summaryrefslogtreecommitdiff
path: root/gdb/rust-lang.c
blob: f0bea374ecb20f40ece3cc7b8c41a6c9c96a1eb3 (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
/* Rust language support routines for GDB, the GNU debugger.

   Copyright (C) 2016-2020 Free Software Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"

#include <ctype.h>

#include "block.h"
#include "c-lang.h"
#include "charset.h"
#include "cp-support.h"
#include "demangle.h"
#include "gdbarch.h"
#include "infcall.h"
#include "objfiles.h"
#include "psymtab.h"
#include "rust-lang.h"
#include "typeprint.h"
#include "valprint.h"
#include "varobj.h"
#include <algorithm>
#include <string>
#include <vector>
#include "cli/cli-style.h"

/* See rust-lang.h.  */

const char *
rust_last_path_segment (const char *path)
{
  const char *result = strrchr (path, ':');

  if (result == NULL)
    return path;
  return result + 1;
}

/* See rust-lang.h.  */

std::string
rust_crate_for_block (const struct block *block)
{
  const char *scope = block_scope (block);

  if (scope[0] == '\0')
    return std::string ();

  return std::string (scope, cp_find_first_component (scope));
}

/* Return true if TYPE, which must be a struct type, represents a Rust
   enum.  */

static bool
rust_enum_p (struct type *type)
{
  /* is_dynamic_type will return true if any field has a dynamic
     attribute -- but we only want to check the top level.  */
  return TYPE_HAS_VARIANT_PARTS (type);
}

/* Return true if TYPE, which must be an already-resolved enum type,
   has no variants.  */

static bool
rust_empty_enum_p (const struct type *type)
{
  return TYPE_NFIELDS (type) == 0;
}

/* Given an already-resolved enum type and contents, find which
   variant is active.  */

static int
rust_enum_variant (struct type *type)
{
  /* The active variant is simply the first non-artificial field.  */
  for (int i = 0; i < TYPE_NFIELDS (type); ++i)
    if (!TYPE_FIELD_ARTIFICIAL (type, i))
      return i;

  /* Perhaps we could get here by trying to print an Ada variant
     record in Rust mode.  Unlikely, but an error is safer than an
     assert.  */
  error (_("Could not find active enum variant"));
}

/* See rust-lang.h.  */

bool
rust_tuple_type_p (struct type *type)
{
  /* The current implementation is a bit of a hack, but there's
     nothing else in the debuginfo to distinguish a tuple from a
     struct.  */
  return (type->code () == TYPE_CODE_STRUCT
	  && type->name () != NULL
	  && type->name ()[0] == '(');
}

/* Return true if all non-static fields of a structlike type are in a
   sequence like __0, __1, __2.  */

static bool
rust_underscore_fields (struct type *type)
{
  int i, field_number;

  field_number = 0;

  if (type->code () != TYPE_CODE_STRUCT)
    return false;
  for (i = 0; i < TYPE_NFIELDS (type); ++i)
    {
      if (!field_is_static (&TYPE_FIELD (type, i)))
	{
	  char buf[20];

	  xsnprintf (buf, sizeof (buf), "__%d", field_number);
	  if (strcmp (buf, TYPE_FIELD_NAME (type, i)) != 0)
	    return false;
	  field_number++;
	}
    }
  return true;
}

/* See rust-lang.h.  */

bool
rust_tuple_struct_type_p (struct type *type)
{
  /* This is just an approximation until DWARF can represent Rust more
     precisely.  We exclude zero-length structs because they may not
     be tuple structs, and there's no way to tell.  */
  return TYPE_NFIELDS (type) > 0 && rust_underscore_fields (type);
}

/* Return true if TYPE is a slice type, otherwise false.  */

static bool
rust_slice_type_p (struct type *type)
{
  return (type->code () == TYPE_CODE_STRUCT
	  && type->name () != NULL
	  && (strncmp (type->name (), "&[", 2) == 0
	      || strcmp (type->name (), "&str") == 0));
}

/* Return true if TYPE is a range type, otherwise false.  */

static bool
rust_range_type_p (struct type *type)
{
  int i;

  if (type->code () != TYPE_CODE_STRUCT
      || TYPE_NFIELDS (type) > 2
      || type->name () == NULL
      || strstr (type->name (), "::Range") == NULL)
    return false;

  if (TYPE_NFIELDS (type) == 0)
    return true;

  i = 0;
  if (strcmp (TYPE_FIELD_NAME (type, 0), "start") == 0)
    {
      if (TYPE_NFIELDS (type) == 1)
	return true;
      i = 1;
    }
  else if (TYPE_NFIELDS (type) == 2)
    {
      /* First field had to be "start".  */
      return false;
    }

  return strcmp (TYPE_FIELD_NAME (type, i), "end") == 0;
}

/* Return true if TYPE is an inclusive range type, otherwise false.
   This is only valid for types which are already known to be range
   types.  */

static bool
rust_inclusive_range_type_p (struct type *type)
{
  return (strstr (type->name (), "::RangeInclusive") != NULL
	  || strstr (type->name (), "::RangeToInclusive") != NULL);
}

/* Return true if TYPE seems to be the type "u8", otherwise false.  */

static bool
rust_u8_type_p (struct type *type)
{
  return (type->code () == TYPE_CODE_INT
	  && TYPE_UNSIGNED (type)
	  && TYPE_LENGTH (type) == 1);
}

/* Return true if TYPE is a Rust character type.  */

static bool
rust_chartype_p (struct type *type)
{
  return (type->code () == TYPE_CODE_CHAR
	  && TYPE_LENGTH (type) == 4
	  && TYPE_UNSIGNED (type));
}

/* Return true if TYPE is a string type.  */

static bool
rust_is_string_type_p (struct type *type)
{
  LONGEST low_bound, high_bound;

  type = check_typedef (type);
  return ((type->code () == TYPE_CODE_STRING)
	  || (type->code () == TYPE_CODE_PTR
	      && (TYPE_TARGET_TYPE (type)->code () == TYPE_CODE_ARRAY
		  && rust_u8_type_p (TYPE_TARGET_TYPE (TYPE_TARGET_TYPE (type)))
		  && get_array_bounds (TYPE_TARGET_TYPE (type), &low_bound,
				       &high_bound)))
	  || (type->code () == TYPE_CODE_STRUCT
	      && !rust_enum_p (type)
	      && rust_slice_type_p (type)
	      && strcmp (type->name (), "&str") == 0));
}

/* If VALUE represents a trait object pointer, return the underlying
   pointer with the correct (i.e., runtime) type.  Otherwise, return
   NULL.  */

static struct value *
rust_get_trait_object_pointer (struct value *value)
{
  struct type *type = check_typedef (value_type (value));

  if (type->code () != TYPE_CODE_STRUCT || TYPE_NFIELDS (type) != 2)
    return NULL;

  /* Try to be a bit resilient if the ABI changes.  */
  int vtable_field = 0;
  for (int i = 0; i < 2; ++i)
    {
      if (strcmp (TYPE_FIELD_NAME (type, i), "vtable") == 0)
	vtable_field = i;
      else if (strcmp (TYPE_FIELD_NAME (type, i), "pointer") != 0)
	return NULL;
    }

  CORE_ADDR vtable = value_as_address (value_field (value, vtable_field));
  struct symbol *symbol = find_symbol_at_address (vtable);
  if (symbol == NULL || symbol->subclass != SYMBOL_RUST_VTABLE)
    return NULL;

  struct rust_vtable_symbol *vtable_sym
    = static_cast<struct rust_vtable_symbol *> (symbol);
  struct type *pointer_type = lookup_pointer_type (vtable_sym->concrete_type);
  return value_cast (pointer_type, value_field (value, 1 - vtable_field));
}



/* la_emitchar implementation for Rust.  */

static void
rust_emitchar (int c, struct type *type, struct ui_file *stream, int quoter)
{
  if (!rust_chartype_p (type))
    generic_emit_char (c, type, stream, quoter,
		       target_charset (get_type_arch (type)));
  else if (c == '\\' || c == quoter)
    fprintf_filtered (stream, "\\%c", c);
  else if (c == '\n')
    fputs_filtered ("\\n", stream);
  else if (c == '\r')
    fputs_filtered ("\\r", stream);
  else if (c == '\t')
    fputs_filtered ("\\t", stream);
  else if (c == '\0')
    fputs_filtered ("\\0", stream);
  else if (c >= 32 && c <= 127 && isprint (c))
    fputc_filtered (c, stream);
  else if (c <= 255)
    fprintf_filtered (stream, "\\x%02x", c);
  else
    fprintf_filtered (stream, "\\u{%06x}", c);
}

/* la_printchar implementation for Rust.  */

static void
rust_printchar (int c, struct type *type, struct ui_file *stream)
{
  fputs_filtered ("'", stream);
  LA_EMIT_CHAR (c, type, stream, '\'');
  fputs_filtered ("'", stream);
}

/* la_printstr implementation for Rust.  */

static void
rust_printstr (struct ui_file *stream, struct type *type,
	       const gdb_byte *string, unsigned int length,
	       const char *user_encoding, int force_ellipses,
	       const struct value_print_options *options)
{
  /* Rust always uses UTF-8, but let the caller override this if need
     be.  */
  const char *encoding = user_encoding;
  if (user_encoding == NULL || !*user_encoding)
    {
      /* In Rust strings, characters are "u8".  */
      if (rust_u8_type_p (type))
	encoding = "UTF-8";
      else
	{
	  /* This is probably some C string, so let's let C deal with
	     it.  */
	  c_printstr (stream, type, string, length, user_encoding,
		      force_ellipses, options);
	  return;
	}
    }

  /* This is not ideal as it doesn't use our character printer.  */
  generic_printstr (stream, type, string, length, encoding, force_ellipses,
		    '"', 0, options);
}



static void rust_value_print_inner (struct value *val, struct ui_file *stream,
				    int recurse,
				    const struct value_print_options *options);

/* Helper function to print a string slice.  */

static void
rust_val_print_str (struct ui_file *stream, struct value *val,
		    const struct value_print_options *options)
{
  struct value *base = value_struct_elt (&val, NULL, "data_ptr", NULL,
					 "slice");
  struct value *len = value_struct_elt (&val, NULL, "length", NULL, "slice");

  val_print_string (TYPE_TARGET_TYPE (value_type (base)), "UTF-8",
		    value_as_address (base), value_as_long (len), stream,
		    options);
}

/* rust_val_print helper for structs and untagged unions.  */

static void
val_print_struct (struct value *val, struct ui_file *stream, int recurse,
		  const struct value_print_options *options)
{
  int i;
  int first_field;
  struct type *type = check_typedef (value_type (val));

  if (rust_slice_type_p (type) && strcmp (type->name (), "&str") == 0)
    {
      /* If what we are printing here is actually a string within a
	 structure then VAL will be the original parent value, while TYPE
	 will be the type of the structure representing the string we want
	 to print.
	 However, RUST_VAL_PRINT_STR looks up the fields of the string
	 inside VAL, assuming that VAL is the string.
	 So, recreate VAL as a value representing just the string.  */
      val = value_at_lazy (type, value_address (val));
      rust_val_print_str (stream, val, options);
      return;
    }

  bool is_tuple = rust_tuple_type_p (type);
  bool is_tuple_struct = !is_tuple && rust_tuple_struct_type_p (type);
  struct value_print_options opts;

  if (!is_tuple)
    {
      if (type->name () != NULL)
        fprintf_filtered (stream, "%s", type->name ());

      if (TYPE_NFIELDS (type) == 0)
        return;

      if (type->name () != NULL)
        fputs_filtered (" ", stream);
    }

  if (is_tuple || is_tuple_struct)
    fputs_filtered ("(", stream);
  else
    fputs_filtered ("{", stream);

  opts = *options;
  opts.deref_ref = 0;

  first_field = 1;
  for (i = 0; i < TYPE_NFIELDS (type); ++i)
    {
      if (field_is_static (&TYPE_FIELD (type, i)))
        continue;

      if (!first_field)
        fputs_filtered (",", stream);

      if (options->prettyformat)
        {
	  fputs_filtered ("\n", stream);
	  print_spaces_filtered (2 + 2 * recurse, stream);
        }
      else if (!first_field)
        fputs_filtered (" ", stream);

      first_field = 0;

      if (!is_tuple && !is_tuple_struct)
        {
	  fputs_styled (TYPE_FIELD_NAME (type, i),
			variable_name_style.style (), stream);
	  fputs_filtered (": ", stream);
        }

      rust_value_print_inner (value_field (val, i), stream, recurse + 1,
			      &opts);
    }

  if (options->prettyformat)
    {
      fputs_filtered ("\n", stream);
      print_spaces_filtered (2 * recurse, stream);
    }

  if (is_tuple || is_tuple_struct)
    fputs_filtered (")", stream);
  else
    fputs_filtered ("}", stream);
}

/* rust_val_print helper for discriminated unions (Rust enums).  */

static void
rust_print_enum (struct value *val, struct ui_file *stream, int recurse,
		 const struct value_print_options *options)
{
  struct value_print_options opts = *options;
  struct type *type = check_typedef (value_type (val));

  opts.deref_ref = 0;

  gdb_assert (rust_enum_p (type));
  gdb::array_view<const gdb_byte> view (value_contents_for_printing (val),
					TYPE_LENGTH (value_type (val)));
  type = resolve_dynamic_type (type, view, value_address (val));

  if (rust_empty_enum_p (type))
    {
      /* Print the enum type name here to be more clear.  */
      fprintf_filtered (stream, _("%s {%p[<No data fields>%p]}"),
			type->name (),
			metadata_style.style ().ptr (), nullptr);
      return;
    }

  int variant_fieldno = rust_enum_variant (type);
  val = value_field (val, variant_fieldno);
  struct type *variant_type = TYPE_FIELD_TYPE (type, variant_fieldno);

  int nfields = TYPE_NFIELDS (variant_type);

  bool is_tuple = rust_tuple_struct_type_p (variant_type);

  fprintf_filtered (stream, "%s", variant_type->name ());
  if (nfields == 0)
    {
      /* In case of a nullary variant like 'None', just output
	 the name. */
      return;
    }

  /* In case of a non-nullary variant, we output 'Foo(x,y,z)'. */
  if (is_tuple)
    fprintf_filtered (stream, "(");
  else
    {
      /* struct variant.  */
      fprintf_filtered (stream, "{");
    }

  bool first_field = true;
  for (int j = 0; j < TYPE_NFIELDS (variant_type); j++)
    {
      if (!first_field)
	fputs_filtered (", ", stream);
      first_field = false;

      if (!is_tuple)
	fprintf_filtered (stream, "%ps: ",
			  styled_string (variable_name_style.style (),
					 TYPE_FIELD_NAME (variant_type, j)));

      rust_value_print_inner (value_field (val, j), stream, recurse + 1,
			      &opts);
    }

  if (is_tuple)
    fputs_filtered (")", stream);
  else
    fputs_filtered ("}", stream);
}

static const struct generic_val_print_decorations rust_decorations =
{
  /* Complex isn't used in Rust, but we provide C-ish values just in
     case.  */
  "",
  " + ",
  " * I",
  "true",
  "false",
  "()",
  "[",
  "]"
};

/* la_value_print_inner implementation for Rust.  */
static void
rust_value_print_inner (struct value *val, struct ui_file *stream,
			int recurse,
			const struct value_print_options *options)
{
  struct value_print_options opts = *options;
  opts.deref_ref = 1;

  if (opts.prettyformat == Val_prettyformat_default)
    opts.prettyformat = (opts.prettyformat_structs
			 ? Val_prettyformat : Val_no_prettyformat);

  struct type *type = check_typedef (value_type (val));
  switch (type->code ())
    {
    case TYPE_CODE_PTR:
      {
	LONGEST low_bound, high_bound;
	
	if (TYPE_TARGET_TYPE (type)->code () == TYPE_CODE_ARRAY
	    && rust_u8_type_p (TYPE_TARGET_TYPE (TYPE_TARGET_TYPE (type)))
	    && get_array_bounds (TYPE_TARGET_TYPE (type), &low_bound,
				 &high_bound))
	  {
	    /* We have a pointer to a byte string, so just print
	       that.  */
	    struct type *elttype = check_typedef (TYPE_TARGET_TYPE (type));
	    CORE_ADDR addr = value_as_address (val);
	    struct gdbarch *arch = get_type_arch (type);

	    if (opts.addressprint)
	      {
		fputs_filtered (paddress (arch, addr), stream);
		fputs_filtered (" ", stream);
	      }

	    fputs_filtered ("b", stream);
	    val_print_string (TYPE_TARGET_TYPE (elttype), "ASCII", addr,
			      high_bound - low_bound + 1, stream,
			      &opts);
	    break;
	  }
      }
      goto generic_print;

    case TYPE_CODE_METHODPTR:
    case TYPE_CODE_MEMBERPTR:
      c_value_print_inner (val, stream, recurse, &opts);
      break;

    case TYPE_CODE_INT:
      /* Recognize the unit type.  */
      if (TYPE_UNSIGNED (type) && TYPE_LENGTH (type) == 0
	  && type->name () != NULL && strcmp (type->name (), "()") == 0)
	{
	  fputs_filtered ("()", stream);
	  break;
	}
      goto generic_print;

    case TYPE_CODE_STRING:
      {
	LONGEST low_bound, high_bound;

	if (!get_array_bounds (type, &low_bound, &high_bound))
	  error (_("Could not determine the array bounds"));

	/* If we see a plain TYPE_CODE_STRING, then we're printing a
	   byte string, hence the choice of "ASCII" as the
	   encoding.  */
	fputs_filtered ("b", stream);
	rust_printstr (stream, TYPE_TARGET_TYPE (type),
		       value_contents_for_printing (val),
		       high_bound - low_bound + 1, "ASCII", 0, &opts);
      }
      break;

    case TYPE_CODE_ARRAY:
      {
	LONGEST low_bound, high_bound;

	if (get_array_bounds (type, &low_bound, &high_bound)
	    && high_bound - low_bound + 1 == 0)
	  fputs_filtered ("[]", stream);
	else
	  goto generic_print;
      }
      break;

    case TYPE_CODE_UNION:
      /* Untagged unions are printed as if they are structs.  Since
	 the field bit positions overlap in the debuginfo, the code
	 for printing a union is same as that for a struct, the only
	 difference is that the input type will have overlapping
	 fields.  */
      val_print_struct (val, stream, recurse, &opts);
      break;

    case TYPE_CODE_STRUCT:
      if (rust_enum_p (type))
	rust_print_enum (val, stream, recurse, &opts);
      else
	val_print_struct (val, stream, recurse, &opts);
      break;

    default:
    generic_print:
      /* Nothing special yet.  */
      generic_value_print (val, stream, recurse, &opts, &rust_decorations);
    }
}



static void
rust_internal_print_type (struct type *type, const char *varstring,
			  struct ui_file *stream, int show, int level,
			  const struct type_print_options *flags,
			  bool for_rust_enum, print_offset_data *podata);

/* Print a struct or union typedef.  */
static void
rust_print_struct_def (struct type *type, const char *varstring,
		       struct ui_file *stream, int show, int level,
		       const struct type_print_options *flags,
		       bool for_rust_enum, print_offset_data *podata)
{
  /* Print a tuple type simply.  */
  if (rust_tuple_type_p (type))
    {
      fputs_filtered (type->name (), stream);
      return;
    }

  /* If we see a base class, delegate to C.  */
  if (TYPE_N_BASECLASSES (type) > 0)
    c_print_type (type, varstring, stream, show, level, flags);

  if (flags->print_offsets)
    {
      /* Temporarily bump the level so that the output lines up
	 correctly.  */
      level += 2;
    }

  /* Compute properties of TYPE here because, in the enum case, the
     rest of the code ends up looking only at the variant part.  */
  const char *tagname = type->name ();
  bool is_tuple_struct = rust_tuple_struct_type_p (type);
  bool is_tuple = rust_tuple_type_p (type);
  bool is_enum = rust_enum_p (type);

  if (for_rust_enum)
    {
      /* Already printing an outer enum, so nothing to print here.  */
    }
  else
    {
      /* This code path is also used by unions and enums.  */
      if (is_enum)
	{
	  fputs_filtered ("enum ", stream);
	  dynamic_prop *prop = type->dyn_prop (DYN_PROP_VARIANT_PARTS);
	  if (prop != nullptr && prop->kind == PROP_TYPE)
	    type = prop->data.original_type;
	}
      else if (type->code () == TYPE_CODE_STRUCT)
	fputs_filtered ("struct ", stream);
      else
	fputs_filtered ("union ", stream);

      if (tagname != NULL)
	fputs_filtered (tagname, stream);
    }

  if (TYPE_NFIELDS (type) == 0 && !is_tuple)
    return;
  if (for_rust_enum && !flags->print_offsets)
    fputs_filtered (is_tuple_struct ? "(" : "{", stream);
  else
    fputs_filtered (is_tuple_struct ? " (\n" : " {\n", stream);

  /* When printing offsets, we rearrange the fields into storage
     order.  This lets us show holes more clearly.  We work using
     field indices here because it simplifies calls to
     print_offset_data::update below.  */
  std::vector<int> fields;
  for (int i = 0; i < TYPE_NFIELDS (type); ++i)
    {
      if (field_is_static (&TYPE_FIELD (type, i)))
	continue;
      if (is_enum && TYPE_FIELD_ARTIFICIAL (type, i))
	continue;
      fields.push_back (i);
    }
  if (flags->print_offsets)
    std::sort (fields.begin (), fields.end (),
	       [&] (int a, int b)
	       {
		 return (TYPE_FIELD_BITPOS (type, a)
			 < TYPE_FIELD_BITPOS (type, b));
	       });

  for (int i : fields)
    {
      QUIT;

      gdb_assert (!field_is_static (&TYPE_FIELD (type, i)));
      gdb_assert (! (is_enum && TYPE_FIELD_ARTIFICIAL (type, i)));

      if (flags->print_offsets)
	podata->update (type, i, stream);

      /* We'd like to print "pub" here as needed, but rustc
	 doesn't emit the debuginfo, and our types don't have
	 cplus_struct_type attached.  */

      /* For a tuple struct we print the type but nothing
	 else.  */
      if (!for_rust_enum || flags->print_offsets)
	print_spaces_filtered (level + 2, stream);
      if (is_enum)
	fputs_styled (TYPE_FIELD_NAME (type, i), variable_name_style.style (),
		      stream);
      else if (!is_tuple_struct)
	fprintf_filtered (stream, "%ps: ",
			  styled_string (variable_name_style.style (),
					 TYPE_FIELD_NAME (type, i)));

      rust_internal_print_type (TYPE_FIELD_TYPE (type, i), NULL,
				stream, (is_enum ? show : show - 1),
				level + 2, flags, is_enum, podata);
      if (!for_rust_enum || flags->print_offsets)
	fputs_filtered (",\n", stream);
      /* Note that this check of "I" is ok because we only sorted the
	 fields by offset when print_offsets was set, so we won't take
	 this branch in that case.  */
      else if (i + 1 < TYPE_NFIELDS (type))
	fputs_filtered (", ", stream);
    }

  if (flags->print_offsets)
    {
      /* Undo the temporary level increase we did above.  */
      level -= 2;
      podata->finish (type, level, stream);
      print_spaces_filtered (print_offset_data::indentation, stream);
      if (level == 0)
	print_spaces_filtered (2, stream);
    }
  if (!for_rust_enum || flags->print_offsets)
    print_spaces_filtered (level, stream);
  fputs_filtered (is_tuple_struct ? ")" : "}", stream);
}

/* la_print_typedef implementation for Rust.  */

static void
rust_print_typedef (struct type *type,
		    struct symbol *new_symbol,
		    struct ui_file *stream)
{
  type = check_typedef (type);
  fprintf_filtered (stream, "type %s = ", new_symbol->print_name ());
  type_print (type, "", stream, 0);
  fprintf_filtered (stream, ";");
}

/* la_print_type implementation for Rust.  */

static void
rust_internal_print_type (struct type *type, const char *varstring,
			  struct ui_file *stream, int show, int level,
			  const struct type_print_options *flags,
			  bool for_rust_enum, print_offset_data *podata)
{
  QUIT;
  if (show <= 0
      && type->name () != NULL)
    {
      /* Rust calls the unit type "void" in its debuginfo,
         but we don't want to print it as that.  */
      if (type->code () == TYPE_CODE_VOID)
        fputs_filtered ("()", stream);
      else
        fputs_filtered (type->name (), stream);
      return;
    }

  type = check_typedef (type);
  switch (type->code ())
    {
    case TYPE_CODE_VOID:
      /* If we have an enum, we've already printed the type's
	 unqualified name, and there is nothing else to print
	 here.  */
      if (!for_rust_enum)
	fputs_filtered ("()", stream);
      break;

    case TYPE_CODE_FUNC:
      /* Delegate varargs to the C printer.  */
      if (TYPE_VARARGS (type))
	goto c_printer;

      fputs_filtered ("fn ", stream);
      if (varstring != NULL)
	fputs_filtered (varstring, stream);
      fputs_filtered ("(", stream);
      for (int i = 0; i < TYPE_NFIELDS (type); ++i)
	{
	  QUIT;
	  if (i > 0)
	    fputs_filtered (", ", stream);
	  rust_internal_print_type (TYPE_FIELD_TYPE (type, i), "", stream,
				    -1, 0, flags, false, podata);
	}
      fputs_filtered (")", stream);
      /* If it returns unit, we can omit the return type.  */
      if (TYPE_TARGET_TYPE (type)->code () != TYPE_CODE_VOID)
        {
          fputs_filtered (" -> ", stream);
          rust_internal_print_type (TYPE_TARGET_TYPE (type), "", stream,
				    -1, 0, flags, false, podata);
        }
      break;

    case TYPE_CODE_ARRAY:
      {
	LONGEST low_bound, high_bound;

	fputs_filtered ("[", stream);
	rust_internal_print_type (TYPE_TARGET_TYPE (type), NULL,
				  stream, show - 1, level, flags, false,
				  podata);

	if (TYPE_HIGH_BOUND_KIND (TYPE_INDEX_TYPE (type)) == PROP_LOCEXPR
	    || TYPE_HIGH_BOUND_KIND (TYPE_INDEX_TYPE (type)) == PROP_LOCLIST)
	  fprintf_filtered (stream, "; variable length");
	else if (get_array_bounds (type, &low_bound, &high_bound))
	  fprintf_filtered (stream, "; %s",
			    plongest (high_bound - low_bound + 1));
	fputs_filtered ("]", stream);
      }
      break;

    case TYPE_CODE_UNION:
    case TYPE_CODE_STRUCT:
      rust_print_struct_def (type, varstring, stream, show, level, flags,
			     for_rust_enum, podata);
      break;

    case TYPE_CODE_ENUM:
      {
	int len = 0;

	fputs_filtered ("enum ", stream);
	if (type->name () != NULL)
	  {
	    fputs_filtered (type->name (), stream);
	    fputs_filtered (" ", stream);
	    len = strlen (type->name ());
	  }
	fputs_filtered ("{\n", stream);

	for (int i = 0; i < TYPE_NFIELDS (type); ++i)
	  {
	    const char *name = TYPE_FIELD_NAME (type, i);

	    QUIT;

	    if (len > 0
		&& strncmp (name, type->name (), len) == 0
		&& name[len] == ':'
		&& name[len + 1] == ':')
	      name += len + 2;
	    fprintfi_filtered (level + 2, stream, "%ps,\n",
			       styled_string (variable_name_style.style (),
					      name));
	  }

	fputs_filtered ("}", stream);
      }
      break;

    case TYPE_CODE_PTR:
      {
	if (type->name () != nullptr)
	  fputs_filtered (type->name (), stream);
	else
	  {
	    /* We currently can't distinguish between pointers and
	       references.  */
	    fputs_filtered ("*mut ", stream);
	    type_print (TYPE_TARGET_TYPE (type), "", stream, 0);
	  }
      }
      break;

    default:
    c_printer:
      c_print_type (type, varstring, stream, show, level, flags);
    }
}

static void
rust_print_type (struct type *type, const char *varstring,
		 struct ui_file *stream, int show, int level,
		 const struct type_print_options *flags)
{
  print_offset_data podata;
  rust_internal_print_type (type, varstring, stream, show, level,
			    flags, false, &podata);
}



/* Like arch_composite_type, but uses TYPE to decide how to allocate
   -- either on an obstack or on a gdbarch.  */

static struct type *
rust_composite_type (struct type *original,
		     const char *name,
		     const char *field1, struct type *type1,
		     const char *field2, struct type *type2)
{
  struct type *result = alloc_type_copy (original);
  int i, nfields, bitpos;

  nfields = 0;
  if (field1 != NULL)
    ++nfields;
  if (field2 != NULL)
    ++nfields;

  result->set_code (TYPE_CODE_STRUCT);
  result->set_name (name);

  result->set_num_fields (nfields);
  TYPE_FIELDS (result)
    = (struct field *) TYPE_ZALLOC (result, nfields * sizeof (struct field));

  i = 0;
  bitpos = 0;
  if (field1 != NULL)
    {
      struct field *field = &TYPE_FIELD (result, i);

      SET_FIELD_BITPOS (*field, bitpos);
      bitpos += TYPE_LENGTH (type1) * TARGET_CHAR_BIT;

      FIELD_NAME (*field) = field1;
      FIELD_TYPE (*field) = type1;
      ++i;
    }
  if (field2 != NULL)
    {
      struct field *field = &TYPE_FIELD (result, i);
      unsigned align = type_align (type2);

      if (align != 0)
	{
	  int delta;

	  align *= TARGET_CHAR_BIT;
	  delta = bitpos % align;
	  if (delta != 0)
	    bitpos += align - delta;
	}
      SET_FIELD_BITPOS (*field, bitpos);

      FIELD_NAME (*field) = field2;
      FIELD_TYPE (*field) = type2;
      ++i;
    }

  if (i > 0)
    TYPE_LENGTH (result)
      = (TYPE_FIELD_BITPOS (result, i - 1) / TARGET_CHAR_BIT +
	 TYPE_LENGTH (TYPE_FIELD_TYPE (result, i - 1)));
  return result;
}

/* See rust-lang.h.  */

struct type *
rust_slice_type (const char *name, struct type *elt_type,
		 struct type *usize_type)
{
  struct type *type;

  elt_type = lookup_pointer_type (elt_type);
  type = rust_composite_type (elt_type, name,
			      "data_ptr", elt_type,
			      "length", usize_type);

  return type;
}

enum rust_primitive_types
{
  rust_primitive_bool,
  rust_primitive_char,
  rust_primitive_i8,
  rust_primitive_u8,
  rust_primitive_i16,
  rust_primitive_u16,
  rust_primitive_i32,
  rust_primitive_u32,
  rust_primitive_i64,
  rust_primitive_u64,
  rust_primitive_isize,
  rust_primitive_usize,
  rust_primitive_f32,
  rust_primitive_f64,
  rust_primitive_unit,
  rust_primitive_str,
  nr_rust_primitive_types
};

/* la_language_arch_info implementation for Rust.  */

static void
rust_language_arch_info (struct gdbarch *gdbarch,
			 struct language_arch_info *lai)
{
  const struct builtin_type *builtin = builtin_type (gdbarch);
  struct type *tem;
  struct type **types;
  unsigned int length;

  types = GDBARCH_OBSTACK_CALLOC (gdbarch, nr_rust_primitive_types + 1,
				  struct type *);

  types[rust_primitive_bool] = arch_boolean_type (gdbarch, 8, 1, "bool");
  types[rust_primitive_char] = arch_character_type (gdbarch, 32, 1, "char");
  types[rust_primitive_i8] = arch_integer_type (gdbarch, 8, 0, "i8");
  types[rust_primitive_u8] = arch_integer_type (gdbarch, 8, 1, "u8");
  types[rust_primitive_i16] = arch_integer_type (gdbarch, 16, 0, "i16");
  types[rust_primitive_u16] = arch_integer_type (gdbarch, 16, 1, "u16");
  types[rust_primitive_i32] = arch_integer_type (gdbarch, 32, 0, "i32");
  types[rust_primitive_u32] = arch_integer_type (gdbarch, 32, 1, "u32");
  types[rust_primitive_i64] = arch_integer_type (gdbarch, 64, 0, "i64");
  types[rust_primitive_u64] = arch_integer_type (gdbarch, 64, 1, "u64");

  length = 8 * TYPE_LENGTH (builtin->builtin_data_ptr);
  types[rust_primitive_isize] = arch_integer_type (gdbarch, length, 0, "isize");
  types[rust_primitive_usize] = arch_integer_type (gdbarch, length, 1, "usize");

  types[rust_primitive_f32] = arch_float_type (gdbarch, 32, "f32",
					       floatformats_ieee_single);
  types[rust_primitive_f64] = arch_float_type (gdbarch, 64, "f64",
					       floatformats_ieee_double);

  types[rust_primitive_unit] = arch_integer_type (gdbarch, 0, 1, "()");

  tem = make_cv_type (1, 0, types[rust_primitive_u8], NULL);
  types[rust_primitive_str] = rust_slice_type ("&str", tem,
					       types[rust_primitive_usize]);

  lai->primitive_type_vector = types;
  lai->bool_type_default = types[rust_primitive_bool];
  lai->string_char_type = types[rust_primitive_u8];
}



/* A helper for rust_evaluate_subexp that handles OP_FUNCALL.  */

static struct value *
rust_evaluate_funcall (struct expression *exp, int *pos, enum noside noside)
{
  int i;
  int num_args = exp->elts[*pos + 1].longconst;
  const char *method;
  struct value *function, *result, *arg0;
  struct type *type, *fn_type;
  const struct block *block;
  struct block_symbol sym;

  /* For an ordinary function call we can simply defer to the
     generic implementation.  */
  if (exp->elts[*pos + 3].opcode != STRUCTOP_STRUCT)
    return evaluate_subexp_standard (NULL, exp, pos, noside);

  /* Skip over the OP_FUNCALL and the STRUCTOP_STRUCT.  */
  *pos += 4;
  method = &exp->elts[*pos + 1].string;
  *pos += 3 + BYTES_TO_EXP_ELEM (exp->elts[*pos].longconst + 1);

  /* Evaluate the argument to STRUCTOP_STRUCT, then find its
     type in order to look up the method.  */
  arg0 = evaluate_subexp (NULL_TYPE, exp, pos, noside);

  if (noside == EVAL_SKIP)
    {
      for (i = 0; i < num_args; ++i)
	evaluate_subexp (NULL_TYPE, exp, pos, noside);
      return arg0;
    }

  std::vector<struct value *> args (num_args + 1);
  args[0] = arg0;

  /* We don't yet implement real Deref semantics.  */
  while (value_type (args[0])->code () == TYPE_CODE_PTR)
    args[0] = value_ind (args[0]);

  type = value_type (args[0]);
  if ((type->code () != TYPE_CODE_STRUCT
       && type->code () != TYPE_CODE_UNION
       && type->code () != TYPE_CODE_ENUM)
      || rust_tuple_type_p (type))
    error (_("Method calls only supported on struct or enum types"));
  if (type->name () == NULL)
    error (_("Method call on nameless type"));

  std::string name = std::string (type->name ()) + "::" + method;

  block = get_selected_block (0);
  sym = lookup_symbol (name.c_str (), block, VAR_DOMAIN, NULL);
  if (sym.symbol == NULL)
    error (_("Could not find function named '%s'"), name.c_str ());

  fn_type = SYMBOL_TYPE (sym.symbol);
  if (TYPE_NFIELDS (fn_type) == 0)
    error (_("Function '%s' takes no arguments"), name.c_str ());

  if (TYPE_FIELD_TYPE (fn_type, 0)->code () == TYPE_CODE_PTR)
    args[0] = value_addr (args[0]);

  function = address_of_variable (sym.symbol, block);

  for (i = 0; i < num_args; ++i)
    args[i + 1] = evaluate_subexp (NULL_TYPE, exp, pos, noside);

  if (noside == EVAL_AVOID_SIDE_EFFECTS)
    result = value_zero (TYPE_TARGET_TYPE (fn_type), not_lval);
  else
    result = call_function_by_hand (function, NULL, args);
  return result;
}

/* A helper for rust_evaluate_subexp that handles OP_RANGE.  */

static struct value *
rust_range (struct expression *exp, int *pos, enum noside noside)
{
  enum range_type kind;
  struct value *low = NULL, *high = NULL;
  struct value *addrval, *result;
  CORE_ADDR addr;
  struct type *range_type;
  struct type *index_type;
  struct type *temp_type;
  const char *name;

  kind = (enum range_type) longest_to_int (exp->elts[*pos + 1].longconst);
  *pos += 3;

  if (kind == HIGH_BOUND_DEFAULT || kind == NONE_BOUND_DEFAULT
      || kind == NONE_BOUND_DEFAULT_EXCLUSIVE)
    low = evaluate_subexp (NULL_TYPE, exp, pos, noside);
  if (kind == LOW_BOUND_DEFAULT || kind == LOW_BOUND_DEFAULT_EXCLUSIVE
      || kind == NONE_BOUND_DEFAULT || kind == NONE_BOUND_DEFAULT_EXCLUSIVE)
    high = evaluate_subexp (NULL_TYPE, exp, pos, noside);
  bool inclusive = (kind == NONE_BOUND_DEFAULT || kind == LOW_BOUND_DEFAULT);

  if (noside == EVAL_SKIP)
    return value_from_longest (builtin_type (exp->gdbarch)->builtin_int, 1);

  if (low == NULL)
    {
      if (high == NULL)
	{
	  index_type = NULL;
	  name = "std::ops::RangeFull";
	}
      else
	{
	  index_type = value_type (high);
	  name = (inclusive
		  ? "std::ops::RangeToInclusive" : "std::ops::RangeTo");
	}
    }
  else
    {
      if (high == NULL)
	{
	  index_type = value_type (low);
	  name = "std::ops::RangeFrom";
	}
      else
	{
	  if (!types_equal (value_type (low), value_type (high)))
	    error (_("Range expression with different types"));
	  index_type = value_type (low);
	  name = inclusive ? "std::ops::RangeInclusive" : "std::ops::Range";
	}
    }

  /* If we don't have an index type, just allocate this on the
     arch.  Here any type will do.  */
  temp_type = (index_type == NULL
	       ? language_bool_type (exp->language_defn, exp->gdbarch)
	       : index_type);
  /* It would be nicer to cache the range type.  */
  range_type = rust_composite_type (temp_type, name,
				    low == NULL ? NULL : "start", index_type,
				    high == NULL ? NULL : "end", index_type);

  if (noside == EVAL_AVOID_SIDE_EFFECTS)
    return value_zero (range_type, lval_memory);

  addrval = value_allocate_space_in_inferior (TYPE_LENGTH (range_type));
  addr = value_as_long (addrval);
  result = value_at_lazy (range_type, addr);

  if (low != NULL)
    {
      struct value *start = value_struct_elt (&result, NULL, "start", NULL,
					      "range");

      value_assign (start, low);
    }

  if (high != NULL)
    {
      struct value *end = value_struct_elt (&result, NULL, "end", NULL,
					    "range");

      value_assign (end, high);
    }

  result = value_at_lazy (range_type, addr);
  return result;
}

/* A helper function to compute the range and kind given a range
   value.  TYPE is the type of the range value.  RANGE is the range
   value.  LOW, HIGH, and KIND are out parameters.  The LOW and HIGH
   parameters might be filled in, or might not be, depending on the
   kind of range this is.  KIND will always be set to the appropriate
   value describing the kind of range, and this can be used to
   determine whether LOW or HIGH are valid.  */

static void
rust_compute_range (struct type *type, struct value *range,
		    LONGEST *low, LONGEST *high,
		    enum range_type *kind)
{
  int i;

  *low = 0;
  *high = 0;
  *kind = BOTH_BOUND_DEFAULT;

  if (TYPE_NFIELDS (type) == 0)
    return;

  i = 0;
  if (strcmp (TYPE_FIELD_NAME (type, 0), "start") == 0)
    {
      *kind = HIGH_BOUND_DEFAULT;
      *low = value_as_long (value_field (range, 0));
      ++i;
    }
  if (TYPE_NFIELDS (type) > i
      && strcmp (TYPE_FIELD_NAME (type, i), "end") == 0)
    {
      *kind = (*kind == BOTH_BOUND_DEFAULT
	       ? LOW_BOUND_DEFAULT : NONE_BOUND_DEFAULT);
      *high = value_as_long (value_field (range, i));

      if (rust_inclusive_range_type_p (type))
	++*high;
    }
}

/* A helper for rust_evaluate_subexp that handles BINOP_SUBSCRIPT.  */

static struct value *
rust_subscript (struct expression *exp, int *pos, enum noside noside,
		int for_addr)
{
  struct value *lhs, *rhs, *result;
  struct type *rhstype;
  LONGEST low, high_bound;
  /* Initialized to appease the compiler.  */
  enum range_type kind = BOTH_BOUND_DEFAULT;
  LONGEST high = 0;
  int want_slice = 0;

  ++*pos;
  lhs = evaluate_subexp (NULL_TYPE, exp, pos, noside);
  rhs = evaluate_subexp (NULL_TYPE, exp, pos, noside);

  if (noside == EVAL_SKIP)
    return lhs;

  rhstype = check_typedef (value_type (rhs));
  if (rust_range_type_p (rhstype))
    {
      if (!for_addr)
	error (_("Can't take slice of array without '&'"));
      rust_compute_range (rhstype, rhs, &low, &high, &kind);
      want_slice = 1;
    }
  else
    low = value_as_long (rhs);

  struct type *type = check_typedef (value_type (lhs));
  if (noside == EVAL_AVOID_SIDE_EFFECTS)
    {
      struct type *base_type = nullptr;
      if (type->code () == TYPE_CODE_ARRAY)
	base_type = TYPE_TARGET_TYPE (type);
      else if (rust_slice_type_p (type))
	{
	  for (int i = 0; i < TYPE_NFIELDS (type); ++i)
	    {
	      if (strcmp (TYPE_FIELD_NAME (type, i), "data_ptr") == 0)
		{
		  base_type = TYPE_TARGET_TYPE (TYPE_FIELD_TYPE (type, i));
		  break;
		}
	    }
	  if (base_type == nullptr)
	    error (_("Could not find 'data_ptr' in slice type"));
	}
      else if (type->code () == TYPE_CODE_PTR)
	base_type = TYPE_TARGET_TYPE (type);
      else
	error (_("Cannot subscript non-array type"));

      struct type *new_type;
      if (want_slice)
	{
	  if (rust_slice_type_p (type))
	    new_type = type;
	  else
	    {
	      struct type *usize
		= language_lookup_primitive_type (exp->language_defn,
						  exp->gdbarch,
						  "usize");
	      new_type = rust_slice_type ("&[*gdb*]", base_type, usize);
	    }
	}
      else
	new_type = base_type;

      return value_zero (new_type, VALUE_LVAL (lhs));
    }
  else
    {
      LONGEST low_bound;
      struct value *base;

      if (type->code () == TYPE_CODE_ARRAY)
	{
	  base = lhs;
	  if (!get_array_bounds (type, &low_bound, &high_bound))
	    error (_("Can't compute array bounds"));
	  if (low_bound != 0)
	    error (_("Found array with non-zero lower bound"));
	  ++high_bound;
	}
      else if (rust_slice_type_p (type))
	{
	  struct value *len;

	  base = value_struct_elt (&lhs, NULL, "data_ptr", NULL, "slice");
	  len = value_struct_elt (&lhs, NULL, "length", NULL, "slice");
	  low_bound = 0;
	  high_bound = value_as_long (len);
	}
      else if (type->code () == TYPE_CODE_PTR)
	{
	  base = lhs;
	  low_bound = 0;
	  high_bound = LONGEST_MAX;
	}
      else
	error (_("Cannot subscript non-array type"));

      if (want_slice
	  && (kind == BOTH_BOUND_DEFAULT || kind == LOW_BOUND_DEFAULT))
	low = low_bound;
      if (low < 0)
	error (_("Index less than zero"));
      if (low > high_bound)
	error (_("Index greater than length"));

      result = value_subscript (base, low);
    }

  if (for_addr)
    {
      if (want_slice)
	{
	  struct type *usize, *slice;
	  CORE_ADDR addr;
	  struct value *addrval, *tem;

	  if (kind == BOTH_BOUND_DEFAULT || kind == HIGH_BOUND_DEFAULT)
	    high = high_bound;
	  if (high < 0)
	    error (_("High index less than zero"));
	  if (low > high)
	    error (_("Low index greater than high index"));
	  if (high > high_bound)
	    error (_("High index greater than length"));

	  usize = language_lookup_primitive_type (exp->language_defn,
						  exp->gdbarch,
						  "usize");
	  const char *new_name = ((type != nullptr
				   && rust_slice_type_p (type))
				  ? type->name () : "&[*gdb*]");

	  slice = rust_slice_type (new_name, value_type (result), usize);

	  addrval = value_allocate_space_in_inferior (TYPE_LENGTH (slice));
	  addr = value_as_long (addrval);
	  tem = value_at_lazy (slice, addr);

	  value_assign (value_field (tem, 0), value_addr (result));
	  value_assign (value_field (tem, 1),
			value_from_longest (usize, high - low));

	  result = value_at_lazy (slice, addr);
	}
      else
	result = value_addr (result);
    }

  return result;
}

/* evaluate_exp implementation for Rust.  */

static struct value *
rust_evaluate_subexp (struct type *expect_type, struct expression *exp,
		      int *pos, enum noside noside)
{
  struct value *result;

  switch (exp->elts[*pos].opcode)
    {
    case UNOP_IND:
      {
	if (noside != EVAL_NORMAL)
	  result = evaluate_subexp_standard (expect_type, exp, pos, noside);
	else
	  {
	    ++*pos;
	    struct value *value = evaluate_subexp (expect_type, exp, pos,
						   noside);

	    struct value *trait_ptr = rust_get_trait_object_pointer (value);
	    if (trait_ptr != NULL)
	      value = trait_ptr;

	    result = value_ind (value);
	  }
      }
      break;

    case UNOP_COMPLEMENT:
      {
	struct value *value;

	++*pos;
	value = evaluate_subexp (NULL_TYPE, exp, pos, noside);
	if (noside == EVAL_SKIP)
	  {
	    /* Preserving the type is enough.  */
	    return value;
	  }
	if (value_type (value)->code () == TYPE_CODE_BOOL)
	  result = value_from_longest (value_type (value),
				       value_logical_not (value));
	else
	  result = value_complement (value);
      }
      break;

    case BINOP_SUBSCRIPT:
      result = rust_subscript (exp, pos, noside, 0);
      break;

    case OP_FUNCALL:
      result = rust_evaluate_funcall (exp, pos, noside);
      break;

    case OP_AGGREGATE:
      {
	int pc = (*pos)++;
	struct type *type = exp->elts[pc + 1].type;
	int arglen = longest_to_int (exp->elts[pc + 2].longconst);
	int i;
	CORE_ADDR addr = 0;
	struct value *addrval = NULL;

	*pos += 3;

	if (noside == EVAL_NORMAL)
	  {
	    addrval = value_allocate_space_in_inferior (TYPE_LENGTH (type));
	    addr = value_as_long (addrval);
	    result = value_at_lazy (type, addr);
	  }

	if (arglen > 0 && exp->elts[*pos].opcode == OP_OTHERS)
	  {
	    struct value *init;

	    ++*pos;
	    init = rust_evaluate_subexp (NULL, exp, pos, noside);
	    if (noside == EVAL_NORMAL)
	      {
		/* This isn't quite right but will do for the time
		   being, seeing that we can't implement the Copy
		   trait anyway.  */
		value_assign (result, init);
	      }

	    --arglen;
	  }

	gdb_assert (arglen % 2 == 0);
	for (i = 0; i < arglen; i += 2)
	  {
	    int len;
	    const char *fieldname;
	    struct value *value, *field;

	    gdb_assert (exp->elts[*pos].opcode == OP_NAME);
	    ++*pos;
	    len = longest_to_int (exp->elts[*pos].longconst);
	    ++*pos;
	    fieldname = &exp->elts[*pos].string;
	    *pos += 2 + BYTES_TO_EXP_ELEM (len + 1);

	    value = rust_evaluate_subexp (NULL, exp, pos, noside);
	    if (noside == EVAL_NORMAL)
	      {
		field = value_struct_elt (&result, NULL, fieldname, NULL,
					  "structure");
		value_assign (field, value);
	      }
	  }

	if (noside == EVAL_SKIP)
	  return value_from_longest (builtin_type (exp->gdbarch)->builtin_int,
				     1);
	else if (noside == EVAL_AVOID_SIDE_EFFECTS)
	  result = allocate_value (type);
	else
	  result = value_at_lazy (type, addr);
      }
      break;

    case OP_RUST_ARRAY:
      {
	(*pos)++;
	int copies;
	struct value *elt;
	struct value *ncopies;

	elt = rust_evaluate_subexp (NULL, exp, pos, noside);
	ncopies = rust_evaluate_subexp (NULL, exp, pos, noside);
	copies = value_as_long (ncopies);
	if (copies < 0)
	  error (_("Array with negative number of elements"));

	if (noside == EVAL_NORMAL)
	  {
	    int i;
	    std::vector<struct value *> eltvec (copies);

	    for (i = 0; i < copies; ++i)
	      eltvec[i] = elt;
	    result = value_array (0, copies - 1, eltvec.data ());
	  }
	else
	  {
	    struct type *arraytype
	      = lookup_array_range_type (value_type (elt), 0, copies - 1);
	    result = allocate_value (arraytype);
	  }
      }
      break;

    case STRUCTOP_ANONYMOUS:
      {
        /* Anonymous field access, i.e. foo.1.  */
        struct value *lhs;
        int pc, field_number, nfields;
        struct type *type;

        pc = (*pos)++;
        field_number = longest_to_int (exp->elts[pc + 1].longconst);
        (*pos) += 2;
        lhs = evaluate_subexp (NULL_TYPE, exp, pos, noside);

        type = value_type (lhs);

	if (type->code () == TYPE_CODE_STRUCT)
	  {
	    struct type *outer_type = NULL;

	    if (rust_enum_p (type))
	      {
		gdb::array_view<const gdb_byte> view (value_contents (lhs),
						      TYPE_LENGTH (type));
		type = resolve_dynamic_type (type, view, value_address (lhs));

		if (rust_empty_enum_p (type))
		  error (_("Cannot access field %d of empty enum %s"),
			 field_number, type->name ());

		int fieldno = rust_enum_variant (type);
		lhs = value_primitive_field (lhs, 0, fieldno, type);
		outer_type = type;
		type = value_type (lhs);
	      }

	    /* Tuples and tuple structs */
	    nfields = TYPE_NFIELDS (type);

	    if (field_number >= nfields || field_number < 0)
	      {
		if (outer_type != NULL)
		  error(_("Cannot access field %d of variant %s::%s, "
			  "there are only %d fields"),
			field_number, outer_type->name (),
			rust_last_path_segment (type->name ()),
			nfields);
		else
		  error(_("Cannot access field %d of %s, "
			  "there are only %d fields"),
			field_number, type->name (), nfields);
	      }

	    /* Tuples are tuple structs too.  */
	    if (!rust_tuple_struct_type_p (type))
	      {
		if (outer_type != NULL)
		  error(_("Variant %s::%s is not a tuple variant"),
			outer_type->name (),
			rust_last_path_segment (type->name ()));
		else
		  error(_("Attempting to access anonymous field %d "
			  "of %s, which is not a tuple, tuple struct, or "
			  "tuple-like variant"),
		      field_number, type->name ());
	      }

	    result = value_primitive_field (lhs, 0, field_number, type);
	  }
	else
	  error(_("Anonymous field access is only allowed on tuples, \
tuple structs, and tuple-like enum variants"));
      }
      break;

    case STRUCTOP_STRUCT:
      {
        struct value *lhs;
        struct type *type;
        int tem, pc;

        pc = (*pos)++;
        tem = longest_to_int (exp->elts[pc + 1].longconst);
        (*pos) += 3 + BYTES_TO_EXP_ELEM (tem + 1);
        lhs = evaluate_subexp (NULL_TYPE, exp, pos, noside);

	const char *field_name = &exp->elts[pc + 2].string;
        type = value_type (lhs);
        if (type->code () == TYPE_CODE_STRUCT && rust_enum_p (type))
	  {
	    gdb::array_view<const gdb_byte> view (value_contents (lhs),
						  TYPE_LENGTH (type));
	    type = resolve_dynamic_type (type, view, value_address (lhs));

	    if (rust_empty_enum_p (type))
	      error (_("Cannot access field %s of empty enum %s"),
		     field_name, type->name ());

	    int fieldno = rust_enum_variant (type);
	    lhs = value_primitive_field (lhs, 0, fieldno, type);

	    struct type *outer_type = type;
	    type = value_type (lhs);
	    if (rust_tuple_type_p (type) || rust_tuple_struct_type_p (type))
		error (_("Attempting to access named field %s of tuple "
			 "variant %s::%s, which has only anonymous fields"),
		       field_name, outer_type->name (),
		       rust_last_path_segment (type->name ()));

	    try
	      {
		result = value_struct_elt (&lhs, NULL, field_name,
					   NULL, "structure");
	      }
	    catch (const gdb_exception_error &except)
	      {
		error (_("Could not find field %s of struct variant %s::%s"),
		       field_name, outer_type->name (),
		       rust_last_path_segment (type->name ()));
	      }
	  }
	else
	  result = value_struct_elt (&lhs, NULL, field_name, NULL, "structure");
	if (noside == EVAL_AVOID_SIDE_EFFECTS)
	  result = value_zero (value_type (result), VALUE_LVAL (result));
      }
      break;

    case OP_RANGE:
      result = rust_range (exp, pos, noside);
      break;

    case UNOP_ADDR:
      /* We might have &array[range], in which case we need to make a
	 slice.  */
      if (exp->elts[*pos + 1].opcode == BINOP_SUBSCRIPT)
	{
	  ++*pos;
	  result = rust_subscript (exp, pos, noside, 1);
	  break;
	}
      /* Fall through.  */
    default:
      result = evaluate_subexp_standard (expect_type, exp, pos, noside);
      break;
    }

  return result;
}

/* operator_length implementation for Rust.  */

static void
rust_operator_length (const struct expression *exp, int pc, int *oplenp,
		      int *argsp)
{
  int oplen = 1;
  int args = 0;

  switch (exp->elts[pc - 1].opcode)
    {
    case OP_AGGREGATE:
      /* We handle aggregate as a type and argument count.  The first
	 argument might be OP_OTHERS.  After that the arguments
	 alternate: first an OP_NAME, then an expression.  */
      oplen = 4;
      args = longest_to_int (exp->elts[pc - 2].longconst);
      break;

    case OP_OTHERS:
      oplen = 1;
      args = 1;
      break;

    case STRUCTOP_ANONYMOUS:
      oplen = 3;
      args = 1;
      break;

    case OP_RUST_ARRAY:
      oplen = 1;
      args = 2;
      break;

    default:
      operator_length_standard (exp, pc, oplenp, argsp);
      return;
    }

  *oplenp = oplen;
  *argsp = args;
}

/* op_name implementation for Rust.  */

static const char *
rust_op_name (enum exp_opcode opcode)
{
  switch (opcode)
    {
    case OP_AGGREGATE:
      return "OP_AGGREGATE";
    case OP_OTHERS:
      return "OP_OTHERS";
    default:
      return op_name_standard (opcode);
    }
}

/* dump_subexp_body implementation for Rust.  */

static int
rust_dump_subexp_body (struct expression *exp, struct ui_file *stream,
		       int elt)
{
  switch (exp->elts[elt].opcode)
    {
    case OP_AGGREGATE:
      {
	int length = longest_to_int (exp->elts[elt + 2].longconst);
	int i;

	fprintf_filtered (stream, "Type @");
	gdb_print_host_address (exp->elts[elt + 1].type, stream);
	fprintf_filtered (stream, " (");
	type_print (exp->elts[elt + 1].type, NULL, stream, 0);
	fprintf_filtered (stream, "), length %d", length);

	elt += 4;
	for (i = 0; i < length; ++i)
	  elt = dump_subexp (exp, stream, elt);
      }
      break;

    case OP_STRING:
    case OP_NAME:
      {
	LONGEST len = exp->elts[elt + 1].longconst;

	fprintf_filtered (stream, "%s: %s",
			  (exp->elts[elt].opcode == OP_STRING
			   ? "string" : "name"),
			  &exp->elts[elt + 2].string);
	elt += 4 + BYTES_TO_EXP_ELEM (len + 1);
      }
      break;

    case OP_OTHERS:
      elt = dump_subexp (exp, stream, elt + 1);
      break;

    case STRUCTOP_ANONYMOUS:
      {
	int field_number;

	field_number = longest_to_int (exp->elts[elt + 1].longconst);

	fprintf_filtered (stream, "Field number: %d", field_number);
	elt = dump_subexp (exp, stream, elt + 3);
      }
      break;

    case OP_RUST_ARRAY:
      ++elt;
      break;

    default:
      elt = dump_subexp_body_standard (exp, stream, elt);
      break;
    }

  return elt;
}

/* print_subexp implementation for Rust.  */

static void
rust_print_subexp (struct expression *exp, int *pos, struct ui_file *stream,
		   enum precedence prec)
{
  switch (exp->elts[*pos].opcode)
    {
    case OP_AGGREGATE:
      {
	int length = longest_to_int (exp->elts[*pos + 2].longconst);
	int i;

	type_print (exp->elts[*pos + 1].type, "", stream, 0);
	fputs_filtered (" { ", stream);

	*pos += 4;
	for (i = 0; i < length; ++i)
	  {
	    rust_print_subexp (exp, pos, stream, prec);
	    fputs_filtered (", ", stream);
	  }
	fputs_filtered (" }", stream);
      }
      break;

    case OP_NAME:
      {
	LONGEST len = exp->elts[*pos + 1].longconst;

	fputs_filtered (&exp->elts[*pos + 2].string, stream);
	*pos += 4 + BYTES_TO_EXP_ELEM (len + 1);
      }
      break;

    case OP_OTHERS:
      {
	fputs_filtered ("<<others>> (", stream);
	++*pos;
	rust_print_subexp (exp, pos, stream, prec);
	fputs_filtered (")", stream);
      }
      break;

    case STRUCTOP_ANONYMOUS:
      {
	int tem = longest_to_int (exp->elts[*pos + 1].longconst);

	(*pos) += 3;
	print_subexp (exp, pos, stream, PREC_SUFFIX);
	fprintf_filtered (stream, ".%d", tem);
      }
      break;

    case OP_RUST_ARRAY:
      ++*pos;
      fprintf_filtered (stream, "[");
      rust_print_subexp (exp, pos, stream, prec);
      fprintf_filtered (stream, "; ");
      rust_print_subexp (exp, pos, stream, prec);
      fprintf_filtered (stream, "]");
      break;

    default:
      print_subexp_standard (exp, pos, stream, prec);
      break;
    }
}

/* operator_check implementation for Rust.  */

static int
rust_operator_check (struct expression *exp, int pos,
		     int (*objfile_func) (struct objfile *objfile,
					  void *data),
		     void *data)
{
  switch (exp->elts[pos].opcode)
    {
    case OP_AGGREGATE:
      {
	struct type *type = exp->elts[pos + 1].type;
	struct objfile *objfile = TYPE_OBJFILE (type);

	if (objfile != NULL && (*objfile_func) (objfile, data))
	  return 1;
      }
      break;

    case OP_OTHERS:
    case OP_NAME:
    case OP_RUST_ARRAY:
      break;

    default:
      return operator_check_standard (exp, pos, objfile_func, data);
    }

  return 0;
}



/* Implementation of la_lookup_symbol_nonlocal for Rust.  */

static struct block_symbol
rust_lookup_symbol_nonlocal (const struct language_defn *langdef,
			     const char *name,
			     const struct block *block,
			     const domain_enum domain)
{
  struct block_symbol result = {};

  if (symbol_lookup_debug)
    {
      fprintf_unfiltered (gdb_stdlog,
			  "rust_lookup_symbol_non_local"
			  " (%s, %s (scope %s), %s)\n",
			  name, host_address_to_string (block),
			  block_scope (block), domain_name (domain));
    }

  /* Look up bare names in the block's scope.  */
  std::string scopedname;
  if (name[cp_find_first_component (name)] == '\0')
    {
      const char *scope = block_scope (block);

      if (scope[0] != '\0')
	{
	  scopedname = std::string (scope) + "::" + name;
	  name = scopedname.c_str ();
	}
      else
	name = NULL;
    }

  if (name != NULL)
    {
      result = lookup_symbol_in_static_block (name, block, domain);
      if (result.symbol == NULL)
	result = lookup_global_symbol (name, block, domain);
    }
  return result;
}



/* la_sniff_from_mangled_name for Rust.  */

static int
rust_sniff_from_mangled_name (const char *mangled, char **demangled)
{
  *demangled = gdb_demangle (mangled, DMGL_PARAMS | DMGL_ANSI);
  return *demangled != NULL;
}



/* la_watch_location_expression for Rust.  */

static gdb::unique_xmalloc_ptr<char>
rust_watch_location_expression (struct type *type, CORE_ADDR addr)
{
  type = check_typedef (TYPE_TARGET_TYPE (check_typedef (type)));
  std::string name = type_to_string (type);
  return gdb::unique_xmalloc_ptr<char>
    (xstrprintf ("*(%s as *mut %s)", core_addr_to_string (addr),
		 name.c_str ()));
}



static const struct exp_descriptor exp_descriptor_rust = 
{
  rust_print_subexp,
  rust_operator_length,
  rust_operator_check,
  rust_op_name,
  rust_dump_subexp_body,
  rust_evaluate_subexp
};

static const char *rust_extensions[] =
{
  ".rs", NULL
};

extern const struct language_defn rust_language_defn =
{
  "rust",
  "Rust",
  language_rust,
  range_check_on,
  case_sensitive_on,
  array_row_major,
  macro_expansion_no,
  rust_extensions,
  &exp_descriptor_rust,
  rust_parse,
  null_post_parser,
  rust_printchar,		/* Print a character constant */
  rust_printstr,		/* Function to print string constant */
  rust_emitchar,		/* Print a single char */
  rust_print_type,		/* Print a type using appropriate syntax */
  rust_print_typedef,		/* Print a typedef using appropriate syntax */
  rust_value_print_inner,	/* la_value_print_inner */
  c_value_print,		/* Print a top-level value */
  default_read_var_value,	/* la_read_var_value */
  NULL,				/* Language specific skip_trampoline */
  NULL,				/* name_of_this */
  false,			/* la_store_sym_names_in_linkage_form_p */
  rust_lookup_symbol_nonlocal,	/* lookup_symbol_nonlocal */
  basic_lookup_transparent_type,/* lookup_transparent_type */
  gdb_demangle,			/* Language specific symbol demangler */
  rust_sniff_from_mangled_name,
  NULL,				/* Language specific
				   class_name_from_physname */
  c_op_print_tab,		/* expression operators for printing */
  1,				/* c-style arrays */
  0,				/* String lower bound */
  default_word_break_characters,
  default_collect_symbol_completion_matches,
  rust_language_arch_info,
  default_print_array_index,
  default_pass_by_reference,
  rust_watch_location_expression,
  NULL,				/* la_get_symbol_name_matcher */
  iterate_over_symbols,
  default_search_name_hash,
  &default_varobj_ops,
  NULL,
  NULL,
  rust_is_string_type_p,
  "{...}"			/* la_struct_too_deep_ellipsis */
};