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
use super::*;
use crate::cmp::Ordering::{self, Equal, Greater, Less};
use crate::intrinsics;
use crate::mem;
use crate::slice::{self, SliceIndex};

#[lang = "const_ptr"]
impl<T: ?Sized> *const T {
    /// Returns `true` if the pointer is null.
    ///
    /// Note that unsized types have many possible null pointers, as only the
    /// raw data pointer is considered, not their length, vtable, etc.
    /// Therefore, two pointers that are null may still not compare equal to
    /// each other.
    ///
    /// ## Behavior during const evaluation
    ///
    /// When this function is used during const evaluation, it may return `false` for pointers
    /// that turn out to be null at runtime. Specifically, when a pointer to some memory
    /// is offset beyond its bounds in such a way that the resulting pointer is null,
    /// the function will still return `false`. There is no way for CTFE to know
    /// the absolute position of that memory, so we cannot tell if the pointer is
    /// null or not.
    ///
    /// # Examples
    ///
    /// Basic usage:
    ///
    /// ```
    /// let s: &str = "Follow the rabbit";
    /// let ptr: *const u8 = s.as_ptr();
    /// assert!(!ptr.is_null());
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    #[rustc_const_unstable(feature = "const_ptr_is_null", issue = "74939")]
    #[inline]
    pub const fn is_null(self) -> bool {
        // Compare via a cast to a thin pointer, so fat pointers are only
        // considering their "data" part for null-ness.
        (self as *const u8).guaranteed_eq(null())
    }

    /// Casts to a pointer of another type.
    #[stable(feature = "ptr_cast", since = "1.38.0")]
    #[rustc_const_stable(feature = "const_ptr_cast", since = "1.38.0")]
    #[inline]
    pub const fn cast<U>(self) -> *const U {
        self as _
    }

    /// Decompose a (possibly wide) pointer into its address and metadata components.
    ///
    /// The pointer can be later reconstructed with [`from_raw_parts`].
    #[unstable(feature = "ptr_metadata", issue = "81513")]
    #[rustc_const_unstable(feature = "ptr_metadata", issue = "81513")]
    #[inline]
    pub const fn to_raw_parts(self) -> (*const (), <T as super::Pointee>::Metadata) {
        (self.cast(), metadata(self))
    }

    /// Returns `None` if the pointer is null, or else returns a shared reference to
    /// the value wrapped in `Some`. If the value may be uninitialized, [`as_uninit_ref`]
    /// must be used instead.
    ///
    /// [`as_uninit_ref`]: #method.as_uninit_ref
    ///
    /// # Safety
    ///
    /// When calling this method, you have to ensure that *either* the pointer is null *or*
    /// all of the following is true:
    ///
    /// * The pointer must be properly aligned.
    ///
    /// * It must be "dereferencable" in the sense defined in [the module documentation].
    ///
    /// * The pointer must point to an initialized instance of `T`.
    ///
    /// * You must enforce Rust's aliasing rules, since the returned lifetime `'a` is
    ///   arbitrarily chosen and does not necessarily reflect the actual lifetime of the data.
    ///   In particular, for the duration of this lifetime, the memory the pointer points to must
    ///   not get mutated (except inside `UnsafeCell`).
    ///
    /// This applies even if the result of this method is unused!
    /// (The part about being initialized is not yet fully decided, but until
    /// it is, the only safe approach is to ensure that they are indeed initialized.)
    ///
    /// [the module documentation]: crate::ptr#safety
    ///
    /// # Examples
    ///
    /// Basic usage:
    ///
    /// ```
    /// let ptr: *const u8 = &10u8 as *const u8;
    ///
    /// unsafe {
    ///     if let Some(val_back) = ptr.as_ref() {
    ///         println!("We got back the value: {}!", val_back);
    ///     }
    /// }
    /// ```
    ///
    /// # Null-unchecked version
    ///
    /// If you are sure the pointer can never be null and are looking for some kind of
    /// `as_ref_unchecked` that returns the `&T` instead of `Option<&T>`, know that you can
    /// dereference the pointer directly.
    ///
    /// ```
    /// let ptr: *const u8 = &10u8 as *const u8;
    ///
    /// unsafe {
    ///     let val_back = &*ptr;
    ///     println!("We got back the value: {}!", val_back);
    /// }
    /// ```
    #[stable(feature = "ptr_as_ref", since = "1.9.0")]
    #[inline]
    pub unsafe fn as_ref<'a>(self) -> Option<&'a T> {
        // SAFETY: the caller must guarantee that `self` is valid
        // for a reference if it isn't null.
        if self.is_null() { None } else { unsafe { Some(&*self) } }
    }

    /// Returns `None` if the pointer is null, or else returns a shared reference to
    /// the value wrapped in `Some`. In contrast to [`as_ref`], this does not require
    /// that the value has to be initialized.
    ///
    /// [`as_ref`]: #method.as_ref
    ///
    /// # Safety
    ///
    /// When calling this method, you have to ensure that *either* the pointer is null *or*
    /// all of the following is true:
    ///
    /// * The pointer must be properly aligned.
    ///
    /// * It must be "dereferencable" in the sense defined in [the module documentation].
    ///
    /// * You must enforce Rust's aliasing rules, since the returned lifetime `'a` is
    ///   arbitrarily chosen and does not necessarily reflect the actual lifetime of the data.
    ///   In particular, for the duration of this lifetime, the memory the pointer points to must
    ///   not get mutated (except inside `UnsafeCell`).
    ///
    /// This applies even if the result of this method is unused!
    ///
    /// [the module documentation]: crate::ptr#safety
    ///
    /// # Examples
    ///
    /// Basic usage:
    ///
    /// ```
    /// #![feature(ptr_as_uninit)]
    ///
    /// let ptr: *const u8 = &10u8 as *const u8;
    ///
    /// unsafe {
    ///     if let Some(val_back) = ptr.as_uninit_ref() {
    ///         println!("We got back the value: {}!", val_back.assume_init());
    ///     }
    /// }
    /// ```
    #[inline]
    #[unstable(feature = "ptr_as_uninit", issue = "75402")]
    pub unsafe fn as_uninit_ref<'a>(self) -> Option<&'a MaybeUninit<T>>
    where
        T: Sized,
    {
        // SAFETY: the caller must guarantee that `self` meets all the
        // requirements for a reference.
        if self.is_null() { None } else { Some(unsafe { &*(self as *const MaybeUninit<T>) }) }
    }

    /// Calculates the offset from a pointer.
    ///
    /// `count` is in units of T; e.g., a `count` of 3 represents a pointer
    /// offset of `3 * size_of::<T>()` bytes.
    ///
    /// # Safety
    ///
    /// If any of the following conditions are violated, the result is Undefined
    /// Behavior:
    ///
    /// * Both the starting and resulting pointer must be either in bounds or one
    ///   byte past the end of the same [allocated object].
    ///
    /// * The computed offset, **in bytes**, cannot overflow an `isize`.
    ///
    /// * The offset being in bounds cannot rely on "wrapping around" the address
    ///   space. That is, the infinite-precision sum, **in bytes** must fit in a usize.
    ///
    /// The compiler and standard library generally tries to ensure allocations
    /// never reach a size where an offset is a concern. For instance, `Vec`
    /// and `Box` ensure they never allocate more than `isize::MAX` bytes, so
    /// `vec.as_ptr().add(vec.len())` is always safe.
    ///
    /// Most platforms fundamentally can't even construct such an allocation.
    /// For instance, no known 64-bit platform can ever serve a request
    /// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space.
    /// However, some 32-bit and 16-bit platforms may successfully serve a request for
    /// more than `isize::MAX` bytes with things like Physical Address
    /// Extension. As such, memory acquired directly from allocators or memory
    /// mapped files *may* be too large to handle with this function.
    ///
    /// Consider using [`wrapping_offset`] instead if these constraints are
    /// difficult to satisfy. The only advantage of this method is that it
    /// enables more aggressive compiler optimizations.
    ///
    /// [`wrapping_offset`]: #method.wrapping_offset
    /// [allocated object]: crate::ptr#allocated-object
    ///
    /// # Examples
    ///
    /// Basic usage:
    ///
    /// ```
    /// let s: &str = "123";
    /// let ptr: *const u8 = s.as_ptr();
    ///
    /// unsafe {
    ///     println!("{}", *ptr.offset(1) as char);
    ///     println!("{}", *ptr.offset(2) as char);
    /// }
    /// ```
    #[stable(feature = "rust1", since = "1.0.0")]
    #[must_use = "returns a new pointer rather than modifying its argument"]
    #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
    #[inline(always)]
    pub const unsafe fn offset(self, count: isize) -> *const T
    where
        T: Sized,
    {
        // SAFETY: the caller must uphold the safety contract for `offset`.
        unsafe { intrinsics::offset(self, count) }
    }

    /// Calculates the offset from a pointer using wrapping arithmetic.
    ///
    /// `count` is in units of T; e.g., a `count` of 3 represents a pointer
    /// offset of `3 * size_of::<T>()` bytes.
    ///
    /// # Safety
    ///
    /// This operation itself is always safe, but using the resulting pointer is not.
    ///
    /// The resulting pointer "remembers" the [allocated object] that `self` points to; it must not
    /// be used to read or write other allocated objects.
    ///
    /// In other words, `let z = x.wrapping_offset((y as isize) - (x as isize))` does *not* make `z`
    /// the same as `y` even if we assume `T` has size `1` and there is no overflow: `z` is still
    /// attached to the object `x` is attached to, and dereferencing it is Undefined Behavior unless
    /// `x` and `y` point into the same allocated object.
    ///
    /// Compared to [`offset`], this method basically delays the requirement of staying within the
    /// same allocated object: [`offset`] is immediate Undefined Behavior when crossing object
    /// boundaries; `wrapping_offset` produces a pointer but still leads to Undefined Behavior if a
    /// pointer is dereferenced when it is out-of-bounds of the object it is attached to. [`offset`]
    /// can be optimized better and is thus preferable in performance-sensitive code.
    ///
    /// The delayed check only considers the value of the pointer that was dereferenced, not the
    /// intermediate values used during the computation of the final result. For example,
    /// `x.wrapping_offset(o).wrapping_offset(o.wrapping_neg())` is always the same as `x`. In other
    /// words, leaving the allocated object and then re-entering it later is permitted.
    ///
    /// [`offset`]: #method.offset
    /// [allocated object]: crate::ptr#allocated-object
    ///
    /// # Examples
    ///
    /// Basic usage:
    ///
    /// ```
    /// // Iterate using a raw pointer in increments of two elements
    /// let data = [1u8, 2, 3, 4, 5];
    /// let mut ptr: *const u8 = data.as_ptr();
    /// let step = 2;
    /// let end_rounded_up = ptr.wrapping_offset(6);
    ///
    /// // This loop prints "1, 3, 5, "
    /// while ptr != end_rounded_up {
    ///     unsafe {
    ///         print!("{}, ", *ptr);
    ///     }
    ///     ptr = ptr.wrapping_offset(step);
    /// }
    /// ```
    #[stable(feature = "ptr_wrapping_offset", since = "1.16.0")]
    #[must_use = "returns a new pointer rather than modifying its argument"]
    #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
    #[inline(always)]
    pub const fn wrapping_offset(self, count: isize) -> *const T
    where
        T: Sized,
    {
        // SAFETY: the `arith_offset` intrinsic has no prerequisites to be called.
        unsafe { intrinsics::arith_offset(self, count) }
    }

    /// Calculates the distance between two pointers. The returned value is in
    /// units of T: the distance in bytes is divided by `mem::size_of::<T>()`.
    ///
    /// This function is the inverse of [`offset`].
    ///
    /// [`offset`]: #method.offset
    ///
    /// # Safety
    ///
    /// If any of the following conditions are violated, the result is Undefined
    /// Behavior:
    ///
    /// * Both the starting and other pointer must be either in bounds or one
    ///   byte past the end of the same [allocated object].
    ///
    /// * Both pointers must be *derived from* a pointer to the same object.
    ///   (See below for an example.)
    ///
    /// * The distance between the pointers, in bytes, must be an exact multiple
    ///   of the size of `T`.
    ///
    /// * The distance between the pointers, **in bytes**, cannot overflow an `isize`.
    ///
    /// * The distance being in bounds cannot rely on "wrapping around" the address space.
    ///
    /// Rust types are never larger than `isize::MAX` and Rust allocations never wrap around the
    /// address space, so two pointers within some value of any Rust type `T` will always satisfy
    /// the last two conditions. The standard library also generally ensures that allocations
    /// never reach a size where an offset is a concern. For instance, `Vec` and `Box` ensure they
    /// never allocate more than `isize::MAX` bytes, so `ptr_into_vec.offset_from(vec.as_ptr())`
    /// always satisfies the last two conditions.
    ///
    /// Most platforms fundamentally can't even construct such a large allocation.
    /// For instance, no known 64-bit platform can ever serve a request
    /// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space.
    /// However, some 32-bit and 16-bit platforms may successfully serve a request for
    /// more than `isize::MAX` bytes with things like Physical Address
    /// Extension. As such, memory acquired directly from allocators or memory
    /// mapped files *may* be too large to handle with this function.
    /// (Note that [`offset`] and [`add`] also have a similar limitation and hence cannot be used on
    /// such large allocations either.)
    ///
    /// [`add`]: #method.add
    /// [allocated object]: crate::ptr#allocated-object
    ///
    /// # Panics
    ///
    /// This function panics if `T` is a Zero-Sized Type ("ZST").
    ///
    /// # Examples
    ///
    /// Basic usage:
    ///
    /// ```
    /// let a = [0; 5];
    /// let ptr1: *const i32 = &a[1];
    /// let ptr2: *const i32 = &a[3];
    /// unsafe {
    ///     assert_eq!(ptr2.offset_from(ptr1), 2);
    ///     assert_eq!(ptr1.offset_from(ptr2), -2);
    ///     assert_eq!(ptr1.offset(2), ptr2);
    ///     assert_eq!(ptr2.offset(-2), ptr1);
    /// }
    /// ```
    ///
    /// *Incorrect* usage:
    ///
    /// ```rust,no_run
    /// let ptr1 = Box::into_raw(Box::new(0u8)) as *const u8;
    /// let ptr2 = Box::into_raw(Box::new(1u8)) as *const u8;
    /// let diff = (ptr2 as isize).wrapping_sub(ptr1 as isize);
    /// // Make ptr2_other an "alias" of ptr2, but derived from ptr1.
    /// let ptr2_other = (ptr1 as *const u8).wrapping_offset(diff);
    /// assert_eq!(ptr2 as usize, ptr2_other as usize);
    /// // Since ptr2_other and ptr2 are derived from pointers to different objects,
    /// // computing their offset is undefined behavior, even though
    /// // they point to the same address!
    /// unsafe {
    ///     let zero = ptr2_other.offset_from(ptr2); // Undefined Behavior
    /// }
    /// ```
    #[stable(feature = "ptr_offset_from", since = "1.47.0")]
    #[rustc_const_unstable(feature = "const_ptr_offset_from", issue = "41079")]
    #[inline]
    pub const unsafe fn offset_from(self, origin: *const T) -> isize
    where
        T: Sized,
    {
        let pointee_size = mem::size_of::<T>();
        assert!(0 < pointee_size && pointee_size <= isize::MAX as usize);
        // SAFETY: the caller must uphold the safety contract for `ptr_offset_from`.
        unsafe { intrinsics::ptr_offset_from(self, origin) }
    }

    /// Returns whether two pointers are guaranteed to be equal.
    ///
    /// At runtime this function behaves like `self == other`.
    /// However, in some contexts (e.g., compile-time evaluation),
    /// it is not always possible to determine equality of two pointers, so this function may
    /// spuriously return `false` for pointers that later actually turn out to be equal.
    /// But when it returns `true`, the pointers are guaranteed to be equal.
    ///
    /// This function is the mirror of [`guaranteed_ne`], but not its inverse. There are pointer
    /// comparisons for which both functions return `false`.
    ///
    /// [`guaranteed_ne`]: #method.guaranteed_ne
    ///
    /// The return value may change depending on the compiler version and unsafe code might not
    /// rely on the result of this function for soundness. It is suggested to only use this function
    /// for performance optimizations where spurious `false` return values by this function do not
    /// affect the outcome, but just the performance.
    /// The consequences of using this method to make runtime and compile-time code behave
    /// differently have not been explored. This method should not be used to introduce such
    /// differences, and it should also not be stabilized before we have a better understanding
    /// of this issue.
    #[unstable(feature = "const_raw_ptr_comparison", issue = "53020")]
    #[rustc_const_unstable(feature = "const_raw_ptr_comparison", issue = "53020")]
    #[inline]
    pub const fn guaranteed_eq(self, other: *const T) -> bool
    where
        T: Sized,
    {
        intrinsics::ptr_guaranteed_eq(self, other)
    }

    /// Returns whether two pointers are guaranteed to be unequal.
    ///
    /// At runtime this function behaves like `self != other`.
    /// However, in some contexts (e.g., compile-time evaluation),
    /// it is not always possible to determine the inequality of two pointers, so this function may
    /// spuriously return `false` for pointers that later actually turn out to be unequal.
    /// But when it returns `true`, the pointers are guaranteed to be unequal.
    ///
    /// This function is the mirror of [`guaranteed_eq`], but not its inverse. There are pointer
    /// comparisons for which both functions return `false`.
    ///
    /// [`guaranteed_eq`]: #method.guaranteed_eq
    ///
    /// The return value may change depending on the compiler version and unsafe code might not
    /// rely on the result of this function for soundness. It is suggested to only use this function
    /// for performance optimizations where spurious `false` return values by this function do not
    /// affect the outcome, but just the performance.
    /// The consequences of using this method to make runtime and compile-time code behave
    /// differently have not been explored. This method should not be used to introduce such
    /// differences, and it should also not be stabilized before we have a better understanding
    /// of this issue.
    #[unstable(feature = "const_raw_ptr_comparison", issue = "53020")]
    #[rustc_const_unstable(feature = "const_raw_ptr_comparison", issue = "53020")]
    #[inline]
    pub const fn guaranteed_ne(self, other: *const T) -> bool
    where
        T: Sized,
    {
        intrinsics::ptr_guaranteed_ne(self, other)
    }

    /// Calculates the offset from a pointer (convenience for `.offset(count as isize)`).
    ///
    /// `count` is in units of T; e.g., a `count` of 3 represents a pointer
    /// offset of `3 * size_of::<T>()` bytes.
    ///
    /// # Safety
    ///
    /// If any of the following conditions are violated, the result is Undefined
    /// Behavior:
    ///
    /// * Both the starting and resulting pointer must be either in bounds or one
    ///   byte past the end of the same [allocated object].
    ///
    /// * The computed offset, **in bytes**, cannot overflow an `isize`.
    ///
    /// * The offset being in bounds cannot rely on "wrapping around" the address
    ///   space. That is, the infinite-precision sum must fit in a `usize`.
    ///
    /// The compiler and standard library generally tries to ensure allocations
    /// never reach a size where an offset is a concern. For instance, `Vec`
    /// and `Box` ensure they never allocate more than `isize::MAX` bytes, so
    /// `vec.as_ptr().add(vec.len())` is always safe.
    ///
    /// Most platforms fundamentally can't even construct such an allocation.
    /// For instance, no known 64-bit platform can ever serve a request
    /// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space.
    /// However, some 32-bit and 16-bit platforms may successfully serve a request for
    /// more than `isize::MAX` bytes with things like Physical Address
    /// Extension. As such, memory acquired directly from allocators or memory
    /// mapped files *may* be too large to handle with this function.
    ///
    /// Consider using [`wrapping_add`] instead if these constraints are
    /// difficult to satisfy. The only advantage of this method is that it
    /// enables more aggressive compiler optimizations.
    ///
    /// [`wrapping_add`]: #method.wrapping_add
    /// [allocated object]: crate::ptr#allocated-object
    ///
    /// # Examples
    ///
    /// Basic usage:
    ///
    /// ```
    /// let s: &str = "123";
    /// let ptr: *const u8 = s.as_ptr();
    ///
    /// unsafe {
    ///     println!("{}", *ptr.add(1) as char);
    ///     println!("{}", *ptr.add(2) as char);
    /// }
    /// ```
    #[stable(feature = "pointer_methods", since = "1.26.0")]
    #[must_use = "returns a new pointer rather than modifying its argument"]
    #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
    #[inline(always)]
    pub const unsafe fn add(self, count: usize) -> Self
    where
        T: Sized,
    {
        // SAFETY: the caller must uphold the safety contract for `offset`.
        unsafe { self.offset(count as isize) }
    }

    /// Calculates the offset from a pointer (convenience for
    /// `.offset((count as isize).wrapping_neg())`).
    ///
    /// `count` is in units of T; e.g., a `count` of 3 represents a pointer
    /// offset of `3 * size_of::<T>()` bytes.
    ///
    /// # Safety
    ///
    /// If any of the following conditions are violated, the result is Undefined
    /// Behavior:
    ///
    /// * Both the starting and resulting pointer must be either in bounds or one
    ///   byte past the end of the same [allocated object].
    ///
    /// * The computed offset cannot exceed `isize::MAX` **bytes**.
    ///
    /// * The offset being in bounds cannot rely on "wrapping around" the address
    ///   space. That is, the infinite-precision sum must fit in a usize.
    ///
    /// The compiler and standard library generally tries to ensure allocations
    /// never reach a size where an offset is a concern. For instance, `Vec`
    /// and `Box` ensure they never allocate more than `isize::MAX` bytes, so
    /// `vec.as_ptr().add(vec.len()).sub(vec.len())` is always safe.
    ///
    /// Most platforms fundamentally can't even construct such an allocation.
    /// For instance, no known 64-bit platform can ever serve a request
    /// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space.
    /// However, some 32-bit and 16-bit platforms may successfully serve a request for
    /// more than `isize::MAX` bytes with things like Physical Address
    /// Extension. As such, memory acquired directly from allocators or memory
    /// mapped files *may* be too large to handle with this function.
    ///
    /// Consider using [`wrapping_sub`] instead if these constraints are
    /// difficult to satisfy. The only advantage of this method is that it
    /// enables more aggressive compiler optimizations.
    ///
    /// [`wrapping_sub`]: #method.wrapping_sub
    /// [allocated object]: crate::ptr#allocated-object
    ///
    /// # Examples
    ///
    /// Basic usage:
    ///
    /// ```
    /// let s: &str = "123";
    ///
    /// unsafe {
    ///     let end: *const u8 = s.as_ptr().add(3);
    ///     println!("{}", *end.sub(1) as char);
    ///     println!("{}", *end.sub(2) as char);
    /// }
    /// ```
    #[stable(feature = "pointer_methods", since = "1.26.0")]
    #[must_use = "returns a new pointer rather than modifying its argument"]
    #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
    #[inline]
    pub const unsafe fn sub(self, count: usize) -> Self
    where
        T: Sized,
    {
        // SAFETY: the caller must uphold the safety contract for `offset`.
        unsafe { self.offset((count as isize).wrapping_neg()) }
    }

    /// Calculates the offset from a pointer using wrapping arithmetic.
    /// (convenience for `.wrapping_offset(count as isize)`)
    ///
    /// `count` is in units of T; e.g., a `count` of 3 represents a pointer
    /// offset of `3 * size_of::<T>()` bytes.
    ///
    /// # Safety
    ///
    /// This operation itself is always safe, but using the resulting pointer is not.
    ///
    /// The resulting pointer "remembers" the [allocated object] that `self` points to; it must not
    /// be used to read or write other allocated objects.
    ///
    /// In other words, `let z = x.wrapping_add((y as usize) - (x as usize))` does *not* make `z`
    /// the same as `y` even if we assume `T` has size `1` and there is no overflow: `z` is still
    /// attached to the object `x` is attached to, and dereferencing it is Undefined Behavior unless
    /// `x` and `y` point into the same allocated object.
    ///
    /// Compared to [`add`], this method basically delays the requirement of staying within the
    /// same allocated object: [`add`] is immediate Undefined Behavior when crossing object
    /// boundaries; `wrapping_add` produces a pointer but still leads to Undefined Behavior if a
    /// pointer is dereferenced when it is out-of-bounds of the object it is attached to. [`add`]
    /// can be optimized better and is thus preferable in performance-sensitive code.
    ///
    /// The delayed check only considers the value of the pointer that was dereferenced, not the
    /// intermediate values used during the computation of the final result. For example,
    /// `x.wrapping_add(o).wrapping_sub(o)` is always the same as `x`. In other words, leaving the
    /// allocated object and then re-entering it later is permitted.
    ///
    /// [`add`]: #method.add
    /// [allocated object]: crate::ptr#allocated-object
    ///
    /// # Examples
    ///
    /// Basic usage:
    ///
    /// ```
    /// // Iterate using a raw pointer in increments of two elements
    /// let data = [1u8, 2, 3, 4, 5];
    /// let mut ptr: *const u8 = data.as_ptr();
    /// let step = 2;
    /// let end_rounded_up = ptr.wrapping_add(6);
    ///
    /// // This loop prints "1, 3, 5, "
    /// while ptr != end_rounded_up {
    ///     unsafe {
    ///         print!("{}, ", *ptr);
    ///     }
    ///     ptr = ptr.wrapping_add(step);
    /// }
    /// ```
    #[stable(feature = "pointer_methods", since = "1.26.0")]
    #[must_use = "returns a new pointer rather than modifying its argument"]
    #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
    #[inline(always)]
    pub const fn wrapping_add(self, count: usize) -> Self
    where
        T: Sized,
    {
        self.wrapping_offset(count as isize)
    }

    /// Calculates the offset from a pointer using wrapping arithmetic.
    /// (convenience for `.wrapping_offset((count as isize).wrapping_neg())`)
    ///
    /// `count` is in units of T; e.g., a `count` of 3 represents a pointer
    /// offset of `3 * size_of::<T>()` bytes.
    ///
    /// # Safety
    ///
    /// This operation itself is always safe, but using the resulting pointer is not.
    ///
    /// The resulting pointer "remembers" the [allocated object] that `self` points to; it must not
    /// be used to read or write other allocated objects.
    ///
    /// In other words, `let z = x.wrapping_sub((x as usize) - (y as usize))` does *not* make `z`
    /// the same as `y` even if we assume `T` has size `1` and there is no overflow: `z` is still
    /// attached to the object `x` is attached to, and dereferencing it is Undefined Behavior unless
    /// `x` and `y` point into the same allocated object.
    ///
    /// Compared to [`sub`], this method basically delays the requirement of staying within the
    /// same allocated object: [`sub`] is immediate Undefined Behavior when crossing object
    /// boundaries; `wrapping_sub` produces a pointer but still leads to Undefined Behavior if a
    /// pointer is dereferenced when it is out-of-bounds of the object it is attached to. [`sub`]
    /// can be optimized better and is thus preferable in performance-sensitive code.
    ///
    /// The delayed check only considers the value of the pointer that was dereferenced, not the
    /// intermediate values used during the computation of the final result. For example,
    /// `x.wrapping_add(o).wrapping_sub(o)` is always the same as `x`. In other words, leaving the
    /// allocated object and then re-entering it later is permitted.
    ///
    /// [`sub`]: #method.sub
    /// [allocated object]: crate::ptr#allocated-object
    ///
    /// # Examples
    ///
    /// Basic usage:
    ///
    /// ```
    /// // Iterate using a raw pointer in increments of two elements (backwards)
    /// let data = [1u8, 2, 3, 4, 5];
    /// let mut ptr: *const u8 = data.as_ptr();
    /// let start_rounded_down = ptr.wrapping_sub(2);
    /// ptr = ptr.wrapping_add(4);
    /// let step = 2;
    /// // This loop prints "5, 3, 1, "
    /// while ptr != start_rounded_down {
    ///     unsafe {
    ///         print!("{}, ", *ptr);
    ///     }
    ///     ptr = ptr.wrapping_sub(step);
    /// }
    /// ```
    #[stable(feature = "pointer_methods", since = "1.26.0")]
    #[must_use = "returns a new pointer rather than modifying its argument"]
    #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
    #[inline]
    pub const fn wrapping_sub(self, count: usize) -> Self
    where
        T: Sized,
    {
        self.wrapping_offset((count as isize).wrapping_neg())
    }

    /// Sets the pointer value to `ptr`.
    ///
    /// In case `self` is a (fat) pointer to an unsized type, this operation
    /// will only affect the pointer part, whereas for (thin) pointers to
    /// sized types, this has the same effect as a simple assignment.
    ///
    /// The resulting pointer will have provenance of `val`, i.e., for a fat
    /// pointer, this operation is semantically the same as creating a new
    /// fat pointer with the data pointer value of `val` but the metadata of
    /// `self`.
    ///
    /// # Examples
    ///
    /// This function is primarily useful for allowing byte-wise pointer
    /// arithmetic on potentially fat pointers:
    ///
    /// ```
    /// #![feature(set_ptr_value)]
    /// # use core::fmt::Debug;
    /// let arr: [i32; 3] = [1, 2, 3];
    /// let mut ptr = arr.as_ptr() as *const dyn Debug;
    /// let thin = ptr as *const u8;
    /// unsafe {
    ///     ptr = ptr.set_ptr_value(thin.add(8));
    ///     # assert_eq!(*(ptr as *const i32), 3);
    ///     println!("{:?}", &*ptr); // will print "3"
    /// }
    /// ```
    #[unstable(feature = "set_ptr_value", issue = "75091")]
    #[must_use = "returns a new pointer rather than modifying its argument"]
    #[inline]
    pub fn set_ptr_value(mut self, val: *const u8) -> Self {
        let thin = &mut self as *mut *const T as *mut *const u8;
        // SAFETY: In case of a thin pointer, this operations is identical
        // to a simple assignment. In case of a fat pointer, with the current
        // fat pointer layout implementation, the first field of such a
        // pointer is always the data pointer, which is likewise assigned.
        unsafe { *thin = val };
        self
    }

    /// Reads the value from `self` without moving it. This leaves the
    /// memory in `self` unchanged.
    ///
    /// See [`ptr::read`] for safety concerns and examples.
    ///
    /// [`ptr::read`]: crate::ptr::read()
    #[stable(feature = "pointer_methods", since = "1.26.0")]
    #[rustc_const_unstable(feature = "const_ptr_read", issue = "80377")]
    #[inline]
    pub const unsafe fn read(self) -> T
    where
        T: Sized,
    {
        // SAFETY: the caller must uphold the safety contract for `read`.
        unsafe { read(self) }
    }

    /// Performs a volatile read of the value from `self` without moving it. This
    /// leaves the memory in `self` unchanged.
    ///
    /// Volatile operations are intended to act on I/O memory, and are guaranteed
    /// to not be elided or reordered by the compiler across other volatile
    /// operations.
    ///
    /// See [`ptr::read_volatile`] for safety concerns and examples.
    ///
    /// [`ptr::read_volatile`]: crate::ptr::read_volatile()
    #[stable(feature = "pointer_methods", since = "1.26.0")]
    #[inline]
    pub unsafe fn read_volatile(self) -> T
    where
        T: Sized,
    {
        // SAFETY: the caller must uphold the safety contract for `read_volatile`.
        unsafe { read_volatile(self) }
    }

    /// Reads the value from `self` without moving it. This leaves the
    /// memory in `self` unchanged.
    ///
    /// Unlike `read`, the pointer may be unaligned.
    ///
    /// See [`ptr::read_unaligned`] for safety concerns and examples.
    ///
    /// [`ptr::read_unaligned`]: crate::ptr::read_unaligned()
    #[stable(feature = "pointer_methods", since = "1.26.0")]
    #[rustc_const_unstable(feature = "const_ptr_read", issue = "80377")]
    #[inline]
    pub const unsafe fn read_unaligned(self) -> T
    where
        T: Sized,
    {
        // SAFETY: the caller must uphold the safety contract for `read_unaligned`.
        unsafe { read_unaligned(self) }
    }

    /// Copies `count * size_of<T>` bytes from `self` to `dest`. The source
    /// and destination may overlap.
    ///
    /// NOTE: this has the *same* argument order as [`ptr::copy`].
    ///
    /// See [`ptr::copy`] for safety concerns and examples.
    ///
    /// [`ptr::copy`]: crate::ptr::copy()
    #[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
    #[stable(feature = "pointer_methods", since = "1.26.0")]
    #[inline]
    pub const unsafe fn copy_to(self, dest: *mut T, count: usize)
    where
        T: Sized,
    {
        // SAFETY: the caller must uphold the safety contract for `copy`.
        unsafe { copy(self, dest, count) }
    }

    /// Copies `count * size_of<T>` bytes from `self` to `dest`. The source
    /// and destination may *not* overlap.
    ///
    /// NOTE: this has the *same* argument order as [`ptr::copy_nonoverlapping`].
    ///
    /// See [`ptr::copy_nonoverlapping`] for safety concerns and examples.
    ///
    /// [`ptr::copy_nonoverlapping`]: crate::ptr::copy_nonoverlapping()
    #[rustc_const_unstable(feature = "const_intrinsic_copy", issue = "80697")]
    #[stable(feature = "pointer_methods", since = "1.26.0")]
    #[inline]
    pub const unsafe fn copy_to_nonoverlapping(self, dest: *mut T, count: usize)
    where
        T: Sized,
    {
        // SAFETY: the caller must uphold the safety contract for `copy_nonoverlapping`.
        unsafe { copy_nonoverlapping(self, dest, count) }
    }

    /// Computes the offset that needs to be applied to the pointer in order to make it aligned to
    /// `align`.
    ///
    /// If it is not possible to align the pointer, the implementation returns
    /// `usize::MAX`. It is permissible for the implementation to *always*
    /// return `usize::MAX`. Only your algorithm's performance can depend
    /// on getting a usable offset here, not its correctness.
    ///
    /// The offset is expressed in number of `T` elements, and not bytes. The value returned can be
    /// used with the `wrapping_add` method.
    ///
    /// There are no guarantees whatsoever that offsetting the pointer will not overflow or go
    /// beyond the allocation that the pointer points into. It is up to the caller to ensure that
    /// the returned offset is correct in all terms other than alignment.
    ///
    /// # Panics
    ///
    /// The function panics if `align` is not a power-of-two.
    ///
    /// # Examples
    ///
    /// Accessing adjacent `u8` as `u16`
    ///
    /// ```
    /// # fn foo(n: usize) {
    /// # use std::mem::align_of;
    /// # unsafe {
    /// let x = [5u8, 6u8, 7u8, 8u8, 9u8];
    /// let ptr = x.as_ptr().add(n) as *const u8;
    /// let offset = ptr.align_offset(align_of::<u16>());
    /// if offset < x.len() - n - 1 {
    ///     let u16_ptr = ptr.add(offset) as *const u16;
    ///     assert_ne!(*u16_ptr, 500);
    /// } else {
    ///     // while the pointer can be aligned via `offset`, it would point
    ///     // outside the allocation
    /// }
    /// # } }
    /// ```
    #[stable(feature = "align_offset", since = "1.36.0")]
    pub fn align_offset(self, align: usize) -> usize
    where
        T: Sized,
    {
        if !align.is_power_of_two() {
            panic!("align_offset: align is not a power-of-two");
        }
        // SAFETY: `align` has been checked to be a power of 2 above
        unsafe { align_offset(self, align) }
    }
}

#[lang = "const_slice_ptr"]
impl<T> *const [T] {
    /// Returns the length of a raw slice.
    ///
    /// The returned value is the number of **elements**, not the number of bytes.
    ///
    /// This function is safe, even when the raw slice cannot be cast to a slice
    /// reference because the pointer is null or unaligned.
    ///
    /// # Examples
    ///
    /// ```rust
    /// #![feature(slice_ptr_len)]
    ///
    /// use std::ptr;
    ///
    /// let slice: *const [i8] = ptr::slice_from_raw_parts(ptr::null(), 3);
    /// assert_eq!(slice.len(), 3);
    /// ```
    #[inline]
    #[unstable(feature = "slice_ptr_len", issue = "71146")]
    #[rustc_const_unstable(feature = "const_slice_ptr_len", issue = "71146")]
    pub const fn len(self) -> usize {
        metadata(self)
    }

    /// Returns a raw pointer to the slice's buffer.
    ///
    /// This is equivalent to casting `self` to `*const T`, but more type-safe.
    ///
    /// # Examples
    ///
    /// ```rust
    /// #![feature(slice_ptr_get)]
    /// use std::ptr;
    ///
    /// let slice: *const [i8] = ptr::slice_from_raw_parts(ptr::null(), 3);
    /// assert_eq!(slice.as_ptr(), 0 as *const i8);
    /// ```
    #[inline]
    #[unstable(feature = "slice_ptr_get", issue = "74265")]
    #[rustc_const_unstable(feature = "slice_ptr_get", issue = "74265")]
    pub const fn as_ptr(self) -> *const T {
        self as *const T
    }

    /// Returns a raw pointer to an element or subslice, without doing bounds
    /// checking.
    ///
    /// Calling this method with an out-of-bounds index or when `self` is not dereferencable
    /// is *[undefined behavior]* even if the resulting pointer is not used.
    ///
    /// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
    ///
    /// # Examples
    ///
    /// ```
    /// #![feature(slice_ptr_get)]
    ///
    /// let x = &[1, 2, 4] as *const [i32];
    ///
    /// unsafe {
    ///     assert_eq!(x.get_unchecked(1), x.as_ptr().add(1));
    /// }
    /// ```
    #[unstable(feature = "slice_ptr_get", issue = "74265")]
    #[inline]
    pub unsafe fn get_unchecked<I>(self, index: I) -> *const I::Output
    where
        I: SliceIndex<[T]>,
    {
        // SAFETY: the caller ensures that `self` is dereferencable and `index` in-bounds.
        unsafe { index.get_unchecked(self) }
    }

    /// Returns `None` if the pointer is null, or else returns a shared slice to
    /// the value wrapped in `Some`. In contrast to [`as_ref`], this does not require
    /// that the value has to be initialized.
    ///
    /// [`as_ref`]: #method.as_ref
    ///
    /// # Safety
    ///
    /// When calling this method, you have to ensure that *either* the pointer is null *or*
    /// all of the following is true:
    ///
    /// * The pointer must be [valid] for reads for `ptr.len() * mem::size_of::<T>()` many bytes,
    ///   and it must be properly aligned. This means in particular:
    ///
    ///     * The entire memory range of this slice must be contained within a single [allocated object]!
    ///       Slices can never span across multiple allocated objects.
    ///
    ///     * The pointer must be aligned even for zero-length slices. One
    ///       reason for this is that enum layout optimizations may rely on references
    ///       (including slices of any length) being aligned and non-null to distinguish
    ///       them from other data. You can obtain a pointer that is usable as `data`
    ///       for zero-length slices using [`NonNull::dangling()`].
    ///
    /// * The total size `ptr.len() * mem::size_of::<T>()` of the slice must be no larger than `isize::MAX`.
    ///   See the safety documentation of [`pointer::offset`].
    ///
    /// * You must enforce Rust's aliasing rules, since the returned lifetime `'a` is
    ///   arbitrarily chosen and does not necessarily reflect the actual lifetime of the data.
    ///   In particular, for the duration of this lifetime, the memory the pointer points to must
    ///   not get mutated (except inside `UnsafeCell`).
    ///
    /// This applies even if the result of this method is unused!
    ///
    /// See also [`slice::from_raw_parts`][].
    ///
    /// [valid]: crate::ptr#safety
    /// [allocated object]: crate::ptr#allocated-object
    #[inline]
    #[unstable(feature = "ptr_as_uninit", issue = "75402")]
    pub unsafe fn as_uninit_slice<'a>(self) -> Option<&'a [MaybeUninit<T>]> {
        if self.is_null() {
            None
        } else {
            // SAFETY: the caller must uphold the safety contract for `as_uninit_slice`.
            Some(unsafe { slice::from_raw_parts(self as *const MaybeUninit<T>, self.len()) })
        }
    }
}

// Equality for pointers
#[stable(feature = "rust1", since = "1.0.0")]
impl<T: ?Sized> PartialEq for *const T {
    #[inline]
    fn eq(&self, other: &*const T) -> bool {
        *self == *other
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl<T: ?Sized> Eq for *const T {}

// Comparison for pointers
#[stable(feature = "rust1", since = "1.0.0")]
impl<T: ?Sized> Ord for *const T {
    #[inline]
    fn cmp(&self, other: &*const T) -> Ordering {
        if self < other {
            Less
        } else if self == other {
            Equal
        } else {
            Greater
        }
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl<T: ?Sized> PartialOrd for *const T {
    #[inline]
    fn partial_cmp(&self, other: &*const T) -> Option<Ordering> {
        Some(self.cmp(other))
    }

    #[inline]
    fn lt(&self, other: &*const T) -> bool {
        *self < *other
    }

    #[inline]
    fn le(&self, other: &*const T) -> bool {
        *self <= *other
    }

    #[inline]
    fn gt(&self, other: &*const T) -> bool {
        *self > *other
    }

    #[inline]
    fn ge(&self, other: &*const T) -> bool {
        *self >= *other
    }
}