1 /// A macro for defining #[cfg] if-else statements. 2 /// 3 /// This is similar to the `if/elif` C preprocessor macro by allowing definition 4 /// of a cascade of `#[cfg]` cases, emitting the implementation which matches 5 /// first. 6 /// 7 /// This allows you to conveniently provide a long list #[cfg]'d blocks of code 8 /// without having to rewrite each clause multiple times. 9 macro_rules! cfg_if { 10 // match if/else chains with a final `else` 11 ($( 12 if #[cfg($($meta:meta),*)] { $($it:item)* } 13 ) else * else { 14 $($it2:item)* 15 }) => { 16 cfg_if! { 17 @__items 18 () ; 19 $( ( ($($meta),*) ($($it)*) ), )* 20 ( () ($($it2)*) ), 21 } 22 }; 23 24 // match if/else chains lacking a final `else` 25 ( 26 if #[cfg($($i_met:meta),*)] { $($i_it:item)* } 27 $( 28 else if #[cfg($($e_met:meta),*)] { $($e_it:item)* } 29 )* 30 ) => { 31 cfg_if! { 32 @__items 33 () ; 34 ( ($($i_met),*) ($($i_it)*) ), 35 $( ( ($($e_met),*) ($($e_it)*) ), )* 36 ( () () ), 37 } 38 }; 39 40 // Internal and recursive macro to emit all the items 41 // 42 // Collects all the negated `cfg`s in a list at the beginning and after the 43 // semicolon is all the remaining items 44 (@__items ($($not:meta,)*) ; ) => {}; 45 (@__items ($($not:meta,)*) ; ( ($($m:meta),*) ($($it:item)*) ), 46 $($rest:tt)*) => { 47 // Emit all items within one block, applying an appropriate #[cfg]. The 48 // #[cfg] will require all `$m` matchers specified and must also negate 49 // all previous matchers. 50 cfg_if! { @__apply cfg(all($($m,)* not(any($($not),*)))), $($it)* } 51 52 // Recurse to emit all other items in `$rest`, and when we do so add all 53 // our `$m` matchers to the list of `$not` matchers as future emissions 54 // will have to negate everything we just matched as well. 55 cfg_if! { @__items ($($not,)* $($m,)*) ; $($rest)* } 56 }; 57 58 // Internal macro to Apply a cfg attribute to a list of items 59 (@__apply $m:meta, $($it:item)*) => { 60 $(#[$m] $it)* 61 }; 62 } 63 64 /// Create an internal crate prelude with `core` reexports and common types. 65 macro_rules! prelude { 66 () => { 67 /// Frequently-used types that are available on all platforms 68 /// 69 /// We need to reexport the core types so this works with `rust-dep-of-std`. 70 mod prelude { 71 // Exports from `core` 72 #[allow(unused_imports)] 73 pub(crate) use ::core::clone::Clone; 74 #[allow(unused_imports)] 75 pub(crate) use ::core::marker::{Copy, Send, Sync}; 76 #[allow(unused_imports)] 77 pub(crate) use ::core::option::Option; 78 #[allow(unused_imports)] 79 pub(crate) use ::core::{fmt, hash, iter, mem}; 80 81 // Commonly used types defined in this crate 82 #[allow(unused_imports)] 83 pub(crate) use crate::{ 84 c_char, c_double, c_float, c_int, c_long, c_longlong, c_short, c_uchar, c_uint, 85 c_ulong, c_ulonglong, c_ushort, c_void, intptr_t, size_t, ssize_t, uintptr_t, 86 }; 87 } 88 }; 89 } 90 91 /// Implement `Clone` and `Copy` for a struct, as well as `Debug`, `Eq`, `Hash`, and 92 /// `PartialEq` if the `extra_traits` feature is enabled. 93 /// 94 /// Use [`s_no_extra_traits`] for structs where the `extra_traits` feature does not 95 /// make sense, and for unions. 96 macro_rules! s { 97 ($( 98 $(#[$attr:meta])* 99 pub $t:ident $i:ident { $($field:tt)* } 100 )*) => ($( 101 s!(it: $(#[$attr])* pub $t $i { $($field)* }); 102 )*); 103 104 (it: $(#[$attr:meta])* pub union $i:ident { $($field:tt)* }) => ( 105 compile_error!("unions cannot derive extra traits, use s_no_extra_traits instead"); 106 ); 107 108 (it: $(#[$attr:meta])* pub struct $i:ident { $($field:tt)* }) => ( 109 __item! { 110 #[repr(C)] 111 #[cfg_attr( 112 feature = "extra_traits", 113 ::core::prelude::v1::derive(Debug, Eq, Hash, PartialEq) 114 )] 115 #[::core::prelude::v1::derive(::core::clone::Clone, ::core::marker::Copy)] 116 #[allow(deprecated)] 117 $(#[$attr])* 118 pub struct $i { $($field)* } 119 } 120 ); 121 } 122 123 /// Implement `Clone` and `Copy` for a tuple struct, as well as `Debug`, `Eq`, `Hash`, 124 /// and `PartialEq` if the `extra_traits` feature is enabled. 125 /// 126 /// This is the same as [`s`] but works for tuple structs. 127 macro_rules! s_paren { 128 ($( 129 $(#[$attr:meta])* 130 pub struct $i:ident ( $($field:tt)* ); 131 )*) => ($( 132 __item! { 133 #[cfg_attr( 134 feature = "extra_traits", 135 ::core::prelude::v1::derive(Debug, Eq, Hash, PartialEq) 136 )] 137 #[::core::prelude::v1::derive(::core::clone::Clone, ::core::marker::Copy)] 138 $(#[$attr])* 139 pub struct $i ( $($field)* ); 140 } 141 )*); 142 } 143 144 /// Implement `Clone` and `Copy` for a struct with no `extra_traits` feature. 145 /// 146 /// Most items will prefer to use [`s`]. 147 macro_rules! s_no_extra_traits { 148 ($( 149 $(#[$attr:meta])* 150 pub $t:ident $i:ident { $($field:tt)* } 151 )*) => ($( 152 s_no_extra_traits!(it: $(#[$attr])* pub $t $i { $($field)* }); 153 )*); 154 155 (it: $(#[$attr:meta])* pub union $i:ident { $($field:tt)* }) => ( 156 __item! { 157 #[repr(C)] 158 #[::core::prelude::v1::derive(::core::clone::Clone, ::core::marker::Copy)] 159 $(#[$attr])* 160 pub union $i { $($field)* } 161 } 162 163 #[cfg(feature = "extra_traits")] 164 impl ::core::fmt::Debug for $i { 165 fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result { 166 f.debug_struct(::core::stringify!($i)).finish_non_exhaustive() 167 } 168 } 169 ); 170 171 (it: $(#[$attr:meta])* pub struct $i:ident { $($field:tt)* }) => ( 172 __item! { 173 #[repr(C)] 174 #[::core::prelude::v1::derive(::core::clone::Clone, ::core::marker::Copy)] 175 $(#[$attr])* 176 pub struct $i { $($field)* } 177 } 178 ); 179 } 180 181 /// Specify that an enum should have no traits that aren't specified in the macro 182 /// invocation, i.e. no `Clone` or `Copy`. 183 macro_rules! missing { 184 ($( 185 $(#[$attr:meta])* 186 pub enum $i:ident {} 187 )*) => ($( 188 $(#[$attr])* 189 #[allow(missing_copy_implementations)] 190 pub enum $i { } 191 )*); 192 } 193 194 /// Implement `Clone` and `Copy` for an enum, as well as `Debug`, `Eq`, `Hash`, and 195 /// `PartialEq` if the `extra_traits` feature is enabled. 196 macro_rules! e { 197 ($( 198 $(#[$attr:meta])* 199 pub enum $i:ident { $($field:tt)* } 200 )*) => ($( 201 __item! { 202 #[cfg_attr( 203 feature = "extra_traits", 204 ::core::prelude::v1::derive(Debug, Eq, Hash, PartialEq) 205 )] 206 #[::core::prelude::v1::derive(::core::clone::Clone, ::core::marker::Copy)] 207 $(#[$attr])* 208 pub enum $i { $($field)* } 209 } 210 )*); 211 } 212 213 // This is a pretty horrible hack to allow us to conditionally mark some functions as 'const', 214 // without requiring users of this macro to care "libc_const_extern_fn". 215 // 216 // When 'libc_const_extern_fn' is enabled, we emit the captured 'const' keyword in the expanded 217 // function. 218 // 219 // When 'libc_const_extern_fn' is disabled, we always emit a plain 'pub unsafe extern fn'. 220 // Note that the expression matched by the macro is exactly the same - this allows 221 // users of this macro to work whether or not 'libc_const_extern_fn' is enabled 222 // 223 // Unfortunately, we need to duplicate most of this macro between the 'cfg_if' blocks. 224 // This is because 'const unsafe extern fn' won't even parse on older compilers, 225 // so we need to avoid emitting it at all of 'libc_const_extern_fn'. 226 // 227 // Specifically, moving the 'cfg_if' into the macro body will *not* work. Doing so would cause the 228 // '#[cfg(libc_const_extern_fn)]' to be emitted into user code. The 'cfg' gate will not stop Rust 229 // from trying to parse the 'pub const unsafe extern fn', so users would get a compiler error even 230 // when the 'libc_const_extern_fn' feature is disabled. 231 232 // FIXME(ctest): ctest can't handle `const extern` functions, we should be able to remove this 233 // cfg completely. 234 // FIXME(ctest): ctest can't handle `$(,)?` so we use `$(,)*` which isn't quite correct. 235 cfg_if! { 236 if #[cfg(libc_const_extern_fn)] { 237 /// Define an `unsafe` function that is const as long as `libc_const_extern_fn` is enabled. 238 macro_rules! f { 239 ($( 240 $(#[$attr:meta])* 241 pub $({$constness:ident})* fn $i:ident($($arg:ident: $argty:ty),* $(,)*) -> $ret:ty 242 $body:block 243 )*) => ($( 244 #[inline] 245 $(#[$attr])* 246 pub $($constness)* unsafe extern "C" fn $i($($arg: $argty),*) -> $ret 247 $body 248 )*) 249 } 250 251 /// Define a safe function that is const as long as `libc_const_extern_fn` is enabled. 252 macro_rules! safe_f { 253 ($( 254 $(#[$attr:meta])* 255 pub $({$constness:ident})* fn $i:ident($($arg:ident: $argty:ty),* $(,)*) -> $ret:ty 256 $body:block 257 )*) => ($( 258 #[inline] 259 $(#[$attr])* 260 pub $($constness)* extern "C" fn $i($($arg: $argty),*) -> $ret 261 $body 262 )*) 263 } 264 265 /// A nonpublic function that is const as long as `libc_const_extern_fn` is enabled. 266 macro_rules! const_fn { 267 ($( 268 $(#[$attr:meta])* 269 $({$constness:ident})* fn $i:ident($($arg:ident: $argty:ty),* $(,)*) -> $ret:ty 270 $body:block 271 )*) => ($( 272 #[inline] 273 $(#[$attr])* 274 $($constness)* fn $i($($arg: $argty),*) -> $ret 275 $body 276 )*) 277 } 278 } else { 279 /// Define an `unsafe` function that is const as long as `libc_const_extern_fn` is enabled. 280 macro_rules! f { 281 ($( 282 $(#[$attr:meta])* 283 pub $({$constness:ident})* fn $i:ident($($arg:ident: $argty:ty),* $(,)*) -> $ret:ty 284 $body:block 285 )*) => ($( 286 #[inline] 287 $(#[$attr])* 288 pub unsafe extern "C" fn $i($($arg: $argty),*) -> $ret 289 $body 290 )*) 291 } 292 293 /// Define a safe function that is const as long as `libc_const_extern_fn` is enabled. 294 macro_rules! safe_f { 295 ($( 296 $(#[$attr:meta])* 297 pub $({$constness:ident})* fn $i:ident($($arg:ident: $argty:ty),* $(,)*) -> $ret:ty 298 $body:block 299 )*) => ($( 300 #[inline] 301 $(#[$attr])* 302 pub extern "C" fn $i($($arg: $argty),*) -> $ret 303 $body 304 )*) 305 } 306 307 /// A nonpublic function that is const as long as `libc_const_extern_fn` is enabled. 308 macro_rules! const_fn { 309 ($( 310 $(#[$attr:meta])* 311 $({$constness:ident})* fn $i:ident($($arg:ident: $argty:ty),* $(,)*) -> $ret:ty 312 $body:block 313 )*) => ($( 314 #[inline] 315 $(#[$attr])* 316 fn $i($($arg: $argty),*) -> $ret 317 $body 318 )*) 319 } 320 } 321 } 322 323 macro_rules! __item { 324 ($i:item) => { 325 $i 326 }; 327 } 328 329 // This macro is used to deprecate items that should be accessed via the mach2 crate 330 macro_rules! deprecated_mach { 331 (pub const $id:ident: $ty:ty = $expr:expr;) => { 332 #[deprecated( 333 since = "0.2.55", 334 note = "Use the `mach2` crate instead", 335 )] 336 #[allow(deprecated)] 337 pub const $id: $ty = $expr; 338 }; 339 ($(pub const $id:ident: $ty:ty = $expr:expr;)*) => { 340 $( 341 deprecated_mach!( 342 pub const $id: $ty = $expr; 343 ); 344 )* 345 }; 346 (pub type $id:ident = $ty:ty;) => { 347 #[deprecated( 348 since = "0.2.55", 349 note = "Use the `mach2` crate instead", 350 )] 351 #[allow(deprecated)] 352 pub type $id = $ty; 353 }; 354 ($(pub type $id:ident = $ty:ty;)*) => { 355 $( 356 deprecated_mach!( 357 pub type $id = $ty; 358 ); 359 )* 360 } 361 } 362