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 #[allow(unused_macros)] 10 macro_rules! cfg_if { 11 // match if/else chains with a final `else` 12 ($( 13 if #[cfg($($meta:meta),*)] { $($it:item)* } 14 ) else * else { 15 $($it2:item)* 16 }) => { 17 cfg_if! { 18 @__items 19 () ; 20 $( ( ($($meta),*) ($($it)*) ), )* 21 ( () ($($it2)*) ), 22 } 23 }; 24 25 // match if/else chains lacking a final `else` 26 ( 27 if #[cfg($($i_met:meta),*)] { $($i_it:item)* } 28 $( 29 else if #[cfg($($e_met:meta),*)] { $($e_it:item)* } 30 )* 31 ) => { 32 cfg_if! { 33 @__items 34 () ; 35 ( ($($i_met),*) ($($i_it)*) ), 36 $( ( ($($e_met),*) ($($e_it)*) ), )* 37 ( () () ), 38 } 39 }; 40 41 // Internal and recursive macro to emit all the items 42 // 43 // Collects all the negated `cfg`s in a list at the beginning and after the 44 // semicolon is all the remaining items 45 (@__items ($($not:meta,)*) ; ) => {}; 46 (@__items ($($not:meta,)*) ; ( ($($m:meta),*) ($($it:item)*) ), 47 $($rest:tt)*) => { 48 // Emit all items within one block, applying an appropriate #[cfg]. The 49 // #[cfg] will require all `$m` matchers specified and must also negate 50 // all previous matchers. 51 cfg_if! { @__apply cfg(all($($m,)* not(any($($not),*)))), $($it)* } 52 53 // Recurse to emit all other items in `$rest`, and when we do so add all 54 // our `$m` matchers to the list of `$not` matchers as future emissions 55 // will have to negate everything we just matched as well. 56 cfg_if! { @__items ($($not,)* $($m,)*) ; $($rest)* } 57 }; 58 59 // Internal macro to Apply a cfg attribute to a list of items 60 (@__apply $m:meta, $($it:item)*) => { 61 $(#[$m] $it)* 62 }; 63 } 64 65 #[allow(unused_macros)] 66 macro_rules! s { 67 ($($(#[$attr:meta])* pub $t:ident $i:ident { $($field:tt)* })*) => ($( 68 s!(it: $(#[$attr])* pub $t $i { $($field)* }); 69 )*); 70 (it: $(#[$attr:meta])* pub union $i:ident { $($field:tt)* }) => ( 71 compile_error!("unions cannot derive extra traits, use s_no_extra_traits instead"); 72 ); 73 (it: $(#[$attr:meta])* pub struct $i:ident { $($field:tt)* }) => ( 74 __item! { 75 #[repr(C)] 76 #[cfg_attr(feature = "extra_traits", derive(Debug, Eq, Hash, PartialEq))] 77 #[allow(deprecated)] 78 $(#[$attr])* 79 pub struct $i { $($field)* } 80 } 81 #[allow(deprecated)] 82 impl ::Copy for $i {} 83 #[allow(deprecated)] 84 impl ::Clone for $i { 85 fn clone(&self) -> $i { *self } 86 } 87 ); 88 } 89 90 #[allow(unused_macros)] 91 macro_rules! s_no_extra_traits { 92 ($($(#[$attr:meta])* pub $t:ident $i:ident { $($field:tt)* })*) => ($( 93 s_no_extra_traits!(it: $(#[$attr])* pub $t $i { $($field)* }); 94 )*); 95 (it: $(#[$attr:meta])* pub union $i:ident { $($field:tt)* }) => ( 96 cfg_if! { 97 if #[cfg(libc_union)] { 98 __item! { 99 #[repr(C)] 100 $(#[$attr])* 101 pub union $i { $($field)* } 102 } 103 104 impl ::Copy for $i {} 105 impl ::Clone for $i { 106 fn clone(&self) -> $i { *self } 107 } 108 } 109 } 110 ); 111 (it: $(#[$attr:meta])* pub struct $i:ident { $($field:tt)* }) => ( 112 __item! { 113 #[repr(C)] 114 $(#[$attr])* 115 pub struct $i { $($field)* } 116 } 117 #[allow(deprecated)] 118 impl ::Copy for $i {} 119 #[allow(deprecated)] 120 impl ::Clone for $i { 121 fn clone(&self) -> $i { *self } 122 } 123 ); 124 } 125 126 #[allow(unused_macros)] 127 macro_rules! e { 128 ($($(#[$attr:meta])* pub enum $i:ident { $($field:tt)* })*) => ($( 129 __item! { 130 #[cfg_attr(feature = "extra_traits", derive(Debug, Eq, Hash, PartialEq))] 131 $(#[$attr])* 132 pub enum $i { $($field)* } 133 } 134 impl ::Copy for $i {} 135 impl ::Clone for $i { 136 fn clone(&self) -> $i { *self } 137 } 138 )*); 139 } 140 141 #[allow(unused_macros)] 142 macro_rules! s_paren { 143 ($($(#[$attr:meta])* pub struct $i:ident ( $($field:tt)* ); )* ) => ($( 144 __item! { 145 #[cfg_attr(feature = "extra_traits", derive(Debug, Eq, Hash, PartialEq))] 146 $(#[$attr])* 147 pub struct $i ( $($field)* ); 148 } 149 impl ::Copy for $i {} 150 impl ::Clone for $i { 151 fn clone(&self) -> $i { *self } 152 } 153 )*); 154 } 155 156 // This is a pretty horrible hack to allow us to conditionally mark 157 // some functions as 'const', without requiring users of this macro 158 // to care about the "const-extern-fn" feature. 159 // 160 // When 'const-extern-fn' is enabled, we emit the captured 'const' keyword 161 // in the expanded function. 162 // 163 // When 'const-extern-fn' is disabled, we always emit a plain 'pub unsafe extern fn'. 164 // Note that the expression matched by the macro is exactly the same - this allows 165 // users of this macro to work whether or not 'const-extern-fn' is enabled 166 // 167 // Unfortunately, we need to duplicate most of this macro between the 'cfg_if' blocks. 168 // This is because 'const unsafe extern fn' won't even parse on older compilers, 169 // so we need to avoid emitting it at all of 'const-extern-fn'. 170 // 171 // Specifically, moving the 'cfg_if' into the macro body will *not* work. 172 // Doing so would cause the '#[cfg(feature = "const-extern-fn")]' to be emitted 173 // into user code. The 'cfg' gate will not stop Rust from trying to parse the 174 // 'pub const unsafe extern fn', so users would get a compiler error even when 175 // the 'const-extern-fn' feature is disabled 176 // 177 // Note that users of this macro need to place 'const' in a weird position 178 // (after the closing ')' for the arguments, but before the return type). 179 // This was the only way I could satisfy the following two requirements: 180 // 1. Avoid ambiguity errors from 'macro_rules!' (which happen when writing '$foo:ident fn' 181 // 2. Allow users of this macro to mix 'pub fn foo' and 'pub const fn bar' within the same 182 // 'f!' block 183 cfg_if! { 184 if #[cfg(libc_const_extern_fn)] { 185 #[allow(unused_macros)] 186 macro_rules! f { 187 ($($(#[$attr:meta])* pub $({$constness:ident})* fn $i:ident( 188 $($arg:ident: $argty:ty),* 189 ) -> $ret:ty { 190 $($body:stmt);* 191 })*) => ($( 192 #[inline] 193 $(#[$attr])* 194 pub $($constness)* unsafe extern fn $i($($arg: $argty),* 195 ) -> $ret { 196 $($body);* 197 } 198 )*) 199 } 200 201 #[allow(unused_macros)] 202 macro_rules! safe_f { 203 ($($(#[$attr:meta])* pub $({$constness:ident})* fn $i:ident( 204 $($arg:ident: $argty:ty),* 205 ) -> $ret:ty { 206 $($body:stmt);* 207 })*) => ($( 208 #[inline] 209 $(#[$attr])* 210 pub $($constness)* extern fn $i($($arg: $argty),* 211 ) -> $ret { 212 $($body);* 213 } 214 )*) 215 } 216 217 #[allow(unused_macros)] 218 macro_rules! const_fn { 219 ($($(#[$attr:meta])* $({$constness:ident})* fn $i:ident( 220 $($arg:ident: $argty:ty),* 221 ) -> $ret:ty { 222 $($body:stmt);* 223 })*) => ($( 224 #[inline] 225 $(#[$attr])* 226 $($constness)* fn $i($($arg: $argty),* 227 ) -> $ret { 228 $($body);* 229 } 230 )*) 231 } 232 233 } else { 234 #[allow(unused_macros)] 235 macro_rules! f { 236 ($($(#[$attr:meta])* pub $({$constness:ident})* fn $i:ident( 237 $($arg:ident: $argty:ty),* 238 ) -> $ret:ty { 239 $($body:stmt);* 240 })*) => ($( 241 #[inline] 242 $(#[$attr])* 243 pub unsafe extern fn $i($($arg: $argty),* 244 ) -> $ret { 245 $($body);* 246 } 247 )*) 248 } 249 250 #[allow(unused_macros)] 251 macro_rules! safe_f { 252 ($($(#[$attr:meta])* pub $({$constness:ident})* fn $i:ident( 253 $($arg:ident: $argty:ty),* 254 ) -> $ret:ty { 255 $($body:stmt);* 256 })*) => ($( 257 #[inline] 258 $(#[$attr])* 259 pub extern fn $i($($arg: $argty),* 260 ) -> $ret { 261 $($body);* 262 } 263 )*) 264 } 265 266 #[allow(unused_macros)] 267 macro_rules! const_fn { 268 ($($(#[$attr:meta])* $({$constness:ident})* fn $i:ident( 269 $($arg:ident: $argty:ty),* 270 ) -> $ret:ty { 271 $($body:stmt);* 272 })*) => ($( 273 #[inline] 274 $(#[$attr])* 275 fn $i($($arg: $argty),* 276 ) -> $ret { 277 $($body);* 278 } 279 )*) 280 } 281 } 282 } 283 284 #[allow(unused_macros)] 285 macro_rules! __item { 286 ($i:item) => { 287 $i 288 }; 289 } 290 291 #[allow(unused_macros)] 292 macro_rules! align_const { 293 ($($(#[$attr:meta])* 294 pub const $name:ident : $t1:ty 295 = $t2:ident { $($field:tt)* };)*) => ($( 296 #[cfg(libc_align)] 297 $(#[$attr])* 298 pub const $name : $t1 = $t2 { 299 $($field)* 300 }; 301 #[cfg(not(libc_align))] 302 $(#[$attr])* 303 pub const $name : $t1 = $t2 { 304 $($field)* 305 __align: [], 306 }; 307 )*) 308 } 309 310 // This macro is used to deprecate items that should be accessed via the mach crate 311 #[allow(unused_macros)] 312 macro_rules! deprecated_mach { 313 (pub const $id:ident: $ty:ty = $expr:expr;) => { 314 #[deprecated( 315 since = "0.2.55", 316 note = "Use the `mach` crate instead", 317 )] 318 #[allow(deprecated)] 319 pub const $id: $ty = $expr; 320 }; 321 ($(pub const $id:ident: $ty:ty = $expr:expr;)*) => { 322 $( 323 deprecated_mach!( 324 pub const $id: $ty = $expr; 325 ); 326 )* 327 }; 328 (pub type $id:ident = $ty:ty;) => { 329 #[deprecated( 330 since = "0.2.55", 331 note = "Use the `mach` crate instead", 332 )] 333 #[allow(deprecated)] 334 pub type $id = $ty; 335 }; 336 ($(pub type $id:ident = $ty:ty;)*) => { 337 $( 338 deprecated_mach!( 339 pub type $id = $ty; 340 ); 341 )* 342 } 343 } 344