libc/macros.rs
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/// A macro for defining #[cfg] if-else statements.
///
/// This is similar to the `if/elif` C preprocessor macro by allowing definition
/// of a cascade of `#[cfg]` cases, emitting the implementation which matches
/// first.
///
/// This allows you to conveniently provide a long list #[cfg]'d blocks of code
/// without having to rewrite each clause multiple times.
macro_rules! cfg_if {
// match if/else chains with a final `else`
($(
if #[cfg($($meta:meta),*)] { $($it:item)* }
) else * else {
$($it2:item)*
}) => {
cfg_if! {
@__items
() ;
$( ( ($($meta),*) ($($it)*) ), )*
( () ($($it2)*) ),
}
};
// match if/else chains lacking a final `else`
(
if #[cfg($($i_met:meta),*)] { $($i_it:item)* }
$(
else if #[cfg($($e_met:meta),*)] { $($e_it:item)* }
)*
) => {
cfg_if! {
@__items
() ;
( ($($i_met),*) ($($i_it)*) ),
$( ( ($($e_met),*) ($($e_it)*) ), )*
( () () ),
}
};
// Internal and recursive macro to emit all the items
//
// Collects all the negated `cfg`s in a list at the beginning and after the
// semicolon is all the remaining items
(@__items ($($not:meta,)*) ; ) => {};
(@__items ($($not:meta,)*) ; ( ($($m:meta),*) ($($it:item)*) ),
$($rest:tt)*) => {
// Emit all items within one block, applying an appropriate #[cfg]. The
// #[cfg] will require all `$m` matchers specified and must also negate
// all previous matchers.
cfg_if! { @__apply cfg(all($($m,)* not(any($($not),*)))), $($it)* }
// Recurse to emit all other items in `$rest`, and when we do so add all
// our `$m` matchers to the list of `$not` matchers as future emissions
// will have to negate everything we just matched as well.
cfg_if! { @__items ($($not,)* $($m,)*) ; $($rest)* }
};
// Internal macro to Apply a cfg attribute to a list of items
(@__apply $m:meta, $($it:item)*) => {
$(#[$m] $it)*
};
}
macro_rules! s {
($($(#[$attr:meta])* pub $t:ident $i:ident { $($field:tt)* })*) => ($(
s!(it: $(#[$attr])* pub $t $i { $($field)* });
)*);
(it: $(#[$attr:meta])* pub union $i:ident { $($field:tt)* }) => (
compile_error!("unions cannot derive extra traits, use s_no_extra_traits instead");
);
(it: $(#[$attr:meta])* pub struct $i:ident { $($field:tt)* }) => (
__item! {
#[repr(C)]
#[cfg_attr(feature = "extra_traits", derive(Debug, Eq, Hash, PartialEq))]
#[allow(deprecated)]
$(#[$attr])*
pub struct $i { $($field)* }
}
#[allow(deprecated)]
impl ::Copy for $i {}
#[allow(deprecated)]
impl ::Clone for $i {
fn clone(&self) -> $i { *self }
}
);
}
macro_rules! s_no_extra_traits {
($($(#[$attr:meta])* pub $t:ident $i:ident { $($field:tt)* })*) => ($(
s_no_extra_traits!(it: $(#[$attr])* pub $t $i { $($field)* });
)*);
(it: $(#[$attr:meta])* pub union $i:ident { $($field:tt)* }) => (
cfg_if! {
if #[cfg(libc_union)] {
__item! {
#[repr(C)]
$(#[$attr])*
pub union $i { $($field)* }
}
impl ::Copy for $i {}
impl ::Clone for $i {
fn clone(&self) -> $i { *self }
}
}
}
);
(it: $(#[$attr:meta])* pub struct $i:ident { $($field:tt)* }) => (
__item! {
#[repr(C)]
$(#[$attr])*
pub struct $i { $($field)* }
}
#[allow(deprecated)]
impl ::Copy for $i {}
#[allow(deprecated)]
impl ::Clone for $i {
fn clone(&self) -> $i { *self }
}
);
}
macro_rules! missing {
($($(#[$attr:meta])* pub enum $i:ident {})*) => ($(
$(#[$attr])* #[allow(missing_copy_implementations)] pub enum $i { }
)*);
}
macro_rules! e {
($($(#[$attr:meta])* pub enum $i:ident { $($field:tt)* })*) => ($(
__item! {
#[cfg_attr(feature = "extra_traits", derive(Debug, Eq, Hash, PartialEq))]
$(#[$attr])*
pub enum $i { $($field)* }
}
impl ::Copy for $i {}
impl ::Clone for $i {
fn clone(&self) -> $i { *self }
}
)*);
}
macro_rules! s_paren {
($($(#[$attr:meta])* pub struct $i:ident ( $($field:tt)* ); )* ) => ($(
__item! {
#[cfg_attr(feature = "extra_traits", derive(Debug, Eq, Hash, PartialEq))]
$(#[$attr])*
pub struct $i ( $($field)* );
}
impl ::Copy for $i {}
impl ::Clone for $i {
fn clone(&self) -> $i { *self }
}
)*);
}
// This is a pretty horrible hack to allow us to conditionally mark
// some functions as 'const', without requiring users of this macro
// to care about the "const-extern-fn" feature.
//
// When 'const-extern-fn' is enabled, we emit the captured 'const' keyword
// in the expanded function.
//
// When 'const-extern-fn' is disabled, we always emit a plain 'pub unsafe extern fn'.
// Note that the expression matched by the macro is exactly the same - this allows
// users of this macro to work whether or not 'const-extern-fn' is enabled
//
// Unfortunately, we need to duplicate most of this macro between the 'cfg_if' blocks.
// This is because 'const unsafe extern fn' won't even parse on older compilers,
// so we need to avoid emitting it at all of 'const-extern-fn'.
//
// Specifically, moving the 'cfg_if' into the macro body will *not* work.
// Doing so would cause the '#[cfg(feature = "const-extern-fn")]' to be emitted
// into user code. The 'cfg' gate will not stop Rust from trying to parse the
// 'pub const unsafe extern fn', so users would get a compiler error even when
// the 'const-extern-fn' feature is disabled
//
// Note that users of this macro need to place 'const' in a weird position
// (after the closing ')' for the arguments, but before the return type).
// This was the only way I could satisfy the following two requirements:
// 1. Avoid ambiguity errors from 'macro_rules!' (which happen when writing '$foo:ident fn'
// 2. Allow users of this macro to mix 'pub fn foo' and 'pub const fn bar' within the same
// 'f!' block
cfg_if! {
if #[cfg(libc_const_extern_fn)] {
macro_rules! f {
($($(#[$attr:meta])* pub $({$constness:ident})* fn $i:ident(
$($arg:ident: $argty:ty),*
) -> $ret:ty {
$($body:stmt);*
})*) => ($(
#[inline]
$(#[$attr])*
pub $($constness)* unsafe extern fn $i($($arg: $argty),*
) -> $ret {
$($body);*
}
)*)
}
macro_rules! safe_f {
($($(#[$attr:meta])* pub $({$constness:ident})* fn $i:ident(
$($arg:ident: $argty:ty),*
) -> $ret:ty {
$($body:stmt);*
})*) => ($(
#[inline]
$(#[$attr])*
pub $($constness)* extern fn $i($($arg: $argty),*
) -> $ret {
$($body);*
}
)*)
}
macro_rules! const_fn {
($($(#[$attr:meta])* $({$constness:ident})* fn $i:ident(
$($arg:ident: $argty:ty),*
) -> $ret:ty {
$($body:stmt);*
})*) => ($(
#[inline]
$(#[$attr])*
$($constness)* fn $i($($arg: $argty),*
) -> $ret {
$($body);*
}
)*)
}
} else {
macro_rules! f {
($($(#[$attr:meta])* pub $({$constness:ident})* fn $i:ident(
$($arg:ident: $argty:ty),*
) -> $ret:ty {
$($body:stmt);*
})*) => ($(
#[inline]
$(#[$attr])*
pub unsafe extern fn $i($($arg: $argty),*
) -> $ret {
$($body);*
}
)*)
}
macro_rules! safe_f {
($($(#[$attr:meta])* pub $({$constness:ident})* fn $i:ident(
$($arg:ident: $argty:ty),*
) -> $ret:ty {
$($body:stmt);*
})*) => ($(
#[inline]
$(#[$attr])*
pub extern fn $i($($arg: $argty),*
) -> $ret {
$($body);*
}
)*)
}
macro_rules! const_fn {
($($(#[$attr:meta])* $({$constness:ident})* fn $i:ident(
$($arg:ident: $argty:ty),*
) -> $ret:ty {
$($body:stmt);*
})*) => ($(
#[inline]
$(#[$attr])*
fn $i($($arg: $argty),*
) -> $ret {
$($body);*
}
)*)
}
}
}
macro_rules! __item {
($i:item) => {
$i
};
}
macro_rules! align_const {
($($(#[$attr:meta])*
pub const $name:ident : $t1:ty
= $t2:ident { $($field:tt)* };)*) => ($(
#[cfg(libc_align)]
$(#[$attr])*
pub const $name : $t1 = $t2 {
$($field)*
};
#[cfg(not(libc_align))]
$(#[$attr])*
pub const $name : $t1 = $t2 {
$($field)*
__align: [],
};
)*)
}
// This macro is used to deprecate items that should be accessed via the mach2 crate
macro_rules! deprecated_mach {
(pub const $id:ident: $ty:ty = $expr:expr;) => {
#[deprecated(
since = "0.2.55",
note = "Use the `mach2` crate instead",
)]
#[allow(deprecated)]
pub const $id: $ty = $expr;
};
($(pub const $id:ident: $ty:ty = $expr:expr;)*) => {
$(
deprecated_mach!(
pub const $id: $ty = $expr;
);
)*
};
(pub type $id:ident = $ty:ty;) => {
#[deprecated(
since = "0.2.55",
note = "Use the `mach2` crate instead",
)]
#[allow(deprecated)]
pub type $id = $ty;
};
($(pub type $id:ident = $ty:ty;)*) => {
$(
deprecated_mach!(
pub type $id = $ty;
);
)*
}
}
#[cfg(not(libc_ptr_addr_of))]
macro_rules! ptr_addr_of {
($place:expr) => {
&$place
};
}
#[cfg(libc_ptr_addr_of)]
macro_rules! ptr_addr_of {
($place:expr) => {
::core::ptr::addr_of!($place)
};
}