConstructor() && !fun->isGenerator()))
            return true;

        if (!ResolveInterpretedFunctionPrototype(cx, fun, id))
            return false;

        *resolvedp = true;
        return true;
    }

    bool isLength = JSID_IS_ATOM(id, cx->names().length);
    if (isLength || JSID_IS_ATOM(id, cx->names().name)) {
        MOZ_ASSERT(!IsInternalFunctionObject(*obj));

        RootedValue v(cx);

        // Since f.length and f.name are configurable, they could be resolved
        // and then deleted:
        //     function f(x) {}
        //     assertEq(f.length, 1);
        //     delete f.length;
        //     assertEq(f.name, "f");
        //     delete f.name;
        // Afterwards, asking for f.length or f.name again will cause this
        // resolve hook to run again. Defining the property again the second
        // time through would be a bug.
        //     assertEq(f.length, 0);  // gets Function.prototype.length!
        //     assertEq(f.name, "");  // gets Function.prototype.name!
        // We use the RESOLVED_LENGTH and RESOLVED_NAME flags as a hack to prevent this
        // bug.
        if (isLength) {
            if (fun->hasResolvedLength())
                return true;

            if (!fun->getUnresolvedLength(cx, &v))
                return false;
        } else {
            if (fun->hasResolvedName())
                return true;

            // Don't define an own .name property for unnamed functions.
            JSAtom* name = fun->getUnresolvedName(cx);
            if (name == nullptr)
                return true;

            v.setString(name);
        }

        if (!NativeDefineProperty(cx, fun, id, v, nullptr, nullptr,
                                  JSPROP_READONLY | JSPROP_RESOLVING))
        {
            return false;
        }

        if (isLength)
            fun->setResolvedLength();
        else
            fun->setResolvedName();

        *resolvedp = true;
        return true;
    }

    return true;
}

template<XDRMode mode>
bool
js::XDRInterpretedFunction(XDRState<mode>* xdr, HandleScope enclosingScope,
                           HandleScript enclosingScript, MutableHandleFunction objp)
{
    enum FirstWordFlag {
        HasAtom             = 0x1,
        IsStarGenerator     = 0x2,
        IsLazy              = 0x4,
        HasSingletonType    = 0x8
    };

    /* NB: Keep this in sync with CloneInnerInterpretedFunction. */
    RootedAtom atom(xdr->cx());
    uint32_t firstword = 0;        /* bitmask of FirstWordFlag */
    uint32_t flagsword = 0;        /* word for argument count and fun->flags */

    JSContext* cx = xdr->cx();
    RootedFunction fun(cx);
    RootedScript script(cx);
    Rooted<LazyScript*> lazy(cx);

    if (mode == XDR_ENCODE) {
        fun = objp;
        if (!fun->isInterpreted()) {
            JSAutoByteString funNameBytes;
            if (const char* name = GetFunctionNameBytes(cx, fun, &funNameBytes)) {
                JS_ReportErrorNumberLatin1(cx, GetErrorMessage, nullptr,
                                           JSMSG_NOT_SCRIPTED_FUNCTION, name);
            }
            return false;
        }

        if (fun->explicitName() || fun->hasCompileTimeName() || fun->hasGuessedAtom())
            firstword |= HasAtom;

        if (fun->isStarGenerator())
            firstword |= IsStarGenerator;

        if (fun->isInterpretedLazy()) {
            // Encode a lazy script.
            firstword |= IsLazy;
            lazy = fun->lazyScript();
        } else {
            // Encode the script.
            script = fun->nonLazyScript();
        }

        if (fun->isSingleton())
            firstword |= HasSingletonType;

        atom = fun->displayAtom();
        flagsword = (fun->nargs() << 16) |
                    (fun->flags() & ~JSFunction::NO_XDR_FLAGS);

        // The environment of any function which is not reused will always be
        // null, it is later defined when a function is cloned or reused to
        // mirror the scope chain.
        MOZ_ASSERT_IF(fun->isSingleton() &&
                      !((lazy && lazy->hasBeenCloned()) || (script && script->hasBeenCloned())),
                      fun->environment() == nullptr);
    }

    if (!xdr->codeUint32(&firstword))
        return false;

    if ((firstword & HasAtom) && !XDRAtom(xdr, &atom))
        return false;
    if (!xdr->codeUint32(&flagsword))
        return false;

    if (mode == XDR_DECODE) {
        RootedObject proto(cx);
        if (firstword & IsStarGenerator) {
            proto = GlobalObject::getOrCreateStarGeneratorFunctionPrototype(cx, cx->global());
            if (!proto)
                return false;
        }

        gc::AllocKind allocKind = gc::AllocKind::FUNCTION;
        if (uint16_t(flagsword) & JSFunction::EXTENDED)
            allocKind = gc::AllocKind::FUNCTION_EXTENDED;
        fun = NewFunctionWithProto(cx, nullptr, 0, JSFunction::INTERPRETED,
                                   /* enclosingDynamicScope = */ nullptr, nullptr, proto,
                                   allocKind, TenuredObject);
        if (!fun)
            return false;
        script = nullptr;
    }

    if (firstword & IsLazy) {
        if (!XDRLazyScript(xdr, enclosingScope, enclosingScript, fun, &lazy))
            return false;
    } else {
        if (!XDRScript(xdr, enclosingScope, enclosingScript, fun, &script))
            return false;
    }

    if (mode == XDR_DECODE) {
        fun->setArgCount(flagsword >> 16);
        fun->setFlags(uint16_t(flagsword));
        fun->initAtom(atom);
        if (firstword & IsLazy) {
            MOZ_ASSERT(fun->lazyScript() == lazy);
        } else {
            MOZ_ASSERT(fun->nonLazyScript() == script);
            MOZ_ASSERT(fun->nargs() == script->numArgs());
        }

        bool singleton = firstword & HasSingletonType;
        if (!JSFunction::setTypeForScriptedFunction(cx, fun, singleton))
            return false;
        objp.set(fun);
    }

    // Verify marker at end of function to detect buffer truncation.
    if (!xdr->codeMarker(0xA0129CD1))
        return false;

    return true;
}

template bool
js::XDRInterpretedFunction(XDRState<XDR_ENCODE>*, HandleScope, HandleScript, MutableHandleFunction);

template bool
js::XDRInterpretedFunction(XDRState<XDR_DECODE>*, HandleScope, HandleScript, MutableHandleFunction);

/* ES6 (04-25-16) 19.2.3.6 Function.prototype [ @@hasInstance ] */
bool
js::fun_symbolHasInstance(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (args.length() < 1) {
        args.rval().setBoolean(false);
        return true;
    }

    /* Step 1. */
    HandleValue func = args.thisv();

    // Primitives are non-callable and will always return false from
    // OrdinaryHasInstance.
    if (!func.isObject()) {
        args.rval().setBoolean(false);
        return true;
    }

    RootedObject obj(cx, &func.toObject());

    /* Step 2. */
    bool result;
    if (!OrdinaryHasInstance(cx, obj, args[0], &result))
        return false;

    args.rval().setBoolean(result);
    return true;
}

/*
 * ES6 (4-25-16) 7.3.19 OrdinaryHasInstance
 */
bool
JS::OrdinaryHasInstance(JSContext* cx, HandleObject objArg, HandleValue v, bool* bp)
{
    RootedObject obj(cx, objArg);

    /* Step 1. */
    if (!obj->isCallable()) {
        *bp = false;
        return true;
    }

    /* Step 2. */
    if (obj->is<JSFunction>() && obj->isBoundFunction()) {
        /* Steps 2a-b. */
        obj = obj->as<JSFunction>().getBoundFunctionTarget();
        return InstanceOfOperator(cx, obj, v, bp);
    }

    /* Step 3. */
    if (!v.isObject()) {
        *bp = false;
        return true;
    }

    /* Step 4. */
    RootedValue pval(cx);
    if (!GetProperty(cx, obj, obj, cx->names().prototype, &pval))
        return false;

    /* Step 5. */
    if (pval.isPrimitive()) {
        /*
         * Throw a runtime error if instanceof is called on a function that
         * has a non-object as its .prototype value.
         */
        RootedValue val(cx, ObjectValue(*obj));
        ReportValueError(cx, JSMSG_BAD_PROTOTYPE, -1, val, nullptr);
        return false;
    }

    /* Step 6. */
    RootedObject pobj(cx, &pval.toObject());
    bool isDelegate;
    if (!IsDelegate(cx, pobj, v, &isDelegate))
        return false;
    *bp = isDelegate;
    return true;
}

inline void
JSFunction::trace(JSTracer* trc)
{
    if (isExtended()) {
        TraceRange(trc, ArrayLength(toExtended()->extendedSlots),
                   (GCPtrValue*)toExtended()->extendedSlots, "nativeReserved");
    }

    TraceNullableEdge(trc, &atom_, "atom");

    if (isInterpreted()) {
        // Functions can be be marked as interpreted despite having no script
        // yet at some points when parsing, and can be lazy with no lazy script
        // for self-hosted code.
        if (hasScript() && !hasUncompiledScript())
            TraceManuallyBarrieredEdge(trc, &u.i.s.script_, "script");
        else if (isInterpretedLazy() && u.i.s.lazy_)
            TraceManuallyBarrieredEdge(trc, &u.i.s.lazy_, "lazyScript");

        if (u.i.env_)
            TraceManuallyBarrieredEdge(trc, &u.i.env_, "fun_environment");
    }
}

static void
fun_trace(JSTracer* trc, JSObject* obj)
{
    obj->as<JSFunction>().trace(trc);
}

static bool
ThrowTypeError(JSContext* cx, unsigned argc, Value* vp)
{
    ThrowTypeErrorBehavior(cx);
    return false;
}

static JSObject*
CreateFunctionConstructor(JSContext* cx, JSProtoKey key)
{
    Rooted<GlobalObject*> global(cx, cx->global());
    RootedObject functionProto(cx, &global->getPrototype(JSProto_Function).toObject());

    RootedObject functionCtor(cx,
      NewFunctionWithProto(cx, Function, 1, JSFunction::NATIVE_CTOR,
                           nullptr, HandlePropertyName(cx->names().Function),
                           functionProto, AllocKind::FUNCTION, SingletonObject));
    if (!functionCtor)
        return nullptr;

    return functionCtor;

}

static JSObject*
CreateFunctionPrototype(JSContext* cx, JSProtoKey key)
{
    Rooted<GlobalObject*> self(cx, cx->global());

    RootedObject objectProto(cx, &self->getPrototype(JSProto_Object).toObject());
    /*
     * Bizarrely, |Function.prototype| must be an interpreted function, so
     * give it the guts to be one.
     */
    RootedObject enclosingEnv(cx, &self->lexicalEnvironment());
    JSObject* functionProto_ =
        NewFunctionWithProto(cx, nullptr, 0, JSFunction::INTERPRETED,
                             enclosingEnv, nullptr, objectProto, AllocKind::FUNCTION,
                             SingletonObject);
    if (!functionProto_)
        return nullptr;

    RootedFunction functionProto(cx, &functionProto_->as<JSFunction>());

    const char* rawSource = "() {\n}";
    size_t sourceLen = strlen(rawSource);
    mozilla::UniquePtr<char16_t[], JS::FreePolicy> source(InflateString(cx, rawSource, &sourceLen));
    if (!source)
        return nullptr;

    ScriptSource* ss = cx->new_<ScriptSource>();
    if (!ss)
        return nullptr;
    ScriptSourceHolder ssHolder(ss);
    if (!ss->setSource(cx, mozilla::Move(source), sourceLen))
        return nullptr;

    CompileOptions options(cx);
    options.setNoScriptRval(true)
           .setVersion(JSVERSION_DEFAULT);
    RootedScriptSource sourceObject(cx, ScriptSourceObject::create(cx, ss));
    if (!sourceObject || !ScriptSourceObject::initFromOptions(cx, sourceObject, options))
        return nullptr;

    RootedScript script(cx, JSScript::Create(cx,
                                             options,
                                             sourceObject,
                                             0,
                                             ss->length()));
    if (!script || !JSScript::initFunctionPrototype(cx, script, functionProto))
        return nullptr;

    functionProto->initScript(script);
    ObjectGroup* protoGroup = functionProto->getGroup(cx);
    if (!protoGroup)
        return nullptr;

    protoGroup->setInterpretedFunction(functionProto);

    /*
     * The default 'new' group of Function.prototype is required by type
     * inference to have unknown properties, to simplify handling of e.g.
     * NewFunctionClone.
     */
    if (!JSObject::setNewGroupUnknown(cx, &JSFunction::class_, functionProto))
        return nullptr;

    // Set the prototype before we call NewFunctionWithProto below. This
    // ensures EmptyShape::getInitialShape can share function shapes.
    self->setPrototype(key, ObjectValue(*functionProto));

    // Construct the unique [[%ThrowTypeError%]] function object, used only for
    // "callee" and "caller" accessors on strict mode arguments objects.  (The
    // spec also uses this for "arguments" and "caller" on various functions,
    // but we're experimenting with implementing them using accessors on
    // |Function.prototype| right now.)
    //
    // Note that we can't use NewFunction here, even though we want the normal
    // Function.prototype for our proto, because we're still in the middle of
    // creating that as far as the world is concerned, so things will get all
    // confused.
    RootedFunction throwTypeError(cx,
      NewFunctionWithProto(cx, ThrowTypeError, 0, JSFunction::NATIVE_FUN,
                           nullptr, nullptr, functionProto, AllocKind::FUNCTION,
                           SingletonObject));
    if (!throwTypeError || !PreventExtensions(cx, throwTypeError))
        return nullptr;

    self->setThrowTypeError(throwTypeError);

    return functionProto;
}

static const ClassOps JSFunctionClassOps = {
    nullptr,                 /* addProperty */
    nullptr,                 /* delProperty */
    nullptr,                 /* getProperty */
    nullptr,                 /* setProperty */
    fun_enumerate,
    fun_resolve,
    fun_mayResolve,
    nullptr,                 /* finalize    */
    nullptr,                 /* call        */
    nullptr,
    nullptr,                 /* construct   */
    fun_trace,
};

static const ClassSpec JSFunctionClassSpec = {
    CreateFunctionConstructor,
    CreateFunctionPrototype,
    nullptr,
    nullptr,
    function_methods,
    function_properties
};

const Class JSFunction::class_ = {
    js_Function_str,
    JSCLASS_HAS_CACHED_PROTO(JSProto_Function),
    &JSFunctionClassOps,
    &JSFunctionClassSpec
};

const Class* const js::FunctionClassPtr = &JSFunction::class_;

/* Find the body of a function (not including braces). */
bool
js::FindBody(JSContext* cx, HandleFunction fun, HandleLinearString src, size_t* bodyStart,
             size_t* bodyEnd)
{
    // We don't need principals, since those are only used for error reporting.
    CompileOptions options(cx);
    options.setFileAndLine("internal-findBody", 0);

    // For asm.js/wasm modules, there's no script.
    if (fun->hasScript())
        options.setVersion(fun->nonLazyScript()->getVersion());

    AutoKeepAtoms keepAtoms(cx->perThreadData);

    AutoStableStringChars stableChars(cx);
    if (!stableChars.initTwoByte(cx, src))
        return false;

    const mozilla::Range<const char16_t> srcChars = stableChars.twoByteRange();
    TokenStream ts(cx, options, srcChars.begin().get(), srcChars.length(), nullptr);
    int nest = 0;
    bool onward = true;
    // Skip arguments list.
    do {
        TokenKind tt;
        if (!ts.getToken(&tt))
            return false;
        switch (tt) {
          case TOK_NAME:
          case TOK_YIELD:
            if (nest == 0)
                onward = false;
            break;
          case TOK_LP:
            nest++;
            break;
          case TOK_RP:
            if (--nest == 0)
                onward = false;
            break;
          default:
            break;
        }
    } while (onward);
    TokenKind tt;
    if (!ts.getToken(&tt))
        return false;
    if (tt == TOK_ARROW) {
        if (!ts.getToken(&tt))
            return false;
    }
    bool braced = tt == TOK_LC;
    MOZ_ASSERT_IF(fun->isExprBody(), !braced);
    *bodyStart = ts.currentToken().pos.begin;
    if (braced)
        *bodyStart += 1;
    mozilla::RangedPtr<const char16_t> end = srcChars.end();
    if (end[-1] == '}') {
        end--;
    } else {
        MOZ_ASSERT(!braced);
        for (; unicode::IsSpaceOrBOM2(end[-1]); end--)
            ;
    }
    *bodyEnd = end - srcChars.begin();
    MOZ_ASSERT(*bodyStart <= *bodyEnd);
    return true;
}

JSString*
js::FunctionToString(JSContext* cx, HandleFunction fun, bool prettyPrint)
{
    if (fun->isInterpretedLazy() && !fun->getOrCreateScript(cx))
        return nullptr;

    if (IsAsmJSModule(fun))
        return AsmJSModuleToString(cx, fun, !prettyPrint);
    if (IsAsmJSFunction(fun))
        return AsmJSFunctionToString(cx, fun);

    if (IsWrappedAsyncFunction(fun)) {
        RootedFunction unwrapped(cx, GetUnwrappedAsyncFunction(fun));
        return FunctionToString(cx, unwrapped, prettyPrint);
    }

    StringBuffer out(cx);
    RootedScript script(cx);

    if (fun->hasScript()) {
        script = fun->nonLazyScript();
        if (script->isGeneratorExp()) {
            if (!out.append("function genexp() {") ||
                !out.append("\n    [generator expression]\n") ||
                !out.append("}"))
            {
                return nullptr;
            }
            return out.finishString();
        }
    }

    if (fun->isAsync()) {
        if (!out.append("async "))
            return nullptr;
    }

    bool funIsMethodOrNonArrowLambda = (fun->isLambda() && !fun->isArrow()) || fun->isMethod() ||
                                        fun->isGetter() || fun->isSetter();
    bool haveSource = fun->isInterpreted() && !fun->isSelfHostedBuiltin();

    // If we're not in pretty mode, put parentheses around lambda functions and methods.
    if (haveSource && !prettyPrint && funIsMethodOrNonArrowLambda) {
        if (!out.append("("))
            return nullptr;
    }
    if (!fun->isArrow()) {
        bool ok;
        if (fun->isStarGenerator() && !fun->isAsync())
            ok = out.append("function* ");
        else
            ok = out.append("function ");
        if (!ok)
            return nullptr;
    }
    if (fun->explicitName()) {
        if (!out.append(fun->explicitName()))
            return nullptr;
    }

    if (haveSource && !script->scriptSource()->hasSourceData() &&
        !JSScript::loadSource(cx, script->scriptSource(), &haveSource))
    {
        return nullptr;
    }
    if (haveSource) {
        Rooted<JSFlatString*> src(cx, script->sourceData(cx));
        if (!src)
            return nullptr;

        if (!out.append(src))
            return nullptr;

        if (!prettyPrint && funIsMethodOrNonArrowLambda) {
            if (!out.append(")"))
                return nullptr;
        }
    } else if (fun->isInterpreted() && !fun->isSelfHostedBuiltin()) {
        if (!out.append("() {\n    ") ||
            !out.append("[sourceless code]") ||
            !out.append("\n}"))
        {
            return nullptr;
        }
    } else {
        MOZ_ASSERT(!fun->isExprBody());

        bool derived = fun->infallibleIsDefaultClassConstructor(cx);
        if (derived && fun->isDerivedClassConstructor()) {
            if (!out.append("(...args) {\n    ") ||
                !out.append("super(...args);\n}"))
            {
                return nullptr;
            }
        } else {
            if (!out.append("() {\n    "))
                return nullptr;

            if (!derived) {
                if (!out.append("[native code]"))
                    return nullptr;
            }

            if (!out.append("\n}"))
                return nullptr;
        }
    }
    return out.finishString();
}

JSString*
fun_toStringHelper(JSContext* cx, HandleObject obj, unsigned indent)
{
    if (!obj->is<JSFunction>()) {
        if (JSFunToStringOp op = obj->getOpsFunToString())
            return op(cx, obj, indent);

        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                                  JSMSG_INCOMPATIBLE_PROTO,
                                  js_Function_str, js_toString_str, "object");
        return nullptr;
    }

    RootedFunction fun(cx, &obj->as<JSFunction>());
    return FunctionToString(cx, fun, indent != JS_DONT_PRETTY_PRINT);
}

bool
js::FunctionHasDefaultHasInstance(JSFunction* fun, const WellKnownSymbols& symbols)
{
    jsid id = SYMBOL_TO_JSID(symbols.hasInstance);
    Shape* shape = fun->lookupPure(id);
    if (shape) {
        if (!shape->hasSlot() || !shape->hasDefaultGetter())
            return false;
        const Value hasInstance = fun->as<NativeObject>().getSlot(shape->slot());
        return IsNativeFunction(hasInstance, js::fun_symbolHasInstance);
    }
    return true;
}

bool
js::fun_toString(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    MOZ_ASSERT(IsFunctionObject(args.calleev()));

    uint32_t indent = 0;

    if (args.length() != 0 && !ToUint32(cx, args[0], &indent))
        return false;

    RootedObject obj(cx, ToObject(cx, args.thisv()));
    if (!obj)
        return false;

    RootedString str(cx, fun_toStringHelper(cx, obj, indent));
    if (!str)
        return false;

    args.rval().setString(str);
    return true;
}

#if JS_HAS_TOSOURCE
static bool
fun_toSource(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    MOZ_ASSERT(IsFunctionObject(args.calleev()));

    RootedObject obj(cx, ToObject(cx, args.thisv()));
    if (!obj)
        return false;

    RootedString str(cx);
    if (obj->isCallable())
        str = fun_toStringHelper(cx, obj, JS_DONT_PRETTY_PRINT);
    else
        str = ObjectToSource(cx, obj);

    if (!str)
        return false;
    args.rval().setString(str);
    return true;
}
#endif

bool
js::fun_call(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    HandleValue func = args.thisv();

    // We don't need to do this -- Call would do it for us -- but the error
    // message is *much* better if we do this here.  (Without this,
    // JSDVG_SEARCH_STACK tries to decompile |func| as if it were |this| in
    // the scripted caller's frame -- so for example
    //
    //   Function.prototype.call.call({});
    //
    // would identify |{}| as |this| as being the result of evaluating
    // |Function.prototype.call| and would conclude, "Function.prototype.call
    // is not a function".  Grotesque.)
    if (!IsCallable(func)) {
        ReportIncompatibleMethod(cx, args, &JSFunction::class_);
        return false;
    }

    size_t argCount = args.length();
    if (argCount > 0)
        argCount--; // strip off provided |this|

    InvokeArgs iargs(cx);
    if (!iargs.init(cx, argCount))
        return false;

    for (size_t i = 0; i < argCount; i++)
        iargs[i].set(args[i + 1]);

    return Call(cx, func, args.get(0), iargs, args.rval());
}

// ES5 15.3.4.3
bool
js::fun_apply(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    // Step 1.
    //
    // Note that we must check callability here, not at actual call time,
    // because extracting argument values from the provided arraylike might
    // have side effects or throw an exception.
    HandleValue fval = args.thisv();
    if (!IsCallable(fval)) {
        ReportIncompatibleMethod(cx, args, &JSFunction::class_);
        return false;
    }

    // Step 2.
    if (args.length() < 2 || args[1].isNullOrUndefined())
        return fun_call(cx, (args.length() > 0) ? 1 : 0, vp);

    InvokeArgs args2(cx);

    // A JS_OPTIMIZED_ARGUMENTS magic value means that 'arguments' flows into
    // this apply call from a scripted caller and, as an optimization, we've
    // avoided creating it since apply can simply pull the argument values from
    // the calling frame (which we must do now).
    if (args[1].isMagic(JS_OPTIMIZED_ARGUMENTS)) {
        // Step 3-6.
        ScriptFrameIter iter(cx);
        MOZ_ASSERT(iter.numActualArgs() <= ARGS_LENGTH_MAX);
        if (!args2.init(cx, iter.numActualArgs()))
            return false;

        // Steps 7-8.
        iter.unaliasedForEachActual(cx, CopyTo(args2.array()));
    } else {
        // Step 3.
        if (!args[1].isObject()) {
            JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
                                      JSMSG_BAD_APPLY_ARGS, js_apply_str);
            return false;
        }

        // Steps 4-5 (note erratum removing steps originally numbered 5 and 7 in
        // original version of ES5).
        RootedObject aobj(cx, &args[1].toObject());
        uint32_t length;
        if (!GetLengthProperty(cx, aobj, &length))
            return false;

        // Step 6.
        if (!args2.init(cx, length))
            return false;

        MOZ_ASSERT(length <= ARGS_LENGTH_MAX);

        // Steps 7-8.
        if (!GetElements(cx, aobj, length, args2.array()))
            return false;
    }

    // Step 9.
    return Call(cx, fval, args[0], args2, args.rval());
}

bool
JSFunction::infallibleIsDefaultClassConstructor(JSContext* cx) const
{
    if (!isSelfHostedBuiltin())
        return false;

    bool isDefault = false;
    if (isInterpretedLazy()) {
        JSAtom* name = &getExtendedSlot(LAZY_FUNCTION_NAME_SLOT).toString()->asAtom();
        isDefault = name == cx->names().DefaultDerivedClassConstructor ||
                    name == cx->names().DefaultBaseClassConstructor;
    } else {
        isDefault = nonLazyScript()->isDefaultClassConstructor();
    }

    MOZ_ASSERT_IF(isDefault, isConstructor());
    MOZ_ASSERT_IF(isDefault, isClassConstructor());
    return isDefault;
}

bool
JSFunction::isDerivedClassConstructor()
{
    bool derived;
    if (isInterpretedLazy()) {
        // There is only one plausible lazy self-hosted derived
        // constructor.
        if (isSelfHostedBuiltin()) {
            JSAtom* name = &getExtendedSlot(LAZY_FUNCTION_NAME_SLOT).toString()->asAtom();

            // This function is called from places without access to a
            // JSContext. Trace some plumbing to get what we want.
            derived = name == compartment()->runtimeFromAnyThread()->
                              commonNames->DefaultDerivedClassConstructor;
        } else {
            derived = lazyScript()->isDerivedClassConstructor();
        }
    } else {
        derived = nonLazyScript()->isDerivedClassConstructor();
    }
    MOZ_ASSERT_IF(derived, isClassConstructor());
    return derived;
}

bool
JSFunction::getLength(JSContext* cx, uint16_t* length)
{
    JS::RootedFunction self(cx, this);
    MOZ_ASSERT(!self->isBoundFunction());
    if (self->isInterpretedLazy() && !self->getOrCreateScript(cx))
        return false;

    *length = self->isNative() ? self->nargs() : self->nonLazyScript()->funLength();
    return true;
}

bool
JSFunction::getUnresolvedLength(JSContext* cx, MutableHandleValue v)
{
    MOZ_ASSERT(!IsInternalFunctionObject(*this));
    MOZ_ASSERT(!hasResolvedLength());

    // Bound functions' length can have values up to MAX_SAFE_INTEGER, so
    // they're handled differently from other functions.
    if (isBoundFunction()) {
        MOZ_ASSERT(getExtendedSlot(BOUND_FUN_LENGTH_SLOT).isNumber());
        v.set(getExtendedSlot(BOUND_FUN_LENGTH_SLOT));
        return true;
    }

    uint16_t length;
    if (!getLength(cx, &length))
        return false;

    v.setInt32(length);
    return true;
}

JSAtom*
JSFunction::getUnresolvedName(JSContext* cx)
{
    MOZ_ASSERT(!IsInternalFunctionObject(*this));
    MOZ_ASSERT(!hasResolvedName());

    if (isClassConstructor()) {
        // It's impossible to have an empty named class expression. We use
        // empty as a sentinel when creating default class constructors.
        MOZ_ASSERT(explicitOrCompileTimeName() != cx->names().empty);

        // Unnamed class expressions should not get a .name property at all.
        return explicitOrCompileTimeName();
    }

    return explicitOrCompileTimeName() != nullptr ? explicitOrCompileTimeName()
                                                  : cx->names().empty;
}

static const js::Value&
BoundFunctionEnvironmentSlotValue(const JSFunction* fun, uint32_t slotIndex)
{
    MOZ_ASSERT(fun->isBoundFunction());
    MOZ_ASSERT(fun->environment()->is<CallObject>());
    CallObject* callObject = &fun->environment()->as<CallObject>();
    return callObject->getSlot(slotIndex);
}

JSObject*
JSFunction::getBoundFunctionTarget() const
{
    js::Value targetVal = BoundFunctionEnvironmentSlotValue(this, JSSLOT_BOUND_FUNCTION_TARGET);
    MOZ_ASSERT(IsCallable(targetVal));
    return &targetVal.toObject();
}

const js::Value&
JSFunction::getBoundFunctionThis() const
{
    return BoundFunctionEnvironmentSlotValue(this, JSSLOT_BOUND_FUNCTION_THIS);
}

static ArrayObject*
GetBoundFunctionArguments(const JSFunction* boundFun)
{
    js::Value argsVal = BoundFunctionEnvironmentSlotValue(boundFun, JSSLOT_BOUND_FUNCTION_ARGS);
    return &argsVal.toObject().as<ArrayObject>();
}

const js::Value&
JSFunction::getBoundFunctionArgument(JSContext* cx, unsigned which) const
{
    MOZ_ASSERT(which < getBoundFunctionArgumentCount());

    RootedArrayObject boundArgs(cx, GetBoundFunctionArguments(this));
    RootedValue res(cx);
    return boundArgs->getDenseElement(which);
}

size_t
JSFunction::getBoundFunctionArgumentCount() const
{
    return GetBoundFunctionArguments(this)->length();
}

/* static */ bool
JSFunction::createScriptForLazilyInterpretedFunction(JSContext* cx, HandleFunction fun)
{
    MOZ_ASSERT(fun->isInterpretedLazy());

    Rooted<LazyScript*> lazy(cx, fun->lazyScriptOrNull());
    if (lazy) {
        RootedScript script(cx, lazy->maybeScript());

        // Only functions without inner functions or direct eval are
        // re-lazified. Functions with either of those are on the static scope
        // chain of their inner functions, or in the case of eval, possibly
        // eval'd inner functions. This prohibits re-lazification as
        // StaticScopeIter queries needsCallObject of those functions, which
        // requires a non-lazy script.  Note that if this ever changes,
        // XDRRelazificationInfo will have to be fixed.
        bool canRelazify = !lazy->numInnerFunctions() && !lazy->hasDirectEval();

        if (script) {
            fun->setUnlazifiedScript(script);
            // Remember the lazy script on the compiled script, so it can be
            // stored on the function again in case of re-lazification.
            if (canRelazify)
                script->setLazyScript(lazy);
            return true;
        }

        if (fun != lazy->functionNonDelazifying()) {
            if (!lazy->functionDelazifying(cx))
                return false;
            script = lazy->functionNonDelazifying()->nonLazyScript();
            if (!script)
                return false;

            fun->setUnlazifiedScript(script);
            return true;
        }

        // Lazy script caching is only supported for leaf functions. If a
        // script with inner functions was returned by the cache, those inner
        // functions would be delazified when deep cloning the script, even if
        // they have never executed.
        //
        // Additionally, the lazy script cache is not used during incremental
        // GCs, to avoid resurrecting dead scripts after incremental sweeping
        // has started.
        if (canRelazify && !JS::IsIncrementalGCInProgress(cx)) {
            LazyScriptCache::Lookup lookup(cx, lazy);
            cx->caches.lazyScriptCache.lookup(lookup, script.address());
        }

        if (script) {
            RootedScope enclosingScope(cx, lazy->enclosingScope());
            RootedScript clonedScript(cx, CloneScriptIntoFunction(cx, enclosingScope, fun, script));
            if (!clonedScript)
                return false;

            clonedScript->setSourceObject(lazy->sourceObject());

            fun->initAtom(script->functionNonDelazifying()->displayAtom());

            if (!lazy->maybeScript())
                lazy->initScript(clonedScript);
            return true;
        }

        MOZ_ASSERT(lazy->scriptSource()->hasSourceData());

        // Parse and compile the script from source.
        size_t lazyLength = lazy->end() - lazy->begin();
        UncompressedSourceCache::AutoHoldEntry holder;
        const char16_t* chars = lazy->scriptSource()->chars(cx, holder, lazy->begin(), lazyLength);
        if (!chars)
            return false;

        if (!frontend::CompileLazyFunction(cx, lazy, chars, lazyLength)) {
            // The frontend may have linked the function and the non-lazy
            // script together during bytecode compilation. Reset it now on
            // error.
            fun->initLazyScript(lazy);
            if (lazy->hasScript())
                lazy->resetScript();
            return false;
        }

        script = fun->nonLazyScript();

        // Remember the compiled script on the lazy script itself, in case
        // there are clones of the function still pointing to the lazy script.
        if (!lazy->maybeScript())
            lazy->initScript(script);

        // Try to insert the newly compiled script into the lazy script cache.
        if (canRelazify) {
            // A script's starting column isn't set by the bytecode emitter, so
            // specify this from the lazy script so that if an identical lazy
            // script is encountered later a match can be determined.
            script->setColumn(lazy->column());

            LazyScriptCache::Lookup lookup(cx, lazy);
            cx->caches.lazyScriptCache.insert(lookup, script);

            // Remember the lazy script on the compiled script, so it can be
            // stored on the function again in case of re-lazification.
            // Only functions without inner functions are re-lazified.
            script->setLazyScript(lazy);
        }
        return true;
    }

    /* Lazily cloned self-hosted script. */
    MOZ_ASSERT(fun->isSelfHostedBuiltin());
    RootedAtom funAtom(cx, &fun->getExtendedSlot(LAZY_FUNCTION_NAME_SLOT).toString()->asAtom());
    if (!funAtom)
        return false;
    Rooted<PropertyName*> funName(cx, funAtom->asPropertyName());
    return cx->runtime()->cloneSelfHostedFunctionScript(cx, funName, fun);
}

void
JSFunction::maybeRelazify(JSRuntime* rt)
{
    // Try to relazify functions with a non-lazy script. Note: functions can be
    // marked as interpreted despite having no script yet at some points when
    // parsing.
    if (!hasScript() || !u.i.s.script_)
        return;

    // Don't relazify functions in compartments that are active.
    JSCompartment* comp = compartment();
    if (comp->hasBeenEntered() && !rt->allowRelazificationForTesting)
        return;

    // The caller should have checked we're not in the self-hosting zone (it's
    // shared with worker runtimes so relazifying functions in it will race).
    MOZ_ASSERT(!comp->isSelfHosting);

    // Don't relazify if the compartment is being debugged.
    if (comp->isDebuggee())
        return;

    // Don't relazify if the compartment and/or runtime is instrumented to
    // collect code coverage for analysis.
    if (comp->collectCoverageForDebug())
        return;

    // Don't relazify functions with JIT code.
    if (!u.i.s.script_->isRelazifiable())
        return;

    // To delazify self-hosted builtins we need the name of the function
    // to clone. This name is stored in the first extended slot. Since
    // that slot is sometimes also used for other purposes, make sure it
    // contains a string.
    if (isSelfHostedBuiltin() &&
        (!isExtended() || !getExtendedSlot(LAZY_FUNCTION_NAME_SLOT).isString()))
    {
        return;
    }

    JSScript* script = nonLazyScript();

    flags_ &= ~INTERPRETED;
    flags_ |= INTERPRETED_LAZY;
    LazyScript* lazy = script->maybeLazyScript();
    u.i.s.lazy_ = lazy;
    if (lazy) {
        MOZ_ASSERT(!isSelfHostedBuiltin());
    } else {
        MOZ_ASSERT(isSelfHostedBuiltin());
        MOZ_ASSERT(isExtended());
        MOZ_ASSERT(getExtendedSlot(LAZY_FUNCTION_NAME_SLOT).toString()->isAtom());
    }

    comp->scheduleDelazificationForDebugger();
}

static bool
fun_isGenerator(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    JSFunction* fun;
    if (!IsFunctionObject(args.thisv(), &fun)) {
        args.rval().setBoolean(false);
        return true;
    }

    args.rval().setBoolean(fun->isGenerator());
    return true;
}

const JSFunctionSpec js::function_methods[] = {
#if JS_HAS_TOSOURCE
    JS_FN(js_toSource_str,   fun_toSource,   0,0),
#endif
    JS_FN(js_toString_str,   fun_toString,   0,0),
    JS_FN(js_apply_str,      fun_apply,      2,0),
    JS_FN(js_call_str,       fun_call,       1,0),
    JS_FN("isGenerator",     fun_isGenerator,0,0),
    JS_SELF_HOSTED_FN("bind", "FunctionBind", 2, 0),
    JS_SYM_FN(hasInstance, fun_symbolHasInstance, 1, JSPROP_READONLY | JSPROP_PERMANENT),
    JS_FS_END
};

// ES 2017 draft rev 0f10dba4ad18de92d47d421f378233a2eae8f077 19.2.1.1.1.
static bool
FunctionConstructor(JSContext* cx, const CallArgs& args, GeneratorKind generatorKind,
                    FunctionAsyncKind asyncKind)
{
    // Block this call if security callbacks forbid it.
    Rooted<GlobalObject*> global(cx, &args.callee().global());
    if (!GlobalObject::isRuntimeCodeGenEnabled(cx, global)) {
        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_CSP_BLOCKED_FUNCTION);
        return false;
    }

    bool isStarGenerator = generatorKind == StarGenerator;
    bool isAsync = asyncKind == AsyncFunction;
    MOZ_ASSERT(generatorKind != LegacyGenerator);
    MOZ_ASSERT_IF(isAsync, isStarGenerator);
    MOZ_ASSERT_IF(!isStarGenerator, !isAsync);

    RootedScript maybeScript(cx);
    const char* filename;
    unsigned lineno;
    bool mutedErrors;
    uint32_t pcOffset;
    DescribeScriptedCallerForCompilation(cx, &maybeScript, &filename, &lineno, &pcOffset,
                                         &mutedErrors);

    const char* introductionType = "Function";
    if (isAsync)
        introductionType = "AsyncFunction";
    else if (generatorKind != NotGenerator)
        introductionType = "GeneratorFunction";

    const char* introducerFilename = filename;
    if (maybeScript && maybeScript->scriptSource()->introducerFilename())
        introducerFilename = maybeScript->scriptSource()->introducerFilename();

    CompileOptions options(cx);
    // Use line 0 to make the function body starts from line 1.
    options.setMutedErrors(mutedErrors)
           .setFileAndLine(filename, 0)
           .setNoScriptRval(false)
           .setIntroductionInfo(introducerFilename, introductionType, lineno, maybeScript, pcOffset);

    StringBuffer sb(cx);

    if (!sb.append('('))
        return false;

    if (args.length() > 1) {
        RootedString str(cx);

        // Steps 5-6, 9.
        unsigned n = args.length() - 1;

        for (unsigned i = 0; i < n; i++) {
            // Steps 9.a-b, 9.d.i-ii.
            str = ToString<CanGC>(cx, args[i]);
            if (!str)
                return false;

            // Steps 9.b, 9.d.iii.
            if (!sb.append(str))
                 return false;

            if (i < args.length() - 2) {
                // Step 9.d.iii.
                if (!sb.append(", "))
                    return false;
            }
        }
    }

    // Remember the position of ")".
    Maybe<uint32_t> parameterListEnd = Some(uint32_t(sb.length()));
    MOZ_ASSERT(FunctionConstructorMedialSigils[0] == ')');

    if (!sb.append(FunctionConstructorMedialSigils))
        return false;

    if (args.length() > 0) {
        // Steps 7-8, 10.
        RootedString body(cx, ToString<CanGC>(cx, args[args.length() - 1]));
        if (!body || !sb.append(body))
             return false;
     }

    if (!sb.append(FunctionConstructorFinalBrace))
        return false;

    // The parser only accepts two byte strings.
    if (!sb.ensureTwoByteChars())
        return false;

    RootedString functionText(cx, sb.finishString());
    if (!functionText)
        return false;

    /*
     * NB: (new Function) is not lexically closed by its caller, it's just an
     * anonymous function in the top-level scope that its constructor inhabits.
     * Thus 'var x = 42; f = new Function("return x"); print(f())' prints 42,
     * and so would a call to f from another top-level's script or function.
     */
    RootedAtom anonymousAtom(cx, cx->names().anonymous);

    // Step 24.
    RootedObject proto(cx);
    if (!isAsync) {
        if (!GetPrototypeFromCallableConstructor(cx, args, &proto))
            return false;
    }

    // Step 4.d, use %Generator% as the fallback prototype.
    // Also use %Generator% for the unwrapped function of async functions.
    if (!proto && isStarGenerator) {
        proto = GlobalObject::getOrCreateStarGeneratorFunctionPrototype(cx, global);
        if (!proto)
            return false;
    }

    // Step 25-32 (reordered).
    RootedObject globalLexical(cx, &global->lexicalEnvironment());
    AllocKind allocKind = isAsync ? AllocKind::FUNCTION_EXTENDED : AllocKind::FUNCTION;
    RootedFunction fun(cx, NewFunctionWithProto(cx, nullptr, 0,
                                                JSFunction::INTERPRETED_LAMBDA, globalLexical,
                                                anonymousAtom, proto,
                                                allocKind, TenuredObject));
    if (!fun)
        return false;

    if (!JSFunction::setTypeForScriptedFunction(cx, fun))
        return false;

    // Steps 2.a-b, 3.a-b, 4.a-b, 11-23.
    AutoStableStringChars stableChars(cx);
    if (!stableChars.initTwoByte(cx, functionText))
        return false;

    mozilla::Range<const char16_t> chars = stableChars.twoByteRange();
    SourceBufferHolder::Ownership ownership = stableChars.maybeGiveOwnershipToCaller()
                                              ? SourceBufferHolder::GiveOwnership
                                              : SourceBufferHolder::NoOwnership;
    bool ok;
    SourceBufferHolder srcBuf(chars.begin().get(), chars.length(), ownership);
    if (isAsync)
        ok = frontend::CompileStandaloneAsyncFunction(cx, &fun, options, srcBuf, parameterListEnd);
    else if (isStarGenerator)
        ok = frontend::CompileStandaloneGenerator(cx, &fun, options, srcBuf, parameterListEnd);
    else
        ok = frontend::CompileStandaloneFunction(cx, &fun, options, srcBuf, parameterListEnd);

    // Step 33.
    args.rval().setObject(*fun);
    return ok;
}

bool
js::Function(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    return FunctionConstructor(cx, args, NotGenerator, SyncFunction);
}

bool
js::Generator(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    return FunctionConstructor(cx, args, StarGenerator, SyncFunction);
}

bool
js::AsyncFunctionConstructor(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    // Save the callee before its reset in FunctionConstructor().
    RootedObject newTarget(cx);
    if (args.isConstructing())
        newTarget = &args.newTarget().toObject();
    else
        newTarget = &args.callee();

    if (!FunctionConstructor(cx, args, StarGenerator, AsyncFunction))
        return false;

    // ES2017, draft rev 0f10dba4ad18de92d47d421f378233a2eae8f077
    // 19.2.1.1.1 Runtime Semantics: CreateDynamicFunction, step 24.
    RootedObject proto(cx);
    if (!GetPrototypeFromConstructor(cx, newTarget, &proto))
        return false;

    // 19.2.1.1.1, step 4.d, use %AsyncFunctionPrototype% as the fallback.
    if (!proto) {
        proto = GlobalObject::getOrCreateAsyncFunctionPrototype(cx, cx->global());
        if (!proto)
            return false;
    }

    RootedFunction unwrapped(cx, &args.rval().toObject().as<JSFunction>());
    RootedObject wrapped(cx, WrapAsyncFunctionWithProto(cx, unwrapped, proto));
    if (!wrapped)
        return false;

    args.rval().setObject(*wrapped);
    return true;
}

bool
JSFunction::isBuiltinFunctionConstructor()
{
    return maybeNative() == Function || maybeNative() == Generator;
}

bool
JSFunction::needsExtraBodyVarEnvironment() const
{
    MOZ_ASSERT(!isInterpretedLazy());

    if (isNative())
        return false;

    if (!nonLazyScript()->functionHasExtraBodyVarScope())
        return false;

    return nonLazyScript()->functionExtraBodyVarScope()->hasEnvironment();
}

bool
JSFunction::needsNamedLambdaEnvironment() const
{
    MOZ_ASSERT(!isInterpretedLazy());

    if (!isNamedLambda())
        return false;

    LexicalScope* scope = nonLazyScript()->maybeNamedLambdaScope();
    if (!scope)
        return false;

    return scope->hasEnvironment();
}

JSFunction*
js::NewNativeFunction(ExclusiveContext* cx, Native native, unsigned nargs, HandleAtom atom,
                      gc::AllocKind allocKind /* = AllocKind::FUNCTION */,
                      NewObjectKind newKind /* = SingletonObject */)
{
    MOZ_ASSERT(native);
    return NewFunctionWithProto(cx, native, nargs, JSFunction::NATIVE_FUN,
                                nullptr, atom, nullptr, allocKind, newKind);
}

JSFunction*
js::NewNativeConstructor(ExclusiveContext* cx, Native native, unsigned nargs, HandleAtom atom,
                         gc::AllocKind allocKind /* = AllocKind::FUNCTION */,
                         NewObjectKind newKind /* = SingletonObject */,
                         JSFunction::Flags flags /* = JSFunction::NATIVE_CTOR */)
{
    MOZ_ASSERT(native);
    MOZ_ASSERT(flags & JSFunction::NATIVE_CTOR);
    return NewFunctionWithProto(cx, native, nargs, flags, nullptr, atom,
                                nullptr, allocKind, newKind);
}

JSFunction*
js::NewScriptedFunction(ExclusiveContext* cx, unsigned nargs,
                        JSFunction::Flags flags, HandleAtom atom,
                        HandleObject proto /* = nullptr */,
                        gc::AllocKind allocKind /* = AllocKind::FUNCTION */,
                        NewObjectKind newKind /* = GenericObject */,
                        HandleObject enclosingEnvArg /* = nullptr */)
{
    RootedObject enclosingEnv(cx, enclosingEnvArg);
    if (!enclosingEnv)
        enclosingEnv = &cx->global()->lexicalEnvironment();
    return NewFunctionWithProto(cx, nullptr, nargs, flags, enclosingEnv,
                                atom, proto, allocKind, newKind);
}

#ifdef DEBUG
static bool
NewFunctionEnvironmentIsWellFormed(ExclusiveContext* cx, HandleObject env)
{
    // Assert that the terminating environment is null, global, or a debug
    // scope proxy. All other cases of polluting global scope behavior are
    // handled by EnvironmentObjects (viz. non-syntactic DynamicWithObject and
    // NonSyntacticVariablesObject).
    RootedObject terminatingEnv(cx, SkipEnvironmentObjects(env));
    return !terminatingEnv || terminatingEnv == cx->global() ||
           terminatingEnv->is<DebugEnvironmentProxy>();
}
#endif

JSFunction*
js::NewFunctionWithProto(ExclusiveContext* cx, Native native,
                         unsigned nargs, JSFunction::Flags flags, HandleObject enclosingEnv,
                         HandleAtom atom, HandleObject proto,
                         gc::AllocKind allocKind /* = AllocKind::FUNCTION */,
                         NewObjectKind newKind /* = GenericObject */,
                         NewFunctionProtoHandling protoHandling /* = NewFunctionClassProto */)
{
    MOZ_ASSERT(allocKind == AllocKind::FUNCTION || allocKind == AllocKind::FUNCTION_EXTENDED);
    MOZ_ASSERT_IF(native, !enclosingEnv);
    MOZ_ASSERT(NewFunctionEnvironmentIsWellFormed(cx, enclosingEnv));

    RootedObject funobj(cx);
    if (protoHandling == NewFunctionClassProto) {
        funobj = NewObjectWithClassProto(cx, &JSFunction::class_, proto, allocKind,
                                         newKind);
    } else {
        funobj = NewObjectWithGivenTaggedProto(cx, &JSFunction::class_, AsTaggedProto(proto),
                                               allocKind, newKind);
    }
    if (!funobj)
        return nullptr;

    RootedFunction fun(cx, &funobj->as<JSFunction>());

    if (allocKind == AllocKind::FUNCTION_EXTENDED)
        flags = JSFunction::Flags(flags | JSFunction::EXTENDED);

    /* Initialize all function members. */
    fun->setArgCount(uint16_t(nargs));
    fun->setFlags(flags);
    if (fun->isInterpreted()) {
        MOZ_ASSERT(!native);
        if (fun->isInterpretedLazy())
            fun->initLazyScript(nullptr);
        else
            fun->initScript(nullptr);
        fun->initEnvironment(enclosingEnv);
    } else {
        MOZ_ASSERT(fun->isNative());
        MOZ_ASSERT(native);
        fun->initNative(native, nullptr);
    }
    if (allocKind == AllocKind::FUNCTION_EXTENDED)
        fun->initializeExtended();
    fun->initAtom(atom);

    return fun;
}

bool
js::CanReuseScriptForClone(JSCompartment* compartment, HandleFunction fun,
                           HandleObject newParent)
{
    if (compartment != fun->compartment() ||
        fun->isSingleton() ||
        ObjectGroup::useSingletonForClone(fun))
    {
        return false;
    }

    if (newParent->is<GlobalObject>())
        return true;

    // Don't need to clone the script if newParent is a syntactic scope, since
    // in that case we have some actual scope objects on our scope chain and
    // whatnot; whoever put them there should be responsible for setting our
    // script's flags appropriately.  We hit this case for JSOP_LAMBDA, for
    // example.
    if (IsSyntacticEnvironment(newParent))
        return true;

    // We need to clone the script if we're interpreted and not already marked
    // as having a non-syntactic scope. If we're lazy, go ahead and clone the
    // script; see the big comment at the end of CopyScriptInternal for the
    // explanation of what's going on there.
    return !fun->isInterpreted() ||
           (fun->hasScript() && fun->nonLazyScript()->hasNonSyntacticScope());
}

static inline JSFunction*
NewFunctionClone(JSContext* cx, HandleFunction fun, NewObjectKind newKind,
                 gc::AllocKind allocKind, HandleObject proto)
{
    RootedObject cloneProto(cx, proto);
    if (!proto && fun->isStarGenerator()) {
        cloneProto = GlobalObject::getOrCreateStarGeneratorFunctionPrototype(cx, cx->global());
        if (!cloneProto)
            return nullptr;
    }

    JSObject* cloneobj = NewObjectWithClassProto(cx, &JSFunction::class_, cloneProto,
                                                 allocKind, newKind);
    if (!cloneobj)
        return nullptr;
    RootedFunction clone(cx, &cloneobj->as<JSFunction>());

    uint16_t flags = fun->flags() & ~JSFunction::EXTENDED;
    if (allocKind == AllocKind::FUNCTION_EXTENDED)
        flags |= JSFunction::EXTENDED;

    clone->setArgCount(fun->nargs());
    clone->setFlags(flags);
    clone->initAtom(fun->displayAtom());

    if (allocKind == AllocKind::FUNCTION_EXTENDED) {
        if (fun->isExtended() && fun->compartment() == cx->compartment()) {
            for (unsigned i = 0; i < FunctionExtended::NUM_EXTENDED_SLOTS; i++)
                clone->initExtendedSlot(i, fun->getExtendedSlot(i));
        } else {
            clone->initializeExtended();
        }
    }

    return clone;
}

JSFunction*
js::CloneFunctionReuseScript(JSContext* cx, HandleFunction fun, HandleObject enclosingEnv,
                             gc::AllocKind allocKind /* = FUNCTION */ ,
                             NewObjectKind newKind /* = GenericObject */,
                             HandleObject proto /* = nullptr */)
{
    MOZ_ASSERT(NewFunctionEnvironmentIsWellFormed(cx, enclosingEnv));
    MOZ_ASSERT(!fun->isBoundFunction());
    MOZ_ASSERT(CanReuseScriptForClone(cx->compartment(), fun, enclosingEnv));

    RootedFunction clone(cx, NewFunctionClone(cx, fun, newKind, allocKind, proto));
    if (!clone)
        return nullptr;

    if (fun->hasScript()) {
        clone->initScript(fun->nonLazyScript());
        clone->initEnvironment(enclosingEnv);
    } else if (fun->isInterpretedLazy()) {
        MOZ_ASSERT(fun->compartment() == clone->compartment());
        LazyScript* lazy = fun->lazyScriptOrNull();
        clone->initLazyScript(lazy);
        clone->initEnvironment(enclosingEnv);
    } else {
        clone->initNative(fun->native(), fun->jitInfo());
    }

    /*
     * Clone the function, reusing its script. We can use the same group as
     * the original function provided that its prototype is correct.
     */
    if (fun->staticPrototype() == clone->staticPrototype())
        clone->setGroup(fun->group());
    return clone;
}

JSFunction*
js::CloneFunctionAndScript(JSContext* cx, HandleFunction fun, HandleObject enclosingEnv,
                           HandleScope newScope, gc::AllocKind allocKind /* = FUNCTION */,
                           HandleObject proto /* = nullptr */)
{
    MOZ_ASSERT(NewFunctionEnvironmentIsWellFormed(cx, enclosingEnv));
    MOZ_ASSERT(!fun->isBoundFunction());

    JSScript::AutoDelazify funScript(cx);
    if (fun->isInterpreted()) {
        funScript = fun;
        if (!funScript)
            return nullptr;
    }

    RootedFunction clone(cx, NewFunctionClone(cx, fun, SingletonObject, allocKind, proto));
    if (!clone)
        return nullptr;

    if (fun->hasScript()) {
        clone->initScript(nullptr);
        clone->initEnvironment(enclosingEnv);
    } else {
        clone->initNative(fun->native(), fun->jitInfo());
    }

    /*
     * Across compartments or if we have to introduce a non-syntactic scope we
     * have to clone the script for interpreted functions. Cross-compartment
     * cloning only happens via JSAPI (JS::CloneFunctionObject) which
     * dynamically ensures that 'script' has no enclosing lexical scope (only
     * the global scope or other non-lexical scope).
     */
#ifdef DEBUG
    RootedObject terminatingEnv(cx, enclosingEnv);
    while (IsSyntacticEnvironment(terminatingEnv))
        terminatingEnv = terminatingEnv->enclosingEnvironment();
    MOZ_ASSERT_IF(!terminatingEnv->is<GlobalObject>(),
                  newScope->hasOnChain(ScopeKind::NonSyntactic));
#endif

    if (clone->isInterpreted()) {
        RootedScript script(cx, fun->nonLazyScript());
        MOZ_ASSERT(script->compartment() == fun->compartment());
        MOZ_ASSERT(cx->compartment() == clone->compartment(),
                   "Otherwise we could relazify clone below!");

        RootedScript clonedScript(cx, CloneScriptIntoFunction(cx, newScope, clone, script));
        if (!clonedScript)
            return nullptr;
        Debugger::onNewScript(cx, clonedScript);
    }

    return clone;
}

/*
 * Return an atom for use as the name of a builtin method with the given
 * property id.
 *
 * Function names are always strings. If id is the well-known @@iterator
 * symbol, this returns "[Symbol.iterator]".  If a prefix is supplied the final
 * name is |prefix + " " + name|. A prefix cannot be supplied if id is a
 * symbol value.
 *
 * Implements steps 3-5 of 9.2.11 SetFunctionName in ES2016.
 */
JSAtom*
js::IdToFunctionName(JSContext* cx, HandleId id,
                     FunctionPrefixKind prefixKind /* = FunctionPrefixKind::None */)
{
    // No prefix fastpath.
    if (JSID_IS_ATOM(id) && prefixKind == FunctionPrefixKind::None)
        return JSID_TO_ATOM(id);

    // Step 3 (implicit).

    // Step 4.
    if (JSID_IS_SYMBOL(id)) {
        // Step 4.a.
        RootedAtom desc(cx, JSID_TO_SYMBOL(id)->description());

        // Step 4.b, no prefix fastpath.
        if (!desc && prefixKind == FunctionPrefixKind::None)
            return cx->names().empty;

        // Step 5 (reordered).
        StringBuffer sb(cx);
        if (prefixKind == FunctionPrefixKind::Get) {
            if (!sb.append("get "))
                return nullptr;
        } else if (prefixKind == FunctionPrefixKind::Set) {
            if (!sb.append("set "))
                return nullptr;
        }

        // Step 4.b.
        if (desc) {
            // Step 4.c.
            if (!sb.append('[') || !sb.append(desc) || !sb.append(']'))
                return nullptr;
        }
        return sb.finishAtom();
    }

    RootedValue idv(cx, IdToValue(id));
    RootedAtom name(cx, ToAtom<CanGC>(cx, idv));
    if (!name)
        return nullptr;

    // Step 5.
    return NameToFunctionName(cx, name, prefixKind);
}

JSAtom*
js::NameToFunctionName(ExclusiveContext* cx, HandleAtom name,
                       FunctionPrefixKind prefixKind /* = FunctionPrefixKind::None */)
{
    if (prefixKind == FunctionPrefixKind::None)
        return name;

    StringBuffer sb(cx);
    if (prefixKind == FunctionPrefixKind::Get) {
        if (!sb.append("get "))
            return nullptr;
    } else {
        if (!sb.append("set "))
            return nullptr;
    }
    if (!sb.append(name))
        return nullptr;
    return sb.finishAtom();
}

bool
js::SetFunctionNameIfNoOwnName(JSContext* cx, HandleFunction fun, HandleValue name,
                               FunctionPrefixKind prefixKind)
{
    MOZ_ASSERT(name.isString() || name.isSymbol() || name.isNumber());

    if (fun->isClassConstructor()) {
        // A class may have static 'name' method or accessor.
        RootedId nameId(cx, NameToId(cx->names().name));
        bool result;
        if (!HasOwnProperty(cx, fun, nameId, &result))
            return false;

        if (result)
            return true;
    } else {
        // Anonymous function shouldn't have own 'name' property at this point.
        MOZ_ASSERT(!fun->containsPure(cx->names().name));
    }

    RootedId id(cx);
    if (!ValueToId<CanGC>(cx, name, &id))
        return false;

    RootedAtom funNameAtom(cx, IdToFunctionName(cx, id, prefixKind));
    if (!funNameAtom)
        return false;

    RootedValue funNameVal(cx, StringValue(funNameAtom));
    if (!NativeDefineProperty(cx, fun, cx->names().name, funNameVal, nullptr, nullptr,
                              JSPROP_READONLY))
    {
        return false;
    }
    return true;
}

JSFunction*
js::DefineFunction(JSContext* cx, HandleObject obj, HandleId id, Native native,
                   unsigned nargs, unsigned flags, AllocKind allocKind /* = AllocKind::FUNCTION */)
{
    GetterOp gop;
    SetterOp sop;
    if (flags & JSFUN_STUB_GSOPS) {
        /*
         * JSFUN_STUB_GSOPS is a request flag only, not stored in fun->flags or
         * the defined property's attributes. This allows us to encode another,
         * internal flag using the same bit, JSFUN_EXPR_CLOSURE -- see jsfun.h
         * for more on this.
         */
        flags &= ~JSFUN_STUB_GSOPS;
        gop = nullptr;
        sop = nullptr;
    } else {
        gop = obj->getClass()->getGetProperty();
        sop = obj->getClass()->getSetProperty();
        MOZ_ASSERT(gop != JS_PropertyStub);
        MOZ_ASSERT(sop != JS_StrictPropertyStub);
    }

    RootedAtom atom(cx, IdToFunctionName(cx, id));
    if (!atom)
        return nullptr;

    RootedFunction fun(cx);
    if (!native)
        fun = NewScriptedFunction(cx, nargs,
                                  JSFunction::INTERPRETED_LAZY, atom,
                                  /* proto = */ nullptr,
                                  allocKind, GenericObject, obj);
    else if (flags & JSFUN_CONSTRUCTOR)
        fun = NewNativeConstructor(cx, native, nargs, atom, allocKind);
    else
        fun = NewNativeFunction(cx, native, nargs, atom, allocKind);

    if (!fun)
        return nullptr;

    RootedValue funVal(cx, ObjectValue(*fun));
    if (!DefineProperty(cx, obj, id, funVal, gop, sop, flags & ~JSFUN_FLAGS_MASK))
        return nullptr;

    return fun;
}

void
js::ReportIncompatibleMethod(JSContext* cx, const CallArgs& args, const Class* clasp)
{
    RootedValue thisv(cx, args.thisv());

#ifdef DEBUG
    if (thisv.isObject()) {
        MOZ_ASSERT(thisv.toObject().getClass() != clasp ||
                   !thisv.toObject().isNative() ||
                   !thisv.toObject().staticPrototype() ||
                   thisv.toObject().staticPrototype()->getClass() != clasp);
    } else if (thisv.isString()) {
        MOZ_ASSERT(clasp != &StringObject::class_);
    } else if (thisv.isNumber()) {
        MOZ_ASSERT(clasp != &NumberObject::class_);
    } else if (thisv.isBoolean()) {
        MOZ_ASSERT(clasp != &BooleanObject::class_);
    } else if (thisv.isSymbol()) {
        MOZ_ASSERT(clasp != &SymbolObject::class_);
    } else {
        MOZ_ASSERT(thisv.isUndefined() || thisv.isNull());
    }
#endif

    if (JSFunction* fun = ReportIfNotFunction(cx, args.calleev())) {
        JSAutoByteString funNameBytes;
        if (const char* funName = GetFunctionNameBytes(cx, fun, &funNameBytes)) {
            JS_ReportErrorNumberLatin1(cx, GetErrorMessage, nullptr, JSMSG_INCOMPATIBLE_PROTO,
                                       clasp->name, funName, InformalValueTypeName(thisv));
        }
    }
}

void
js::ReportIncompatible(JSContext* cx, const CallArgs& args)
{
    if (JSFunction* fun = ReportIfNotFunction(cx, args.calleev())) {
        JSAutoByteString funNameBytes;
        if (const char* funName = GetFunctionNameBytes(cx, fun, &funNameBytes)) {
            JS_ReportErrorNumberLatin1(cx, GetErrorMessage, nullptr, JSMSG_INCOMPATIBLE_METHOD,
                                       funName, "method", InformalValueTypeName(args.thisv()));
        }
    }
}

namespace JS {
namespace detail {

JS_PUBLIC_API(void)
CheckIsValidConstructible(const Value& calleev)
{
    JSObject* callee = &calleev.toObject();
    if (callee->is<JSFunction>())
        MOZ_ASSERT(callee->as<JSFunction>().isConstructor());
    else
        MOZ_ASSERT(callee->constructHook() != nullptr);
}

} // namespace detail
} // namespace JS