primitive_docs.rs.html -- source
Description: Source to the Rust file `src/libstd/primitive_docs.rs`.
Keywords: rust, rustlang, rust-lang

       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

    #[doc(primitive = "bool")]
    #[doc(alias = "true")]
    #[doc(alias = "false")]
    //
    /// The boolean type.
    ///
    /// The `bool` represents a value, which could only be either `true` or `false`. If you cast
    /// a `bool` into an integer, `true` will be 1 and `false` will be 0.
    ///
    /// # Basic usage
    ///
    /// `bool` implements various traits, such as [`BitAnd`], [`BitOr`], [`Not`], etc.,
    /// which allow us to perform boolean operations using `&`, `|` and `!`.
    ///
    /// `if` always demands a `bool` value. [`assert!`], being an important macro in testing,
    /// checks whether an expression returns `true`.
    ///
    /// ```
    /// let bool_val = true & false | false;
    /// assert!(!bool_val);
    /// ```
    ///
    /// [`assert!`]: macro.assert.html
    /// [`BitAnd`]: ops/trait.BitAnd.html
    /// [`BitOr`]: ops/trait.BitOr.html
    /// [`Not`]: ops/trait.Not.html
    ///
    /// # Examples
    ///
    /// A trivial example of the usage of `bool`,
    ///
    /// ```
    /// let praise_the_borrow_checker = true;
    ///
    /// // using the `if` conditional
    /// if praise_the_borrow_checker {
    ///     println!("oh, yeah!");
    /// } else {
    ///     println!("what?!!");
    /// }
    ///
    /// // ... or, a match pattern
    /// match praise_the_borrow_checker {
    ///     true => println!("keep praising!"),
    ///     false => println!("you should praise!"),
    /// }
    /// ```
    ///
    /// Also, since `bool` implements the [`Copy`](marker/trait.Copy.html) trait, we don't
    /// have to worry about the move semantics (just like the integer and float primitives).
    ///
    /// Now an example of `bool` cast to integer type:
    ///
    /// ```
    /// assert_eq!(true as i32, 1);
    /// assert_eq!(false as i32, 0);
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    mod prim_bool { }

    #[doc(primitive = "never")]
    #[doc(alias = "!")]
    //
    /// The `!` type, also called "never".
    ///
    /// `!` represents the type of computations which never resolve to any value at all. For example,
    /// the [`exit`] function `fn exit(code: i32) -> !` exits the process without ever returning, and
    /// so returns `!`.
    ///
    /// `break`, `continue` and `return` expressions also have type `!`. For example we are allowed to
    /// write:
    ///
    /// ```
    /// #![feature(never_type)]
    /// # fn foo() -> u32 {
    /// let x: ! = {
    ///     return 123
    /// };
    /// # }
    /// ```
    ///
    /// Although the `let` is pointless here, it illustrates the meaning of `!`. Since `x` is never
    /// assigned a value (because `return` returns from the entire function), `x` can be given type
    /// `!`. We could also replace `return 123` with a `panic!` or a never-ending `loop` and this code
    /// would still be valid.
    ///
    /// A more realistic usage of `!` is in this code:
    ///
    /// ```
    /// # fn get_a_number() -> Option<u32> { None }
    /// # loop {
    /// let num: u32 = match get_a_number() {
    ///     Some(num) => num,
    ///     None => break,
    /// };
    /// # }
    /// ```
    ///
    /// Both match arms must produce values of type [`u32`], but since `break` never produces a value
    /// at all we know it can never produce a value which isn't a [`u32`]. This illustrates another
    /// behaviour of the `!` type - expressions with type `!` will coerce into any other type.
    ///
    /// [`u32`]: primitive.str.html
    /// [`exit`]: process/fn.exit.html
    ///
    /// # `!` and generics
    ///
    /// ## Infallible errors
    ///
    /// The main place you'll see `!` used explicitly is in generic code. Consider the [`FromStr`]
    /// trait:
    ///
    /// ```
    /// trait FromStr: Sized {
    ///     type Err;
    ///     fn from_str(s: &str) -> Result<Self, Self::Err>;
    /// }
    /// ```
    ///
    /// When implementing this trait for [`String`] we need to pick a type for [`Err`]. And since
    /// converting a string into a string will never result in an error, the appropriate type is `!`.
    /// (Currently the type actually used is an enum with no variants, though this is only because `!`
    /// was added to Rust at a later date and it may change in the future). With an [`Err`] type of
    /// `!`, if we have to call [`String::from_str`] for some reason the result will be a
    /// [`Result<String, !>`] which we can unpack like this:
    ///
    /// ```ignore (string-from-str-error-type-is-not-never-yet)
    /// #[feature(exhaustive_patterns)]
    /// // NOTE: This does not work today!
    /// let Ok(s) = String::from_str("hello");
    /// ```
    ///
    /// Since the [`Err`] variant contains a `!`, it can never occur. If the `exhaustive_patterns`
    /// feature is present this means we can exhaustively match on [`Result<T, !>`] by just taking the
    /// [`Ok`] variant. This illustrates another behaviour of `!` - it can be used to "delete" certain
    /// enum variants from generic types like `Result`.
    ///
    /// ## Infinite loops
    ///
    /// While [`Result<T, !>`] is very useful for removing errors, `!` can also be used to remove
    /// successes as well. If we think of [`Result<T, !>`] as "if this function returns, it has not
    /// errored," we get a very intuitive idea of [`Result<!, E>`] as well: if the function returns, it
    /// *has* errored.
    ///
    /// For example, consider the case of a simple web server, which can be simplified to:
    ///
    /// ```ignore (hypothetical-example)
    /// loop {
    ///     let (client, request) = get_request().expect("disconnected");
    ///     let response = request.process();
    ///     response.send(client);
    /// }
    /// ```
    ///
    /// Currently, this isn't ideal, because we simply panic whenever we fail to get a new connection.
    /// Instead, we'd like to keep track of this error, like this:
    ///
    /// ```ignore (hypothetical-example)
    /// loop {
    ///     match get_request() {
    ///         Err(err) => break err,
    ///         Ok((client, request)) => {
    ///             let response = request.process();
    ///             response.send(client);
    ///         },
    ///     }
    /// }
    /// ```
    ///
    /// Now, when the server disconnects, we exit the loop with an error instead of panicking. While it
    /// might be intuitive to simply return the error, we might want to wrap it in a [`Result<!, E>`]
    /// instead:
    ///
    /// ```ignore (hypothetical-example)
    /// fn server_loop() -> Result<!, ConnectionError> {
    ///     loop {
    ///         let (client, request) = get_request()?;
    ///         let response = request.process();
    ///         response.send(client);
    ///     }
    /// }
    /// ```
    ///
    /// Now, we can use `?` instead of `match`, and the return type makes a lot more sense: if the loop
    /// ever stops, it means that an error occurred. We don't even have to wrap the loop in an `Ok`
    /// because `!` coerces to `Result<!, ConnectionError>` automatically.
    ///
    /// [`String::from_str`]: str/trait.FromStr.html#tymethod.from_str
    /// [`Result<String, !>`]: result/enum.Result.html
    /// [`Result<T, !>`]: result/enum.Result.html
    /// [`Result<!, E>`]: result/enum.Result.html
    /// [`Ok`]: result/enum.Result.html#variant.Ok
    /// [`String`]: string/struct.String.html
    /// [`Err`]: result/enum.Result.html#variant.Err
    /// [`FromStr`]: str/trait.FromStr.html
    ///
    /// # `!` and traits
    ///
    /// When writing your own traits, `!` should have an `impl` whenever there is an obvious `impl`
    /// which doesn't `panic!`. As it turns out, most traits can have an `impl` for `!`. Take [`Debug`]
    /// for example:
    ///
    /// ```
    /// #![feature(never_type)]
    /// # use std::fmt;
    /// # trait Debug {
    /// # fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result;
    /// # }
    /// impl Debug for ! {
    ///     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
    ///         *self
    ///     }
    /// }
    /// ```
    ///
    /// Once again we're using `!`'s ability to coerce into any other type, in this case
    /// [`fmt::Result`]. Since this method takes a `&!` as an argument we know that it can never be
    /// called (because there is no value of type `!` for it to be called with). Writing `*self`
    /// essentially tells the compiler "We know that this code can never be run, so just treat the
    /// entire function body as having type [`fmt::Result`]". This pattern can be used a lot when
    /// implementing traits for `!`. Generally, any trait which only has methods which take a `self`
    /// parameter should have such an impl.
    ///
    /// On the other hand, one trait which would not be appropriate to implement is [`Default`]:
    ///
    /// ```
    /// trait Default {
    ///     fn default() -> Self;
    /// }
    /// ```
    ///
    /// Since `!` has no values, it has no default value either. It's true that we could write an
    /// `impl` for this which simply panics, but the same is true for any type (we could `impl
    /// Default` for (eg.) [`File`] by just making [`default()`] panic.)
    ///
    /// [`fmt::Result`]: fmt/type.Result.html
    /// [`File`]: fs/struct.File.html
    /// [`Debug`]: fmt/trait.Debug.html
    /// [`Default`]: default/trait.Default.html
    /// [`default()`]: default/trait.Default.html#tymethod.default
    ///
    #[unstable(feature = "never_type", issue = "35121")]
    mod prim_never { }

    #[doc(primitive = "char")]
    //
    /// A character type.
    ///
    /// The `char` type represents a single character. More specifically, since
    /// 'character' isn't a well-defined concept in Unicode, `char` is a '[Unicode
    /// scalar value]', which is similar to, but not the same as, a '[Unicode code
    /// point]'.
    ///
    /// [Unicode scalar value]: http://www.unicode.org/glossary/#unicode_scalar_value
    /// [Unicode code point]: http://www.unicode.org/glossary/#code_point
    ///
    /// This documentation describes a number of methods and trait implementations on the
    /// `char` type. For technical reasons, there is additional, separate
    /// documentation in [the `std::char` module](char/index.html) as well.
    ///
    /// # Representation
    ///
    /// `char` is always four bytes in size. This is a different representation than
    /// a given character would have as part of a [`String`]. For example:
    ///
    /// ```
    /// let v = vec!['h', 'e', 'l', 'l', 'o'];
    ///
    /// // five elements times four bytes for each element
    /// assert_eq!(20, v.len() * std::mem::size_of::<char>());
    ///
    /// let s = String::from("hello");
    ///
    /// // five elements times one byte per element
    /// assert_eq!(5, s.len() * std::mem::size_of::<u8>());
    /// ```
    ///
    /// [`String`]: string/struct.String.html
    ///
    /// As always, remember that a human intuition for 'character' may not map to
    /// Unicode's definitions. For example, despite looking similar, the 'é'
    /// character is one Unicode code point while 'é' is two Unicode code points:
    ///
    /// ```
    /// let mut chars = "é".chars();
    /// // U+00e9: 'latin small letter e with acute'
    /// assert_eq!(Some('\u{00e9}'), chars.next());
    /// assert_eq!(None, chars.next());
    ///
    /// let mut chars = "é".chars();
    /// // U+0065: 'latin small letter e'
    /// assert_eq!(Some('\u{0065}'), chars.next());
    /// // U+0301: 'combining acute accent'
    /// assert_eq!(Some('\u{0301}'), chars.next());
    /// assert_eq!(None, chars.next());
    /// ```
    ///
    /// This means that the contents of the first string above _will_ fit into a
    /// `char` while the contents of the second string _will not_. Trying to create
    /// a `char` literal with the contents of the second string gives an error:
    ///
    /// ```text
    /// error: character literal may only contain one codepoint: 'é'
    /// let c = 'é';
    ///         ^^^
    /// ```
    ///
    /// Another implication of the 4-byte fixed size of a `char` is that
    /// per-`char` processing can end up using a lot more memory:
    ///
    /// ```
    /// let s = String::from("love: ❤️");
    /// let v: Vec<char> = s.chars().collect();
    ///
    /// assert_eq!(12, std::mem::size_of_val(&s[..]));
    /// assert_eq!(32, std::mem::size_of_val(&v[..]));
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    mod prim_char { }

    #[doc(primitive = "unit")]
    //
    /// The `()` type, sometimes called "unit" or "nil".
    ///
    /// The `()` type has exactly one value `()`, and is used when there
    /// is no other meaningful value that could be returned. `()` is most
    /// commonly seen implicitly: functions without a `-> ...` implicitly
    /// have return type `()`, that is, these are equivalent:
    ///
    /// ```rust
    /// fn long() -> () {}
    ///
    /// fn short() {}
    /// ```
    ///
    /// The semicolon `;` can be used to discard the result of an
    /// expression at the end of a block, making the expression (and thus
    /// the block) evaluate to `()`. For example,
    ///
    /// ```rust
    /// fn returns_i64() -> i64 {
    ///     1i64
    /// }
    /// fn returns_unit() {
    ///     1i64;
    /// }
    ///
    /// let is_i64 = {
    ///     returns_i64()
    /// };
    /// let is_unit = {
    ///     returns_i64();
    /// };
    /// ```
    ///
    #[stable(feature = "rust1", since = "1.0.0")]
    mod prim_unit { }

    #[doc(primitive = "pointer")]
    //
    /// Raw, unsafe pointers, `*const T`, and `*mut T`.
    ///
    /// *[See also the `std::ptr` module](ptr/index.html).*
    ///
    /// Working with raw pointers in Rust is uncommon,
    /// typically limited to a few patterns.
    ///
    /// Use the [`null`] and [`null_mut`] functions to create null pointers, and the
    /// [`is_null`] method of the `*const T` and `*mut T` types to check for null.
    /// The `*const T` and `*mut T` types also define the [`offset`] method, for
    /// pointer math.
    ///
    /// # Common ways to create raw pointers
    ///
    /// ## 1. Coerce a reference (`&T`) or mutable reference (`&mut T`).
    ///
    /// ```
    /// let my_num: i32 = 10;
    /// let my_num_ptr: *const i32 = &my_num;
    /// let mut my_speed: i32 = 88;
    /// let my_speed_ptr: *mut i32 = &mut my_speed;
    /// ```
    ///
    /// To get a pointer to a boxed value, dereference the box:
    ///
    /// ```
    /// let my_num: Box<i32> = Box::new(10);
    /// let my_num_ptr: *const i32 = &*my_num;
    /// let mut my_speed: Box<i32> = Box::new(88);
    /// let my_speed_ptr: *mut i32 = &mut *my_speed;
    /// ```
    ///
    /// This does not take ownership of the original allocation
    /// and requires no resource management later,
    /// but you must not use the pointer after its lifetime.
    ///
    /// ## 2. Consume a box (`Box<T>`).
    ///
    /// The [`into_raw`] function consumes a box and returns
    /// the raw pointer. It doesn't destroy `T` or deallocate any memory.
    ///
    /// ```
    /// let my_speed: Box<i32> = Box::new(88);
    /// let my_speed: *mut i32 = Box::into_raw(my_speed);
    ///
    /// // By taking ownership of the original `Box<T>` though
    /// // we are obligated to put it together later to be destroyed.
    /// unsafe {
    ///     drop(Box::from_raw(my_speed));
    /// }
    /// ```
    ///
    /// Note that here the call to [`drop`] is for clarity - it indicates
    /// that we are done with the given value and it should be destroyed.
    ///
    /// ## 3. Get it from C.
    ///
    /// ```
    /// # #![feature(rustc_private)]
    /// extern crate libc;
    ///
    /// use std::mem;
    ///
    /// fn main() {
    ///     unsafe {
    ///         let my_num: *mut i32 = libc::malloc(mem::size_of::<i32>()) as *mut i32;
    ///         if my_num.is_null() {
    ///             panic!("failed to allocate memory");
    ///         }
    ///         libc::free(my_num as *mut libc::c_void);
    ///     }
    /// }
    /// ```
    ///
    /// Usually you wouldn't literally use `malloc` and `free` from Rust,
    /// but C APIs hand out a lot of pointers generally, so are a common source
    /// of raw pointers in Rust.
    ///
    /// [`null`]: ../std/ptr/fn.null.html
    /// [`null_mut`]: ../std/ptr/fn.null_mut.html
    /// [`is_null`]: ../std/primitive.pointer.html#method.is_null
    /// [`offset`]: ../std/primitive.pointer.html#method.offset
    /// [`into_raw`]: ../std/boxed/struct.Box.html#method.into_raw
    /// [`drop`]: ../std/mem/fn.drop.html
    #[stable(feature = "rust1", since = "1.0.0")]
    mod prim_pointer { }

    #[doc(primitive = "array")]
    //
    /// A fixed-size array, denoted `[T; N]`, for the element type, `T`, and the
    /// non-negative compile-time constant size, `N`.
    ///
    /// There are two syntactic forms for creating an array:
    ///
    /// * A list with each element, i.e., `[x, y, z]`.
    /// * A repeat expression `[x; N]`, which produces an array with `N` copies of `x`.
    ///   The type of `x` must be [`Copy`][copy].
    ///
    /// Arrays of sizes from 0 to 32 (inclusive) implement the following traits if
    /// the element type allows it:
    ///
    /// - [`Debug`][debug]
    /// - [`IntoIterator`][intoiterator] (implemented for `&[T; N]` and `&mut [T; N]`)
    /// - [`PartialEq`][partialeq], [`PartialOrd`][partialord], [`Eq`][eq], [`Ord`][ord]
    /// - [`Hash`][hash]
    /// - [`AsRef`][asref], [`AsMut`][asmut]
    /// - [`Borrow`][borrow], [`BorrowMut`][borrowmut]
    /// - [`Default`][default]
    ///
    /// This limitation on the size `N` exists because Rust does not yet support
    /// code that is generic over the size of an array type. `[Foo; 3]` and `[Bar; 3]`
    /// are instances of same generic type `[T; 3]`, but `[Foo; 3]` and `[Foo; 5]` are
    /// entirely different types. As a stopgap, trait implementations are
    /// statically generated up to size 32.
    ///
    /// Arrays of *any* size are [`Copy`][copy] if the element type is [`Copy`][copy]
    /// and [`Clone`][clone] if the element type is [`Clone`][clone]. This works
    /// because [`Copy`][copy] and [`Clone`][clone] traits are specially known
    /// to the compiler.
    ///
    /// Arrays coerce to [slices (`[T]`)][slice], so a slice method may be called on
    /// an array. Indeed, this provides most of the API for working with arrays.
    /// Slices have a dynamic size and do not coerce to arrays.
    ///
    /// There is no way to move elements out of an array. See [`mem::replace`][replace]
    /// for an alternative.
    ///
    /// # Examples
    ///
    /// ```
    /// let mut array: [i32; 3] = [0; 3];
    ///
    /// array[1] = 1;
    /// array[2] = 2;
    ///
    /// assert_eq!([1, 2], &array[1..]);
    ///
    /// // This loop prints: 0 1 2
    /// for x in &array {
    ///     print!("{} ", x);
    /// }
    /// ```
    ///
    /// An array itself is not iterable:
    ///
    /// ```compile_fail,E0277
    /// let array: [i32; 3] = [0; 3];
    ///
    /// for x in array { }
    /// // error: the trait bound `[i32; 3]: std::iter::Iterator` is not satisfied
    /// ```
    ///
    /// The solution is to coerce the array to a slice by calling a slice method:
    ///
    /// ```
    /// # let array: [i32; 3] = [0; 3];
    /// for x in array.iter() { }
    /// ```
    ///
    /// If the array has 32 or fewer elements (see above), you can also use the
    /// array reference's [`IntoIterator`] implementation:
    ///
    /// ```
    /// # let array: [i32; 3] = [0; 3];
    /// for x in &array { }
    /// ```
    ///
    /// [slice]: primitive.slice.html
    /// [copy]: marker/trait.Copy.html
    /// [clone]: clone/trait.Clone.html
    /// [debug]: fmt/trait.Debug.html
    /// [intoiterator]: iter/trait.IntoIterator.html
    /// [partialeq]: cmp/trait.PartialEq.html
    /// [partialord]: cmp/trait.PartialOrd.html
    /// [eq]: cmp/trait.Eq.html
    /// [ord]: cmp/trait.Ord.html
    /// [hash]: hash/trait.Hash.html
    /// [asref]: convert/trait.AsRef.html
    /// [asmut]: convert/trait.AsMut.html
    /// [borrow]: borrow/trait.Borrow.html
    /// [borrowmut]: borrow/trait.BorrowMut.html
    /// [default]: default/trait.Default.html
    /// [replace]: mem/fn.replace.html
    /// [`IntoIterator`]: iter/trait.IntoIterator.html
    ///
    #[stable(feature = "rust1", since = "1.0.0")]
    mod prim_array { }

    #[doc(primitive = "slice")]
    #[doc(alias = "[")]
    #[doc(alias = "]")]
    #[doc(alias = "[]")]
    /// A dynamically-sized view into a contiguous sequence, `[T]`.
    ///
    /// *[See also the `std::slice` module](slice/index.html).*
    ///
    /// Slices are a view into a block of memory represented as a pointer and a
    /// length.
    ///
    /// ```
    /// // slicing a Vec
    /// let vec = vec![1, 2, 3];
    /// let int_slice = &vec[..];
    /// // coercing an array to a slice
    /// let str_slice: &[&str] = &["one", "two", "three"];
    /// ```
    ///
    /// Slices are either mutable or shared. The shared slice type is `&[T]`,
    /// while the mutable slice type is `&mut [T]`, where `T` represents the element
    /// type. For example, you can mutate the block of memory that a mutable slice
    /// points to:
    ///
    /// ```
    /// let mut x = [1, 2, 3];
    /// let x = &mut x[..]; // Take a full slice of `x`.
    /// x[1] = 7;
    /// assert_eq!(x, &[1, 7, 3]);
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    mod prim_slice { }

    #[doc(primitive = "str")]
    //
    /// String slices.
    ///
    /// *[See also the `std::str` module](str/index.html).*
    ///
    /// The `str` type, also called a 'string slice', is the most primitive string
    /// type. It is usually seen in its borrowed form, `&str`. It is also the type
    /// of string literals, `&'static str`.
    ///
    /// String slices are always valid UTF-8.
    ///
    /// # Examples
    ///
    /// String literals are string slices:
    ///
    /// ```
    /// let hello = "Hello, world!";
    ///
    /// // with an explicit type annotation
    /// let hello: &'static str = "Hello, world!";
    /// ```
    ///
    /// They are `'static` because they're stored directly in the final binary, and
    /// so will be valid for the `'static` duration.
    ///
    /// # Representation
    ///
    /// A `&str` is made up of two components: a pointer to some bytes, and a
    /// length. You can look at these with the [`as_ptr`] and [`len`] methods:
    ///
    /// ```
    /// use std::slice;
    /// use std::str;
    ///
    /// let story = "Once upon a time...";
    ///
    /// let ptr = story.as_ptr();
    /// let len = story.len();
    ///
    /// // story has nineteen bytes
    /// assert_eq!(19, len);
    ///
    /// // We can re-build a str out of ptr and len. This is all unsafe because
    /// // we are responsible for making sure the two components are valid:
    /// let s = unsafe {
    ///     // First, we build a &[u8]...
    ///     let slice = slice::from_raw_parts(ptr, len);
    ///
    ///     // ... and then convert that slice into a string slice
    ///     str::from_utf8(slice)
    /// };
    ///
    /// assert_eq!(s, Ok(story));
    /// ```
    ///
    /// [`as_ptr`]: #method.as_ptr
    /// [`len`]: #method.len
    ///
    /// Note: This example shows the internals of `&str`. `unsafe` should not be
    /// used to get a string slice under normal circumstances. Use `as_slice`
    /// instead.
    #[stable(feature = "rust1", since = "1.0.0")]
    mod prim_str { }

    #[doc(primitive = "tuple")]
    #[doc(alias = "(")]
    #[doc(alias = ")")]
    #[doc(alias = "()")]
    //
    /// A finite heterogeneous sequence, `(T, U, ..)`.
    ///
    /// Let's cover each of those in turn:
    ///
    /// Tuples are *finite*. In other words, a tuple has a length. Here's a tuple
    /// of length `3`:
    ///
    /// ```
    /// ("hello", 5, 'c');
    /// ```
    ///
    /// 'Length' is also sometimes called 'arity' here; each tuple of a different
    /// length is a different, distinct type.
    ///
    /// Tuples are *heterogeneous*. This means that each element of the tuple can
    /// have a different type. In that tuple above, it has the type:
    ///
    /// ```
    /// # let _:
    /// (&'static str, i32, char)
    /// # = ("hello", 5, 'c');
    /// ```
    ///
    /// Tuples are a *sequence*. This means that they can be accessed by position;
    /// this is called 'tuple indexing', and it looks like this:
    ///
    /// ```rust
    /// let tuple = ("hello", 5, 'c');
    ///
    /// assert_eq!(tuple.0, "hello");
    /// assert_eq!(tuple.1, 5);
    /// assert_eq!(tuple.2, 'c');
    /// ```
    ///
    /// For more about tuples, see [the book](../book/ch03-02-data-types.html#the-tuple-type).
    ///
    /// # Trait implementations
    ///
    /// If every type inside a tuple implements one of the following traits, then a
    /// tuple itself also implements it.
    ///
    /// * [`Clone`]
    /// * [`Copy`]
    /// * [`PartialEq`]
    /// * [`Eq`]
    /// * [`PartialOrd`]
    /// * [`Ord`]
    /// * [`Debug`]
    /// * [`Default`]
    /// * [`Hash`]
    ///
    /// [`Clone`]: clone/trait.Clone.html
    /// [`Copy`]: marker/trait.Copy.html
    /// [`PartialEq`]: cmp/trait.PartialEq.html
    /// [`Eq`]: cmp/trait.Eq.html
    /// [`PartialOrd`]: cmp/trait.PartialOrd.html
    /// [`Ord`]: cmp/trait.Ord.html
    /// [`Debug`]: fmt/trait.Debug.html
    /// [`Default`]: default/trait.Default.html
    /// [`Hash`]: hash/trait.Hash.html
    ///
    /// Due to a temporary restriction in Rust's type system, these traits are only
    /// implemented on tuples of arity 12 or less. In the future, this may change.
    ///
    /// # Examples
    ///
    /// Basic usage:
    ///
    /// ```
    /// let tuple = ("hello", 5, 'c');
    ///
    /// assert_eq!(tuple.0, "hello");
    /// ```
    ///
    /// Tuples are often used as a return type when you want to return more than
    /// one value:
    ///
    /// ```
    /// fn calculate_point() -> (i32, i32) {
    ///     // Don't do a calculation, that's not the point of the example
    ///     (4, 5)
    /// }
    ///
    /// let point = calculate_point();
    ///
    /// assert_eq!(point.0, 4);
    /// assert_eq!(point.1, 5);
    ///
    /// // Combining this with patterns can be nicer.
    ///
    /// let (x, y) = calculate_point();
    ///
    /// assert_eq!(x, 4);
    /// assert_eq!(y, 5);
    /// ```
    ///
    #[stable(feature = "rust1", since = "1.0.0")]
    mod prim_tuple { }

    #[doc(primitive = "f32")]
    /// The 32-bit floating point type.
    ///
    /// *[See also the `std::f32` module](f32/index.html).*
    ///
    #[stable(feature = "rust1", since = "1.0.0")]
    mod prim_f32 { }

    #[doc(primitive = "f64")]
    //
    /// The 64-bit floating point type.
    ///
    /// *[See also the `std::f64` module](f64/index.html).*
    ///
    #[stable(feature = "rust1", since = "1.0.0")]
    mod prim_f64 { }

    #[doc(primitive = "i8")]
    //
    /// The 8-bit signed integer type.
    ///
    /// *[See also the `std::i8` module](i8/index.html).*
    #[stable(feature = "rust1", since = "1.0.0")]
    mod prim_i8 { }

    #[doc(primitive = "i16")]
    //
    /// The 16-bit signed integer type.
    ///
    /// *[See also the `std::i16` module](i16/index.html).*
    #[stable(feature = "rust1", since = "1.0.0")]
    mod prim_i16 { }

    #[doc(primitive = "i32")]
    //
    /// The 32-bit signed integer type.
    ///
    /// *[See also the `std::i32` module](i32/index.html).*
    #[stable(feature = "rust1", since = "1.0.0")]
    mod prim_i32 { }

    #[doc(primitive = "i64")]
    //
    /// The 64-bit signed integer type.
    ///
    /// *[See also the `std::i64` module](i64/index.html).*
    #[stable(feature = "rust1", since = "1.0.0")]
    mod prim_i64 { }

    #[doc(primitive = "i128")]
    //
    /// The 128-bit signed integer type.
    ///
    /// *[See also the `std::i128` module](i128/index.html).*
    #[stable(feature = "i128", since="1.26.0")]
    mod prim_i128 { }

    #[doc(primitive = "u8")]
    //
    /// The 8-bit unsigned integer type.
    ///
    /// *[See also the `std::u8` module](u8/index.html).*
    #[stable(feature = "rust1", since = "1.0.0")]
    mod prim_u8 { }

    #[doc(primitive = "u16")]
    //
    /// The 16-bit unsigned integer type.
    ///
    /// *[See also the `std::u16` module](u16/index.html).*
    #[stable(feature = "rust1", since = "1.0.0")]
    mod prim_u16 { }

    #[doc(primitive = "u32")]
    //
    /// The 32-bit unsigned integer type.
    ///
    /// *[See also the `std::u32` module](u32/index.html).*
    #[stable(feature = "rust1", since = "1.0.0")]
    mod prim_u32 { }

    #[doc(primitive = "u64")]
    //
    /// The 64-bit unsigned integer type.
    ///
    /// *[See also the `std::u64` module](u64/index.html).*
    #[stable(feature = "rust1", since = "1.0.0")]
    mod prim_u64 { }

    #[doc(primitive = "u128")]
    //
    /// The 128-bit unsigned integer type.
    ///
    /// *[See also the `std::u128` module](u128/index.html).*
    #[stable(feature = "i128", since="1.26.0")]
    mod prim_u128 { }

    #[doc(primitive = "isize")]
    //
    /// The pointer-sized signed integer type.
    ///
    /// *[See also the `std::isize` module](isize/index.html).*
    ///
    /// The size of this primitive is how many bytes it takes to reference any
    /// location in memory. For example, on a 32 bit target, this is 4 bytes
    /// and on a 64 bit target, this is 8 bytes.
    #[stable(feature = "rust1", since = "1.0.0")]
    mod prim_isize { }

    #[doc(primitive = "usize")]
    //
    /// The pointer-sized unsigned integer type.
    ///
    /// *[See also the `std::usize` module](usize/index.html).*
    ///
    /// The size of this primitive is how many bytes it takes to reference any
    /// location in memory. For example, on a 32 bit target, this is 4 bytes
    /// and on a 64 bit target, this is 8 bytes.
    #[stable(feature = "rust1", since = "1.0.0")]
    mod prim_usize { }

    #[doc(primitive = "reference")]
    #[doc(alias = "&")]
    //
    /// References, both shared and mutable.
    ///
    /// A reference represents a borrow of some owned value. You can get one by using the `&` or `&mut`
    /// operators on a value, or by using a `ref` or `ref mut` pattern.
    ///
    /// For those familiar with pointers, a reference is just a pointer that is assumed to not be null.
    /// In fact, `Option<&T>` has the same memory representation as a nullable pointer, and can be
    /// passed across FFI boundaries as such.
    ///
    /// In most cases, references can be used much like the original value. Field access, method
    /// calling, and indexing work the same (save for mutability rules, of course). In addition, the
    /// comparison operators transparently defer to the referent's implementation, allowing references
    /// to be compared the same as owned values.
    ///
    /// References have a lifetime attached to them, which represents the scope for which the borrow is
    /// valid. A lifetime is said to "outlive" another one if its representative scope is as long or
    /// longer than the other. The `'static` lifetime is the longest lifetime, which represents the
    /// total life of the program. For example, string literals have a `'static` lifetime because the
    /// text data is embedded into the binary of the program, rather than in an allocation that needs
    /// to be dynamically managed.
    ///
    /// `&mut T` references can be freely coerced into `&T` references with the same referent type, and
    /// references with longer lifetimes can be freely coerced into references with shorter ones.
    ///
    /// Reference equality by address, instead of comparing the values pointed to, is accomplished via
    /// implicit reference-pointer coercion and raw pointer equality via [`ptr::eq`], while
    /// [`PartialEq`] compares values.
    ///
    /// [`ptr::eq`]: ptr/fn.eq.html
    /// [`PartialEq`]: cmp/trait.PartialEq.html
    ///
    /// ```
    /// use std::ptr;
    ///
    /// let five = 5;
    /// let other_five = 5;
    /// let five_ref = &five;
    /// let same_five_ref = &five;
    /// let other_five_ref = &other_five;
    ///
    /// assert!(five_ref == same_five_ref);
    /// assert!(five_ref == other_five_ref);
    ///
    /// assert!(ptr::eq(five_ref, same_five_ref));
    /// assert!(!ptr::eq(five_ref, other_five_ref));
    /// ```
    ///
    /// For more information on how to use references, see [the book's section on "References and
    /// Borrowing"][book-refs].
    ///
    /// [book-refs]: ../book/ch04-02-references-and-borrowing.html
    ///
    /// # Trait implementations
    ///
    /// The following traits are implemented for all `&T`, regardless of the type of its referent:
    ///
    /// * [`Copy`]
    /// * [`Clone`] \(Note that this will not defer to `T`'s `Clone` implementation if it exists!)
    /// * [`Deref`]
    /// * [`Borrow`]
    /// * [`Pointer`]
    ///
    /// [`Copy`]: marker/trait.Copy.html
    /// [`Clone`]: clone/trait.Clone.html
    /// [`Deref`]: ops/trait.Deref.html
    /// [`Borrow`]: borrow/trait.Borrow.html
    /// [`Pointer`]: fmt/trait.Pointer.html
    ///
    /// `&mut T` references get all of the above except `Copy` and `Clone` (to prevent creating
    /// multiple simultaneous mutable borrows), plus the following, regardless of the type of its
    /// referent:
    ///
    /// * [`DerefMut`]
    /// * [`BorrowMut`]
    ///
    /// [`DerefMut`]: ops/trait.DerefMut.html
    /// [`BorrowMut`]: borrow/trait.BorrowMut.html
    ///
    /// The following traits are implemented on `&T` references if the underlying `T` also implements
    /// that trait:
    ///
    /// * All the traits in [`std::fmt`] except [`Pointer`] and [`fmt::Write`]
    /// * [`PartialOrd`]
    /// * [`Ord`]
    /// * [`PartialEq`]
    /// * [`Eq`]
    /// * [`AsRef`]
    /// * [`Fn`] \(in addition, `&T` references get [`FnMut`] and [`FnOnce`] if `T: Fn`)
    /// * [`Hash`]
    /// * [`ToSocketAddrs`]
    ///
    /// [`std::fmt`]: fmt/index.html
    /// [`fmt::Write`]: fmt/trait.Write.html
    /// [`PartialOrd`]: cmp/trait.PartialOrd.html
    /// [`Ord`]: cmp/trait.Ord.html
    /// [`PartialEq`]: cmp/trait.PartialEq.html
    /// [`Eq`]: cmp/trait.Eq.html
    /// [`AsRef`]: convert/trait.AsRef.html
    /// [`Fn`]: ops/trait.Fn.html
    /// [`FnMut`]: ops/trait.FnMut.html
    /// [`FnOnce`]: ops/trait.FnOnce.html
    /// [`Hash`]: hash/trait.Hash.html
    /// [`ToSocketAddrs`]: net/trait.ToSocketAddrs.html
    ///
    /// `&mut T` references get all of the above except `ToSocketAddrs`, plus the following, if `T`
    /// implements that trait:
    ///
    /// * [`AsMut`]
    /// * [`FnMut`] \(in addition, `&mut T` references get [`FnOnce`] if `T: FnMut`)
    /// * [`fmt::Write`]
    /// * [`Iterator`]
    /// * [`DoubleEndedIterator`]
    /// * [`ExactSizeIterator`]
    /// * [`FusedIterator`]
    /// * [`TrustedLen`]
    /// * [`Send`] \(note that `&T` references only get `Send` if `T: Sync`)
    /// * [`io::Write`]
    /// * [`Read`]
    /// * [`Seek`]
    /// * [`BufRead`]
    ///
    /// [`AsMut`]: convert/trait.AsMut.html
    /// [`Iterator`]: iter/trait.Iterator.html
    /// [`DoubleEndedIterator`]: iter/trait.DoubleEndedIterator.html
    /// [`ExactSizeIterator`]: iter/trait.ExactSizeIterator.html
    /// [`FusedIterator`]: iter/trait.FusedIterator.html
    /// [`TrustedLen`]: iter/trait.TrustedLen.html
    /// [`Send`]: marker/trait.Send.html
    /// [`io::Write`]: io/trait.Write.html
    /// [`Read`]: io/trait.Read.html
    /// [`Seek`]: io/trait.Seek.html
    /// [`BufRead`]: io/trait.BufRead.html
    ///
    /// Note that due to method call deref coercion, simply calling a trait method will act like they
    /// work on references as well as they do on owned values! The implementations described here are
    /// meant for generic contexts, where the final type `T` is a type parameter or otherwise not
    /// locally known.
    #[stable(feature = "rust1", since = "1.0.0")]
    mod prim_ref { }

    #[doc(primitive = "fn")]
    //
    /// Function pointers, like `fn(usize) -> bool`.
    ///
    /// *See also the traits [`Fn`], [`FnMut`], and [`FnOnce`].*
    ///
    /// [`Fn`]: ops/trait.Fn.html
    /// [`FnMut`]: ops/trait.FnMut.html
    /// [`FnOnce`]: ops/trait.FnOnce.html
    ///
    /// Plain function pointers are obtained by casting either plain functions, or closures that don't
    /// capture an environment:
    ///
    /// ```
    /// fn add_one(x: usize) -> usize {
    ///     x + 1
    /// }
    ///
    /// let ptr: fn(usize) -> usize = add_one;
    /// assert_eq!(ptr(5), 6);
    ///
    /// let clos: fn(usize) -> usize = |x| x + 5;
    /// assert_eq!(clos(5), 10);
    /// ```
    ///
    /// In addition to varying based on their signature, function pointers come in two flavors: safe
    /// and unsafe. Plain `fn()` function pointers can only point to safe functions,
    /// while `unsafe fn()` function pointers can point to safe or unsafe functions.
    ///
    /// ```
    /// fn add_one(x: usize) -> usize {
    ///     x + 1
    /// }
    ///
    /// unsafe fn add_one_unsafely(x: usize) -> usize {
    ///     x + 1
    /// }
    ///
    /// let safe_ptr: fn(usize) -> usize = add_one;
    ///
    /// //ERROR: mismatched types: expected normal fn, found unsafe fn
    /// //let bad_ptr: fn(usize) -> usize = add_one_unsafely;
    ///
    /// let unsafe_ptr: unsafe fn(usize) -> usize = add_one_unsafely;
    /// let really_safe_ptr: unsafe fn(usize) -> usize = add_one;
    /// ```
    ///
    /// On top of that, function pointers can vary based on what ABI they use. This is achieved by
    /// adding the `extern` keyword to the type name, followed by the ABI in question. For example,
    /// `fn()` is different from `extern "C" fn()`, which itself is different from `extern "stdcall"
    /// fn()`, and so on for the various ABIs that Rust supports.  Non-`extern` functions have an ABI
    /// of `"Rust"`, and `extern` functions without an explicit ABI have an ABI of `"C"`. For more
    /// information, see [the nomicon's section on foreign calling conventions][nomicon-abi].
    ///
    /// [nomicon-abi]: ../nomicon/ffi.html#foreign-calling-conventions
    ///
    /// Extern function declarations with the "C" or "cdecl" ABIs can also be *variadic*, allowing them
    /// to be called with a variable number of arguments. Normal rust functions, even those with an
    /// `extern "ABI"`, cannot be variadic. For more information, see [the nomicon's section on
    /// variadic functions][nomicon-variadic].
    ///
    /// [nomicon-variadic]: ../nomicon/ffi.html#variadic-functions
    ///
    /// These markers can be combined, so `unsafe extern "stdcall" fn()` is a valid type.
    ///
    /// Like references in rust, function pointers are assumed to not be null, so if you want to pass a
    /// function pointer over FFI and be able to accommodate null pointers, make your type
    /// `Option<fn()>` with your required signature.
    ///
    /// Function pointers implement the following traits:
    ///
    /// * [`Clone`]
    /// * [`PartialEq`]
    /// * [`Eq`]
    /// * [`PartialOrd`]
    /// * [`Ord`]
    /// * [`Hash`]
    /// * [`Pointer`]
    /// * [`Debug`]
    ///
    /// [`Clone`]: clone/trait.Clone.html
    /// [`PartialEq`]: cmp/trait.PartialEq.html
    /// [`Eq`]: cmp/trait.Eq.html
    /// [`PartialOrd`]: cmp/trait.PartialOrd.html
    /// [`Ord`]: cmp/trait.Ord.html
    /// [`Hash`]: hash/trait.Hash.html
    /// [`Pointer`]: fmt/trait.Pointer.html
    /// [`Debug`]: fmt/trait.Debug.html
    ///
    /// Due to a temporary restriction in Rust's type system, these traits are only implemented on
    /// functions that take 12 arguments or less, with the `"Rust"` and `"C"` ABIs. In the future, this
    /// may change.
    ///
    /// In addition, function pointers of *any* signature, ABI, or safety are [`Copy`], and all *safe*
    /// function pointers implement [`Fn`], [`FnMut`], and [`FnOnce`]. This works because these traits
    /// are specially known to the compiler.
    ///
    /// [`Copy`]: marker/trait.Copy.html
    #[stable(feature = "rust1", since = "1.0.0")]
    mod prim_fn { }

# Help

## Keyboard Shortcuts

`?`
  Show this help dialog
`S`
  Focus the search field
`↑`
  Move up in search results
`↓`
  Move down in search results
`↹`
  Switch tab
`⏎`
  Go to active search result
`+`
  Expand all sections
`-`
  Collapse all sections

## Search Tricks

Prefix searches with a type followed by a colon (e.g., `fn:`) to restrict the search to a given type.

Accepted types are: `fn`, `mod`, `struct`, `enum`, `trait`, `type`, `macro`, and `const`.

Search functions by type signature (e.g., `vec -> usize` or `* -> vec`)

Search multiple things at once by splitting your query with comma (e.g., `str,u8` or `String,struct:Vec,test`)