diff options
Diffstat (limited to 'library/std_detect/src/detect/macros.rs')
| -rw-r--r-- | library/std_detect/src/detect/macros.rs | 204 |
1 files changed, 204 insertions, 0 deletions
diff --git a/library/std_detect/src/detect/macros.rs b/library/std_detect/src/detect/macros.rs new file mode 100644 index 00000000000..a2994fb7daa --- /dev/null +++ b/library/std_detect/src/detect/macros.rs @@ -0,0 +1,204 @@ +#[macro_export] +#[allow_internal_unstable(stdarch_internal)] +#[unstable(feature = "stdarch_internal", issue = "none")] +macro_rules! detect_feature { + ($feature:tt, $feature_lit:tt) => { + $crate::detect_feature!($feature, $feature_lit : $feature_lit) + }; + ($feature:tt, $feature_lit:tt : $($target_feature_lit:tt),*) => { + $(cfg!(target_feature = $target_feature_lit) ||)* + $crate::detect::__is_feature_detected::$feature() + }; + ($feature:tt, $feature_lit:tt, without cfg check: true) => { + $crate::detect::__is_feature_detected::$feature() + }; +} + +#[allow(unused_macros, reason = "it's used in the features! macro below")] +macro_rules! check_cfg_feature { + ($feature:tt, $feature_lit:tt) => { + check_cfg_feature!($feature, $feature_lit : $feature_lit) + }; + ($feature:tt, $feature_lit:tt : $($target_feature_lit:tt),*) => { + $(cfg!(target_feature = $target_feature_lit);)* + }; + ($feature:tt, $feature_lit:tt, without cfg check: $feature_cfg_check:literal) => { + #[allow(unexpected_cfgs, reason = $feature_lit)] + { cfg!(target_feature = $feature_lit) } + }; +} + +#[allow(unused)] +macro_rules! features { + ( + @TARGET: $target:ident; + @CFG: $cfg:meta; + @MACRO_NAME: $macro_name:ident; + @MACRO_ATTRS: $(#[$macro_attrs:meta])* + $(@BIND_FEATURE_NAME: $bind_feature:tt; $feature_impl:tt; $(#[$deprecate_attr:meta];)?)* + $(@NO_RUNTIME_DETECTION: $nort_feature:tt; )* + $(@FEATURE: #[$stability_attr:meta] $feature:ident: $feature_lit:tt; + $(without cfg check: $feature_cfg_check:tt;)? + $(implied by target_features: [$($target_feature_lit:tt),*];)? + $(#[$feature_comment:meta])*)* + ) => { + #[macro_export] + $(#[$macro_attrs])* + #[allow_internal_unstable(stdarch_internal)] + #[cfg($cfg)] + #[doc(cfg($cfg))] + macro_rules! $macro_name { + $( + ($feature_lit) => { + $crate::detect_feature!($feature, $feature_lit $(, without cfg check: $feature_cfg_check)? $(: $($target_feature_lit),*)?) + }; + )* + $( + ($bind_feature) => { + { + $( + #[$deprecate_attr] macro_rules! deprecated_feature { {} => {}; } + deprecated_feature! {}; + )? + $crate::$macro_name!($feature_impl) + } + }; + )* + $( + ($nort_feature) => { + compile_error!( + concat!( + stringify!($nort_feature), + " feature cannot be detected at run-time" + ) + ) + }; + )* + ($t:tt,) => { + $crate::$macro_name!($t); + }; + ($t:tt) => { + compile_error!( + concat!( + concat!("unknown ", stringify!($target)), + concat!(" target feature: ", $t) + ) + ) + }; + } + + $(#[$macro_attrs])* + #[macro_export] + #[cfg(not($cfg))] + #[doc(cfg($cfg))] + macro_rules! $macro_name { + $( + ($feature_lit) => { + compile_error!( + concat!( + r#"This macro cannot be used on the current target. + You can prevent it from being used in other architectures by + guarding it behind a cfg("#, + stringify!($cfg), + ")." + ) + ) + }; + )* + $( + ($bind_feature) => { $crate::$macro_name!($feature_impl) }; + )* + $( + ($nort_feature) => { + compile_error!( + concat!( + stringify!($nort_feature), + " feature cannot be detected at run-time" + ) + ) + }; + )* + ($t:tt,) => { + $crate::$macro_name!($t); + }; + ($t:tt) => { + compile_error!( + concat!( + concat!("unknown ", stringify!($target)), + concat!(" target feature: ", $t) + ) + ) + }; + } + + #[test] + #[deny(unexpected_cfgs)] + #[deny(unfulfilled_lint_expectations)] + fn unexpected_cfgs() { + $( + check_cfg_feature!($feature, $feature_lit $(, without cfg check: $feature_cfg_check)? $(: $($target_feature_lit),*)?); + )* + } + + /// Each variant denotes a position in a bitset for a particular feature. + /// + /// PLEASE: do not use this, it is an implementation detail subject + /// to change. + #[doc(hidden)] + #[allow(non_camel_case_types)] + #[derive(Copy, Clone)] + #[repr(u8)] + #[unstable(feature = "stdarch_internal", issue = "none")] + #[cfg($cfg)] + pub(crate) enum Feature { + $( + $(#[$feature_comment])* + $feature, + )* + + // Do not add variants after last: + _last + } + + #[cfg($cfg)] + impl Feature { + pub(crate) fn to_str(self) -> &'static str { + match self { + $(Feature::$feature => $feature_lit,)* + Feature::_last => unreachable!(), + } + } + + #[cfg(feature = "std_detect_env_override")] + pub(crate) fn from_str(s: &str) -> Result<Feature, ()> { + match s { + $($feature_lit => Ok(Feature::$feature),)* + _ => Err(()) + } + } + } + + /// Each function performs run-time feature detection for a single + /// feature. This allow us to use stability attributes on a per feature + /// basis. + /// + /// PLEASE: do not use this, it is an implementation detail subject + /// to change. + #[doc(hidden)] + #[cfg($cfg)] + #[unstable(feature = "stdarch_internal", issue = "none")] + pub mod __is_feature_detected { + $( + + /// PLEASE: do not use this, it is an implementation detail + /// subject to change. + #[inline] + #[doc(hidden)] + #[$stability_attr] + pub fn $feature() -> bool { + $crate::detect::check_for($crate::detect::Feature::$feature) + } + )* + } + }; +} |