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
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
use rustc_arena::TypedArena;
use rustc_ast::CRATE_NODE_ID;
use rustc_data_structures::fx::FxHashSet;
use rustc_data_structures::fx::FxIndexMap;
use rustc_data_structures::memmap::Mmap;
use rustc_data_structures::temp_dir::MaybeTempDir;
use rustc_errors::{ErrorGuaranteed, Handler};
use rustc_fs_util::{fix_windows_verbatim_for_gcc, try_canonicalize};
use rustc_hir::def_id::{CrateNum, LOCAL_CRATE};
use rustc_metadata::find_native_static_library;
use rustc_metadata::fs::{copy_to_stdout, emit_wrapper_file, METADATA_FILENAME};
use rustc_middle::middle::debugger_visualizer::DebuggerVisualizerFile;
use rustc_middle::middle::dependency_format::Linkage;
use rustc_middle::middle::exported_symbols::SymbolExportKind;
use rustc_session::config::{self, CFGuard, CrateType, DebugInfo, OutFileName, Strip};
use rustc_session::config::{OutputFilenames, OutputType, PrintKind, SplitDwarfKind};
use rustc_session::cstore::DllImport;
use rustc_session::output::{check_file_is_writeable, invalid_output_for_target, out_filename};
use rustc_session::search_paths::PathKind;
use rustc_session::utils::NativeLibKind;
/// For all the linkers we support, and information they might
/// need out of the shared crate context before we get rid of it.
use rustc_session::{filesearch, Session};
use rustc_span::symbol::Symbol;
use rustc_target::spec::crt_objects::{CrtObjects, LinkSelfContainedDefault};
use rustc_target::spec::{Cc, LinkOutputKind, LinkerFlavor, Lld, PanicStrategy};
use rustc_target::spec::{RelocModel, RelroLevel, SanitizerSet, SplitDebuginfo};

use super::archive::{ArchiveBuilder, ArchiveBuilderBuilder};
use super::command::Command;
use super::linker::{self, Linker};
use super::metadata::{create_wrapper_file, MetadataPosition};
use super::rpath::{self, RPathConfig};
use crate::{
    errors, looks_like_rust_object_file, CodegenResults, CompiledModule, CrateInfo, NativeLib,
};

use cc::windows_registry;
use regex::Regex;
use tempfile::Builder as TempFileBuilder;

use itertools::Itertools;
use std::cell::OnceCell;
use std::collections::BTreeSet;
use std::ffi::OsString;
use std::fs::{read, File, OpenOptions};
use std::io::{BufWriter, Write};
use std::ops::Deref;
use std::path::{Path, PathBuf};
use std::process::{ExitStatus, Output, Stdio};
use std::{env, fmt, fs, io, mem, str};

pub fn ensure_removed(diag_handler: &Handler, path: &Path) {
    if let Err(e) = fs::remove_file(path) {
        if e.kind() != io::ErrorKind::NotFound {
            diag_handler.err(format!("failed to remove {}: {}", path.display(), e));
        }
    }
}

/// Performs the linkage portion of the compilation phase. This will generate all
/// of the requested outputs for this compilation session.
pub fn link_binary<'a>(
    sess: &'a Session,
    archive_builder_builder: &dyn ArchiveBuilderBuilder,
    codegen_results: &CodegenResults,
    outputs: &OutputFilenames,
) -> Result<(), ErrorGuaranteed> {
    let _timer = sess.timer("link_binary");
    let output_metadata = sess.opts.output_types.contains_key(&OutputType::Metadata);
    let mut tempfiles_for_stdout_output: Vec<PathBuf> = Vec::new();
    for &crate_type in &codegen_results.crate_info.crate_types {
        // Ignore executable crates if we have -Z no-codegen, as they will error.
        if (sess.opts.unstable_opts.no_codegen || !sess.opts.output_types.should_codegen())
            && !output_metadata
            && crate_type == CrateType::Executable
        {
            continue;
        }

        if invalid_output_for_target(sess, crate_type) {
            bug!(
                "invalid output type `{:?}` for target os `{}`",
                crate_type,
                sess.opts.target_triple
            );
        }

        sess.time("link_binary_check_files_are_writeable", || {
            for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) {
                check_file_is_writeable(obj, sess);
            }
        });

        if outputs.outputs.should_link() {
            let tmpdir = TempFileBuilder::new()
                .prefix("rustc")
                .tempdir()
                .unwrap_or_else(|error| sess.emit_fatal(errors::CreateTempDir { error }));
            let path = MaybeTempDir::new(tmpdir, sess.opts.cg.save_temps);
            let output = out_filename(
                sess,
                crate_type,
                outputs,
                codegen_results.crate_info.local_crate_name,
            );
            let crate_name = format!("{}", codegen_results.crate_info.local_crate_name);
            let out_filename =
                output.file_for_writing(outputs, OutputType::Exe, Some(crate_name.as_str()));
            match crate_type {
                CrateType::Rlib => {
                    let _timer = sess.timer("link_rlib");
                    info!("preparing rlib to {:?}", out_filename);
                    link_rlib(
                        sess,
                        archive_builder_builder,
                        codegen_results,
                        RlibFlavor::Normal,
                        &path,
                    )?
                    .build(&out_filename);
                }
                CrateType::Staticlib => {
                    link_staticlib(
                        sess,
                        archive_builder_builder,
                        codegen_results,
                        &out_filename,
                        &path,
                    )?;
                }
                _ => {
                    link_natively(
                        sess,
                        archive_builder_builder,
                        crate_type,
                        &out_filename,
                        codegen_results,
                        path.as_ref(),
                    )?;
                }
            }
            if sess.opts.json_artifact_notifications {
                sess.parse_sess.span_diagnostic.emit_artifact_notification(&out_filename, "link");
            }

            if sess.prof.enabled() {
                if let Some(artifact_name) = out_filename.file_name() {
                    // Record size for self-profiling
                    let file_size = std::fs::metadata(&out_filename).map(|m| m.len()).unwrap_or(0);

                    sess.prof.artifact_size(
                        "linked_artifact",
                        artifact_name.to_string_lossy(),
                        file_size,
                    );
                }
            }

            if output.is_stdout() {
                if output.is_tty() {
                    sess.emit_err(errors::BinaryOutputToTty {
                        shorthand: OutputType::Exe.shorthand(),
                    });
                } else if let Err(e) = copy_to_stdout(&out_filename) {
                    sess.emit_err(errors::CopyPath::new(&out_filename, output.as_path(), e));
                }
                tempfiles_for_stdout_output.push(out_filename);
            }
        }
    }

    // Remove the temporary object file and metadata if we aren't saving temps.
    sess.time("link_binary_remove_temps", || {
        // If the user requests that temporaries are saved, don't delete any.
        if sess.opts.cg.save_temps {
            return;
        }

        let maybe_remove_temps_from_module =
            |preserve_objects: bool, preserve_dwarf_objects: bool, module: &CompiledModule| {
                if !preserve_objects {
                    if let Some(ref obj) = module.object {
                        ensure_removed(sess.diagnostic(), obj);
                    }
                }

                if !preserve_dwarf_objects {
                    if let Some(ref dwo_obj) = module.dwarf_object {
                        ensure_removed(sess.diagnostic(), dwo_obj);
                    }
                }
            };

        let remove_temps_from_module =
            |module: &CompiledModule| maybe_remove_temps_from_module(false, false, module);

        // Otherwise, always remove the metadata and allocator module temporaries.
        if let Some(ref metadata_module) = codegen_results.metadata_module {
            remove_temps_from_module(metadata_module);
        }

        if let Some(ref allocator_module) = codegen_results.allocator_module {
            remove_temps_from_module(allocator_module);
        }

        // Remove the temporary files if output goes to stdout
        for temp in tempfiles_for_stdout_output {
            ensure_removed(sess.diagnostic(), &temp);
        }

        // If no requested outputs require linking, then the object temporaries should
        // be kept.
        if !sess.opts.output_types.should_link() {
            return;
        }

        // Potentially keep objects for their debuginfo.
        let (preserve_objects, preserve_dwarf_objects) = preserve_objects_for_their_debuginfo(sess);
        debug!(?preserve_objects, ?preserve_dwarf_objects);

        for module in &codegen_results.modules {
            maybe_remove_temps_from_module(preserve_objects, preserve_dwarf_objects, module);
        }
    });

    Ok(())
}

// Crate type is not passed when calculating the dylibs to include for LTO. In that case all
// crate types must use the same dependency formats.
pub fn each_linked_rlib(
    info: &CrateInfo,
    crate_type: Option<CrateType>,
    f: &mut dyn FnMut(CrateNum, &Path),
) -> Result<(), errors::LinkRlibError> {
    let crates = info.used_crates.iter();

    let fmts = if crate_type.is_none() {
        for combination in info.dependency_formats.iter().combinations(2) {
            let (ty1, list1) = &combination[0];
            let (ty2, list2) = &combination[1];
            if list1 != list2 {
                return Err(errors::LinkRlibError::IncompatibleDependencyFormats {
                    ty1: format!("{ty1:?}"),
                    ty2: format!("{ty2:?}"),
                    list1: format!("{list1:?}"),
                    list2: format!("{list2:?}"),
                });
            }
        }
        if info.dependency_formats.is_empty() {
            return Err(errors::LinkRlibError::MissingFormat);
        }
        &info.dependency_formats[0].1
    } else {
        let fmts = info
            .dependency_formats
            .iter()
            .find_map(|&(ty, ref list)| if Some(ty) == crate_type { Some(list) } else { None });

        let Some(fmts) = fmts else {
            return Err(errors::LinkRlibError::MissingFormat);
        };

        fmts
    };

    for &cnum in crates {
        match fmts.get(cnum.as_usize() - 1) {
            Some(&Linkage::NotLinked | &Linkage::Dynamic | &Linkage::IncludedFromDylib) => continue,
            Some(_) => {}
            None => return Err(errors::LinkRlibError::MissingFormat),
        }
        let crate_name = info.crate_name[&cnum];
        let used_crate_source = &info.used_crate_source[&cnum];
        if let Some((path, _)) = &used_crate_source.rlib {
            f(cnum, &path);
        } else {
            if used_crate_source.rmeta.is_some() {
                return Err(errors::LinkRlibError::OnlyRmetaFound { crate_name });
            } else {
                return Err(errors::LinkRlibError::NotFound { crate_name });
            }
        }
    }
    Ok(())
}

/// Create an 'rlib'.
///
/// An rlib in its current incarnation is essentially a renamed .a file (with "dummy" object files).
/// The rlib primarily contains the object file of the crate, but it also some of the object files
/// from native libraries.
fn link_rlib<'a>(
    sess: &'a Session,
    archive_builder_builder: &dyn ArchiveBuilderBuilder,
    codegen_results: &CodegenResults,
    flavor: RlibFlavor,
    tmpdir: &MaybeTempDir,
) -> Result<Box<dyn ArchiveBuilder<'a> + 'a>, ErrorGuaranteed> {
    let lib_search_paths = archive_search_paths(sess);

    let mut ab = archive_builder_builder.new_archive_builder(sess);

    let trailing_metadata = match flavor {
        RlibFlavor::Normal => {
            let (metadata, metadata_position) =
                create_wrapper_file(sess, b".rmeta".to_vec(), codegen_results.metadata.raw_data());
            let metadata = emit_wrapper_file(sess, &metadata, tmpdir, METADATA_FILENAME);
            match metadata_position {
                MetadataPosition::First => {
                    // Most of the time metadata in rlib files is wrapped in a "dummy" object
                    // file for the target platform so the rlib can be processed entirely by
                    // normal linkers for the platform. Sometimes this is not possible however.
                    // If it is possible however, placing the metadata object first improves
                    // performance of getting metadata from rlibs.
                    ab.add_file(&metadata);
                    None
                }
                MetadataPosition::Last => Some(metadata),
            }
        }

        RlibFlavor::StaticlibBase => None,
    };

    for m in &codegen_results.modules {
        if let Some(obj) = m.object.as_ref() {
            ab.add_file(obj);
        }

        if let Some(dwarf_obj) = m.dwarf_object.as_ref() {
            ab.add_file(dwarf_obj);
        }
    }

    match flavor {
        RlibFlavor::Normal => {}
        RlibFlavor::StaticlibBase => {
            let obj = codegen_results.allocator_module.as_ref().and_then(|m| m.object.as_ref());
            if let Some(obj) = obj {
                ab.add_file(obj);
            }
        }
    }

    // Used if packed_bundled_libs flag enabled.
    let mut packed_bundled_libs = Vec::new();

    // Note that in this loop we are ignoring the value of `lib.cfg`. That is,
    // we may not be configured to actually include a static library if we're
    // adding it here. That's because later when we consume this rlib we'll
    // decide whether we actually needed the static library or not.
    //
    // To do this "correctly" we'd need to keep track of which libraries added
    // which object files to the archive. We don't do that here, however. The
    // #[link(cfg(..))] feature is unstable, though, and only intended to get
    // liblibc working. In that sense the check below just indicates that if
    // there are any libraries we want to omit object files for at link time we
    // just exclude all custom object files.
    //
    // Eventually if we want to stabilize or flesh out the #[link(cfg(..))]
    // feature then we'll need to figure out how to record what objects were
    // loaded from the libraries found here and then encode that into the
    // metadata of the rlib we're generating somehow.
    for lib in codegen_results.crate_info.used_libraries.iter() {
        let NativeLibKind::Static { bundle: None | Some(true), .. } = lib.kind else {
            continue;
        };
        if flavor == RlibFlavor::Normal && let Some(filename) = lib.filename {
            let path = find_native_static_library(filename.as_str(), true, &lib_search_paths, sess);
            let src = read(path).map_err(|e| sess.emit_fatal(errors::ReadFileError {message: e }))?;
            let (data, _) = create_wrapper_file(sess, b".bundled_lib".to_vec(), &src);
            let wrapper_file = emit_wrapper_file(sess, &data, tmpdir, filename.as_str());
            packed_bundled_libs.push(wrapper_file);
        } else {
            let path =
                find_native_static_library(lib.name.as_str(), lib.verbatim, &lib_search_paths, sess);
            ab.add_archive(&path, Box::new(|_| false)).unwrap_or_else(|error| {
                sess.emit_fatal(errors::AddNativeLibrary { library_path: path, error })});
        }
    }

    for (raw_dylib_name, raw_dylib_imports) in
        collate_raw_dylibs(sess, codegen_results.crate_info.used_libraries.iter())?
    {
        let output_path = archive_builder_builder.create_dll_import_lib(
            sess,
            &raw_dylib_name,
            &raw_dylib_imports,
            tmpdir.as_ref(),
            true,
        );

        ab.add_archive(&output_path, Box::new(|_| false)).unwrap_or_else(|error| {
            sess.emit_fatal(errors::AddNativeLibrary { library_path: output_path, error });
        });
    }

    if let Some(trailing_metadata) = trailing_metadata {
        // Note that it is important that we add all of our non-object "magical
        // files" *after* all of the object files in the archive. The reason for
        // this is as follows:
        //
        // * When performing LTO, this archive will be modified to remove
        //   objects from above. The reason for this is described below.
        //
        // * When the system linker looks at an archive, it will attempt to
        //   determine the architecture of the archive in order to see whether its
        //   linkable.
        //
        //   The algorithm for this detection is: iterate over the files in the
        //   archive. Skip magical SYMDEF names. Interpret the first file as an
        //   object file. Read architecture from the object file.
        //
        // * As one can probably see, if "metadata" and "foo.bc" were placed
        //   before all of the objects, then the architecture of this archive would
        //   not be correctly inferred once 'foo.o' is removed.
        //
        // * Most of the time metadata in rlib files is wrapped in a "dummy" object
        //   file for the target platform so the rlib can be processed entirely by
        //   normal linkers for the platform. Sometimes this is not possible however.
        //
        // Basically, all this means is that this code should not move above the
        // code above.
        ab.add_file(&trailing_metadata);
    }

    // Add all bundled static native library dependencies.
    // Archives added to the end of .rlib archive, see comment above for the reason.
    for lib in packed_bundled_libs {
        ab.add_file(&lib)
    }

    return Ok(ab);
}

/// Extract all symbols defined in raw-dylib libraries, collated by library name.
///
/// If we have multiple extern blocks that specify symbols defined in the same raw-dylib library,
/// then the CodegenResults value contains one NativeLib instance for each block. However, the
/// linker appears to expect only a single import library for each library used, so we need to
/// collate the symbols together by library name before generating the import libraries.
fn collate_raw_dylibs<'a, 'b>(
    sess: &'a Session,
    used_libraries: impl IntoIterator<Item = &'b NativeLib>,
) -> Result<Vec<(String, Vec<DllImport>)>, ErrorGuaranteed> {
    // Use index maps to preserve original order of imports and libraries.
    let mut dylib_table = FxIndexMap::<String, FxIndexMap<Symbol, &DllImport>>::default();

    for lib in used_libraries {
        if lib.kind == NativeLibKind::RawDylib {
            let ext = if lib.verbatim { "" } else { ".dll" };
            let name = format!("{}{}", lib.name, ext);
            let imports = dylib_table.entry(name.clone()).or_default();
            for import in &lib.dll_imports {
                if let Some(old_import) = imports.insert(import.name, import) {
                    // FIXME: when we add support for ordinals, figure out if we need to do anything
                    // if we have two DllImport values with the same name but different ordinals.
                    if import.calling_convention != old_import.calling_convention {
                        sess.emit_err(errors::MultipleExternalFuncDecl {
                            span: import.span,
                            function: import.name,
                            library_name: &name,
                        });
                    }
                }
            }
        }
    }
    sess.compile_status()?;
    Ok(dylib_table
        .into_iter()
        .map(|(name, imports)| {
            (name, imports.into_iter().map(|(_, import)| import.clone()).collect())
        })
        .collect())
}

/// Create a static archive.
///
/// This is essentially the same thing as an rlib, but it also involves adding all of the upstream
/// crates' objects into the archive. This will slurp in all of the native libraries of upstream
/// dependencies as well.
///
/// Additionally, there's no way for us to link dynamic libraries, so we warn about all dynamic
/// library dependencies that they're not linked in.
///
/// There's no need to include metadata in a static archive, so ensure to not link in the metadata
/// object file (and also don't prepare the archive with a metadata file).
fn link_staticlib<'a>(
    sess: &'a Session,
    archive_builder_builder: &dyn ArchiveBuilderBuilder,
    codegen_results: &CodegenResults,
    out_filename: &Path,
    tempdir: &MaybeTempDir,
) -> Result<(), ErrorGuaranteed> {
    info!("preparing staticlib to {:?}", out_filename);
    let mut ab = link_rlib(
        sess,
        archive_builder_builder,
        codegen_results,
        RlibFlavor::StaticlibBase,
        tempdir,
    )?;
    let mut all_native_libs = vec![];

    let res = each_linked_rlib(
        &codegen_results.crate_info,
        Some(CrateType::Staticlib),
        &mut |cnum, path| {
            let lto = are_upstream_rust_objects_already_included(sess)
                && !ignored_for_lto(sess, &codegen_results.crate_info, cnum);

            let native_libs = codegen_results.crate_info.native_libraries[&cnum].iter();
            let relevant = native_libs.clone().filter(|lib| relevant_lib(sess, &lib));
            let relevant_libs: FxHashSet<_> = relevant.filter_map(|lib| lib.filename).collect();

            let bundled_libs: FxHashSet<_> = native_libs.filter_map(|lib| lib.filename).collect();
            ab.add_archive(
                path,
                Box::new(move |fname: &str| {
                    // Ignore metadata files, no matter the name.
                    if fname == METADATA_FILENAME {
                        return true;
                    }

                    // Don't include Rust objects if LTO is enabled
                    if lto && looks_like_rust_object_file(fname) {
                        return true;
                    }

                    // Skip objects for bundled libs.
                    if bundled_libs.contains(&Symbol::intern(fname)) {
                        return true;
                    }

                    false
                }),
            )
            .unwrap();

            archive_builder_builder
                .extract_bundled_libs(path, tempdir.as_ref(), &relevant_libs)
                .unwrap_or_else(|e| sess.emit_fatal(e));
            for filename in relevant_libs {
                let joined = tempdir.as_ref().join(filename.as_str());
                let path = joined.as_path();
                ab.add_archive(path, Box::new(|_| false)).unwrap();
            }

            all_native_libs
                .extend(codegen_results.crate_info.native_libraries[&cnum].iter().cloned());
        },
    );
    if let Err(e) = res {
        sess.emit_fatal(e);
    }

    ab.build(out_filename);

    let crates = codegen_results.crate_info.used_crates.iter();

    let fmts = codegen_results
        .crate_info
        .dependency_formats
        .iter()
        .find_map(|&(ty, ref list)| if ty == CrateType::Staticlib { Some(list) } else { None })
        .expect("no dependency formats for staticlib");

    let mut all_rust_dylibs = vec![];
    for &cnum in crates {
        match fmts.get(cnum.as_usize() - 1) {
            Some(&Linkage::Dynamic) => {}
            _ => continue,
        }
        let crate_name = codegen_results.crate_info.crate_name[&cnum];
        let used_crate_source = &codegen_results.crate_info.used_crate_source[&cnum];
        if let Some((path, _)) = &used_crate_source.dylib {
            all_rust_dylibs.push(&**path);
        } else {
            if used_crate_source.rmeta.is_some() {
                sess.emit_fatal(errors::LinkRlibError::OnlyRmetaFound { crate_name });
            } else {
                sess.emit_fatal(errors::LinkRlibError::NotFound { crate_name });
            }
        }
    }

    all_native_libs.extend_from_slice(&codegen_results.crate_info.used_libraries);

    for print in &sess.opts.prints {
        if print.kind == PrintKind::NativeStaticLibs {
            print_native_static_libs(sess, &print.out, &all_native_libs, &all_rust_dylibs);
        }
    }

    Ok(())
}

/// Use `thorin` (rust implementation of a dwarf packaging utility) to link DWARF objects into a
/// DWARF package.
fn link_dwarf_object<'a>(
    sess: &'a Session,
    cg_results: &CodegenResults,
    executable_out_filename: &Path,
) {
    let mut dwp_out_filename = executable_out_filename.to_path_buf().into_os_string();
    dwp_out_filename.push(".dwp");
    debug!(?dwp_out_filename, ?executable_out_filename);

    #[derive(Default)]
    struct ThorinSession<Relocations> {
        arena_data: TypedArena<Vec<u8>>,
        arena_mmap: TypedArena<Mmap>,
        arena_relocations: TypedArena<Relocations>,
    }

    impl<Relocations> ThorinSession<Relocations> {
        fn alloc_mmap(&self, data: Mmap) -> &Mmap {
            &*self.arena_mmap.alloc(data)
        }
    }

    impl<Relocations> thorin::Session<Relocations> for ThorinSession<Relocations> {
        fn alloc_data(&self, data: Vec<u8>) -> &[u8] {
            &*self.arena_data.alloc(data)
        }

        fn alloc_relocation(&self, data: Relocations) -> &Relocations {
            &*self.arena_relocations.alloc(data)
        }

        fn read_input(&self, path: &Path) -> std::io::Result<&[u8]> {
            let file = File::open(&path)?;
            let mmap = (unsafe { Mmap::map(file) })?;
            Ok(self.alloc_mmap(mmap))
        }
    }

    match sess.time("run_thorin", || -> Result<(), thorin::Error> {
        let thorin_sess = ThorinSession::default();
        let mut package = thorin::DwarfPackage::new(&thorin_sess);

        // Input objs contain .o/.dwo files from the current crate.
        match sess.opts.unstable_opts.split_dwarf_kind {
            SplitDwarfKind::Single => {
                for input_obj in cg_results.modules.iter().filter_map(|m| m.object.as_ref()) {
                    package.add_input_object(input_obj)?;
                }
            }
            SplitDwarfKind::Split => {
                for input_obj in cg_results.modules.iter().filter_map(|m| m.dwarf_object.as_ref()) {
                    package.add_input_object(input_obj)?;
                }
            }
        }

        // Input rlibs contain .o/.dwo files from dependencies.
        let input_rlibs = cg_results
            .crate_info
            .used_crate_source
            .values()
            .filter_map(|csource| csource.rlib.as_ref())
            .map(|(path, _)| path);
        for input_rlib in input_rlibs {
            debug!(?input_rlib);
            package.add_input_object(input_rlib)?;
        }

        // Failing to read the referenced objects is expected for dependencies where the path in the
        // executable will have been cleaned by Cargo, but the referenced objects will be contained
        // within rlibs provided as inputs.
        //
        // If paths have been remapped, then .o/.dwo files from the current crate also won't be
        // found, but are provided explicitly above.
        //
        // Adding an executable is primarily done to make `thorin` check that all the referenced
        // dwarf objects are found in the end.
        package.add_executable(
            &executable_out_filename,
            thorin::MissingReferencedObjectBehaviour::Skip,
        )?;

        let output_stream = BufWriter::new(
            OpenOptions::new()
                .read(true)
                .write(true)
                .create(true)
                .truncate(true)
                .open(dwp_out_filename)?,
        );
        let mut output_stream = object::write::StreamingBuffer::new(output_stream);
        package.finish()?.emit(&mut output_stream)?;
        output_stream.result()?;
        output_stream.into_inner().flush()?;

        Ok(())
    }) {
        Ok(()) => {}
        Err(e) => {
            sess.emit_err(errors::ThorinErrorWrapper(e));
            sess.abort_if_errors();
        }
    }
}

/// Create a dynamic library or executable.
///
/// This will invoke the system linker/cc to create the resulting file. This links to all upstream
/// files as well.
fn link_natively<'a>(
    sess: &'a Session,
    archive_builder_builder: &dyn ArchiveBuilderBuilder,
    crate_type: CrateType,
    out_filename: &Path,
    codegen_results: &CodegenResults,
    tmpdir: &Path,
) -> Result<(), ErrorGuaranteed> {
    info!("preparing {:?} to {:?}", crate_type, out_filename);
    let (linker_path, flavor) = linker_and_flavor(sess);
    let mut cmd = linker_with_args(
        &linker_path,
        flavor,
        sess,
        archive_builder_builder,
        crate_type,
        tmpdir,
        out_filename,
        codegen_results,
    )?;

    linker::disable_localization(&mut cmd);

    for (k, v) in sess.target.link_env.as_ref() {
        cmd.env(k.as_ref(), v.as_ref());
    }
    for k in sess.target.link_env_remove.as_ref() {
        cmd.env_remove(k.as_ref());
    }

    for print in &sess.opts.prints {
        if print.kind == PrintKind::LinkArgs {
            let content = format!("{cmd:?}");
            print.out.overwrite(&content, sess);
        }
    }

    // May have not found libraries in the right formats.
    sess.abort_if_errors();

    // Invoke the system linker
    info!("{:?}", &cmd);
    let retry_on_segfault = env::var("RUSTC_RETRY_LINKER_ON_SEGFAULT").is_ok();
    let unknown_arg_regex =
        Regex::new(r"(unknown|unrecognized) (command line )?(option|argument)").unwrap();
    let mut prog;
    let mut i = 0;
    loop {
        i += 1;
        prog = sess.time("run_linker", || exec_linker(sess, &cmd, out_filename, tmpdir));
        let Ok(ref output) = prog else {
            break;
        };
        if output.status.success() {
            break;
        }
        let mut out = output.stderr.clone();
        out.extend(&output.stdout);
        let out = String::from_utf8_lossy(&out);

        // Check to see if the link failed with an error message that indicates it
        // doesn't recognize the -no-pie option. If so, re-perform the link step
        // without it. This is safe because if the linker doesn't support -no-pie
        // then it should not default to linking executables as pie. Different
        // versions of gcc seem to use different quotes in the error message so
        // don't check for them.
        if matches!(flavor, LinkerFlavor::Gnu(Cc::Yes, _))
            && unknown_arg_regex.is_match(&out)
            && out.contains("-no-pie")
            && cmd.get_args().iter().any(|e| e.to_string_lossy() == "-no-pie")
        {
            info!("linker output: {:?}", out);
            warn!("Linker does not support -no-pie command line option. Retrying without.");
            for arg in cmd.take_args() {
                if arg.to_string_lossy() != "-no-pie" {
                    cmd.arg(arg);
                }
            }
            info!("{:?}", &cmd);
            continue;
        }

        // Detect '-static-pie' used with an older version of gcc or clang not supporting it.
        // Fallback from '-static-pie' to '-static' in that case.
        if matches!(flavor, LinkerFlavor::Gnu(Cc::Yes, _))
            && unknown_arg_regex.is_match(&out)
            && (out.contains("-static-pie") || out.contains("--no-dynamic-linker"))
            && cmd.get_args().iter().any(|e| e.to_string_lossy() == "-static-pie")
        {
            info!("linker output: {:?}", out);
            warn!(
                "Linker does not support -static-pie command line option. Retrying with -static instead."
            );
            // Mirror `add_(pre,post)_link_objects` to replace CRT objects.
            let self_contained = self_contained(sess, crate_type);
            let opts = &sess.target;
            let pre_objects = if self_contained {
                &opts.pre_link_objects_self_contained
            } else {
                &opts.pre_link_objects
            };
            let post_objects = if self_contained {
                &opts.post_link_objects_self_contained
            } else {
                &opts.post_link_objects
            };
            let get_objects = |objects: &CrtObjects, kind| {
                objects
                    .get(&kind)
                    .iter()
                    .copied()
                    .flatten()
                    .map(|obj| get_object_file_path(sess, obj, self_contained).into_os_string())
                    .collect::<Vec<_>>()
            };
            let pre_objects_static_pie = get_objects(pre_objects, LinkOutputKind::StaticPicExe);
            let post_objects_static_pie = get_objects(post_objects, LinkOutputKind::StaticPicExe);
            let mut pre_objects_static = get_objects(pre_objects, LinkOutputKind::StaticNoPicExe);
            let mut post_objects_static = get_objects(post_objects, LinkOutputKind::StaticNoPicExe);
            // Assume that we know insertion positions for the replacement arguments from replaced
            // arguments, which is true for all supported targets.
            assert!(pre_objects_static.is_empty() || !pre_objects_static_pie.is_empty());
            assert!(post_objects_static.is_empty() || !post_objects_static_pie.is_empty());
            for arg in cmd.take_args() {
                if arg.to_string_lossy() == "-static-pie" {
                    // Replace the output kind.
                    cmd.arg("-static");
                } else if pre_objects_static_pie.contains(&arg) {
                    // Replace the pre-link objects (replace the first and remove the rest).
                    cmd.args(mem::take(&mut pre_objects_static));
                } else if post_objects_static_pie.contains(&arg) {
                    // Replace the post-link objects (replace the first and remove the rest).
                    cmd.args(mem::take(&mut post_objects_static));
                } else {
                    cmd.arg(arg);
                }
            }
            info!("{:?}", &cmd);
            continue;
        }

        // Here's a terribly awful hack that really shouldn't be present in any
        // compiler. Here an environment variable is supported to automatically
        // retry the linker invocation if the linker looks like it segfaulted.
        //
        // Gee that seems odd, normally segfaults are things we want to know
        // about!  Unfortunately though in rust-lang/rust#38878 we're
        // experiencing the linker segfaulting on Travis quite a bit which is
        // causing quite a bit of pain to land PRs when they spuriously fail
        // due to a segfault.
        //
        // The issue #38878 has some more debugging information on it as well,
        // but this unfortunately looks like it's just a race condition in
        // macOS's linker with some thread pool working in the background. It
        // seems that no one currently knows a fix for this so in the meantime
        // we're left with this...
        if !retry_on_segfault || i > 3 {
            break;
        }
        let msg_segv = "clang: error: unable to execute command: Segmentation fault: 11";
        let msg_bus = "clang: error: unable to execute command: Bus error: 10";
        if out.contains(msg_segv) || out.contains(msg_bus) {
            warn!(
                ?cmd, %out,
                "looks like the linker segfaulted when we tried to call it, \
                 automatically retrying again",
            );
            continue;
        }

        if is_illegal_instruction(&output.status) {
            warn!(
                ?cmd, %out, status = %output.status,
                "looks like the linker hit an illegal instruction when we \
                 tried to call it, automatically retrying again.",
            );
            continue;
        }

        #[cfg(unix)]
        fn is_illegal_instruction(status: &ExitStatus) -> bool {
            use std::os::unix::prelude::*;
            status.signal() == Some(libc::SIGILL)
        }

        #[cfg(not(unix))]
        fn is_illegal_instruction(_status: &ExitStatus) -> bool {
            false
        }
    }

    match prog {
        Ok(prog) => {
            if !prog.status.success() {
                let mut output = prog.stderr.clone();
                output.extend_from_slice(&prog.stdout);
                let escaped_output = escape_linker_output(&output, flavor);
                // FIXME: Add UI tests for this error.
                let err = errors::LinkingFailed {
                    linker_path: &linker_path,
                    exit_status: prog.status,
                    command: &cmd,
                    escaped_output,
                };
                sess.diagnostic().emit_err(err);
                // If MSVC's `link.exe` was expected but the return code
                // is not a Microsoft LNK error then suggest a way to fix or
                // install the Visual Studio build tools.
                if let Some(code) = prog.status.code() {
                    if sess.target.is_like_msvc
                        && flavor == LinkerFlavor::Msvc(Lld::No)
                        // Respect the command line override
                        && sess.opts.cg.linker.is_none()
                        // Match exactly "link.exe"
                        && linker_path.to_str() == Some("link.exe")
                        // All Microsoft `link.exe` linking error codes are
                        // four digit numbers in the range 1000 to 9999 inclusive
                        && (code < 1000 || code > 9999)
                    {
                        let is_vs_installed = windows_registry::find_vs_version().is_ok();
                        let has_linker = windows_registry::find_tool(
                            &sess.opts.target_triple.triple(),
                            "link.exe",
                        )
                        .is_some();

                        sess.emit_note(errors::LinkExeUnexpectedError);
                        if is_vs_installed && has_linker {
                            // the linker is broken
                            sess.emit_note(errors::RepairVSBuildTools);
                            sess.emit_note(errors::MissingCppBuildToolComponent);
                        } else if is_vs_installed {
                            // the linker is not installed
                            sess.emit_note(errors::SelectCppBuildToolWorkload);
                        } else {
                            // visual studio is not installed
                            sess.emit_note(errors::VisualStudioNotInstalled);
                        }
                    }
                }

                sess.abort_if_errors();
            }
            info!("linker stderr:\n{}", escape_string(&prog.stderr));
            info!("linker stdout:\n{}", escape_string(&prog.stdout));
        }
        Err(e) => {
            let linker_not_found = e.kind() == io::ErrorKind::NotFound;

            if linker_not_found {
                sess.emit_err(errors::LinkerNotFound { linker_path, error: e });
            } else {
                sess.emit_err(errors::UnableToExeLinker {
                    linker_path,
                    error: e,
                    command_formatted: format!("{:?}", &cmd),
                });
            }

            if sess.target.is_like_msvc && linker_not_found {
                sess.emit_note(errors::MsvcMissingLinker);
                sess.emit_note(errors::CheckInstalledVisualStudio);
                sess.emit_note(errors::InsufficientVSCodeProduct);
            }
            sess.abort_if_errors();
        }
    }

    match sess.split_debuginfo() {
        // If split debug information is disabled or located in individual files
        // there's nothing to do here.
        SplitDebuginfo::Off | SplitDebuginfo::Unpacked => {}

        // If packed split-debuginfo is requested, but the final compilation
        // doesn't actually have any debug information, then we skip this step.
        SplitDebuginfo::Packed if sess.opts.debuginfo == DebugInfo::None => {}

        // On macOS the external `dsymutil` tool is used to create the packed
        // debug information. Note that this will read debug information from
        // the objects on the filesystem which we'll clean up later.
        SplitDebuginfo::Packed if sess.target.is_like_osx => {
            let prog = Command::new("dsymutil").arg(out_filename).output();
            match prog {
                Ok(prog) => {
                    if !prog.status.success() {
                        let mut output = prog.stderr.clone();
                        output.extend_from_slice(&prog.stdout);
                        sess.emit_warning(errors::ProcessingDymutilFailed {
                            status: prog.status,
                            output: escape_string(&output),
                        });
                    }
                }
                Err(error) => sess.emit_fatal(errors::UnableToRunDsymutil { error }),
            }
        }

        // On MSVC packed debug information is produced by the linker itself so
        // there's no need to do anything else here.
        SplitDebuginfo::Packed if sess.target.is_like_windows => {}

        // ... and otherwise we're processing a `*.dwp` packed dwarf file.
        //
        // We cannot rely on the .o paths in the executable because they may have been
        // remapped by --remap-path-prefix and therefore invalid, so we need to provide
        // the .o/.dwo paths explicitly.
        SplitDebuginfo::Packed => link_dwarf_object(sess, codegen_results, out_filename),
    }

    let strip = strip_value(sess);

    if sess.target.is_like_osx {
        match (strip, crate_type) {
            (Strip::Debuginfo, _) => {
                strip_symbols_with_external_utility(sess, "strip", &out_filename, Some("-S"))
            }
            // Per the manpage, `-x` is the maximum safe strip level for dynamic libraries. (#93988)
            (Strip::Symbols, CrateType::Dylib | CrateType::Cdylib | CrateType::ProcMacro) => {
                strip_symbols_with_external_utility(sess, "strip", &out_filename, Some("-x"))
            }
            (Strip::Symbols, _) => {
                strip_symbols_with_external_utility(sess, "strip", &out_filename, None)
            }
            (Strip::None, _) => {}
        }
    }

    if sess.target.os == "illumos" {
        // Many illumos systems will have both the native 'strip' utility and
        // the GNU one. Use the native version explicitly and do not rely on
        // what's in the path.
        let stripcmd = "/usr/bin/strip";
        match strip {
            // Always preserve the symbol table (-x).
            Strip::Debuginfo => {
                strip_symbols_with_external_utility(sess, stripcmd, &out_filename, Some("-x"))
            }
            // Strip::Symbols is handled via the --strip-all linker option.
            Strip::Symbols => {}
            Strip::None => {}
        }
    }

    Ok(())
}

// Temporarily support both -Z strip and -C strip
fn strip_value(sess: &Session) -> Strip {
    match (sess.opts.unstable_opts.strip, sess.opts.cg.strip) {
        (s, Strip::None) => s,
        (_, s) => s,
    }
}

fn strip_symbols_with_external_utility<'a>(
    sess: &'a Session,
    util: &str,
    out_filename: &Path,
    option: Option<&str>,
) {
    let mut cmd = Command::new(util);
    if let Some(option) = option {
        cmd.arg(option);
    }
    let prog = cmd.arg(out_filename).output();
    match prog {
        Ok(prog) => {
            if !prog.status.success() {
                let mut output = prog.stderr.clone();
                output.extend_from_slice(&prog.stdout);
                sess.emit_warning(errors::StrippingDebugInfoFailed {
                    util,
                    status: prog.status,
                    output: escape_string(&output),
                });
            }
        }
        Err(error) => sess.emit_fatal(errors::UnableToRun { util, error }),
    }
}

fn escape_string(s: &[u8]) -> String {
    match str::from_utf8(s) {
        Ok(s) => s.to_owned(),
        Err(_) => format!("Non-UTF-8 output: {}", s.escape_ascii()),
    }
}

#[cfg(not(windows))]
fn escape_linker_output(s: &[u8], _flavour: LinkerFlavor) -> String {
    escape_string(s)
}

/// If the output of the msvc linker is not UTF-8 and the host is Windows,
/// then try to convert the string from the OEM encoding.
#[cfg(windows)]
fn escape_linker_output(s: &[u8], flavour: LinkerFlavor) -> String {
    // This only applies to the actual MSVC linker.
    if flavour != LinkerFlavor::Msvc(Lld::No) {
        return escape_string(s);
    }
    match str::from_utf8(s) {
        Ok(s) => return s.to_owned(),
        Err(_) => match win::locale_byte_str_to_string(s, win::oem_code_page()) {
            Some(s) => s,
            // The string is not UTF-8 and isn't valid for the OEM code page
            None => format!("Non-UTF-8 output: {}", s.escape_ascii()),
        },
    }
}

/// Wrappers around the Windows API.
#[cfg(windows)]
mod win {
    use windows::Win32::Globalization::{
        GetLocaleInfoEx, MultiByteToWideChar, CP_OEMCP, LOCALE_IUSEUTF8LEGACYOEMCP,
        LOCALE_NAME_SYSTEM_DEFAULT, LOCALE_RETURN_NUMBER, MB_ERR_INVALID_CHARS,
    };

    /// Get the Windows system OEM code page. This is most notably the code page
    /// used for link.exe's output.
    pub fn oem_code_page() -> u32 {
        unsafe {
            let mut cp: u32 = 0;
            // We're using the `LOCALE_RETURN_NUMBER` flag to return a u32.
            // But the API requires us to pass the data as though it's a [u16] string.
            let len = std::mem::size_of::<u32>() / std::mem::size_of::<u16>();
            let data = std::slice::from_raw_parts_mut(&mut cp as *mut u32 as *mut u16, len);
            let len_written = GetLocaleInfoEx(
                LOCALE_NAME_SYSTEM_DEFAULT,
                LOCALE_IUSEUTF8LEGACYOEMCP | LOCALE_RETURN_NUMBER,
                Some(data),
            );
            if len_written as usize == len { cp } else { CP_OEMCP }
        }
    }
    /// Try to convert a multi-byte string to a UTF-8 string using the given code page
    /// The string does not need to be null terminated.
    ///
    /// This is implemented as a wrapper around `MultiByteToWideChar`.
    /// See <https://learn.microsoft.com/en-us/windows/win32/api/stringapiset/nf-stringapiset-multibytetowidechar>
    ///
    /// It will fail if the multi-byte string is longer than `i32::MAX` or if it contains
    /// any invalid bytes for the expected encoding.
    pub fn locale_byte_str_to_string(s: &[u8], code_page: u32) -> Option<String> {
        // `MultiByteToWideChar` requires a length to be a "positive integer".
        if s.len() > isize::MAX as usize {
            return None;
        }
        // Error if the string is not valid for the expected code page.
        let flags = MB_ERR_INVALID_CHARS;
        // Call MultiByteToWideChar twice.
        // First to calculate the length then to convert the string.
        let mut len = unsafe { MultiByteToWideChar(code_page, flags, s, None) };
        if len > 0 {
            let mut utf16 = vec![0; len as usize];
            len = unsafe { MultiByteToWideChar(code_page, flags, s, Some(&mut utf16)) };
            if len > 0 {
                return utf16.get(..len as usize).map(String::from_utf16_lossy);
            }
        }
        None
    }
}

fn add_sanitizer_libraries(sess: &Session, crate_type: CrateType, linker: &mut dyn Linker) {
    // On macOS the runtimes are distributed as dylibs which should be linked to
    // both executables and dynamic shared objects. Everywhere else the runtimes
    // are currently distributed as static libraries which should be linked to
    // executables only.
    let needs_runtime = !sess.target.is_like_android
        && match crate_type {
            CrateType::Executable => true,
            CrateType::Dylib | CrateType::Cdylib | CrateType::ProcMacro => sess.target.is_like_osx,
            CrateType::Rlib | CrateType::Staticlib => false,
        };

    if !needs_runtime {
        return;
    }

    let sanitizer = sess.opts.unstable_opts.sanitizer;
    if sanitizer.contains(SanitizerSet::ADDRESS) {
        link_sanitizer_runtime(sess, linker, "asan");
    }
    if sanitizer.contains(SanitizerSet::LEAK) {
        link_sanitizer_runtime(sess, linker, "lsan");
    }
    if sanitizer.contains(SanitizerSet::MEMORY) {
        link_sanitizer_runtime(sess, linker, "msan");
    }
    if sanitizer.contains(SanitizerSet::THREAD) {
        link_sanitizer_runtime(sess, linker, "tsan");
    }
    if sanitizer.contains(SanitizerSet::HWADDRESS) {
        link_sanitizer_runtime(sess, linker, "hwasan");
    }
    if sanitizer.contains(SanitizerSet::SAFESTACK) {
        link_sanitizer_runtime(sess, linker, "safestack");
    }
}

fn link_sanitizer_runtime(sess: &Session, linker: &mut dyn Linker, name: &str) {
    fn find_sanitizer_runtime(sess: &Session, filename: &str) -> PathBuf {
        let session_tlib =
            filesearch::make_target_lib_path(&sess.sysroot, sess.opts.target_triple.triple());
        let path = session_tlib.join(filename);
        if path.exists() {
            return session_tlib;
        } else {
            let default_sysroot =
                filesearch::get_or_default_sysroot().expect("Failed finding sysroot");
            let default_tlib = filesearch::make_target_lib_path(
                &default_sysroot,
                sess.opts.target_triple.triple(),
            );
            return default_tlib;
        }
    }

    let channel =
        option_env!("CFG_RELEASE_CHANNEL").map(|channel| format!("-{channel}")).unwrap_or_default();

    if sess.target.is_like_osx {
        // On Apple platforms, the sanitizer is always built as a dylib, and
        // LLVM will link to `@rpath/*.dylib`, so we need to specify an
        // rpath to the library as well (the rpath should be absolute, see
        // PR #41352 for details).
        let filename = format!("rustc{channel}_rt.{name}");
        let path = find_sanitizer_runtime(&sess, &filename);
        let rpath = path.to_str().expect("non-utf8 component in path");
        linker.args(&["-Wl,-rpath", "-Xlinker", rpath]);
        linker.link_dylib(&filename, false, true);
    } else {
        let filename = format!("librustc{channel}_rt.{name}.a");
        let path = find_sanitizer_runtime(&sess, &filename).join(&filename);
        linker.link_whole_rlib(&path);
    }
}

/// Returns a boolean indicating whether the specified crate should be ignored
/// during LTO.
///
/// Crates ignored during LTO are not lumped together in the "massive object
/// file" that we create and are linked in their normal rlib states. See
/// comments below for what crates do not participate in LTO.
///
/// It's unusual for a crate to not participate in LTO. Typically only
/// compiler-specific and unstable crates have a reason to not participate in
/// LTO.
pub fn ignored_for_lto(sess: &Session, info: &CrateInfo, cnum: CrateNum) -> bool {
    // If our target enables builtin function lowering in LLVM then the
    // crates providing these functions don't participate in LTO (e.g.
    // no_builtins or compiler builtins crates).
    !sess.target.no_builtins
        && (info.compiler_builtins == Some(cnum) || info.is_no_builtins.contains(&cnum))
}

/// This functions tries to determine the appropriate linker (and corresponding LinkerFlavor) to use
pub fn linker_and_flavor(sess: &Session) -> (PathBuf, LinkerFlavor) {
    fn infer_from(
        sess: &Session,
        linker: Option<PathBuf>,
        flavor: Option<LinkerFlavor>,
    ) -> Option<(PathBuf, LinkerFlavor)> {
        match (linker, flavor) {
            (Some(linker), Some(flavor)) => Some((linker, flavor)),
            // only the linker flavor is known; use the default linker for the selected flavor
            (None, Some(flavor)) => Some((
                PathBuf::from(match flavor {
                    LinkerFlavor::Gnu(Cc::Yes, _)
                    | LinkerFlavor::Darwin(Cc::Yes, _)
                    | LinkerFlavor::WasmLld(Cc::Yes)
                    | LinkerFlavor::Unix(Cc::Yes) => {
                        if cfg!(any(target_os = "solaris", target_os = "illumos")) {
                            // On historical Solaris systems, "cc" may have
                            // been Sun Studio, which is not flag-compatible
                            // with "gcc". This history casts a long shadow,
                            // and many modern illumos distributions today
                            // ship GCC as "gcc" without also making it
                            // available as "cc".
                            "gcc"
                        } else {
                            "cc"
                        }
                    }
                    LinkerFlavor::Gnu(_, Lld::Yes)
                    | LinkerFlavor::Darwin(_, Lld::Yes)
                    | LinkerFlavor::WasmLld(..)
                    | LinkerFlavor::Msvc(Lld::Yes) => "lld",
                    LinkerFlavor::Gnu(..) | LinkerFlavor::Darwin(..) | LinkerFlavor::Unix(..) => {
                        "ld"
                    }
                    LinkerFlavor::Msvc(..) => "link.exe",
                    LinkerFlavor::EmCc => {
                        if cfg!(windows) {
                            "emcc.bat"
                        } else {
                            "emcc"
                        }
                    }
                    LinkerFlavor::Bpf => "bpf-linker",
                    LinkerFlavor::Ptx => "rust-ptx-linker",
                }),
                flavor,
            )),
            (Some(linker), None) => {
                let stem = linker.file_stem().and_then(|stem| stem.to_str()).unwrap_or_else(|| {
                    sess.emit_fatal(errors::LinkerFileStem);
                });
                let flavor = sess.target.linker_flavor.with_linker_hints(stem);
                Some((linker, flavor))
            }
            (None, None) => None,
        }
    }

    // linker and linker flavor specified via command line have precedence over what the target
    // specification specifies
    let linker_flavor =
        sess.opts.cg.linker_flavor.map(|flavor| sess.target.linker_flavor.with_cli_hints(flavor));
    if let Some(ret) = infer_from(sess, sess.opts.cg.linker.clone(), linker_flavor) {
        return ret;
    }

    if let Some(ret) = infer_from(
        sess,
        sess.target.linker.as_deref().map(PathBuf::from),
        Some(sess.target.linker_flavor),
    ) {
        return ret;
    }

    bug!("Not enough information provided to determine how to invoke the linker");
}

/// Returns a pair of boolean indicating whether we should preserve the object and
/// dwarf object files on the filesystem for their debug information. This is often
/// useful with split-dwarf like schemes.
fn preserve_objects_for_their_debuginfo(sess: &Session) -> (bool, bool) {
    // If the objects don't have debuginfo there's nothing to preserve.
    if sess.opts.debuginfo == config::DebugInfo::None {
        return (false, false);
    }

    match (sess.split_debuginfo(), sess.opts.unstable_opts.split_dwarf_kind) {
        // If there is no split debuginfo then do not preserve objects.
        (SplitDebuginfo::Off, _) => (false, false),
        // If there is packed split debuginfo, then the debuginfo in the objects
        // has been packaged and the objects can be deleted.
        (SplitDebuginfo::Packed, _) => (false, false),
        // If there is unpacked split debuginfo and the current target can not use
        // split dwarf, then keep objects.
        (SplitDebuginfo::Unpacked, _) if !sess.target_can_use_split_dwarf() => (true, false),
        // If there is unpacked split debuginfo and the target can use split dwarf, then
        // keep the object containing that debuginfo (whether that is an object file or
        // dwarf object file depends on the split dwarf kind).
        (SplitDebuginfo::Unpacked, SplitDwarfKind::Single) => (true, false),
        (SplitDebuginfo::Unpacked, SplitDwarfKind::Split) => (false, true),
    }
}

fn archive_search_paths(sess: &Session) -> Vec<PathBuf> {
    sess.target_filesearch(PathKind::Native).search_path_dirs()
}

#[derive(PartialEq)]
enum RlibFlavor {
    Normal,
    StaticlibBase,
}

fn print_native_static_libs(
    sess: &Session,
    out: &OutFileName,
    all_native_libs: &[NativeLib],
    all_rust_dylibs: &[&Path],
) {
    let mut lib_args: Vec<_> = all_native_libs
        .iter()
        .filter(|l| relevant_lib(sess, l))
        // Deduplication of successive repeated libraries, see rust-lang/rust#113209
        //
        // note: we don't use PartialEq/Eq because NativeLib transitively depends on local
        // elements like spans, which we don't care about and would make the deduplication impossible
        .dedup_by(|l1, l2| l1.name == l2.name && l1.kind == l2.kind && l1.verbatim == l2.verbatim)
        .filter_map(|lib| {
            let name = lib.name;
            match lib.kind {
                NativeLibKind::Static { bundle: Some(false), .. }
                | NativeLibKind::Dylib { .. }
                | NativeLibKind::Unspecified => {
                    let verbatim = lib.verbatim;
                    if sess.target.is_like_msvc {
                        Some(format!("{}{}", name, if verbatim { "" } else { ".lib" }))
                    } else if sess.target.linker_flavor.is_gnu() {
                        Some(format!("-l{}{}", if verbatim { ":" } else { "" }, name))
                    } else {
                        Some(format!("-l{name}"))
                    }
                }
                NativeLibKind::Framework { .. } => {
                    // ld-only syntax, since there are no frameworks in MSVC
                    Some(format!("-framework {name}"))
                }
                // These are included, no need to print them
                NativeLibKind::Static { bundle: None | Some(true), .. }
                | NativeLibKind::LinkArg
                | NativeLibKind::WasmImportModule
                | NativeLibKind::RawDylib => None,
            }
        })
        .collect();
    for path in all_rust_dylibs {
        // FIXME deduplicate with add_dynamic_crate

        // Just need to tell the linker about where the library lives and
        // what its name is
        let parent = path.parent();
        if let Some(dir) = parent {
            let dir = fix_windows_verbatim_for_gcc(dir);
            if sess.target.is_like_msvc {
                let mut arg = String::from("/LIBPATH:");
                arg.push_str(&dir.display().to_string());
                lib_args.push(arg);
            } else {
                lib_args.push("-L".to_owned());
                lib_args.push(dir.display().to_string());
            }
        }
        let stem = path.file_stem().unwrap().to_str().unwrap();
        // Convert library file-stem into a cc -l argument.
        let prefix = if stem.starts_with("lib") && !sess.target.is_like_windows { 3 } else { 0 };
        let lib = &stem[prefix..];
        let path = parent.unwrap_or_else(|| Path::new(""));
        if sess.target.is_like_msvc {
            // When producing a dll, the MSVC linker may not actually emit a
            // `foo.lib` file if the dll doesn't actually export any symbols, so we
            // check to see if the file is there and just omit linking to it if it's
            // not present.
            let name = format!("{lib}.dll.lib");
            if path.join(&name).exists() {
                lib_args.push(name);
            }
        } else {
            lib_args.push(format!("-l{lib}"));
        }
    }

    match out {
        OutFileName::Real(path) => {
            out.overwrite(&lib_args.join(" "), sess);
            if !lib_args.is_empty() {
                sess.emit_note(errors::StaticLibraryNativeArtifactsToFile { path });
            }
        }
        OutFileName::Stdout => {
            if !lib_args.is_empty() {
                sess.emit_note(errors::StaticLibraryNativeArtifacts);
                // Prefix for greppability
                // Note: This must not be translated as tools are allowed to depend on this exact string.
                sess.note_without_error(format!("native-static-libs: {}", &lib_args.join(" ")));
            }
        }
    }
}

fn get_object_file_path(sess: &Session, name: &str, self_contained: bool) -> PathBuf {
    let fs = sess.target_filesearch(PathKind::Native);
    let file_path = fs.get_lib_path().join(name);
    if file_path.exists() {
        return file_path;
    }
    // Special directory with objects used only in self-contained linkage mode
    if self_contained {
        let file_path = fs.get_self_contained_lib_path().join(name);
        if file_path.exists() {
            return file_path;
        }
    }
    for search_path in fs.search_paths() {
        let file_path = search_path.dir.join(name);
        if file_path.exists() {
            return file_path;
        }
    }
    PathBuf::from(name)
}

fn exec_linker(
    sess: &Session,
    cmd: &Command,
    out_filename: &Path,
    tmpdir: &Path,
) -> io::Result<Output> {
    // When attempting to spawn the linker we run a risk of blowing out the
    // size limits for spawning a new process with respect to the arguments
    // we pass on the command line.
    //
    // Here we attempt to handle errors from the OS saying "your list of
    // arguments is too big" by reinvoking the linker again with an `@`-file
    // that contains all the arguments. The theory is that this is then
    // accepted on all linkers and the linker will read all its options out of
    // there instead of looking at the command line.
    if !cmd.very_likely_to_exceed_some_spawn_limit() {
        match cmd.command().stdout(Stdio::piped()).stderr(Stdio::piped()).spawn() {
            Ok(child) => {
                let output = child.wait_with_output();
                flush_linked_file(&output, out_filename)?;
                return output;
            }
            Err(ref e) if command_line_too_big(e) => {
                info!("command line to linker was too big: {}", e);
            }
            Err(e) => return Err(e),
        }
    }

    info!("falling back to passing arguments to linker via an @-file");
    let mut cmd2 = cmd.clone();
    let mut args = String::new();
    for arg in cmd2.take_args() {
        args.push_str(
            &Escape { arg: arg.to_str().unwrap(), is_like_msvc: sess.target.is_like_msvc }
                .to_string(),
        );
        args.push('\n');
    }
    let file = tmpdir.join("linker-arguments");
    let bytes = if sess.target.is_like_msvc {
        let mut out = Vec::with_capacity((1 + args.len()) * 2);
        // start the stream with a UTF-16 BOM
        for c in std::iter::once(0xFEFF).chain(args.encode_utf16()) {
            // encode in little endian
            out.push(c as u8);
            out.push((c >> 8) as u8);
        }
        out
    } else {
        args.into_bytes()
    };
    fs::write(&file, &bytes)?;
    cmd2.arg(format!("@{}", file.display()));
    info!("invoking linker {:?}", cmd2);
    let output = cmd2.output();
    flush_linked_file(&output, out_filename)?;
    return output;

    #[cfg(not(windows))]
    fn flush_linked_file(_: &io::Result<Output>, _: &Path) -> io::Result<()> {
        Ok(())
    }

    #[cfg(windows)]
    fn flush_linked_file(
        command_output: &io::Result<Output>,
        out_filename: &Path,
    ) -> io::Result<()> {
        // On Windows, under high I/O load, output buffers are sometimes not flushed,
        // even long after process exit, causing nasty, non-reproducible output bugs.
        //
        // File::sync_all() calls FlushFileBuffers() down the line, which solves the problem.
        //
        // А full writeup of the original Chrome bug can be found at
        // randomascii.wordpress.com/2018/02/25/compiler-bug-linker-bug-windows-kernel-bug/amp

        if let &Ok(ref out) = command_output {
            if out.status.success() {
                if let Ok(of) = fs::OpenOptions::new().write(true).open(out_filename) {
                    of.sync_all()?;
                }
            }
        }

        Ok(())
    }

    #[cfg(unix)]
    fn command_line_too_big(err: &io::Error) -> bool {
        err.raw_os_error() == Some(::libc::E2BIG)
    }

    #[cfg(windows)]
    fn command_line_too_big(err: &io::Error) -> bool {
        const ERROR_FILENAME_EXCED_RANGE: i32 = 206;
        err.raw_os_error() == Some(ERROR_FILENAME_EXCED_RANGE)
    }

    #[cfg(not(any(unix, windows)))]
    fn command_line_too_big(_: &io::Error) -> bool {
        false
    }

    struct Escape<'a> {
        arg: &'a str,
        is_like_msvc: bool,
    }

    impl<'a> fmt::Display for Escape<'a> {
        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
            if self.is_like_msvc {
                // This is "documented" at
                // https://docs.microsoft.com/en-us/cpp/build/reference/at-specify-a-linker-response-file
                //
                // Unfortunately there's not a great specification of the
                // syntax I could find online (at least) but some local
                // testing showed that this seemed sufficient-ish to catch
                // at least a few edge cases.
                write!(f, "\"")?;
                for c in self.arg.chars() {
                    match c {
                        '"' => write!(f, "\\{c}")?,
                        c => write!(f, "{c}")?,
                    }
                }
                write!(f, "\"")?;
            } else {
                // This is documented at https://linux.die.net/man/1/ld, namely:
                //
                // > Options in file are separated by whitespace. A whitespace
                // > character may be included in an option by surrounding the
                // > entire option in either single or double quotes. Any
                // > character (including a backslash) may be included by
                // > prefixing the character to be included with a backslash.
                //
                // We put an argument on each line, so all we need to do is
                // ensure the line is interpreted as one whole argument.
                for c in self.arg.chars() {
                    match c {
                        '\\' | ' ' => write!(f, "\\{c}")?,
                        c => write!(f, "{c}")?,
                    }
                }
            }
            Ok(())
        }
    }
}

fn link_output_kind(sess: &Session, crate_type: CrateType) -> LinkOutputKind {
    let kind = match (crate_type, sess.crt_static(Some(crate_type)), sess.relocation_model()) {
        (CrateType::Executable, _, _) if sess.is_wasi_reactor() => LinkOutputKind::WasiReactorExe,
        (CrateType::Executable, false, RelocModel::Pic | RelocModel::Pie) => {
            LinkOutputKind::DynamicPicExe
        }
        (CrateType::Executable, false, _) => LinkOutputKind::DynamicNoPicExe,
        (CrateType::Executable, true, RelocModel::Pic | RelocModel::Pie) => {
            LinkOutputKind::StaticPicExe
        }
        (CrateType::Executable, true, _) => LinkOutputKind::StaticNoPicExe,
        (_, true, _) => LinkOutputKind::StaticDylib,
        (_, false, _) => LinkOutputKind::DynamicDylib,
    };

    // Adjust the output kind to target capabilities.
    let opts = &sess.target;
    let pic_exe_supported = opts.position_independent_executables;
    let static_pic_exe_supported = opts.static_position_independent_executables;
    let static_dylib_supported = opts.crt_static_allows_dylibs;
    match kind {
        LinkOutputKind::DynamicPicExe if !pic_exe_supported => LinkOutputKind::DynamicNoPicExe,
        LinkOutputKind::StaticPicExe if !static_pic_exe_supported => LinkOutputKind::StaticNoPicExe,
        LinkOutputKind::StaticDylib if !static_dylib_supported => LinkOutputKind::DynamicDylib,
        _ => kind,
    }
}

// Returns true if linker is located within sysroot
fn detect_self_contained_mingw(sess: &Session) -> bool {
    let (linker, _) = linker_and_flavor(&sess);
    // Assume `-C linker=rust-lld` as self-contained mode
    if linker == Path::new("rust-lld") {
        return true;
    }
    let linker_with_extension = if cfg!(windows) && linker.extension().is_none() {
        linker.with_extension("exe")
    } else {
        linker
    };
    for dir in env::split_paths(&env::var_os("PATH").unwrap_or_default()) {
        let full_path = dir.join(&linker_with_extension);
        // If linker comes from sysroot assume self-contained mode
        if full_path.is_file() && !full_path.starts_with(&sess.sysroot) {
            return false;
        }
    }
    true
}

/// Various toolchain components used during linking are used from rustc distribution
/// instead of being found somewhere on the host system.
/// We only provide such support for a very limited number of targets.
fn self_contained(sess: &Session, crate_type: CrateType) -> bool {
    if let Some(self_contained) = sess.opts.cg.link_self_contained.explicitly_set {
        if sess.target.link_self_contained == LinkSelfContainedDefault::False {
            sess.emit_err(errors::UnsupportedLinkSelfContained);
        }
        return self_contained;
    }

    match sess.target.link_self_contained {
        LinkSelfContainedDefault::False => false,
        LinkSelfContainedDefault::True => true,
        // FIXME: Find a better heuristic for "native musl toolchain is available",
        // based on host and linker path, for example.
        // (https://github.com/rust-lang/rust/pull/71769#issuecomment-626330237).
        LinkSelfContainedDefault::Musl => sess.crt_static(Some(crate_type)),
        LinkSelfContainedDefault::Mingw => {
            sess.host == sess.target
                && sess.target.vendor != "uwp"
                && detect_self_contained_mingw(&sess)
        }
    }
}

/// Add pre-link object files defined by the target spec.
fn add_pre_link_objects(
    cmd: &mut dyn Linker,
    sess: &Session,
    flavor: LinkerFlavor,
    link_output_kind: LinkOutputKind,
    self_contained: bool,
) {
    // FIXME: we are currently missing some infra here (per-linker-flavor CRT objects),
    // so Fuchsia has to be special-cased.
    let opts = &sess.target;
    let empty = Default::default();
    let objects = if self_contained {
        &opts.pre_link_objects_self_contained
    } else if !(sess.target.os == "fuchsia" && matches!(flavor, LinkerFlavor::Gnu(Cc::Yes, _))) {
        &opts.pre_link_objects
    } else {
        &empty
    };
    for obj in objects.get(&link_output_kind).iter().copied().flatten() {
        cmd.add_object(&get_object_file_path(sess, obj, self_contained));
    }
}

/// Add post-link object files defined by the target spec.
fn add_post_link_objects(
    cmd: &mut dyn Linker,
    sess: &Session,
    link_output_kind: LinkOutputKind,
    self_contained: bool,
) {
    let objects = if self_contained {
        &sess.target.post_link_objects_self_contained
    } else {
        &sess.target.post_link_objects
    };
    for obj in objects.get(&link_output_kind).iter().copied().flatten() {
        cmd.add_object(&get_object_file_path(sess, obj, self_contained));
    }
}

/// Add arbitrary "pre-link" args defined by the target spec or from command line.
/// FIXME: Determine where exactly these args need to be inserted.
fn add_pre_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
    if let Some(args) = sess.target.pre_link_args.get(&flavor) {
        cmd.args(args.iter().map(Deref::deref));
    }
    cmd.args(&sess.opts.unstable_opts.pre_link_args);
}

/// Add a link script embedded in the target, if applicable.
fn add_link_script(cmd: &mut dyn Linker, sess: &Session, tmpdir: &Path, crate_type: CrateType) {
    match (crate_type, &sess.target.link_script) {
        (CrateType::Cdylib | CrateType::Executable, Some(script)) => {
            if !sess.target.linker_flavor.is_gnu() {
                sess.emit_fatal(errors::LinkScriptUnavailable);
            }

            let file_name = ["rustc", &sess.target.llvm_target, "linkfile.ld"].join("-");

            let path = tmpdir.join(file_name);
            if let Err(error) = fs::write(&path, script.as_ref()) {
                sess.emit_fatal(errors::LinkScriptWriteFailure { path, error });
            }

            cmd.arg("--script");
            cmd.arg(path);
        }
        _ => {}
    }
}

/// Add arbitrary "user defined" args defined from command line.
/// FIXME: Determine where exactly these args need to be inserted.
fn add_user_defined_link_args(cmd: &mut dyn Linker, sess: &Session) {
    cmd.args(&sess.opts.cg.link_args);
}

/// Add arbitrary "late link" args defined by the target spec.
/// FIXME: Determine where exactly these args need to be inserted.
fn add_late_link_args(
    cmd: &mut dyn Linker,
    sess: &Session,
    flavor: LinkerFlavor,
    crate_type: CrateType,
    codegen_results: &CodegenResults,
) {
    let any_dynamic_crate = crate_type == CrateType::Dylib
        || codegen_results.crate_info.dependency_formats.iter().any(|(ty, list)| {
            *ty == crate_type && list.iter().any(|&linkage| linkage == Linkage::Dynamic)
        });
    if any_dynamic_crate {
        if let Some(args) = sess.target.late_link_args_dynamic.get(&flavor) {
            cmd.args(args.iter().map(Deref::deref));
        }
    } else {
        if let Some(args) = sess.target.late_link_args_static.get(&flavor) {
            cmd.args(args.iter().map(Deref::deref));
        }
    }
    if let Some(args) = sess.target.late_link_args.get(&flavor) {
        cmd.args(args.iter().map(Deref::deref));
    }
}

/// Add arbitrary "post-link" args defined by the target spec.
/// FIXME: Determine where exactly these args need to be inserted.
fn add_post_link_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
    if let Some(args) = sess.target.post_link_args.get(&flavor) {
        cmd.args(args.iter().map(Deref::deref));
    }
}

/// Add a synthetic object file that contains reference to all symbols that we want to expose to
/// the linker.
///
/// Background: we implement rlibs as static library (archives). Linkers treat archives
/// differently from object files: all object files participate in linking, while archives will
/// only participate in linking if they can satisfy at least one undefined reference (version
/// scripts doesn't count). This causes `#[no_mangle]` or `#[used]` items to be ignored by the
/// linker, and since they never participate in the linking, using `KEEP` in the linker scripts
/// can't keep them either. This causes #47384.
///
/// To keep them around, we could use `--whole-archive` and equivalents to force rlib to
/// participate in linking like object files, but this proves to be expensive (#93791). Therefore
/// we instead just introduce an undefined reference to them. This could be done by `-u` command
/// line option to the linker or `EXTERN(...)` in linker scripts, however they does not only
/// introduce an undefined reference, but also make them the GC roots, preventing `--gc-sections`
/// from removing them, and this is especially problematic for embedded programming where every
/// byte counts.
///
/// This method creates a synthetic object file, which contains undefined references to all symbols
/// that are necessary for the linking. They are only present in symbol table but not actually
/// used in any sections, so the linker will therefore pick relevant rlibs for linking, but
/// unused `#[no_mangle]` or `#[used]` can still be discard by GC sections.
///
/// There's a few internal crates in the standard library (aka libcore and
/// libstd) which actually have a circular dependence upon one another. This
/// currently arises through "weak lang items" where libcore requires things
/// like `rust_begin_unwind` but libstd ends up defining it. To get this
/// circular dependence to work correctly we declare some of these things
/// in this synthetic object.
fn add_linked_symbol_object(
    cmd: &mut dyn Linker,
    sess: &Session,
    tmpdir: &Path,
    symbols: &[(String, SymbolExportKind)],
) {
    if symbols.is_empty() {
        return;
    }

    let Some(mut file) = super::metadata::create_object_file(sess) else {
        return;
    };

    // NOTE(nbdd0121): MSVC will hang if the input object file contains no sections,
    // so add an empty section.
    if file.format() == object::BinaryFormat::Coff {
        file.add_section(Vec::new(), ".text".into(), object::SectionKind::Text);

        // We handle the name decoration of COFF targets in `symbol_export.rs`, so disable the
        // default mangler in `object` crate.
        file.set_mangling(object::write::Mangling::None);

        // Add feature flags to the object file. On MSVC this is optional but LLD will complain if
        // not present.
        let mut feature = 0;

        if file.architecture() == object::Architecture::I386 {
            // Indicate that all SEH handlers are registered in .sxdata section.
            // We don't have generate any code, so we don't need .sxdata section but LLD still
            // expects us to set this bit (see #96498).
            // Reference: https://docs.microsoft.com/en-us/windows/win32/debug/pe-format
            feature |= 1;
        }

        file.add_symbol(object::write::Symbol {
            name: "@feat.00".into(),
            value: feature,
            size: 0,
            kind: object::SymbolKind::Data,
            scope: object::SymbolScope::Compilation,
            weak: false,
            section: object::write::SymbolSection::Absolute,
            flags: object::SymbolFlags::None,
        });
    }

    for (sym, kind) in symbols.iter() {
        file.add_symbol(object::write::Symbol {
            name: sym.clone().into(),
            value: 0,
            size: 0,
            kind: match kind {
                SymbolExportKind::Text => object::SymbolKind::Text,
                SymbolExportKind::Data => object::SymbolKind::Data,
                SymbolExportKind::Tls => object::SymbolKind::Tls,
            },
            scope: object::SymbolScope::Unknown,
            weak: false,
            section: object::write::SymbolSection::Undefined,
            flags: object::SymbolFlags::None,
        });
    }

    let path = tmpdir.join("symbols.o");
    let result = std::fs::write(&path, file.write().unwrap());
    if let Err(error) = result {
        sess.emit_fatal(errors::FailedToWrite { path, error });
    }
    cmd.add_object(&path);
}

/// Add object files containing code from the current crate.
fn add_local_crate_regular_objects(cmd: &mut dyn Linker, codegen_results: &CodegenResults) {
    for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) {
        cmd.add_object(obj);
    }
}

/// Add object files for allocator code linked once for the whole crate tree.
fn add_local_crate_allocator_objects(cmd: &mut dyn Linker, codegen_results: &CodegenResults) {
    if let Some(obj) = codegen_results.allocator_module.as_ref().and_then(|m| m.object.as_ref()) {
        cmd.add_object(obj);
    }
}

/// Add object files containing metadata for the current crate.
fn add_local_crate_metadata_objects(
    cmd: &mut dyn Linker,
    crate_type: CrateType,
    codegen_results: &CodegenResults,
) {
    // When linking a dynamic library, we put the metadata into a section of the
    // executable. This metadata is in a separate object file from the main
    // object file, so we link that in here.
    if crate_type == CrateType::Dylib || crate_type == CrateType::ProcMacro {
        if let Some(obj) = codegen_results.metadata_module.as_ref().and_then(|m| m.object.as_ref())
        {
            cmd.add_object(obj);
        }
    }
}

/// Add sysroot and other globally set directories to the directory search list.
fn add_library_search_dirs(cmd: &mut dyn Linker, sess: &Session, self_contained: bool) {
    // The default library location, we need this to find the runtime.
    // The location of crates will be determined as needed.
    let lib_path = sess.target_filesearch(PathKind::All).get_lib_path();
    cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));

    // Special directory with libraries used only in self-contained linkage mode
    if self_contained {
        let lib_path = sess.target_filesearch(PathKind::All).get_self_contained_lib_path();
        cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));
    }
}

/// Add options making relocation sections in the produced ELF files read-only
/// and suppressing lazy binding.
fn add_relro_args(cmd: &mut dyn Linker, sess: &Session) {
    match sess.opts.unstable_opts.relro_level.unwrap_or(sess.target.relro_level) {
        RelroLevel::Full => cmd.full_relro(),
        RelroLevel::Partial => cmd.partial_relro(),
        RelroLevel::Off => cmd.no_relro(),
        RelroLevel::None => {}
    }
}

/// Add library search paths used at runtime by dynamic linkers.
fn add_rpath_args(
    cmd: &mut dyn Linker,
    sess: &Session,
    codegen_results: &CodegenResults,
    out_filename: &Path,
) {
    // FIXME (#2397): At some point we want to rpath our guesses as to
    // where extern libraries might live, based on the
    // add_lib_search_paths
    if sess.opts.cg.rpath {
        let libs = codegen_results
            .crate_info
            .used_crates
            .iter()
            .filter_map(|cnum| {
                codegen_results.crate_info.used_crate_source[cnum]
                    .dylib
                    .as_ref()
                    .map(|(path, _)| &**path)
            })
            .collect::<Vec<_>>();
        let mut rpath_config = RPathConfig {
            libs: &*libs,
            out_filename: out_filename.to_path_buf(),
            has_rpath: sess.target.has_rpath,
            is_like_osx: sess.target.is_like_osx,
            linker_is_gnu: sess.target.linker_flavor.is_gnu(),
        };
        cmd.args(&rpath::get_rpath_flags(&mut rpath_config));
    }
}

/// Produce the linker command line containing linker path and arguments.
///
/// When comments in the function say "order-(in)dependent" they mean order-dependence between
/// options and libraries/object files. For example `--whole-archive` (order-dependent) applies
/// to specific libraries passed after it, and `-o` (output file, order-independent) applies
/// to the linking process as a whole.
/// Order-independent options may still override each other in order-dependent fashion,
/// e.g `--foo=yes --foo=no` may be equivalent to `--foo=no`.
fn linker_with_args<'a>(
    path: &Path,
    flavor: LinkerFlavor,
    sess: &'a Session,
    archive_builder_builder: &dyn ArchiveBuilderBuilder,
    crate_type: CrateType,
    tmpdir: &Path,
    out_filename: &Path,
    codegen_results: &CodegenResults,
) -> Result<Command, ErrorGuaranteed> {
    let self_contained = self_contained(sess, crate_type);
    let cmd = &mut *super::linker::get_linker(
        sess,
        path,
        flavor,
        self_contained,
        &codegen_results.crate_info.target_cpu,
    );
    let link_output_kind = link_output_kind(sess, crate_type);

    // ------------ Early order-dependent options ------------

    // If we're building something like a dynamic library then some platforms
    // need to make sure that all symbols are exported correctly from the
    // dynamic library.
    // Must be passed before any libraries to prevent the symbols to export from being thrown away,
    // at least on some platforms (e.g. windows-gnu).
    cmd.export_symbols(
        tmpdir,
        crate_type,
        &codegen_results.crate_info.exported_symbols[&crate_type],
    );

    // Can be used for adding custom CRT objects or overriding order-dependent options above.
    // FIXME: In practice built-in target specs use this for arbitrary order-independent options,
    // introduce a target spec option for order-independent linker options and migrate built-in
    // specs to it.
    add_pre_link_args(cmd, sess, flavor);

    // ------------ Object code and libraries, order-dependent ------------

    // Pre-link CRT objects.
    add_pre_link_objects(cmd, sess, flavor, link_output_kind, self_contained);

    add_linked_symbol_object(
        cmd,
        sess,
        tmpdir,
        &codegen_results.crate_info.linked_symbols[&crate_type],
    );

    // Sanitizer libraries.
    add_sanitizer_libraries(sess, crate_type, cmd);

    // Object code from the current crate.
    // Take careful note of the ordering of the arguments we pass to the linker
    // here. Linkers will assume that things on the left depend on things to the
    // right. Things on the right cannot depend on things on the left. This is
    // all formally implemented in terms of resolving symbols (libs on the right
    // resolve unknown symbols of libs on the left, but not vice versa).
    //
    // For this reason, we have organized the arguments we pass to the linker as
    // such:
    //
    // 1. The local object that LLVM just generated
    // 2. Local native libraries
    // 3. Upstream rust libraries
    // 4. Upstream native libraries
    //
    // The rationale behind this ordering is that those items lower down in the
    // list can't depend on items higher up in the list. For example nothing can
    // depend on what we just generated (e.g., that'd be a circular dependency).
    // Upstream rust libraries are not supposed to depend on our local native
    // libraries as that would violate the structure of the DAG, in that
    // scenario they are required to link to them as well in a shared fashion.
    //
    // Note that upstream rust libraries may contain native dependencies as
    // well, but they also can't depend on what we just started to add to the
    // link line. And finally upstream native libraries can't depend on anything
    // in this DAG so far because they can only depend on other native libraries
    // and such dependencies are also required to be specified.
    add_local_crate_regular_objects(cmd, codegen_results);
    add_local_crate_metadata_objects(cmd, crate_type, codegen_results);
    add_local_crate_allocator_objects(cmd, codegen_results);

    // Avoid linking to dynamic libraries unless they satisfy some undefined symbols
    // at the point at which they are specified on the command line.
    // Must be passed before any (dynamic) libraries to have effect on them.
    // On Solaris-like systems, `-z ignore` acts as both `--as-needed` and `--gc-sections`
    // so it will ignore unreferenced ELF sections from relocatable objects.
    // For that reason, we put this flag after metadata objects as they would otherwise be removed.
    // FIXME: Support more fine-grained dead code removal on Solaris/illumos
    // and move this option back to the top.
    cmd.add_as_needed();

    // Local native libraries of all kinds.
    add_local_native_libraries(
        cmd,
        sess,
        archive_builder_builder,
        codegen_results,
        tmpdir,
        link_output_kind,
    );

    // Upstream rust crates and their non-dynamic native libraries.
    add_upstream_rust_crates(
        cmd,
        sess,
        archive_builder_builder,
        codegen_results,
        crate_type,
        tmpdir,
        link_output_kind,
    );

    // Dynamic native libraries from upstream crates.
    add_upstream_native_libraries(
        cmd,
        sess,
        archive_builder_builder,
        codegen_results,
        tmpdir,
        link_output_kind,
    );

    // Link with the import library generated for any raw-dylib functions.
    for (raw_dylib_name, raw_dylib_imports) in
        collate_raw_dylibs(sess, codegen_results.crate_info.used_libraries.iter())?
    {
        cmd.add_object(&archive_builder_builder.create_dll_import_lib(
            sess,
            &raw_dylib_name,
            &raw_dylib_imports,
            tmpdir,
            true,
        ));
    }
    // As with add_upstream_native_libraries, we need to add the upstream raw-dylib symbols in case
    // they are used within inlined functions or instantiated generic functions. We do this *after*
    // handling the raw-dylib symbols in the current crate to make sure that those are chosen first
    // by the linker.
    let (_, dependency_linkage) = codegen_results
        .crate_info
        .dependency_formats
        .iter()
        .find(|(ty, _)| *ty == crate_type)
        .expect("failed to find crate type in dependency format list");
    let native_libraries_from_nonstatics = codegen_results
        .crate_info
        .native_libraries
        .iter()
        .filter_map(|(cnum, libraries)| {
            (dependency_linkage[cnum.as_usize() - 1] != Linkage::Static).then_some(libraries)
        })
        .flatten();
    for (raw_dylib_name, raw_dylib_imports) in
        collate_raw_dylibs(sess, native_libraries_from_nonstatics)?
    {
        cmd.add_object(&archive_builder_builder.create_dll_import_lib(
            sess,
            &raw_dylib_name,
            &raw_dylib_imports,
            tmpdir,
            false,
        ));
    }

    // Library linking above uses some global state for things like `-Bstatic`/`-Bdynamic` to make
    // command line shorter, reset it to default here before adding more libraries.
    cmd.reset_per_library_state();

    // FIXME: Built-in target specs occasionally use this for linking system libraries,
    // eliminate all such uses by migrating them to `#[link]` attributes in `lib(std,c,unwind)`
    // and remove the option.
    add_late_link_args(cmd, sess, flavor, crate_type, codegen_results);

    // ------------ Arbitrary order-independent options ------------

    // Add order-independent options determined by rustc from its compiler options,
    // target properties and source code.
    add_order_independent_options(
        cmd,
        sess,
        link_output_kind,
        self_contained,
        flavor,
        crate_type,
        codegen_results,
        out_filename,
        tmpdir,
    );

    // Can be used for arbitrary order-independent options.
    // In practice may also be occasionally used for linking native libraries.
    // Passed after compiler-generated options to support manual overriding when necessary.
    add_user_defined_link_args(cmd, sess);

    // ------------ Object code and libraries, order-dependent ------------

    // Post-link CRT objects.
    add_post_link_objects(cmd, sess, link_output_kind, self_contained);

    // ------------ Late order-dependent options ------------

    // Doesn't really make sense.
    // FIXME: In practice built-in target specs use this for arbitrary order-independent options,
    // introduce a target spec option for order-independent linker options, migrate built-in specs
    // to it and remove the option.
    add_post_link_args(cmd, sess, flavor);

    Ok(cmd.take_cmd())
}

fn add_order_independent_options(
    cmd: &mut dyn Linker,
    sess: &Session,
    link_output_kind: LinkOutputKind,
    self_contained: bool,
    flavor: LinkerFlavor,
    crate_type: CrateType,
    codegen_results: &CodegenResults,
    out_filename: &Path,
    tmpdir: &Path,
) {
    // Take care of the flavors and CLI options requesting the `lld` linker.
    add_lld_args(cmd, sess, flavor);

    add_apple_sdk(cmd, sess, flavor);

    add_link_script(cmd, sess, tmpdir, crate_type);

    if sess.target.os == "fuchsia"
        && crate_type == CrateType::Executable
        && !matches!(flavor, LinkerFlavor::Gnu(Cc::Yes, _))
    {
        let prefix = if sess.opts.unstable_opts.sanitizer.contains(SanitizerSet::ADDRESS) {
            "asan/"
        } else {
            ""
        };
        cmd.arg(format!("--dynamic-linker={prefix}ld.so.1"));
    }

    if sess.target.eh_frame_header {
        cmd.add_eh_frame_header();
    }

    // Make the binary compatible with data execution prevention schemes.
    cmd.add_no_exec();

    if self_contained {
        cmd.no_crt_objects();
    }

    if sess.target.os == "emscripten" {
        cmd.arg("-s");
        cmd.arg(if sess.panic_strategy() == PanicStrategy::Abort {
            "DISABLE_EXCEPTION_CATCHING=1"
        } else {
            "DISABLE_EXCEPTION_CATCHING=0"
        });
    }

    if flavor == LinkerFlavor::Ptx {
        // Provide the linker with fallback to internal `target-cpu`.
        cmd.arg("--fallback-arch");
        cmd.arg(&codegen_results.crate_info.target_cpu);
    } else if flavor == LinkerFlavor::Bpf {
        cmd.arg("--cpu");
        cmd.arg(&codegen_results.crate_info.target_cpu);
        if let Some(feat) = [sess.opts.cg.target_feature.as_str(), &sess.target.options.features]
            .into_iter()
            .find(|feat| !feat.is_empty())
        {
            cmd.arg("--cpu-features");
            cmd.arg(feat);
        }
    }

    cmd.linker_plugin_lto();

    add_library_search_dirs(cmd, sess, self_contained);

    cmd.output_filename(out_filename);

    if crate_type == CrateType::Executable && sess.target.is_like_windows {
        if let Some(ref s) = codegen_results.crate_info.windows_subsystem {
            cmd.subsystem(s);
        }
    }

    // Try to strip as much out of the generated object by removing unused
    // sections if possible. See more comments in linker.rs
    if !sess.link_dead_code() {
        // If PGO is enabled sometimes gc_sections will remove the profile data section
        // as it appears to be unused. This can then cause the PGO profile file to lose
        // some functions. If we are generating a profile we shouldn't strip those metadata
        // sections to ensure we have all the data for PGO.
        let keep_metadata =
            crate_type == CrateType::Dylib || sess.opts.cg.profile_generate.enabled();
        if crate_type != CrateType::Executable || !sess.opts.unstable_opts.export_executable_symbols
        {
            cmd.gc_sections(keep_metadata);
        } else {
            cmd.no_gc_sections();
        }
    }

    cmd.set_output_kind(link_output_kind, out_filename);

    add_relro_args(cmd, sess);

    // Pass optimization flags down to the linker.
    cmd.optimize();

    // Gather the set of NatVis files, if any, and write them out to a temp directory.
    let natvis_visualizers = collect_natvis_visualizers(
        tmpdir,
        sess,
        &codegen_results.crate_info.local_crate_name,
        &codegen_results.crate_info.natvis_debugger_visualizers,
    );

    // Pass debuginfo, NatVis debugger visualizers and strip flags down to the linker.
    cmd.debuginfo(strip_value(sess), &natvis_visualizers);

    // We want to prevent the compiler from accidentally leaking in any system libraries,
    // so by default we tell linkers not to link to any default libraries.
    if !sess.opts.cg.default_linker_libraries && sess.target.no_default_libraries {
        cmd.no_default_libraries();
    }

    if sess.opts.cg.profile_generate.enabled() || sess.instrument_coverage() {
        cmd.pgo_gen();
    }

    if sess.opts.cg.control_flow_guard != CFGuard::Disabled {
        cmd.control_flow_guard();
    }

    add_rpath_args(cmd, sess, codegen_results, out_filename);
}

// Write the NatVis debugger visualizer files for each crate to the temp directory and gather the file paths.
fn collect_natvis_visualizers(
    tmpdir: &Path,
    sess: &Session,
    crate_name: &Symbol,
    natvis_debugger_visualizers: &BTreeSet<DebuggerVisualizerFile>,
) -> Vec<PathBuf> {
    let mut visualizer_paths = Vec::with_capacity(natvis_debugger_visualizers.len());

    for (index, visualizer) in natvis_debugger_visualizers.iter().enumerate() {
        let visualizer_out_file = tmpdir.join(format!("{}-{}.natvis", crate_name.as_str(), index));

        match fs::write(&visualizer_out_file, &visualizer.src) {
            Ok(()) => {
                visualizer_paths.push(visualizer_out_file);
            }
            Err(error) => {
                sess.emit_warning(errors::UnableToWriteDebuggerVisualizer {
                    path: visualizer_out_file,
                    error,
                });
            }
        };
    }
    visualizer_paths
}

fn add_native_libs_from_crate(
    cmd: &mut dyn Linker,
    sess: &Session,
    archive_builder_builder: &dyn ArchiveBuilderBuilder,
    codegen_results: &CodegenResults,
    tmpdir: &Path,
    search_paths: &OnceCell<Vec<PathBuf>>,
    bundled_libs: &FxHashSet<Symbol>,
    cnum: CrateNum,
    link_static: bool,
    link_dynamic: bool,
    link_output_kind: LinkOutputKind,
) {
    if !sess.opts.unstable_opts.link_native_libraries {
        // If `-Zlink-native-libraries=false` is set, then the assumption is that an
        // external build system already has the native dependencies defined, and it
        // will provide them to the linker itself.
        return;
    }

    if link_static && cnum != LOCAL_CRATE && !bundled_libs.is_empty() {
        // If rlib contains native libs as archives, unpack them to tmpdir.
        let rlib = &codegen_results.crate_info.used_crate_source[&cnum].rlib.as_ref().unwrap().0;
        archive_builder_builder
            .extract_bundled_libs(rlib, tmpdir, &bundled_libs)
            .unwrap_or_else(|e| sess.emit_fatal(e));
    }

    let native_libs = match cnum {
        LOCAL_CRATE => &codegen_results.crate_info.used_libraries,
        _ => &codegen_results.crate_info.native_libraries[&cnum],
    };

    let mut last = (None, NativeLibKind::Unspecified, false);
    for lib in native_libs {
        if !relevant_lib(sess, lib) {
            continue;
        }

        // Skip if this library is the same as the last.
        last = if (Some(lib.name), lib.kind, lib.verbatim) == last {
            continue;
        } else {
            (Some(lib.name), lib.kind, lib.verbatim)
        };

        let name = lib.name.as_str();
        let verbatim = lib.verbatim;
        match lib.kind {
            NativeLibKind::Static { bundle, whole_archive } => {
                if link_static {
                    let bundle = bundle.unwrap_or(true);
                    let whole_archive = whole_archive == Some(true)
                        // Backward compatibility case: this can be a rlib (so `+whole-archive`
                        // cannot be added explicitly if necessary, see the error in `fn link_rlib`)
                        // compiled as an executable due to `--test`. Use whole-archive implicitly,
                        // like before the introduction of native lib modifiers.
                        || (whole_archive == None
                            && bundle
                            && cnum == LOCAL_CRATE
                            && sess.is_test_crate());

                    if bundle && cnum != LOCAL_CRATE {
                        if let Some(filename) = lib.filename {
                            // If rlib contains native libs as archives, they are unpacked to tmpdir.
                            let path = tmpdir.join(filename.as_str());
                            if whole_archive {
                                cmd.link_whole_rlib(&path);
                            } else {
                                cmd.link_rlib(&path);
                            }
                        }
                    } else {
                        if whole_archive {
                            cmd.link_whole_staticlib(
                                name,
                                verbatim,
                                &search_paths.get_or_init(|| archive_search_paths(sess)),
                            );
                        } else {
                            cmd.link_staticlib(name, verbatim)
                        }
                    }
                }
            }
            NativeLibKind::Dylib { as_needed } => {
                if link_dynamic {
                    cmd.link_dylib(name, verbatim, as_needed.unwrap_or(true))
                }
            }
            NativeLibKind::Unspecified => {
                // If we are generating a static binary, prefer static library when the
                // link kind is unspecified.
                if !link_output_kind.can_link_dylib() && !sess.target.crt_static_allows_dylibs {
                    if link_static {
                        cmd.link_staticlib(name, verbatim)
                    }
                } else {
                    if link_dynamic {
                        cmd.link_dylib(name, verbatim, true);
                    }
                }
            }
            NativeLibKind::Framework { as_needed } => {
                if link_dynamic {
                    cmd.link_framework(name, as_needed.unwrap_or(true))
                }
            }
            NativeLibKind::RawDylib => {
                // Handled separately in `linker_with_args`.
            }
            NativeLibKind::WasmImportModule => {}
            NativeLibKind::LinkArg => {
                if link_static {
                    cmd.arg(name);
                }
            }
        }
    }
}

fn add_local_native_libraries(
    cmd: &mut dyn Linker,
    sess: &Session,
    archive_builder_builder: &dyn ArchiveBuilderBuilder,
    codegen_results: &CodegenResults,
    tmpdir: &Path,
    link_output_kind: LinkOutputKind,
) {
    if sess.opts.unstable_opts.link_native_libraries {
        // User-supplied library search paths (-L on the command line). These are the same paths
        // used to find Rust crates, so some of them may have been added already by the previous
        // crate linking code. This only allows them to be found at compile time so it is still
        // entirely up to outside forces to make sure that library can be found at runtime.
        for search_path in sess.target_filesearch(PathKind::All).search_paths() {
            match search_path.kind {
                PathKind::Framework => cmd.framework_path(&search_path.dir),
                _ => cmd.include_path(&fix_windows_verbatim_for_gcc(&search_path.dir)),
            }
        }
    }

    let search_paths = OnceCell::new();
    // All static and dynamic native library dependencies are linked to the local crate.
    let link_static = true;
    let link_dynamic = true;
    add_native_libs_from_crate(
        cmd,
        sess,
        archive_builder_builder,
        codegen_results,
        tmpdir,
        &search_paths,
        &Default::default(),
        LOCAL_CRATE,
        link_static,
        link_dynamic,
        link_output_kind,
    );
}

fn add_upstream_rust_crates<'a>(
    cmd: &mut dyn Linker,
    sess: &'a Session,
    archive_builder_builder: &dyn ArchiveBuilderBuilder,
    codegen_results: &CodegenResults,
    crate_type: CrateType,
    tmpdir: &Path,
    link_output_kind: LinkOutputKind,
) {
    // All of the heavy lifting has previously been accomplished by the
    // dependency_format module of the compiler. This is just crawling the
    // output of that module, adding crates as necessary.
    //
    // Linking to a rlib involves just passing it to the linker (the linker
    // will slurp up the object files inside), and linking to a dynamic library
    // involves just passing the right -l flag.
    let (_, data) = codegen_results
        .crate_info
        .dependency_formats
        .iter()
        .find(|(ty, _)| *ty == crate_type)
        .expect("failed to find crate type in dependency format list");

    let search_paths = OnceCell::new();
    for &cnum in &codegen_results.crate_info.used_crates {
        // We may not pass all crates through to the linker. Some crates may appear statically in
        // an existing dylib, meaning we'll pick up all the symbols from the dylib.
        // We must always link crates `compiler_builtins` and `profiler_builtins` statically.
        // Even if they were already included into a dylib
        // (e.g. `libstd` when `-C prefer-dynamic` is used).
        // FIXME: `dependency_formats` can report `profiler_builtins` as `NotLinked` for some
        // reason, it shouldn't do that because `profiler_builtins` should indeed be linked.
        let linkage = data[cnum.as_usize() - 1];
        let link_static_crate = linkage == Linkage::Static
            || (linkage == Linkage::IncludedFromDylib || linkage == Linkage::NotLinked)
                && (codegen_results.crate_info.compiler_builtins == Some(cnum)
                    || codegen_results.crate_info.profiler_runtime == Some(cnum));

        let mut bundled_libs = Default::default();
        match linkage {
            Linkage::Static | Linkage::IncludedFromDylib | Linkage::NotLinked => {
                if link_static_crate {
                    bundled_libs = codegen_results.crate_info.native_libraries[&cnum]
                        .iter()
                        .filter_map(|lib| lib.filename)
                        .collect();
                    add_static_crate(
                        cmd,
                        sess,
                        archive_builder_builder,
                        codegen_results,
                        tmpdir,
                        cnum,
                        &bundled_libs,
                    );
                }
            }
            Linkage::Dynamic => {
                let src = &codegen_results.crate_info.used_crate_source[&cnum];
                add_dynamic_crate(cmd, sess, &src.dylib.as_ref().unwrap().0);
            }
        }

        // Static libraries are linked for a subset of linked upstream crates.
        // 1. If the upstream crate is a directly linked rlib then we must link the native library
        // because the rlib is just an archive.
        // 2. If the upstream crate is a dylib or a rlib linked through dylib, then we do not link
        // the native library because it is already linked into the dylib, and even if
        // inline/const/generic functions from the dylib can refer to symbols from the native
        // library, those symbols should be exported and available from the dylib anyway.
        // 3. Libraries bundled into `(compiler,profiler)_builtins` are special, see above.
        let link_static = link_static_crate;
        // Dynamic libraries are not linked here, see the FIXME in `add_upstream_native_libraries`.
        let link_dynamic = false;
        add_native_libs_from_crate(
            cmd,
            sess,
            archive_builder_builder,
            codegen_results,
            tmpdir,
            &search_paths,
            &bundled_libs,
            cnum,
            link_static,
            link_dynamic,
            link_output_kind,
        );
    }
}

fn add_upstream_native_libraries(
    cmd: &mut dyn Linker,
    sess: &Session,
    archive_builder_builder: &dyn ArchiveBuilderBuilder,
    codegen_results: &CodegenResults,
    tmpdir: &Path,
    link_output_kind: LinkOutputKind,
) {
    let search_path = OnceCell::new();
    for &cnum in &codegen_results.crate_info.used_crates {
        // Static libraries are not linked here, they are linked in `add_upstream_rust_crates`.
        // FIXME: Merge this function to `add_upstream_rust_crates` so that all native libraries
        // are linked together with their respective upstream crates, and in their originally
        // specified order. This is slightly breaking due to our use of `--as-needed` (see crater
        // results in https://github.com/rust-lang/rust/pull/102832#issuecomment-1279772306).
        let link_static = false;
        // Dynamic libraries are linked for all linked upstream crates.
        // 1. If the upstream crate is a directly linked rlib then we must link the native library
        // because the rlib is just an archive.
        // 2. If the upstream crate is a dylib or a rlib linked through dylib, then we have to link
        // the native library too because inline/const/generic functions from the dylib can refer
        // to symbols from the native library, so the native library providing those symbols should
        // be available when linking our final binary.
        let link_dynamic = true;
        add_native_libs_from_crate(
            cmd,
            sess,
            archive_builder_builder,
            codegen_results,
            tmpdir,
            &search_path,
            &Default::default(),
            cnum,
            link_static,
            link_dynamic,
            link_output_kind,
        );
    }
}

// Rehome lib paths (which exclude the library file name) that point into the sysroot lib directory
// to be relative to the sysroot directory, which may be a relative path specified by the user.
//
// If the sysroot is a relative path, and the sysroot libs are specified as an absolute path, the
// linker command line can be non-deterministic due to the paths including the current working
// directory. The linker command line needs to be deterministic since it appears inside the PDB
// file generated by the MSVC linker. See https://github.com/rust-lang/rust/issues/112586.
//
// The returned path will always have `fix_windows_verbatim_for_gcc()` applied to it.
fn rehome_sysroot_lib_dir<'a>(sess: &'a Session, lib_dir: &Path) -> PathBuf {
    let sysroot_lib_path = sess.target_filesearch(PathKind::All).get_lib_path();
    let canonical_sysroot_lib_path =
        { try_canonicalize(&sysroot_lib_path).unwrap_or_else(|_| sysroot_lib_path.clone()) };

    let canonical_lib_dir = try_canonicalize(lib_dir).unwrap_or_else(|_| lib_dir.to_path_buf());
    if canonical_lib_dir == canonical_sysroot_lib_path {
        // This path, returned by `target_filesearch().get_lib_path()`, has
        // already had `fix_windows_verbatim_for_gcc()` applied if needed.
        sysroot_lib_path
    } else {
        fix_windows_verbatim_for_gcc(&lib_dir)
    }
}

// Adds the static "rlib" versions of all crates to the command line.
// There's a bit of magic which happens here specifically related to LTO,
// namely that we remove upstream object files.
//
// When performing LTO, almost(*) all of the bytecode from the upstream
// libraries has already been included in our object file output. As a
// result we need to remove the object files in the upstream libraries so
// the linker doesn't try to include them twice (or whine about duplicate
// symbols). We must continue to include the rest of the rlib, however, as
// it may contain static native libraries which must be linked in.
//
// (*) Crates marked with `#![no_builtins]` don't participate in LTO and
// their bytecode wasn't included. The object files in those libraries must
// still be passed to the linker.
//
// Note, however, that if we're not doing LTO we can just pass the rlib
// blindly to the linker (fast) because it's fine if it's not actually
// included as we're at the end of the dependency chain.
fn add_static_crate<'a>(
    cmd: &mut dyn Linker,
    sess: &'a Session,
    archive_builder_builder: &dyn ArchiveBuilderBuilder,
    codegen_results: &CodegenResults,
    tmpdir: &Path,
    cnum: CrateNum,
    bundled_lib_file_names: &FxHashSet<Symbol>,
) {
    let src = &codegen_results.crate_info.used_crate_source[&cnum];
    let cratepath = &src.rlib.as_ref().unwrap().0;

    let mut link_upstream = |path: &Path| {
        let rlib_path = if let Some(dir) = path.parent() {
            let file_name = path.file_name().expect("rlib path has no file name path component");
            rehome_sysroot_lib_dir(sess, &dir).join(file_name)
        } else {
            fix_windows_verbatim_for_gcc(path)
        };
        cmd.link_rlib(&rlib_path);
    };

    if !are_upstream_rust_objects_already_included(sess)
        || ignored_for_lto(sess, &codegen_results.crate_info, cnum)
    {
        link_upstream(cratepath);
        return;
    }

    let dst = tmpdir.join(cratepath.file_name().unwrap());
    let name = cratepath.file_name().unwrap().to_str().unwrap();
    let name = &name[3..name.len() - 5]; // chop off lib/.rlib
    let bundled_lib_file_names = bundled_lib_file_names.clone();

    sess.prof.generic_activity_with_arg("link_altering_rlib", name).run(|| {
        let canonical_name = name.replace('-', "_");
        let upstream_rust_objects_already_included =
            are_upstream_rust_objects_already_included(sess);
        let is_builtins =
            sess.target.no_builtins || !codegen_results.crate_info.is_no_builtins.contains(&cnum);

        let mut archive = archive_builder_builder.new_archive_builder(sess);
        if let Err(error) = archive.add_archive(
            cratepath,
            Box::new(move |f| {
                if f == METADATA_FILENAME {
                    return true;
                }

                let canonical = f.replace('-', "_");

                let is_rust_object =
                    canonical.starts_with(&canonical_name) && looks_like_rust_object_file(&f);

                // If we're performing LTO and this is a rust-generated object
                // file, then we don't need the object file as it's part of the
                // LTO module. Note that `#![no_builtins]` is excluded from LTO,
                // though, so we let that object file slide.
                if upstream_rust_objects_already_included && is_rust_object && is_builtins {
                    return true;
                }

                // We skip native libraries because:
                // 1. This native libraries won't be used from the generated rlib,
                //    so we can throw them away to avoid the copying work.
                // 2. We can't allow it to be a single remaining entry in archive
                //    as some linkers may complain on that.
                if bundled_lib_file_names.contains(&Symbol::intern(f)) {
                    return true;
                }

                false
            }),
        ) {
            sess.emit_fatal(errors::RlibArchiveBuildFailure { error });
        }
        if archive.build(&dst) {
            link_upstream(&dst);
        }
    });
}

// Same thing as above, but for dynamic crates instead of static crates.
fn add_dynamic_crate(cmd: &mut dyn Linker, sess: &Session, cratepath: &Path) {
    // Just need to tell the linker about where the library lives and
    // what its name is
    let parent = cratepath.parent();
    if let Some(dir) = parent {
        cmd.include_path(&rehome_sysroot_lib_dir(sess, dir));
    }
    let stem = cratepath.file_stem().unwrap().to_str().unwrap();
    // Convert library file-stem into a cc -l argument.
    let prefix = if stem.starts_with("lib") && !sess.target.is_like_windows { 3 } else { 0 };
    cmd.link_rust_dylib(&stem[prefix..], parent.unwrap_or_else(|| Path::new("")));
}

fn relevant_lib(sess: &Session, lib: &NativeLib) -> bool {
    match lib.cfg {
        Some(ref cfg) => rustc_attr::cfg_matches(cfg, &sess.parse_sess, CRATE_NODE_ID, None),
        None => true,
    }
}

pub(crate) fn are_upstream_rust_objects_already_included(sess: &Session) -> bool {
    match sess.lto() {
        config::Lto::Fat => true,
        config::Lto::Thin => {
            // If we defer LTO to the linker, we haven't run LTO ourselves, so
            // any upstream object files have not been copied yet.
            !sess.opts.cg.linker_plugin_lto.enabled()
        }
        config::Lto::No | config::Lto::ThinLocal => false,
    }
}

fn add_apple_sdk(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
    let arch = &sess.target.arch;
    let os = &sess.target.os;
    let llvm_target = &sess.target.llvm_target;
    if sess.target.vendor != "apple"
        || !matches!(os.as_ref(), "ios" | "tvos" | "watchos" | "macos")
        || !matches!(flavor, LinkerFlavor::Darwin(..))
    {
        return;
    }

    if os == "macos" && !matches!(flavor, LinkerFlavor::Darwin(Cc::No, _)) {
        return;
    }

    let sdk_name = match (arch.as_ref(), os.as_ref()) {
        ("aarch64", "tvos") => "appletvos",
        ("x86_64", "tvos") => "appletvsimulator",
        ("arm", "ios") => "iphoneos",
        ("aarch64", "ios") if llvm_target.contains("macabi") => "macosx",
        ("aarch64", "ios") if llvm_target.ends_with("-simulator") => "iphonesimulator",
        ("aarch64", "ios") => "iphoneos",
        ("x86", "ios") => "iphonesimulator",
        ("x86_64", "ios") if llvm_target.contains("macabi") => "macosx",
        ("x86_64", "ios") => "iphonesimulator",
        ("x86_64", "watchos") => "watchsimulator",
        ("arm64_32", "watchos") => "watchos",
        ("aarch64", "watchos") if llvm_target.ends_with("-simulator") => "watchsimulator",
        ("aarch64", "watchos") => "watchos",
        ("arm", "watchos") => "watchos",
        (_, "macos") => "macosx",
        _ => {
            sess.emit_err(errors::UnsupportedArch { arch, os });
            return;
        }
    };
    let sdk_root = match get_apple_sdk_root(sdk_name) {
        Ok(s) => s,
        Err(e) => {
            sess.emit_err(e);
            return;
        }
    };

    match flavor {
        LinkerFlavor::Darwin(Cc::Yes, _) => {
            cmd.args(&["-isysroot", &sdk_root, "-Wl,-syslibroot", &sdk_root]);
        }
        LinkerFlavor::Darwin(Cc::No, _) => {
            cmd.args(&["-syslibroot", &sdk_root]);
        }
        _ => unreachable!(),
    }
}

fn get_apple_sdk_root(sdk_name: &str) -> Result<String, errors::AppleSdkRootError<'_>> {
    // Following what clang does
    // (https://github.com/llvm/llvm-project/blob/
    // 296a80102a9b72c3eda80558fb78a3ed8849b341/clang/lib/Driver/ToolChains/Darwin.cpp#L1661-L1678)
    // to allow the SDK path to be set. (For clang, xcrun sets
    // SDKROOT; for rustc, the user or build system can set it, or we
    // can fall back to checking for xcrun on PATH.)
    if let Ok(sdkroot) = env::var("SDKROOT") {
        let p = Path::new(&sdkroot);
        match sdk_name {
            // Ignore `SDKROOT` if it's clearly set for the wrong platform.
            "appletvos"
                if sdkroot.contains("TVSimulator.platform")
                    || sdkroot.contains("MacOSX.platform") => {}
            "appletvsimulator"
                if sdkroot.contains("TVOS.platform") || sdkroot.contains("MacOSX.platform") => {}
            "iphoneos"
                if sdkroot.contains("iPhoneSimulator.platform")
                    || sdkroot.contains("MacOSX.platform") => {}
            "iphonesimulator"
                if sdkroot.contains("iPhoneOS.platform") || sdkroot.contains("MacOSX.platform") => {
            }
            "macosx10.15"
                if sdkroot.contains("iPhoneOS.platform")
                    || sdkroot.contains("iPhoneSimulator.platform") => {}
            "watchos"
                if sdkroot.contains("WatchSimulator.platform")
                    || sdkroot.contains("MacOSX.platform") => {}
            "watchsimulator"
                if sdkroot.contains("WatchOS.platform") || sdkroot.contains("MacOSX.platform") => {}
            // Ignore `SDKROOT` if it's not a valid path.
            _ if !p.is_absolute() || p == Path::new("/") || !p.exists() => {}
            _ => return Ok(sdkroot),
        }
    }
    let res =
        Command::new("xcrun").arg("--show-sdk-path").arg("-sdk").arg(sdk_name).output().and_then(
            |output| {
                if output.status.success() {
                    Ok(String::from_utf8(output.stdout).unwrap())
                } else {
                    let error = String::from_utf8(output.stderr);
                    let error = format!("process exit with error: {}", error.unwrap());
                    Err(io::Error::new(io::ErrorKind::Other, &error[..]))
                }
            },
        );

    match res {
        Ok(output) => Ok(output.trim().to_string()),
        Err(error) => Err(errors::AppleSdkRootError::SdkPath { sdk_name, error }),
    }
}

/// When using the linker flavors opting in to `lld`, or the unstable `-Zgcc-ld=lld` flag, add the
/// necessary paths and arguments to invoke it:
/// - when the self-contained linker flag is active: the build of `lld` distributed with rustc,
/// - or any `lld` available to `cc`.
fn add_lld_args(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
    let unstable_use_lld = sess.opts.unstable_opts.gcc_ld.is_some();
    debug!("add_lld_args requested, flavor: '{flavor:?}', `-Zgcc-ld=lld`: {unstable_use_lld}");

    // Sanity check: using the old unstable `-Zgcc-ld=lld` option requires a `cc`-using flavor.
    let flavor_uses_cc = flavor.uses_cc();
    if unstable_use_lld && !flavor_uses_cc {
        sess.emit_fatal(errors::OptionGccOnly);
    }

    // If the flavor doesn't use a C/C++ compiler to invoke the linker, or doesn't opt in to `lld`,
    // we don't need to do anything.
    let use_lld = flavor.uses_lld() || unstable_use_lld;
    if !flavor_uses_cc || !use_lld {
        return;
    }

    // 1. Implement the "self-contained" part of this feature by adding rustc distribution
    //    directories to the tool's search path.
    let self_contained_linker = sess.opts.cg.link_self_contained.linker() || unstable_use_lld;
    if self_contained_linker {
        for path in sess.get_tools_search_paths(false) {
            cmd.arg({
                let mut arg = OsString::from("-B");
                arg.push(path.join("gcc-ld"));
                arg
            });
        }
    }

    // 2. Implement the "linker flavor" part of this feature by asking `cc` to use some kind of
    //    `lld` as the linker.
    cmd.arg("-fuse-ld=lld");

    if !flavor.is_gnu() {
        // Tell clang to use a non-default LLD flavor.
        // Gcc doesn't understand the target option, but we currently assume
        // that gcc is not used for Apple and Wasm targets (#97402).
        //
        // Note that we don't want to do that by default on macOS: e.g. passing a
        // 10.7 target to LLVM works, but not to recent versions of clang/macOS, as
        // shown in issue #101653 and the discussion in PR #101792.
        //
        // It could be required in some cases of cross-compiling with
        // `-Zgcc-ld=lld`, but this is generally unspecified, and we don't know
        // which specific versions of clang, macOS SDK, host and target OS
        // combinations impact us here.
        //
        // So we do a simple first-approximation until we know more of what the
        // Apple targets require (and which would be handled prior to hitting this
        // `-Zgcc-ld=lld` codepath anyway), but the expectation is that until then
        // this should be manually passed if needed. We specify the target when
        // targeting a different linker flavor on macOS, and that's also always
        // the case when targeting WASM.
        if sess.target.linker_flavor != sess.host.linker_flavor {
            cmd.arg(format!("--target={}", sess.target.llvm_target));
        }
    }
}