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use rustc_target::target_features::Stability;
use crate::Session;
use crate::errors::{ForbiddenCTargetFeature, UnstableCTargetFeature};
pub trait StabilityExt {
/// Returns whether the feature may be toggled via `#[target_feature]` or `-Ctarget-feature`.
/// Otherwise, some features also may only be enabled by flag (target modifier).
/// (It might still be nightly-only even if this returns `true`, so make sure to also check
/// `requires_nightly`.)
fn is_toggle_permitted(&self, sess: &Session) -> Result<(), &'static str>;
/// Check that feature is correctly enabled/disabled by command line flag (emits warnings)
fn verify_feature_enabled_by_flag(&self, sess: &Session, enable: bool, feature: &str);
}
impl StabilityExt for Stability {
fn is_toggle_permitted(&self, sess: &Session) -> Result<(), &'static str> {
match self {
Stability::Forbidden { reason } => Err(reason),
Stability::TargetModifierOnly { reason, flag } => {
if !sess.opts.target_feature_flag_enabled(*flag) { Err(reason) } else { Ok(()) }
}
_ => Ok(()),
}
}
fn verify_feature_enabled_by_flag(&self, sess: &Session, enable: bool, feature: &str) {
if let Err(reason) = self.is_toggle_permitted(sess) {
sess.dcx().emit_warn(ForbiddenCTargetFeature {
feature,
enabled: if enable { "enabled" } else { "disabled" },
reason,
});
} else if self.requires_nightly().is_some() {
// An unstable feature. Warn about using it. It makes little sense
// to hard-error here since we just warn about fully unknown
// features above.
sess.dcx().emit_warn(UnstableCTargetFeature { feature });
}
}
}
pub fn retpoline_features_by_flags(sess: &Session, features: &mut Vec<&str>) {
// -Zretpoline without -Zretpoline-external-thunk enables
// retpoline-indirect-branches and retpoline-indirect-calls target features
let unstable_opts = &sess.opts.unstable_opts;
if unstable_opts.retpoline && !unstable_opts.retpoline_external_thunk {
features.push("+retpoline-indirect-branches");
features.push("+retpoline-indirect-calls");
}
// -Zretpoline-external-thunk (maybe, with -Zretpoline too) enables
// retpoline-external-thunk, retpoline-indirect-branches and
// retpoline-indirect-calls target features
if unstable_opts.retpoline_external_thunk {
features.push("+retpoline-external-thunk");
features.push("+retpoline-indirect-branches");
features.push("+retpoline-indirect-calls");
}
}
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