bjoernager/rust
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generalize 'forbidden feature' concept so that even (un)stable feature can be invalid to toggle

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Also rename some things for extra clarity
This commit is contained in:
Ralf Jung 2024-11-16 10:00:16 +01:00
parent 1f3bf231e1
commit 2d887a5c5c
13 changed files with 468 additions and 401 deletions
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53
compiler/rustc_codegen_ssa/src/target_features.rs
View file

@ -11,7 +11,7 @@ use rustc_middle::ty::TyCtxt;
use rustc_session::parse::feature_err;
use rustc_span::Span;
use rustc_span::symbol::{Symbol, sym};
use rustc_target::target_features::{self, Stability};
use rustc_target::target_features;
use crate::errors;
@ -20,7 +20,7 @@ use crate::errors;
pub(crate) fn from_target_feature_attr(
tcx: TyCtxt<'_>,
attr: &ast::Attribute,
rust_target_features: &UnordMap<String, target_features::Stability>,
rust_target_features: &UnordMap<String, target_features::StabilityComputed>,
target_features: &mut Vec<TargetFeature>,
) {
let Some(list) = attr.meta_item_list() else { return };
@ -63,32 +63,24 @@ pub(crate) fn from_target_feature_attr(
return None;
};
// Only allow target features whose feature gates have been enabled.
let allowed = match stability {
Stability::Forbidden { .. } => false,
Stability::Stable => true,
Stability::Unstable(name) => rust_features.enabled(*name),
};
if !allowed {
match stability {
Stability::Stable => unreachable!(),
&Stability::Unstable(lang_feature_name) => {
feature_err(
&tcx.sess,
lang_feature_name,
item.span(),
format!("the target feature `{feature}` is currently unstable"),
)
.emit();
}
Stability::Forbidden { reason } => {
tcx.dcx().emit_err(errors::ForbiddenTargetFeatureAttr {
span: item.span(),
feature,
reason,
});
}
}
// Only allow target features whose feature gates have been enabled
// and which are permitted to be toggled.
if let Err(reason) = stability.allow_toggle() {
tcx.dcx().emit_err(errors::ForbiddenTargetFeatureAttr {
span: item.span(),
feature,
reason,
});
} else if let Some(nightly_feature) = stability.requires_nightly()
&& !rust_features.enabled(nightly_feature)
{
feature_err(
&tcx.sess,
nightly_feature,
item.span(),
format!("the target feature `{feature}` is currently unstable"),
)
.emit();
}
Some(Symbol::intern(feature))
}));
@ -156,18 +148,19 @@ pub(crate) fn provide(providers: &mut Providers) {
*providers = Providers {
rust_target_features: |tcx, cnum| {
assert_eq!(cnum, LOCAL_CRATE);
let target = &tcx.sess.target;
if tcx.sess.opts.actually_rustdoc {
// rustdoc needs to be able to document functions that use all the features, so
// whitelist them all
rustc_target::target_features::all_rust_features()
.map(|(a, b)| (a.to_string(), b))
.map(|(a, b)| (a.to_string(), b.compute(target)))
.collect()
} else {
tcx.sess
.target
.rust_target_features()
.iter()
.map(|&(a, b, _)| (a.to_string(), b))
.map(|&(a, b, _)| (a.to_string(), b.compute(target)))
.collect()
}
},

4
compiler/rustc_codegen_ssa/src/traits/backend.rs
View file

@ -45,7 +45,9 @@ pub trait CodegenBackend {
fn print(&self, _req: &PrintRequest, _out: &mut String, _sess: &Session) {}
fn target_features(&self, _sess: &Session, _allow_unstable: bool) -> Vec<Symbol> {
/// Returns the features that should be set in `cfg(target_features)`.
/// RUSTC_SPECIFIC_FEATURES should be skipped here, those are handled outside codegen.
fn target_features_cfg(&self, _sess: &Session, _allow_unstable: bool) -> Vec<Symbol> {
vec![]
}