344 lines
11 KiB
Rust
344 lines
11 KiB
Rust
/// A macro for defining #[cfg] if-else statements.
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///
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/// This is similar to the `if/elif` C preprocessor macro by allowing definition
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/// of a cascade of `#[cfg]` cases, emitting the implementation which matches
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/// first.
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///
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/// This allows you to conveniently provide a long list #[cfg]'d blocks of code
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/// without having to rewrite each clause multiple times.
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#[allow(unused_macros)]
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macro_rules! cfg_if {
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// match if/else chains with a final `else`
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($(
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if #[cfg($($meta:meta),*)] { $($it:item)* }
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) else * else {
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$($it2:item)*
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}) => {
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cfg_if! {
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@__items
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() ;
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$( ( ($($meta),*) ($($it)*) ), )*
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( () ($($it2)*) ),
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}
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};
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// match if/else chains lacking a final `else`
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(
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if #[cfg($($i_met:meta),*)] { $($i_it:item)* }
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$(
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else if #[cfg($($e_met:meta),*)] { $($e_it:item)* }
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)*
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) => {
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cfg_if! {
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@__items
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() ;
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( ($($i_met),*) ($($i_it)*) ),
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$( ( ($($e_met),*) ($($e_it)*) ), )*
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( () () ),
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}
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};
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// Internal and recursive macro to emit all the items
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//
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// Collects all the negated `cfg`s in a list at the beginning and after the
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// semicolon is all the remaining items
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(@__items ($($not:meta,)*) ; ) => {};
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(@__items ($($not:meta,)*) ; ( ($($m:meta),*) ($($it:item)*) ),
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$($rest:tt)*) => {
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// Emit all items within one block, applying an appropriate #[cfg]. The
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// #[cfg] will require all `$m` matchers specified and must also negate
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// all previous matchers.
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cfg_if! { @__apply cfg(all($($m,)* not(any($($not),*)))), $($it)* }
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// Recurse to emit all other items in `$rest`, and when we do so add all
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// our `$m` matchers to the list of `$not` matchers as future emissions
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// will have to negate everything we just matched as well.
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cfg_if! { @__items ($($not,)* $($m,)*) ; $($rest)* }
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};
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// Internal macro to Apply a cfg attribute to a list of items
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(@__apply $m:meta, $($it:item)*) => {
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$(#[$m] $it)*
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};
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}
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#[allow(unused_macros)]
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macro_rules! s {
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($($(#[$attr:meta])* pub $t:ident $i:ident { $($field:tt)* })*) => ($(
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s!(it: $(#[$attr])* pub $t $i { $($field)* });
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)*);
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(it: $(#[$attr:meta])* pub union $i:ident { $($field:tt)* }) => (
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compile_error!("unions cannot derive extra traits, use s_no_extra_traits instead");
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);
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(it: $(#[$attr:meta])* pub struct $i:ident { $($field:tt)* }) => (
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__item! {
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#[repr(C)]
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#[cfg_attr(feature = "extra_traits", derive(Debug, Eq, Hash, PartialEq))]
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#[allow(deprecated)]
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$(#[$attr])*
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pub struct $i { $($field)* }
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}
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#[allow(deprecated)]
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impl ::Copy for $i {}
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#[allow(deprecated)]
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impl ::Clone for $i {
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fn clone(&self) -> $i { *self }
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}
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);
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}
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#[allow(unused_macros)]
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macro_rules! s_no_extra_traits {
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($($(#[$attr:meta])* pub $t:ident $i:ident { $($field:tt)* })*) => ($(
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s_no_extra_traits!(it: $(#[$attr])* pub $t $i { $($field)* });
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)*);
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(it: $(#[$attr:meta])* pub union $i:ident { $($field:tt)* }) => (
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cfg_if! {
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if #[cfg(libc_union)] {
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__item! {
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#[repr(C)]
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$(#[$attr])*
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pub union $i { $($field)* }
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}
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impl ::Copy for $i {}
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impl ::Clone for $i {
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fn clone(&self) -> $i { *self }
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}
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}
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}
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);
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(it: $(#[$attr:meta])* pub struct $i:ident { $($field:tt)* }) => (
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__item! {
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#[repr(C)]
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$(#[$attr])*
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pub struct $i { $($field)* }
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}
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#[allow(deprecated)]
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impl ::Copy for $i {}
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#[allow(deprecated)]
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impl ::Clone for $i {
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fn clone(&self) -> $i { *self }
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}
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);
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}
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#[allow(unused_macros)]
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macro_rules! e {
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($($(#[$attr:meta])* pub enum $i:ident { $($field:tt)* })*) => ($(
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__item! {
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#[cfg_attr(feature = "extra_traits", derive(Debug, Eq, Hash, PartialEq))]
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$(#[$attr])*
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pub enum $i { $($field)* }
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}
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impl ::Copy for $i {}
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impl ::Clone for $i {
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fn clone(&self) -> $i { *self }
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}
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)*);
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}
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#[allow(unused_macros)]
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macro_rules! s_paren {
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($($(#[$attr:meta])* pub struct $i:ident ( $($field:tt)* ); )* ) => ($(
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__item! {
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#[cfg_attr(feature = "extra_traits", derive(Debug, Eq, Hash, PartialEq))]
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$(#[$attr])*
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pub struct $i ( $($field)* );
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}
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impl ::Copy for $i {}
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impl ::Clone for $i {
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fn clone(&self) -> $i { *self }
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}
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)*);
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}
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// This is a pretty horrible hack to allow us to conditionally mark
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// some functions as 'const', without requiring users of this macro
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// to care about the "const-extern-fn" feature.
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//
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// When 'const-extern-fn' is enabled, we emit the captured 'const' keyword
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// in the expanded function.
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//
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// When 'const-extern-fn' is disabled, we always emit a plain 'pub unsafe extern fn'.
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// Note that the expression matched by the macro is exactly the same - this allows
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// users of this macro to work whether or not 'const-extern-fn' is enabled
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//
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// Unfortunately, we need to duplicate most of this macro between the 'cfg_if' blocks.
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// This is because 'const unsafe extern fn' won't even parse on older compilers,
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// so we need to avoid emitting it at all of 'const-extern-fn'.
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//
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// Specifically, moving the 'cfg_if' into the macro body will *not* work.
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// Doing so would cause the '#[cfg(feature = "const-extern-fn")]' to be emitted
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// into user code. The 'cfg' gate will not stop Rust from trying to parse the
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// 'pub const unsafe extern fn', so users would get a compiler error even when
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// the 'const-extern-fn' feature is disabled
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//
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// Note that users of this macro need to place 'const' in a weird position
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// (after the closing ')' for the arguments, but before the return type).
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// This was the only way I could satisfy the following two requirements:
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// 1. Avoid ambiguity errors from 'macro_rules!' (which happen when writing '$foo:ident fn'
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// 2. Allow users of this macro to mix 'pub fn foo' and 'pub const fn bar' within the same
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// 'f!' block
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cfg_if! {
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if #[cfg(libc_const_extern_fn)] {
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#[allow(unused_macros)]
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macro_rules! f {
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($($(#[$attr:meta])* pub $({$constness:ident})* fn $i:ident(
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$($arg:ident: $argty:ty),*
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) -> $ret:ty {
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$($body:stmt);*
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})*) => ($(
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#[inline]
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$(#[$attr])*
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pub $($constness)* unsafe extern fn $i($($arg: $argty),*
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) -> $ret {
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$($body);*
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}
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)*)
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}
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#[allow(unused_macros)]
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macro_rules! safe_f {
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($($(#[$attr:meta])* pub $({$constness:ident})* fn $i:ident(
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$($arg:ident: $argty:ty),*
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) -> $ret:ty {
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$($body:stmt);*
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})*) => ($(
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#[inline]
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$(#[$attr])*
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pub $($constness)* extern fn $i($($arg: $argty),*
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) -> $ret {
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$($body);*
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}
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)*)
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}
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#[allow(unused_macros)]
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macro_rules! const_fn {
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($($(#[$attr:meta])* $({$constness:ident})* fn $i:ident(
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$($arg:ident: $argty:ty),*
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) -> $ret:ty {
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$($body:stmt);*
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})*) => ($(
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#[inline]
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$(#[$attr])*
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$($constness)* fn $i($($arg: $argty),*
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) -> $ret {
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$($body);*
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}
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)*)
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}
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} else {
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#[allow(unused_macros)]
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macro_rules! f {
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($($(#[$attr:meta])* pub $({$constness:ident})* fn $i:ident(
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$($arg:ident: $argty:ty),*
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) -> $ret:ty {
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$($body:stmt);*
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})*) => ($(
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#[inline]
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$(#[$attr])*
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pub unsafe extern fn $i($($arg: $argty),*
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) -> $ret {
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$($body);*
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}
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)*)
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}
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#[allow(unused_macros)]
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macro_rules! safe_f {
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($($(#[$attr:meta])* pub $({$constness:ident})* fn $i:ident(
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$($arg:ident: $argty:ty),*
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) -> $ret:ty {
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$($body:stmt);*
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})*) => ($(
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#[inline]
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$(#[$attr])*
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pub extern fn $i($($arg: $argty),*
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) -> $ret {
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$($body);*
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}
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)*)
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}
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#[allow(unused_macros)]
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macro_rules! const_fn {
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($($(#[$attr:meta])* $({$constness:ident})* fn $i:ident(
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$($arg:ident: $argty:ty),*
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) -> $ret:ty {
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$($body:stmt);*
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})*) => ($(
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#[inline]
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$(#[$attr])*
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fn $i($($arg: $argty),*
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) -> $ret {
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$($body);*
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}
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)*)
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}
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}
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}
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#[allow(unused_macros)]
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macro_rules! __item {
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($i:item) => {
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$i
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};
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}
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#[allow(unused_macros)]
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macro_rules! align_const {
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($($(#[$attr:meta])*
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pub const $name:ident : $t1:ty
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= $t2:ident { $($field:tt)* };)*) => ($(
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#[cfg(libc_align)]
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$(#[$attr])*
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pub const $name : $t1 = $t2 {
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$($field)*
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};
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#[cfg(not(libc_align))]
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$(#[$attr])*
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pub const $name : $t1 = $t2 {
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$($field)*
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__align: [],
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};
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)*)
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}
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// This macro is used to deprecate items that should be accessed via the mach crate
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#[allow(unused_macros)]
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macro_rules! deprecated_mach {
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(pub const $id:ident: $ty:ty = $expr:expr;) => {
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#[deprecated(
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since = "0.2.55",
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note = "Use the `mach` crate instead",
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)]
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#[allow(deprecated)]
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pub const $id: $ty = $expr;
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};
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($(pub const $id:ident: $ty:ty = $expr:expr;)*) => {
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$(
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deprecated_mach!(
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pub const $id: $ty = $expr;
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);
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)*
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};
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(pub type $id:ident = $ty:ty;) => {
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#[deprecated(
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since = "0.2.55",
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note = "Use the `mach` crate instead",
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)]
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#[allow(deprecated)]
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pub type $id = $ty;
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};
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($(pub type $id:ident = $ty:ty;)*) => {
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$(
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deprecated_mach!(
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pub type $id = $ty;
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);
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)*
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}
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}
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