library/core/src/convert/num.rs

   1 use super::{From, TryFrom};
   2 use crate::num::TryFromIntError;
   3
   4 mod private {
   5     /// This trait being unreachable from outside the crate
   6     /// prevents other implementations of the `FloatToInt` trait,
   7     /// which allows potentially adding more trait methods after the trait is `#[stable]`.
   8     #[unstable(feature = "convert_float_to_int", issue = "67057")]
   9     pub trait Sealed {}
  10 }
  11
  12 /// Supporting trait for inherent methods of `f32` and `f64` such as `to_int_unchecked`.
  13 /// Typically doesn’t need to be used directly.
  14 #[unstable(feature = "convert_float_to_int", issue = "67057")]
  15 pub trait FloatToInt<Int>: private::Sealed + Sized {
  16     #[unstable(feature = "convert_float_to_int", issue = "67057")]
  17     #[doc(hidden)]
  18     unsafe fn to_int_unchecked(self) -> Int;
  19 }
  20
  21 macro_rules! impl_float_to_int {
  22     ( $Float: ident => $( $Int: ident )+ ) => {
  23         #[unstable(feature = "convert_float_to_int", issue = "67057")]
  24         impl private::Sealed for $Float {}
  25         $(
  26             #[unstable(feature = "convert_float_to_int", issue = "67057")]
  27             impl FloatToInt<$Int> for $Float {
  28                 #[inline]
  29                 unsafe fn to_int_unchecked(self) -> $Int {
  30                     // SAFETY: the safety contract must be upheld by the caller.
  31                     unsafe { crate::intrinsics::float_to_int_unchecked(self) }
  32                 }
  33             }
  34         )+
  35     }
  36 }
  37
  38 impl_float_to_int!(f32 => u8 u16 u32 u64 u128 usize i8 i16 i32 i64 i128 isize);
  39 impl_float_to_int!(f64 => u8 u16 u32 u64 u128 usize i8 i16 i32 i64 i128 isize);
  40
  41 // Conversion traits for primitive integer and float types
  42 // Conversions T -> T are covered by a blanket impl and therefore excluded
  43 // Some conversions from and to usize/isize are not implemented due to portability concerns
  44 macro_rules! impl_from {
  45     ($Small: ty, $Large: ty, #[$attr:meta], $doc: expr) => {
  46         #[$attr]
  47         #[rustc_const_unstable(feature = "const_num_from_num", issue = "87852")]
  48         impl const From<$Small> for $Large {
  49             // Rustdocs on the impl block show a "[+] show undocumented items" toggle.
  50             // Rustdocs on functions do not.
  51             #[doc = $doc]
  52             #[inline(always)]
  53             fn from(small: $Small) -> Self {
  54                 small as Self
  55             }
  56         }
  57     };
  58     ($Small: ty, $Large: ty, #[$attr:meta]) => {
  59         impl_from!($Small,
  60                    $Large,
  61                    #[$attr],
  62                    concat!("Converts `",
  63                            stringify!($Small),
  64                            "` to `",
  65                            stringify!($Large),
  66                            "` losslessly."));
  67     }
  68 }
  69
  70 macro_rules! impl_from_bool {
  71     ($target: ty, #[$attr:meta]) => {
  72         impl_from!(bool, $target, #[$attr], concat!("Converts a `bool` to a `",
  73             stringify!($target), "`. The resulting value is `0` for `false` and `1` for `true`
  74 values.
  75
  76 # Examples
  77
  78 ```
  79 assert_eq!(", stringify!($target), "::from(true), 1);
  80 assert_eq!(", stringify!($target), "::from(false), 0);
  81 ```"));
  82     };
  83 }
  84
  85 // Bool -> Any
  86 impl_from_bool! { u8, #[stable(feature = "from_bool", since = "1.28.0")] }
  87 impl_from_bool! { u16, #[stable(feature = "from_bool", since = "1.28.0")] }
  88 impl_from_bool! { u32, #[stable(feature = "from_bool", since = "1.28.0")] }
  89 impl_from_bool! { u64, #[stable(feature = "from_bool", since = "1.28.0")] }
  90 impl_from_bool! { u128, #[stable(feature = "from_bool", since = "1.28.0")] }
  91 impl_from_bool! { usize, #[stable(feature = "from_bool", since = "1.28.0")] }
  92 impl_from_bool! { i8, #[stable(feature = "from_bool", since = "1.28.0")] }
  93 impl_from_bool! { i16, #[stable(feature = "from_bool", since = "1.28.0")] }
  94 impl_from_bool! { i32, #[stable(feature = "from_bool", since = "1.28.0")] }
  95 impl_from_bool! { i64, #[stable(feature = "from_bool", since = "1.28.0")] }
  96 impl_from_bool! { i128, #[stable(feature = "from_bool", since = "1.28.0")] }
  97 impl_from_bool! { isize, #[stable(feature = "from_bool", since = "1.28.0")] }
  98
  99 // Unsigned -> Unsigned
 100 impl_from! { u8, u16, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
 101 impl_from! { u8, u32, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
 102 impl_from! { u8, u64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
 103 impl_from! { u8, u128, #[stable(feature = "i128", since = "1.26.0")] }
 104 impl_from! { u8, usize, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
 105 impl_from! { u16, u32, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
 106 impl_from! { u16, u64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
 107 impl_from! { u16, u128, #[stable(feature = "i128", since = "1.26.0")] }
 108 impl_from! { u32, u64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
 109 impl_from! { u32, u128, #[stable(feature = "i128", since = "1.26.0")] }
 110 impl_from! { u64, u128, #[stable(feature = "i128", since = "1.26.0")] }
 111
 112 // Signed -> Signed
 113 impl_from! { i8, i16, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
 114 impl_from! { i8, i32, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
 115 impl_from! { i8, i64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
 116 impl_from! { i8, i128, #[stable(feature = "i128", since = "1.26.0")] }
 117 impl_from! { i8, isize, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
 118 impl_from! { i16, i32, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
 119 impl_from! { i16, i64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
 120 impl_from! { i16, i128, #[stable(feature = "i128", since = "1.26.0")] }
 121 impl_from! { i32, i64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
 122 impl_from! { i32, i128, #[stable(feature = "i128", since = "1.26.0")] }
 123 impl_from! { i64, i128, #[stable(feature = "i128", since = "1.26.0")] }
 124
 125 // Unsigned -> Signed
 126 impl_from! { u8, i16, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
 127 impl_from! { u8, i32, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
 128 impl_from! { u8, i64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
 129 impl_from! { u8, i128, #[stable(feature = "i128", since = "1.26.0")] }
 130 impl_from! { u16, i32, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
 131 impl_from! { u16, i64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
 132 impl_from! { u16, i128, #[stable(feature = "i128", since = "1.26.0")] }
 133 impl_from! { u32, i64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
 134 impl_from! { u32, i128, #[stable(feature = "i128", since = "1.26.0")] }
 135 impl_from! { u64, i128, #[stable(feature = "i128", since = "1.26.0")] }
 136
 137 // The C99 standard defines bounds on INTPTR_MIN, INTPTR_MAX, and UINTPTR_MAX
 138 // which imply that pointer-sized integers must be at least 16 bits:
 139 // https://port70.net/~nsz/c/c99/n1256.html#7.18.2.4
 140 impl_from! { u16, usize, #[stable(feature = "lossless_iusize_conv", since = "1.26.0")] }
 141 impl_from! { u8, isize, #[stable(feature = "lossless_iusize_conv", since = "1.26.0")] }
 142 impl_from! { i16, isize, #[stable(feature = "lossless_iusize_conv", since = "1.26.0")] }
 143
 144 // RISC-V defines the possibility of a 128-bit address space (RV128).
 145
 146 // CHERI proposes 256-bit “capabilities”. Unclear if this would be relevant to usize/isize.
 147 // https://www.cl.cam.ac.uk/research/security/ctsrd/pdfs/20171017a-cheri-poster.pdf
 148 // https://www.csl.sri.com/users/neumann/2012resolve-cheri.pdf
 149
 150 // Note: integers can only be represented with full precision in a float if
 151 // they fit in the significand, which is 24 bits in f32 and 53 bits in f64.
 152 // Lossy float conversions are not implemented at this time.
 153
 154 // Signed -> Float
 155 impl_from! { i8, f32, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
 156 impl_from! { i8, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
 157 impl_from! { i16, f32, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
 158 impl_from! { i16, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
 159 impl_from! { i32, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
 160
 161 // Unsigned -> Float
 162 impl_from! { u8, f32, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
 163 impl_from! { u8, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
 164 impl_from! { u16, f32, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
 165 impl_from! { u16, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
 166 impl_from! { u32, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
 167
 168 // Float -> Float
 169 impl_from! { f32, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
 170
 171 // no possible bounds violation
 172 macro_rules! try_from_unbounded {
 173     ($source:ty, $($target:ty),*) => {$(
 174         #[stable(feature = "try_from", since = "1.34.0")]
 175         #[rustc_const_unstable(feature = "const_num_from_num", issue = "87852")]
 176         impl const TryFrom<$source> for $target {
 177             type Error = TryFromIntError;
 178
 179             /// Try to create the target number type from a source
 180             /// number type. This returns an error if the source value
 181             /// is outside of the range of the target type.
 182             #[inline]
 183             fn try_from(value: $source) -> Result<Self, Self::Error> {
 184                 Ok(value as Self)
 185             }
 186         }
 187     )*}
 188 }
 189
 190 // only negative bounds
 191 macro_rules! try_from_lower_bounded {
 192     ($source:ty, $($target:ty),*) => {$(
 193         #[stable(feature = "try_from", since = "1.34.0")]
 194         #[rustc_const_unstable(feature = "const_num_from_num", issue = "87852")]
 195         impl const TryFrom<$source> for $target {
 196             type Error = TryFromIntError;
 197
 198             /// Try to create the target number type from a source
 199             /// number type. This returns an error if the source value
 200             /// is outside of the range of the target type.
 201             #[inline]
 202             fn try_from(u: $source) -> Result<Self, Self::Error> {
 203                 if u >= 0 {
 204                     Ok(u as Self)
 205                 } else {
 206                     Err(TryFromIntError(()))
 207                 }
 208             }
 209         }
 210     )*}
 211 }
 212
 213 // unsigned to signed (only positive bound)
 214 macro_rules! try_from_upper_bounded {
 215     ($source:ty, $($target:ty),*) => {$(
 216         #[stable(feature = "try_from", since = "1.34.0")]
 217         #[rustc_const_unstable(feature = "const_num_from_num", issue = "87852")]
 218         impl const TryFrom<$source> for $target {
 219             type Error = TryFromIntError;
 220
 221             /// Try to create the target number type from a source
 222             /// number type. This returns an error if the source value
 223             /// is outside of the range of the target type.
 224             #[inline]
 225             fn try_from(u: $source) -> Result<Self, Self::Error> {
 226                 if u > (Self::MAX as $source) {
 227                     Err(TryFromIntError(()))
 228                 } else {
 229                     Ok(u as Self)
 230                 }
 231             }
 232         }
 233     )*}
 234 }
 235
 236 // all other cases
 237 macro_rules! try_from_both_bounded {
 238     ($source:ty, $($target:ty),*) => {$(
 239         #[stable(feature = "try_from", since = "1.34.0")]
 240         #[rustc_const_unstable(feature = "const_num_from_num", issue = "87852")]
 241         impl const TryFrom<$source> for $target {
 242             type Error = TryFromIntError;
 243
 244             /// Try to create the target number type from a source
 245             /// number type. This returns an error if the source value
 246             /// is outside of the range of the target type.
 247             #[inline]
 248             fn try_from(u: $source) -> Result<Self, Self::Error> {
 249                 let min = Self::MIN as $source;
 250                 let max = Self::MAX as $source;
 251                 if u < min || u > max {
 252                     Err(TryFromIntError(()))
 253                 } else {
 254                     Ok(u as Self)
 255                 }
 256             }
 257         }
 258     )*}
 259 }
 260
 261 macro_rules! rev {
 262     ($mac:ident, $source:ty, $($target:ty),*) => {$(
 263         $mac!($target, $source);
 264     )*}
 265 }
 266
 267 // intra-sign conversions
 268 try_from_upper_bounded!(u16, u8);
 269 try_from_upper_bounded!(u32, u16, u8);
 270 try_from_upper_bounded!(u64, u32, u16, u8);
 271 try_from_upper_bounded!(u128, u64, u32, u16, u8);
 272
 273 try_from_both_bounded!(i16, i8);
 274 try_from_both_bounded!(i32, i16, i8);
 275 try_from_both_bounded!(i64, i32, i16, i8);
 276 try_from_both_bounded!(i128, i64, i32, i16, i8);
 277
 278 // unsigned-to-signed
 279 try_from_upper_bounded!(u8, i8);
 280 try_from_upper_bounded!(u16, i8, i16);
 281 try_from_upper_bounded!(u32, i8, i16, i32);
 282 try_from_upper_bounded!(u64, i8, i16, i32, i64);
 283 try_from_upper_bounded!(u128, i8, i16, i32, i64, i128);
 284
 285 // signed-to-unsigned
 286 try_from_lower_bounded!(i8, u8, u16, u32, u64, u128);
 287 try_from_lower_bounded!(i16, u16, u32, u64, u128);
 288 try_from_lower_bounded!(i32, u32, u64, u128);
 289 try_from_lower_bounded!(i64, u64, u128);
 290 try_from_lower_bounded!(i128, u128);
 291 try_from_both_bounded!(i16, u8);
 292 try_from_both_bounded!(i32, u16, u8);
 293 try_from_both_bounded!(i64, u32, u16, u8);
 294 try_from_both_bounded!(i128, u64, u32, u16, u8);
 295
 296 // usize/isize
 297 try_from_upper_bounded!(usize, isize);
 298 try_from_lower_bounded!(isize, usize);
 299
 300 #[cfg(target_pointer_width = "16")]
 301 mod ptr_try_from_impls {
 302     use super::TryFromIntError;
 303     use crate::convert::TryFrom;
 304
 305     try_from_upper_bounded!(usize, u8);
 306     try_from_unbounded!(usize, u16, u32, u64, u128);
 307     try_from_upper_bounded!(usize, i8, i16);
 308     try_from_unbounded!(usize, i32, i64, i128);
 309
 310     try_from_both_bounded!(isize, u8);
 311     try_from_lower_bounded!(isize, u16, u32, u64, u128);
 312     try_from_both_bounded!(isize, i8);
 313     try_from_unbounded!(isize, i16, i32, i64, i128);
 314
 315     rev!(try_from_upper_bounded, usize, u32, u64, u128);
 316     rev!(try_from_lower_bounded, usize, i8, i16);
 317     rev!(try_from_both_bounded, usize, i32, i64, i128);
 318
 319     rev!(try_from_upper_bounded, isize, u16, u32, u64, u128);
 320     rev!(try_from_both_bounded, isize, i32, i64, i128);
 321 }
 322
 323 #[cfg(target_pointer_width = "32")]
 324 mod ptr_try_from_impls {
 325     use super::TryFromIntError;
 326     use crate::convert::TryFrom;
 327
 328     try_from_upper_bounded!(usize, u8, u16);
 329     try_from_unbounded!(usize, u32, u64, u128);
 330     try_from_upper_bounded!(usize, i8, i16, i32);
 331     try_from_unbounded!(usize, i64, i128);
 332
 333     try_from_both_bounded!(isize, u8, u16);
 334     try_from_lower_bounded!(isize, u32, u64, u128);
 335     try_from_both_bounded!(isize, i8, i16);
 336     try_from_unbounded!(isize, i32, i64, i128);
 337
 338     rev!(try_from_unbounded, usize, u32);
 339     rev!(try_from_upper_bounded, usize, u64, u128);
 340     rev!(try_from_lower_bounded, usize, i8, i16, i32);
 341     rev!(try_from_both_bounded, usize, i64, i128);
 342
 343     rev!(try_from_unbounded, isize, u16);
 344     rev!(try_from_upper_bounded, isize, u32, u64, u128);
 345     rev!(try_from_unbounded, isize, i32);
 346     rev!(try_from_both_bounded, isize, i64, i128);
 347 }
 348
 349 #[cfg(target_pointer_width = "64")]
 350 mod ptr_try_from_impls {
 351     use super::TryFromIntError;
 352     use crate::convert::TryFrom;
 353
 354     try_from_upper_bounded!(usize, u8, u16, u32);
 355     try_from_unbounded!(usize, u64, u128);
 356     try_from_upper_bounded!(usize, i8, i16, i32, i64);
 357     try_from_unbounded!(usize, i128);
 358
 359     try_from_both_bounded!(isize, u8, u16, u32);
 360     try_from_lower_bounded!(isize, u64, u128);
 361     try_from_both_bounded!(isize, i8, i16, i32);
 362     try_from_unbounded!(isize, i64, i128);
 363
 364     rev!(try_from_unbounded, usize, u32, u64);
 365     rev!(try_from_upper_bounded, usize, u128);
 366     rev!(try_from_lower_bounded, usize, i8, i16, i32, i64);
 367     rev!(try_from_both_bounded, usize, i128);
 368
 369     rev!(try_from_unbounded, isize, u16, u32);
 370     rev!(try_from_upper_bounded, isize, u64, u128);
 371     rev!(try_from_unbounded, isize, i32, i64);
 372     rev!(try_from_both_bounded, isize, i128);
 373 }
 374
 375 // Conversion traits for non-zero integer types
 376 use crate::num::NonZeroI128;
 377 use crate::num::NonZeroI16;
 378 use crate::num::NonZeroI32;
 379 use crate::num::NonZeroI64;
 380 use crate::num::NonZeroI8;
 381 use crate::num::NonZeroIsize;
 382 use crate::num::NonZeroU128;
 383 use crate::num::NonZeroU16;
 384 use crate::num::NonZeroU32;
 385 use crate::num::NonZeroU64;
 386 use crate::num::NonZeroU8;
 387 use crate::num::NonZeroUsize;
 388
 389 macro_rules! nzint_impl_from {
 390     ($Small: ty, $Large: ty, #[$attr:meta], $doc: expr) => {
 391         #[$attr]
 392         #[rustc_const_unstable(feature = "const_num_from_num", issue = "87852")]
 393         impl const From<$Small> for $Large {
 394             // Rustdocs on the impl block show a "[+] show undocumented items" toggle.
 395             // Rustdocs on functions do not.
 396             #[doc = $doc]
 397             #[inline]
 398             fn from(small: $Small) -> Self {
 399                 // SAFETY: input type guarantees the value is non-zero
 400                 unsafe {
 401                     Self::new_unchecked(From::from(small.get()))
 402                 }
 403             }
 404         }
 405     };
 406     ($Small: ty, $Large: ty, #[$attr:meta]) => {
 407         nzint_impl_from!($Small,
 408                    $Large,
 409                    #[$attr],
 410                    concat!("Converts `",
 411                            stringify!($Small),
 412                            "` to `",
 413                            stringify!($Large),
 414                            "` losslessly."));
 415     }
 416 }
 417
 418 // Non-zero Unsigned -> Non-zero Unsigned
 419 nzint_impl_from! { NonZeroU8, NonZeroU16, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 420 nzint_impl_from! { NonZeroU8, NonZeroU32, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 421 nzint_impl_from! { NonZeroU8, NonZeroU64, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 422 nzint_impl_from! { NonZeroU8, NonZeroU128, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 423 nzint_impl_from! { NonZeroU8, NonZeroUsize, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 424 nzint_impl_from! { NonZeroU16, NonZeroU32, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 425 nzint_impl_from! { NonZeroU16, NonZeroU64, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 426 nzint_impl_from! { NonZeroU16, NonZeroU128, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 427 nzint_impl_from! { NonZeroU16, NonZeroUsize, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 428 nzint_impl_from! { NonZeroU32, NonZeroU64, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 429 nzint_impl_from! { NonZeroU32, NonZeroU128, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 430 nzint_impl_from! { NonZeroU64, NonZeroU128, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 431
 432 // Non-zero Signed -> Non-zero Signed
 433 nzint_impl_from! { NonZeroI8, NonZeroI16, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 434 nzint_impl_from! { NonZeroI8, NonZeroI32, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 435 nzint_impl_from! { NonZeroI8, NonZeroI64, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 436 nzint_impl_from! { NonZeroI8, NonZeroI128, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 437 nzint_impl_from! { NonZeroI8, NonZeroIsize, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 438 nzint_impl_from! { NonZeroI16, NonZeroI32, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 439 nzint_impl_from! { NonZeroI16, NonZeroI64, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 440 nzint_impl_from! { NonZeroI16, NonZeroI128, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 441 nzint_impl_from! { NonZeroI16, NonZeroIsize, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 442 nzint_impl_from! { NonZeroI32, NonZeroI64, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 443 nzint_impl_from! { NonZeroI32, NonZeroI128, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 444 nzint_impl_from! { NonZeroI64, NonZeroI128, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 445
 446 // NonZero UnSigned -> Non-zero Signed
 447 nzint_impl_from! { NonZeroU8, NonZeroI16, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 448 nzint_impl_from! { NonZeroU8, NonZeroI32, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 449 nzint_impl_from! { NonZeroU8, NonZeroI64, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 450 nzint_impl_from! { NonZeroU8, NonZeroI128, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 451 nzint_impl_from! { NonZeroU8, NonZeroIsize, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 452 nzint_impl_from! { NonZeroU16, NonZeroI32, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 453 nzint_impl_from! { NonZeroU16, NonZeroI64, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 454 nzint_impl_from! { NonZeroU16, NonZeroI128, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 455 nzint_impl_from! { NonZeroU32, NonZeroI64, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 456 nzint_impl_from! { NonZeroU32, NonZeroI128, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 457 nzint_impl_from! { NonZeroU64, NonZeroI128, #[stable(feature = "nz_int_conv", since = "1.41.0")] }
 458
 459 macro_rules! nzint_impl_try_from_int {
 460     ($Int: ty, $NonZeroInt: ty, #[$attr:meta], $doc: expr) => {
 461         #[$attr]
 462         impl TryFrom<$Int> for $NonZeroInt {
 463             type Error = TryFromIntError;
 464
 465             // Rustdocs on the impl block show a "[+] show undocumented items" toggle.
 466             // Rustdocs on functions do not.
 467             #[doc = $doc]
 468             #[inline]
 469             fn try_from(value: $Int) -> Result<Self, Self::Error> {
 470                 Self::new(value).ok_or(TryFromIntError(()))
 471             }
 472         }
 473     };
 474     ($Int: ty, $NonZeroInt: ty, #[$attr:meta]) => {
 475         nzint_impl_try_from_int!($Int,
 476                                  $NonZeroInt,
 477                                  #[$attr],
 478                                  concat!("Attempts to convert `",
 479                                          stringify!($Int),
 480                                          "` to `",
 481                                          stringify!($NonZeroInt),
 482                                          "`."));
 483     }
 484 }
 485
 486 // Int -> Non-zero Int
 487 nzint_impl_try_from_int! { u8, NonZeroU8, #[stable(feature = "nzint_try_from_int_conv", since = "1.46.0")] }
 488 nzint_impl_try_from_int! { u16, NonZeroU16, #[stable(feature = "nzint_try_from_int_conv", since = "1.46.0")] }
 489 nzint_impl_try_from_int! { u32, NonZeroU32, #[stable(feature = "nzint_try_from_int_conv", since = "1.46.0")] }
 490 nzint_impl_try_from_int! { u64, NonZeroU64, #[stable(feature = "nzint_try_from_int_conv", since = "1.46.0")] }
 491 nzint_impl_try_from_int! { u128, NonZeroU128, #[stable(feature = "nzint_try_from_int_conv", since = "1.46.0")] }
 492 nzint_impl_try_from_int! { usize, NonZeroUsize, #[stable(feature = "nzint_try_from_int_conv", since = "1.46.0")] }
 493 nzint_impl_try_from_int! { i8, NonZeroI8, #[stable(feature = "nzint_try_from_int_conv", since = "1.46.0")] }
 494 nzint_impl_try_from_int! { i16, NonZeroI16, #[stable(feature = "nzint_try_from_int_conv", since = "1.46.0")] }
 495 nzint_impl_try_from_int! { i32, NonZeroI32, #[stable(feature = "nzint_try_from_int_conv", since = "1.46.0")] }
 496 nzint_impl_try_from_int! { i64, NonZeroI64, #[stable(feature = "nzint_try_from_int_conv", since = "1.46.0")] }
 497 nzint_impl_try_from_int! { i128, NonZeroI128, #[stable(feature = "nzint_try_from_int_conv", since = "1.46.0")] }
 498 nzint_impl_try_from_int! { isize, NonZeroIsize, #[stable(feature = "nzint_try_from_int_conv", since = "1.46.0")] }
 499
 500 macro_rules! nzint_impl_try_from_nzint {
 501     ($From:ty => $To:ty, $doc: expr) => {
 502         #[stable(feature = "nzint_try_from_nzint_conv", since = "1.49.0")]
 503         impl TryFrom<$From> for $To {
 504             type Error = TryFromIntError;
 505
 506             // Rustdocs on the impl block show a "[+] show undocumented items" toggle.
 507             // Rustdocs on functions do not.
 508             #[doc = $doc]
 509             #[inline]
 510             fn try_from(value: $From) -> Result<Self, Self::Error> {
 511                 TryFrom::try_from(value.get()).map(|v| {
 512                     // SAFETY: $From is a NonZero type, so v is not zero.
 513                     unsafe { Self::new_unchecked(v) }
 514                 })
 515             }
 516         }
 517     };
 518     ($To:ty: $($From: ty),*) => {$(
 519         nzint_impl_try_from_nzint!(
 520             $From => $To,
 521             concat!(
 522                 "Attempts to convert `",
 523                 stringify!($From),
 524                 "` to `",
 525                 stringify!($To),
 526                 "`.",
 527             )
 528         );
 529     )*};
 530 }
 531
 532 // Non-zero int -> non-zero unsigned int
 533 nzint_impl_try_from_nzint! { NonZeroU8: NonZeroI8, NonZeroU16, NonZeroI16, NonZeroU32, NonZeroI32, NonZeroU64, NonZeroI64, NonZeroU128, NonZeroI128, NonZeroUsize, NonZeroIsize }
 534 nzint_impl_try_from_nzint! { NonZeroU16: NonZeroI8, NonZeroI16, NonZeroU32, NonZeroI32, NonZeroU64, NonZeroI64, NonZeroU128, NonZeroI128, NonZeroUsize, NonZeroIsize }
 535 nzint_impl_try_from_nzint! { NonZeroU32: NonZeroI8, NonZeroI16, NonZeroI32, NonZeroU64, NonZeroI64, NonZeroU128, NonZeroI128, NonZeroUsize, NonZeroIsize }
 536 nzint_impl_try_from_nzint! { NonZeroU64: NonZeroI8, NonZeroI16, NonZeroI32, NonZeroI64, NonZeroU128, NonZeroI128, NonZeroUsize, NonZeroIsize }
 537 nzint_impl_try_from_nzint! { NonZeroU128: NonZeroI8, NonZeroI16, NonZeroI32, NonZeroI64, NonZeroI128, NonZeroUsize, NonZeroIsize }
 538 nzint_impl_try_from_nzint! { NonZeroUsize: NonZeroI8, NonZeroI16, NonZeroU32, NonZeroI32, NonZeroU64, NonZeroI64, NonZeroU128, NonZeroI128, NonZeroIsize }
 539
 540 // Non-zero int -> non-zero signed int
 541 nzint_impl_try_from_nzint! { NonZeroI8: NonZeroU8, NonZeroU16, NonZeroI16, NonZeroU32, NonZeroI32, NonZeroU64, NonZeroI64, NonZeroU128, NonZeroI128, NonZeroUsize, NonZeroIsize }
 542 nzint_impl_try_from_nzint! { NonZeroI16: NonZeroU16, NonZeroU32, NonZeroI32, NonZeroU64, NonZeroI64, NonZeroU128, NonZeroI128, NonZeroUsize, NonZeroIsize }
 543 nzint_impl_try_from_nzint! { NonZeroI32: NonZeroU32, NonZeroU64, NonZeroI64, NonZeroU128, NonZeroI128, NonZeroUsize, NonZeroIsize }
 544 nzint_impl_try_from_nzint! { NonZeroI64: NonZeroU64, NonZeroU128, NonZeroI128, NonZeroUsize, NonZeroIsize }
 545 nzint_impl_try_from_nzint! { NonZeroI128: NonZeroU128, NonZeroUsize, NonZeroIsize }
 546 nzint_impl_try_from_nzint! { NonZeroIsize: NonZeroU16, NonZeroU32, NonZeroI32, NonZeroU64, NonZeroI64, NonZeroU128, NonZeroI128, NonZeroUsize }