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
//! This library provides [`eyre::Report`][Report], a trait object based
//! error handling type for easy idiomatic error handling and reporting in Rust
//! applications.
//!
//! This crate is a fork of [`anyhow`]  with support for customized
//! error reports. For more details on customization, check out the docs on
//! [`eyre::EyreHandler`].
//!
//! ## Custom Report Handlers
//!
//! The heart of this crate is its ability to swap out the Handler type to change
//! what information is carried alongside errors and how the end report is
//! formatted. This crate is meant to be used alongside companion crates that
//! customize its behavior. Below is a list of known crates that export report
//! handlers for eyre and short summaries of what features they provide.
//!
//! - [`stable-eyre`]: Switches the backtrace type from `std`'s to `backtrace-rs`'s
//!   so that it can be captured on stable. The report format is identical to
//!   `DefaultHandler`'s report format.
//! - [`color-eyre`]: Captures a `backtrace::Backtrace` and a
//!   `tracing_error::SpanTrace`. Provides a `Section` trait for attaching warnings
//!   and suggestions to error reports. The end report is then pretty printed with
//!   the help of [`color-backtrace`], [`color-spantrace`], and `ansi_term`. Check
//!   out the README on [`color-eyre`] for details on the report format.
//! - [`simple-eyre`]: A minimal `EyreHandler` that captures no additional
//!   information, for when you do not wish to capture `Backtrace`s with errors.
//! - [`jane-eyre`]: A report handler crate that exists purely for the pun.
//!   Currently just re-exports `color-eyre`.
//!
//! ## Usage Recommendations and Stability Considerations
//!
//! **We recommend users do not re-export types from this library as part their
//! own public API for libraries with external users.** The main reason for this
//! is that it will make your library API break if we ever bump the major version
//! number on eyre and your users upgrade the eyre version they use in their
//! application code before you upgrade your own eyre dep version[^1].
//!
//! However, even beyond this API stability hazard, there are other good reasons
//! to avoid using `eyre::Report` as your public error type.
//!
//! - You export an undocumented error interface that is otherwise still
//! accessible via downcast, making it hard for users to react to specific
//! errors while not preventing them from depending on details you didn't mean
//! to make part of your public API.
//!   - This in turn makes the error types of all libraries you use a part of
//!   your public API as well, and makes changing any of those libraries into
//!   undetectable runtime breakage.
//! - If many of your errors are constructed from strings, you encourage your
//! users to use string comparison for reacting to specific errors, which is
//! brittle and turns updating error messages into potentially undetectable
//! runtime breakage.
//!
//! ## Details
//!
//! - Use `Result<T, eyre::Report>`, or equivalently `eyre::Result<T>`, as the
//!   return type of any fallible function.
//!
//!   Within the function, use `?` to easily propagate any error that implements the
//!   `std::error::Error` trait.
//!
//!   ```rust
//!   # pub trait Deserialize {}
//!   #
//!   # mod serde_json {
//!   #     use super::Deserialize;
//!   #     use std::io;
//!   #
//!   #     pub fn from_str<T: Deserialize>(json: &str) -> io::Result<T> {
//!   #         unimplemented!()
//!   #     }
//!   # }
//!   #
//!   # struct ClusterMap;
//!   #
//!   # impl Deserialize for ClusterMap {}
//!   #
//!   use eyre::Result;
//!
//!   fn get_cluster_info() -> Result<ClusterMap> {
//!       let config = std::fs::read_to_string("cluster.json")?;
//!       let map: ClusterMap = serde_json::from_str(&config)?;
//!       Ok(map)
//!   }
//!   #
//!   # fn main() {}
//!   ```
//!
//! - Wrap a lower level error with a new error created from a message to help the
//!   person troubleshooting understand the chain of failures that occurred. A
//!   low-level error like "No such file or directory" can be annoying to debug
//!   without more information about what higher level step the application was in
//!   the middle of.
//!
//!   ```rust
//!   # struct It;
//!   #
//!   # impl It {
//!   #     fn detach(&self) -> Result<()> {
//!   #         unimplemented!()
//!   #     }
//!   # }
//!   #
//!   use eyre::{WrapErr, Result};
//!
//!   fn main() -> Result<()> {
//!       # return Ok(());
//!       #
//!       # const _: &str = stringify! {
//!       ...
//!       # };
//!       #
//!       # let it = It;
//!       # let path = "./path/to/instrs.json";
//!       #
//!       it.detach().wrap_err("Failed to detach the important thing")?;
//!
//!       let content = std::fs::read(path)
//!           .wrap_err_with(|| format!("Failed to read instrs from {}", path))?;
//!       #
//!       # const _: &str = stringify! {
//!       ...
//!       # };
//!       #
//!       # Ok(())
//!   }
//!   ```
//!
//!   ```console
//!   Error: Failed to read instrs from ./path/to/instrs.json
//!
//!   Caused by:
//!       No such file or directory (os error 2)
//!   ```
//!
//! - Downcasting is supported and can be done by value, by shared reference, or by
//!   mutable reference as needed.
//!
//!   ```rust
//!   # use eyre::{Report, eyre};
//!   # use std::fmt::{self, Display};
//!   # use std::task::Poll;
//!   #
//!   # #[derive(Debug)]
//!   # enum DataStoreError {
//!   #     Censored(()),
//!   # }
//!   #
//!   # impl Display for DataStoreError {
//!   #     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
//!   #         unimplemented!()
//!   #     }
//!   # }
//!   #
//!   # impl std::error::Error for DataStoreError {}
//!   #
//!   # const REDACTED_CONTENT: () = ();
//!   #
//!   # #[cfg(not(feature = "auto-install"))]
//!   # eyre::set_hook(Box::new(eyre::DefaultHandler::default_with)).unwrap();
//!   #
//!   # let error: Report = eyre!("...");
//!   # let root_cause = &error;
//!   #
//!   # let ret =
//!   // If the error was caused by redaction, then return a
//!   // tombstone instead of the content.
//!   match root_cause.downcast_ref::<DataStoreError>() {
//!       Some(DataStoreError::Censored(_)) => Ok(Poll::Ready(REDACTED_CONTENT)),
//!       None => Err(error),
//!   }
//!   # ;
//!   ```
//!
//! - If using the nightly channel, a backtrace is captured and printed with the
//!   error if the underlying error type does not already provide its own. In order
//!   to see backtraces, they must be enabled through the environment variables
//!   described in [`std::backtrace`]:
//!
//!   - If you want panics and errors to both have backtraces, set
//!     `RUST_BACKTRACE=1`;
//!   - If you want only errors to have backtraces, set `RUST_LIB_BACKTRACE=1`;
//!   - If you want only panics to have backtraces, set `RUST_BACKTRACE=1` and
//!     `RUST_LIB_BACKTRACE=0`.
//!
//!   The tracking issue for this feature is [rust-lang/rust#53487].
//!
//!   [`std::backtrace`]: https://doc.rust-lang.org/std/backtrace/index.html#environment-variables
//!   [rust-lang/rust#53487]: https://github.com/rust-lang/rust/issues/53487
//!
//! - Eyre works with any error type that has an impl of `std::error::Error`,
//!   including ones defined in your crate. We do not bundle a `derive(Error)` macro
//!   but you can write the impls yourself or use a standalone macro like
//!   [thiserror].
//!
//!   ```rust
//!   use thiserror::Error;
//!
//!   #[derive(Error, Debug)]
//!   pub enum FormatError {
//!       #[error("Invalid header (expected {expected:?}, got {found:?})")]
//!       InvalidHeader {
//!           expected: String,
//!           found: String,
//!       },
//!       #[error("Missing attribute: {0}")]
//!       MissingAttribute(String),
//!   }
//!   ```
//!
//! - One-off error messages can be constructed using the `eyre!` macro, which
//!   supports string interpolation and produces an `eyre::Report`.
//!
//!   ```rust
//!   # use eyre::{eyre, Result};
//!   #
//!   # fn demo() -> Result<()> {
//!   #     let missing = "...";
//!   return Err(eyre!("Missing attribute: {}", missing));
//!   #     Ok(())
//!   # }
//!   ```
//!
//! - On newer versions of the compiler (i.e. 1.58 and later) this macro also
//!   supports format args captures.
//!
//!   ```rust
//!   # use eyre::{eyre, Result};
//!   #
//!   # fn demo() -> Result<()> {
//!   #     let missing = "...";
//!   # #[cfg(not(eyre_no_fmt_args_capture))]
//!   return Err(eyre!("Missing attribute: {missing}"));
//!   #     Ok(())
//!   # }
//!   ```
//!
//! ## No-std support
//!
//! No-std support was removed in 2020 in [commit 608a16a] due to unaddressed upstream breakages.
//!
//! [commit 608a16a]: https://github.com/eyre-rs/eyre/pull/29/commits/608a16aa2c2c27eca6c88001cc94c6973c18f1d5
//!
//! ## Comparison to failure
//!
//! The `eyre::Report` type works something like `failure::Error`, but unlike
//! failure ours is built around the standard library's `std::error::Error` trait
//! rather than a separate trait `failure::Fail`. The standard library has adopted
//! the necessary improvements for this to be possible as part of [RFC 2504].
//!
//! [RFC 2504]: https://github.com/rust-lang/rfcs/blob/master/text/2504-fix-error.md
//!
//! ## Comparison to thiserror
//!
//! Use `eyre` if you don't think you'll do anything with an error other than
//! report it. This is common in application code. Use `thiserror` if you think
//! you need an error type that can be handled via match or reported. This is
//! common in library crates where you don't know how your users will handle
//! your errors.
//!
//! [thiserror]: https://github.com/dtolnay/thiserror
//!
//! ## Compatibility with `anyhow`
//!
//! This crate does its best to be usable as a drop in replacement of `anyhow` and
//! vice-versa by re-exporting all of the renamed APIs with the names used in
//! `anyhow`, though there are some differences still.
//!
//! #### `Context` and `Option`
//!
//! As part of renaming `Context` to `WrapErr` we also intentionally do not
//! implement `WrapErr` for `Option`. This decision was made because `wrap_err`
//! implies that you're creating a new error that saves the old error as its
//! `source`. With `Option` there is no source error to wrap, so `wrap_err` ends up
//! being somewhat meaningless.
//!
//! Instead `eyre` offers [`OptionExt::ok_or_eyre`] to yield _static_ errors from `None`,
//! and intends for users to use the combinator functions provided by
//! `std`, converting `Option`s to `Result`s, for _dynamic_ errors.
//! So where you would write this with
//! anyhow:
//!
//! ```rust
//! use anyhow::Context;
//!
//! let opt: Option<()> = None;
//! let result_static = opt.context("static error message");
//! let result_dynamic = opt.with_context(|| format!("{} error message", "dynamic"));
//! ```
//!
//! With `eyre` we want users to write:
//!
//! ```rust
//! use eyre::{eyre, OptionExt, Result};
//!
//! # #[cfg(not(feature = "auto-install"))]
//! # eyre::set_hook(Box::new(eyre::DefaultHandler::default_with)).unwrap();
//! #
//! let opt: Option<()> = None;
//! let result_static: Result<()> = opt.ok_or_eyre("static error message");
//! let result_dynamic: Result<()> = opt.ok_or_else(|| eyre!("{} error message", "dynamic"));
//! ```
//!
//! **NOTE**: However, to help with porting we do provide a `ContextCompat` trait which
//! implements `context` for options which you can import to make existing
//! `.context` calls compile.
//!
//! [^1]: example and explanation of breakage <https://github.com/eyre-rs/eyre/issues/30#issuecomment-647650361>
//!
//! [Report]: https://docs.rs/eyre/*/eyre/struct.Report.html
//! [`eyre::EyreHandler`]: https://docs.rs/eyre/*/eyre/trait.EyreHandler.html
//! [`eyre::WrapErr`]: https://docs.rs/eyre/*/eyre/trait.WrapErr.html
//! [`anyhow::Context`]: https://docs.rs/anyhow/*/anyhow/trait.Context.html
//! [`anyhow`]: https://github.com/dtolnay/anyhow
//! [`tracing_error::SpanTrace`]: https://docs.rs/tracing-error/*/tracing_error/struct.SpanTrace.html
//! [`stable-eyre`]: https://github.com/eyre-rs/stable-eyre
//! [`color-eyre`]: https://github.com/eyre-rs/color-eyre
//! [`jane-eyre`]: https://github.com/yaahc/jane-eyre
//! [`simple-eyre`]: https://github.com/eyre-rs/simple-eyre
//! [`color-spantrace`]: https://github.com/eyre-rs/color-spantrace
//! [`color-backtrace`]: https://github.com/athre0z/color-backtrace
#![doc(html_root_url = "https://docs.rs/eyre/0.6.12")]
#![cfg_attr(
    nightly,
    feature(rustdoc_missing_doc_code_examples),
    warn(rustdoc::missing_doc_code_examples)
)]
#![warn(
    missing_debug_implementations,
    missing_docs,
    unsafe_op_in_unsafe_fn,
    rust_2018_idioms,
    unreachable_pub,
    bad_style,
    dead_code,
    improper_ctypes,
    non_shorthand_field_patterns,
    no_mangle_generic_items,
    overflowing_literals,
    path_statements,
    patterns_in_fns_without_body,
    unconditional_recursion,
    unused,
    unused_allocation,
    unused_comparisons,
    unused_parens,
    while_true
)]
#![cfg_attr(backtrace, feature(backtrace))]
#![cfg_attr(doc_cfg, feature(doc_cfg))]
#![allow(
    clippy::needless_doctest_main,
    clippy::new_ret_no_self,
    clippy::wrong_self_convention
)]

extern crate alloc;

#[macro_use]
mod backtrace;
mod chain;
mod context;
mod error;
mod fmt;
mod kind;
mod macros;
mod option;
mod ptr;
mod wrapper;

use crate::backtrace::Backtrace;
use crate::error::ErrorImpl;
use core::fmt::{Debug, Display};

use std::error::Error as StdError;

pub use eyre as format_err;
/// Compatibility re-export of `eyre` for interop with `anyhow`
pub use eyre as anyhow;
use once_cell::sync::OnceCell;
use ptr::OwnedPtr;
#[doc(hidden)]
pub use DefaultHandler as DefaultContext;
#[doc(hidden)]
pub use EyreHandler as EyreContext;
#[doc(hidden)]
pub use Report as ErrReport;
/// Compatibility re-export of `Report` for interop with `anyhow`
pub use Report as Error;
/// Compatibility re-export of `WrapErr` for interop with `anyhow`
pub use WrapErr as Context;

/// The core error reporting type of the library, a wrapper around a dynamic error reporting type.
///
/// `Report` works a lot like `Box<dyn std::error::Error>`, but with these
/// differences:
///
/// - `Report` requires that the error is `Send`, `Sync`, and `'static`.
/// - `Report` guarantees that a backtrace is available, even if the underlying
///   error type does not provide one.
/// - `Report` is represented as a narrow pointer &mdash; exactly one word in
///   size instead of two.
///
/// # Display representations
///
/// When you print an error object using "{}" or to_string(), only the outermost underlying error
/// is printed, not any of the lower level causes. This is exactly as if you had called the Display
/// impl of the error from which you constructed your eyre::Report.
///
/// ```console
/// Failed to read instrs from ./path/to/instrs.json
/// ```
///
/// To print causes as well using eyre's default formatting of causes, use the
/// alternate selector "{:#}".
///
/// ```console
/// Failed to read instrs from ./path/to/instrs.json: No such file or directory (os error 2)
/// ```
///
/// The Debug format "{:?}" includes your backtrace if one was captured. Note
/// that this is the representation you get by default if you return an error
/// from `fn main` instead of printing it explicitly yourself.
///
/// ```console
/// Error: Failed to read instrs from ./path/to/instrs.json
///
/// Caused by:
///     No such file or directory (os error 2)
///
/// Stack backtrace:
///    0: <E as eyre::context::ext::StdError>::ext_report
///              at /git/eyre/src/backtrace.rs:26
///    1: core::result::Result<T,E>::map_err
///              at /git/rustc/src/libcore/result.rs:596
///    2: eyre::context::<impl eyre::WrapErr<T,E,H> for core::result::Result<T,E>>::wrap_err_with
///              at /git/eyre/src/context.rs:58
///    3: testing::main
///              at src/main.rs:5
///    4: std::rt::lang_start
///              at /git/rustc/src/libstd/rt.rs:61
///    5: main
///    6: __libc_start_main
///    7: _start
/// ```
///
/// To see a conventional struct-style Debug representation, use "{:#?}".
///
/// ```console
/// Error {
///     msg: "Failed to read instrs from ./path/to/instrs.json",
///     source: Os {
///         code: 2,
///         kind: NotFound,
///         message: "No such file or directory",
///     },
/// }
/// ```
///
/// If none of the built-in representations are appropriate and you would prefer
/// to render the error and its cause chain yourself, it can be done by defining
/// your own [`EyreHandler`] and [`hook`] to use it.
///
/// [`EyreHandler`]: trait.EyreHandler.html
/// [`hook`]: fn.set_hook.html
#[must_use]
pub struct Report {
    inner: OwnedPtr<ErrorImpl<()>>,
}

type ErrorHook =
    Box<dyn Fn(&(dyn StdError + 'static)) -> Box<dyn EyreHandler> + Sync + Send + 'static>;

static HOOK: OnceCell<ErrorHook> = OnceCell::new();

/// Error indicating that `set_hook` was unable to install the provided ErrorHook
#[derive(Debug, Clone, Copy)]
pub struct InstallError;

impl core::fmt::Display for InstallError {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        f.write_str("cannot install provided ErrorHook, a hook has already been installed")
    }
}

impl StdError for InstallError {}

/// Install the provided error hook for constructing EyreHandlers when converting
/// Errors to Reports
///
/// # Details
///
/// To customize the format and content of error reports from `eyre` you must
/// first define a new `EyreHandler` type to capture and store the extra context
/// and to define the format of how to display the chain of errors and this
/// stored context. Once this type has been defined you must also define a global
/// hook used to construct these handlers whenever `Report`s are constructed.
///
/// # Examples
///
/// ```rust,should_panic
/// use backtrace::Backtrace;
/// use eyre::EyreHandler;
/// use std::error::Error;
/// use std::{fmt, iter};
///
/// fn main() -> eyre::Result<()> {
///     // Install our custom eyre report hook for constructing our custom Handlers
///     install().unwrap();
///
///     // construct a report with, hopefully, our custom handler!
///     let mut report = eyre::eyre!("hello from custom error town!");
///
///     // manually set the custom msg for this report after it has been constructed
///     if let Some(handler) = report.handler_mut().downcast_mut::<Handler>() {
///         handler.custom_msg = Some("you're the best users, you know that right???");
///     }
///
///     // print that shit!!
///     Err(report)
/// }
///
/// // define a handler that captures backtraces unless told not to
/// fn install() -> Result<(), impl Error> {
///     let capture_backtrace = std::env::var("RUST_BACKWARDS_TRACE")
///         .map(|val| val != "0")
///         .unwrap_or(true);
///
///     let hook = Hook { capture_backtrace };
///
///     eyre::set_hook(Box::new(move |e| Box::new(hook.make_handler(e))))
/// }
///
/// struct Hook {
///     capture_backtrace: bool,
/// }
///
/// impl Hook {
///     fn make_handler(&self, _error: &(dyn Error + 'static)) -> Handler {
///         let backtrace = if self.capture_backtrace {
///             Some(Backtrace::new())
///         } else {
///             None
///         };
///
///         Handler {
///             backtrace,
///             custom_msg: None,
///         }
///     }
/// }
///
/// struct Handler {
///     // custom configured backtrace capture
///     backtrace: Option<Backtrace>,
///     // customizable message payload associated with reports
///     custom_msg: Option<&'static str>,
/// }
///
/// impl EyreHandler for Handler {
///     fn debug(&self, error: &(dyn Error + 'static), f: &mut fmt::Formatter<'_>) -> fmt::Result {
///         if f.alternate() {
///             return fmt::Debug::fmt(error, f);
///         }
///
///         let errors = iter::successors(Some(error), |error| (*error).source());
///
///         for (ind, error) in errors.enumerate() {
///             write!(f, "\n{:>4}: {}", ind, error)?;
///         }
///
///         if let Some(backtrace) = self.backtrace.as_ref() {
///             writeln!(f, "\n\nBacktrace:\n{:?}", backtrace)?;
///         }
///
///         if let Some(msg) = self.custom_msg.as_ref() {
///             writeln!(f, "\n\n{}", msg)?;
///         }
///
///         Ok(())
///     }
/// }
/// ```
pub fn set_hook(hook: ErrorHook) -> Result<(), InstallError> {
    HOOK.set(hook).map_err(|_| InstallError)
}

#[cfg_attr(track_caller, track_caller)]
#[cfg_attr(not(track_caller), allow(unused_mut))]
fn capture_handler(error: &(dyn StdError + 'static)) -> Box<dyn EyreHandler> {
    #[cfg(not(feature = "auto-install"))]
    let hook = HOOK
        .get()
        .expect("a handler must always be installed if the `auto-install` feature is disabled")
        .as_ref();

    #[cfg(feature = "auto-install")]
    let hook = HOOK
        .get_or_init(|| Box::new(DefaultHandler::default_with))
        .as_ref();

    let mut handler = hook(error);

    #[cfg(track_caller)]
    {
        handler.track_caller(std::panic::Location::caller())
    }

    handler
}

impl dyn EyreHandler {
    ///
    pub fn is<T: EyreHandler>(&self) -> bool {
        // Get `TypeId` of the type this function is instantiated with.
        let t = core::any::TypeId::of::<T>();

        // Get `TypeId` of the type in the trait object (`self`).
        let concrete = self.type_id();

        // Compare both `TypeId`s on equality.
        t == concrete
    }

    ///
    pub fn downcast_ref<T: EyreHandler>(&self) -> Option<&T> {
        if self.is::<T>() {
            unsafe { Some(&*(self as *const dyn EyreHandler as *const T)) }
        } else {
            None
        }
    }

    ///
    pub fn downcast_mut<T: EyreHandler>(&mut self) -> Option<&mut T> {
        if self.is::<T>() {
            unsafe { Some(&mut *(self as *mut dyn EyreHandler as *mut T)) }
        } else {
            None
        }
    }
}

/// Error Report Handler trait for customizing `eyre::Report`
pub trait EyreHandler: core::any::Any + Send + Sync {
    /// Define the report format
    ///
    /// Used to override the report format of `eyre::Report`
    ///
    /// # Example
    ///
    /// ```rust
    /// use backtrace::Backtrace;
    /// use eyre::EyreHandler;
    /// use eyre::Chain;
    /// use std::error::Error;
    /// use indenter::indented;
    ///
    /// pub struct Handler {
    ///     backtrace: Backtrace,
    /// }
    ///
    /// impl EyreHandler for Handler {
    ///     fn debug(
    ///         &self,
    ///         error: &(dyn Error + 'static),
    ///         f: &mut core::fmt::Formatter<'_>,
    ///     ) -> core::fmt::Result {
    ///         use core::fmt::Write as _;
    ///
    ///         if f.alternate() {
    ///             return core::fmt::Debug::fmt(error, f);
    ///         }
    ///
    ///         write!(f, "{}", error)?;
    ///
    ///         if let Some(cause) = error.source() {
    ///             write!(f, "\n\nCaused by:")?;
    ///             let multiple = cause.source().is_some();
    ///
    ///             for (n, error) in Chain::new(cause).enumerate() {
    ///                 writeln!(f)?;
    ///                 if multiple {
    ///                     write!(indented(f).ind(n), "{}", error)?;
    ///                 } else {
    ///                     write!(indented(f), "{}", error)?;
    ///                 }
    ///             }
    ///         }
    ///
    ///         let backtrace = &self.backtrace;
    ///         write!(f, "\n\nStack backtrace:\n{:?}", backtrace)?;
    ///
    ///         Ok(())
    ///     }
    /// }
    /// ```
    fn debug(
        &self,
        error: &(dyn StdError + 'static),
        f: &mut core::fmt::Formatter<'_>,
    ) -> core::fmt::Result;

    /// Override for the `Display` format
    fn display(
        &self,
        error: &(dyn StdError + 'static),
        f: &mut core::fmt::Formatter<'_>,
    ) -> core::fmt::Result {
        write!(f, "{}", error)?;

        if f.alternate() {
            for cause in crate::chain::Chain::new(error).skip(1) {
                write!(f, ": {}", cause)?;
            }
        }

        Result::Ok(())
    }

    /// Store the location of the caller who constructed this error report
    #[allow(unused_variables)]
    fn track_caller(&mut self, location: &'static std::panic::Location<'static>) {}
}

/// The default provided error report handler for `eyre::Report`.
///
/// On nightly this supports conditionally capturing a `std::backtrace::Backtrace` if the source
/// error did not already capture one.
#[allow(dead_code)]
pub struct DefaultHandler {
    backtrace: Option<Backtrace>,
    #[cfg(track_caller)]
    location: Option<&'static std::panic::Location<'static>>,
}

impl DefaultHandler {
    /// Manual hook which constructs `DefaultHandler`s.
    ///
    /// # Details
    ///
    /// When supplied to the `set_hook` function, `default_with` will cause `eyre::Report` to use
    /// `DefaultHandler` as the error report handler.
    ///
    /// If the `auto-install` feature is enabled, and a user-provided hook for constructing
    /// `EyreHandlers` was not installed using `set_hook`, `DefaultHandler::default_with`
    /// is automatically installed as the hook.
    ///
    /// # Example
    ///
    /// ```rust,should_panic
    /// use eyre::{DefaultHandler, eyre, InstallError, Result, set_hook};
    ///
    /// fn main() -> Result<()> {
    ///     install_default().expect("default handler inexplicably already installed");
    ///     Err(eyre!("hello from default error city!"))
    /// }
    ///
    /// fn install_default() -> Result<(), InstallError> {
    ///     set_hook(Box::new(DefaultHandler::default_with))
    /// }
    ///
    /// ```
    #[allow(unused_variables)]
    #[cfg_attr(not(feature = "auto-install"), allow(dead_code))]
    pub fn default_with(error: &(dyn StdError + 'static)) -> Box<dyn EyreHandler> {
        let backtrace = backtrace_if_absent!(error);

        Box::new(Self {
            backtrace,
            #[cfg(track_caller)]
            location: None,
        })
    }
}

impl core::fmt::Debug for DefaultHandler {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        f.debug_struct("DefaultHandler")
            .field(
                "backtrace",
                match &self.backtrace {
                    Some(_) => &"Some(Backtrace { ... })",
                    None => &"None",
                },
            )
            .finish()
    }
}

impl EyreHandler for DefaultHandler {
    fn debug(
        &self,
        error: &(dyn StdError + 'static),
        f: &mut core::fmt::Formatter<'_>,
    ) -> core::fmt::Result {
        use core::fmt::Write as _;

        if f.alternate() {
            return core::fmt::Debug::fmt(error, f);
        }

        write!(f, "{}", error)?;

        if let Some(cause) = error.source() {
            write!(f, "\n\nCaused by:")?;
            let multiple = cause.source().is_some();
            for (n, error) in crate::chain::Chain::new(cause).enumerate() {
                writeln!(f)?;
                if multiple {
                    write!(indenter::indented(f).ind(n), "{}", error)?;
                } else {
                    write!(indenter::indented(f), "{}", error)?;
                }
            }
        }

        #[cfg(all(track_caller, feature = "track-caller"))]
        {
            if let Some(location) = self.location {
                write!(f, "\n\nLocation:\n")?;
                write!(indenter::indented(f), "{}", location)?;
            }
        }

        #[cfg(backtrace)]
        {
            use std::backtrace::BacktraceStatus;

            let backtrace = self
                .backtrace
                .as_ref()
                .or_else(|| error.backtrace())
                .expect("backtrace capture failed");
            if let BacktraceStatus::Captured = backtrace.status() {
                write!(f, "\n\nStack backtrace:\n{}", backtrace)?;
            }
        }

        Result::Ok(())
    }

    #[cfg(track_caller)]
    fn track_caller(&mut self, location: &'static std::panic::Location<'static>) {
        self.location = Some(location);
    }
}

/// Iterator of a chain of source errors.
///
/// This type is the iterator returned by [`Report::chain`].
///
/// # Example
///
/// ```
/// use eyre::Report;
/// use std::io;
///
/// pub fn underlying_io_error_kind(error: &Report) -> Option<io::ErrorKind> {
///     for cause in error.chain() {
///         if let Some(io_error) = cause.downcast_ref::<io::Error>() {
///             return Some(io_error.kind());
///         }
///     }
///     None
/// }
/// ```
#[derive(Clone)]
#[allow(missing_debug_implementations)]
pub struct Chain<'a> {
    state: crate::chain::ChainState<'a>,
}

/// type alias for `Result<T, Report>`
///
/// This is a reasonable return type to use throughout your application but also for `fn main`; if
/// you do, failures will be printed along with a backtrace if one was captured.
///
/// `eyre::Result` may be used with one *or* two type parameters.
///
/// ```rust
/// use eyre::Result;
///
/// # const IGNORE: &str = stringify! {
/// fn demo1() -> Result<T> {...}
///            // ^ equivalent to std::result::Result<T, eyre::Report>
///
/// fn demo2() -> Result<T, OtherError> {...}
///            // ^ equivalent to std::result::Result<T, OtherError>
/// # };
/// ```
///
/// # Example
///
/// ```
/// # pub trait Deserialize {}
/// #
/// # mod serde_json {
/// #     use super::Deserialize;
/// #     use std::io;
/// #
/// #     pub fn from_str<T: Deserialize>(json: &str) -> io::Result<T> {
/// #         unimplemented!()
/// #     }
/// # }
/// #
/// # #[derive(Debug)]
/// # struct ClusterMap;
/// #
/// # impl Deserialize for ClusterMap {}
/// #
/// use eyre::Result;
///
/// fn main() -> Result<()> {
///     # return Ok(());
///     let config = std::fs::read_to_string("cluster.json")?;
///     let map: ClusterMap = serde_json::from_str(&config)?;
///     println!("cluster info: {:#?}", map);
///     Ok(())
/// }
/// ```
pub type Result<T, E = Report> = core::result::Result<T, E>;

/// Provides the `wrap_err` method for `Result`.
///
/// This trait is sealed and cannot be implemented for types outside of
/// `eyre`.
///
/// # Example
///
/// ```
/// use eyre::{WrapErr, Result};
/// use std::fs;
/// use std::path::PathBuf;
///
/// pub struct ImportantThing {
///     path: PathBuf,
/// }
///
/// impl ImportantThing {
///     # const IGNORE: &'static str = stringify! {
///     pub fn detach(&mut self) -> Result<()> {...}
///     # };
///     # fn detach(&mut self) -> Result<()> {
///     #     unimplemented!()
///     # }
/// }
///
/// pub fn do_it(mut it: ImportantThing) -> Result<Vec<u8>> {
///     it.detach().wrap_err("Failed to detach the important thing")?;
///
///     let path = &it.path;
///     let content = fs::read(path)
///         .wrap_err_with(|| format!("Failed to read instrs from {}", path.display()))?;
///
///     Ok(content)
/// }
/// ```
///
/// When printed, the outermost error would be printed first and the lower
/// level underlying causes would be enumerated below.
///
/// ```console
/// Error: Failed to read instrs from ./path/to/instrs.json
///
/// Caused by:
///     No such file or directory (os error 2)
/// ```
///
/// # Wrapping Types That Don't impl `Error` (e.g. `&str` and `Box<dyn Error>`)
///
/// Due to restrictions for coherence `Report` cannot impl `From` for types that don't impl
/// `Error`. Attempts to do so will give "this type might implement Error in the future" as an
/// error. As such, `wrap_err`, which uses `From` under the hood, cannot be used to wrap these
/// types. Instead we encourage you to use the combinators provided for `Result` in `std`/`core`.
///
/// For example, instead of this:
///
/// ```rust,compile_fail
/// use std::error::Error;
/// use eyre::{WrapErr, Report};
///
/// fn wrap_example(err: Result<(), Box<dyn Error + Send + Sync + 'static>>) -> Result<(), Report> {
///     err.wrap_err("saw a downstream error")
/// }
/// ```
///
/// We encourage you to write this:
///
/// ```rust
/// use std::error::Error;
/// use eyre::{WrapErr, Report, eyre};
///
/// fn wrap_example(err: Result<(), Box<dyn Error + Send + Sync + 'static>>) -> Result<(), Report> {
///     err.map_err(|e| eyre!(e)).wrap_err("saw a downstream error")
/// }
/// ```
///
/// # Effect on downcasting
///
/// After attaching a message of type `D` onto an error of type `E`, the resulting
/// `eyre::Report` may be downcast to `D` **or** to `E`.
///
/// That is, in codebases that rely on downcasting, Eyre's wrap_err supports
/// both of the following use cases:
///
///   - **Attaching messages whose type is insignificant onto errors whose type
///     is used in downcasts.**
///
///     In other error libraries whose wrap_err is not designed this way, it can
///     be risky to introduce messages to existing code because new message might
///     break existing working downcasts. In Eyre, any downcast that worked
///     before adding the message will continue to work after you add a message, so
///     you should freely wrap errors wherever it would be helpful.
///
///     ```
///     # use eyre::bail;
///     # use thiserror::Error;
///     #
///     # #[derive(Error, Debug)]
///     # #[error("???")]
///     # struct SuspiciousError;
///     #
///     # fn helper() -> Result<()> {
///     #     bail!(SuspiciousError);
///     # }
///     #
///     use eyre::{WrapErr, Result};
///
///     fn do_it() -> Result<()> {
///         helper().wrap_err("Failed to complete the work")?;
///         # const IGNORE: &str = stringify! {
///         ...
///         # };
///         # unreachable!()
///     }
///
///     fn main() {
///         # #[cfg(not(feature = "auto-install"))]
///         # eyre::set_hook(Box::new(eyre::DefaultHandler::default_with)).unwrap();
///         let err = do_it().unwrap_err();
///         if let Some(e) = err.downcast_ref::<SuspiciousError>() {
///             // If helper() returned SuspiciousError, this downcast will
///             // correctly succeed even with the message in between.
///             # return;
///         }
///         # panic!("expected downcast to succeed");
///     }
///     ```
///
///   - **Attaching message whose type is used in downcasts onto errors whose
///     type is insignificant.**
///
///     Some codebases prefer to use machine-readable messages to categorize
///     lower level errors in a way that will be actionable to higher levels of
///     the application.
///
///     ```
///     # use eyre::bail;
///     # use thiserror::Error;
///     #
///     # #[derive(Error, Debug)]
///     # #[error("???")]
///     # struct HelperFailed;
///     #
///     # fn helper() -> Result<()> {
///     #     bail!("no such file or directory");
///     # }
///     #
///     use eyre::{WrapErr, Result};
///
///     fn do_it() -> Result<()> {
///         helper().wrap_err(HelperFailed)?;
///         # const IGNORE: &str = stringify! {
///         ...
///         # };
///         # unreachable!()
///     }
///
///     fn main() {
///         # #[cfg(not(feature = "auto-install"))]
///         # eyre::set_hook(Box::new(eyre::DefaultHandler::default_with)).unwrap();
///         let err = do_it().unwrap_err();
///         if let Some(e) = err.downcast_ref::<HelperFailed>() {
///             // If helper failed, this downcast will succeed because
///             // HelperFailed is the message that has been attached to
///             // that error.
///             # return;
///         }
///         # panic!("expected downcast to succeed");
///     }
///     ```
///
/// # `wrap_err` vs `wrap_err_with`
///
/// `wrap_err` incurs a runtime cost even in the non-error case because it requires eagerly
/// constructing the error object. `wrap_err_with` avoids this cost through lazy evaluation. This
/// cost is proportional to the cost of the currently installed [`EyreHandler`]'s creation step.
/// `wrap_err` is useful in cases where an constructed error object already exists.
pub trait WrapErr<T, E>: context::private::Sealed {
    /// Wrap the error value with a new adhoc error
    #[cfg_attr(track_caller, track_caller)]
    fn wrap_err<D>(self, msg: D) -> Result<T, Report>
    where
        D: Display + Send + Sync + 'static;

    /// Wrap the error value with a new adhoc error that is evaluated lazily
    /// only once an error does occur.
    #[cfg_attr(track_caller, track_caller)]
    fn wrap_err_with<D, F>(self, f: F) -> Result<T, Report>
    where
        D: Display + Send + Sync + 'static,
        F: FnOnce() -> D;

    /// Compatibility re-export of wrap_err for interop with `anyhow`
    #[cfg_attr(track_caller, track_caller)]
    fn context<D>(self, msg: D) -> Result<T, Report>
    where
        D: Display + Send + Sync + 'static;

    /// Compatibility re-export of wrap_err_with for interop with `anyhow`
    #[cfg_attr(track_caller, track_caller)]
    fn with_context<D, F>(self, f: F) -> Result<T, Report>
    where
        D: Display + Send + Sync + 'static,
        F: FnOnce() -> D;
}

/// Provides the [`ok_or_eyre`][OptionExt::ok_or_eyre] method for [`Option`].
///
/// This trait is sealed and cannot be implemented for types outside of
/// `eyre`.
///
/// # Example
///
/// ```
/// # #[cfg(not(feature = "auto-install"))]
/// # eyre::set_hook(Box::new(eyre::DefaultHandler::default_with)).unwrap();
/// use eyre::OptionExt;
///
/// let option: Option<()> = None;
///
/// let result = option.ok_or_eyre("static str error");
///
/// assert_eq!(result.unwrap_err().to_string(), "static str error");
/// ```
///
/// # `ok_or_eyre` vs `ok_or_else`
///
/// If string interpolation is required for the generated [report][Report],
/// use [`ok_or_else`][Option::ok_or_else] instead,
/// invoking [`eyre!`] to perform string interpolation:
///
/// ```
/// # #[cfg(not(feature = "auto-install"))]
/// # eyre::set_hook(Box::new(eyre::DefaultHandler::default_with)).unwrap();
/// use eyre::eyre;
///
/// let option: Option<()> = None;
///
/// let result = option.ok_or_else(|| eyre!("{} error", "dynamic"));
///
/// assert_eq!(result.unwrap_err().to_string(), "dynamic error");
/// ```
///
/// `ok_or_eyre` incurs no runtime cost, as the error object
/// is constructed from the provided static argument
/// only in the `None` case.
pub trait OptionExt<T>: context::private::Sealed {
    /// Transform the [`Option<T>`] into a [`Result<T, E>`],
    /// mapping [`Some(v)`][Option::Some] to [`Ok(v)`][Result::Ok]
    /// and [`None`] to [`Report`].
    ///
    /// `ok_or_eyre` allows for eyre [`Report`] error objects
    /// to be lazily created from static messages in the `None` case.
    ///
    /// For dynamic error messages, use [`ok_or_else`][Option::ok_or_else],
    /// invoking [`eyre!`] in the closure to perform string interpolation.
    fn ok_or_eyre<M>(self, message: M) -> crate::Result<T>
    where
        M: Debug + Display + Send + Sync + 'static;
}

/// Provides the `context` method for `Option` when porting from `anyhow`
///
/// This trait is sealed and cannot be implemented for types outside of
/// `eyre`.
///
/// ## Why Doesn't `Eyre` impl `WrapErr` for `Option`?
///
/// `eyre` doesn't impl `WrapErr` for `Option` because `wrap_err` implies that you're creating a
/// new error that saves the previous error as its `source`. Calling `wrap_err` on an `Option` is
/// meaningless because there is no source error. `anyhow` avoids this issue by using a different
/// mental model where you're adding "context" to an error, though this not a mental model for
/// error handling that `eyre` agrees with.
///
/// Instead, `eyre` encourages users to think of each error as distinct, where the previous error
/// is the context being saved by the new error, which is backwards compared to anyhow's model. In
/// this model you're encouraged to use combinators provided by `std` for `Option` to convert an
/// option to a `Result`
///
/// # Example
///
/// Instead of:
///
/// ```rust
/// use eyre::ContextCompat;
///
/// fn get_thing(mut things: impl Iterator<Item = u32>) -> eyre::Result<u32> {
///     things
///         .find(|&thing| thing == 42)
///         .context("the thing wasnt in the list")
/// }
/// ```
///
/// We encourage you to use this:
///
/// ```rust
/// use eyre::eyre;
///
/// fn get_thing(mut things: impl Iterator<Item = u32>) -> eyre::Result<u32> {
///     things
///         .find(|&thing| thing == 42)
///         .ok_or_else(|| eyre!("the thing wasnt in the list"))
/// }
/// ```
pub trait ContextCompat<T>: context::private::Sealed {
    /// Compatibility version of `wrap_err` for creating new errors with new source on `Option`
    /// when porting from `anyhow`
    #[cfg_attr(track_caller, track_caller)]
    fn context<D>(self, msg: D) -> Result<T, Report>
    where
        D: Display + Send + Sync + 'static;

    /// Compatibility version of `wrap_err_with` for creating new errors with new source on `Option`
    /// when porting from `anyhow`
    #[cfg_attr(track_caller, track_caller)]
    fn with_context<D, F>(self, f: F) -> Result<T, Report>
    where
        D: Display + Send + Sync + 'static,
        F: FnOnce() -> D;

    /// Compatibility re-export of `context` for porting from `anyhow` to `eyre`
    #[cfg_attr(track_caller, track_caller)]
    fn wrap_err<D>(self, msg: D) -> Result<T, Report>
    where
        D: Display + Send + Sync + 'static;

    /// Compatibility re-export of `with_context` for porting from `anyhow` to `eyre`
    #[cfg_attr(track_caller, track_caller)]
    fn wrap_err_with<D, F>(self, f: F) -> Result<T, Report>
    where
        D: Display + Send + Sync + 'static,
        F: FnOnce() -> D;
}

/// Equivalent to Ok::<_, eyre::Error>(value).
///
/// This simplifies creation of an eyre::Result in places where type inference
/// cannot deduce the `E` type of the result &mdash; without needing to write
/// `Ok::<_, eyre::Error>(value)`.
///
/// One might think that `eyre::Result::Ok(value)` would work in such cases
/// but it does not.
///
/// ```console
/// error[E0282]: type annotations needed for `std::result::Result<i32, E>`
///   --> src/main.rs:11:13
///    |
/// 11 |     let _ = eyre::Result::Ok(1);
///    |         -   ^^^^^^^^^^^^^^^^ cannot infer type for type parameter `E` declared on the enum `Result`
///    |         |
///    |         consider giving this pattern the explicit type `std::result::Result<i32, E>`, where the type parameter `E` is specified
/// ```
#[allow(non_snake_case)]
pub fn Ok<T>(t: T) -> Result<T> {
    Result::Ok(t)
}

// Not public API. Referenced by macro-generated code.
#[doc(hidden)]
pub mod private {
    use crate::Report;
    use alloc::fmt;
    use core::fmt::{Arguments, Debug, Display};

    pub use alloc::format;
    pub use core::format_args;
    pub use core::result::Result::Err;

    #[doc(hidden)]
    pub mod kind {
        pub use crate::kind::{AdhocKind, TraitKind};

        pub use crate::kind::BoxedKind;
    }

    #[cfg_attr(track_caller, track_caller)]
    pub fn new_adhoc<M>(message: M) -> Report
    where
        M: Display + Debug + Send + Sync + 'static,
    {
        Report::from_adhoc(message)
    }

    #[doc(hidden)]
    #[cold]
    #[cfg_attr(track_caller, track_caller)]
    pub fn format_err(args: Arguments<'_>) -> Report {
        #[cfg(eyre_no_fmt_arguments_as_str)]
        let fmt_arguments_as_str: Option<&str> = None;
        #[cfg(not(eyre_no_fmt_arguments_as_str))]
        let fmt_arguments_as_str = args.as_str();

        if let Some(message) = fmt_arguments_as_str {
            // eyre!("literal"), can downcast to &'static str
            Report::msg(message)
        } else {
            // eyre!("interpolate {var}"), can downcast to String
            Report::msg(fmt::format(args))
        }
    }
}