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Add an experimental unsafe(force_target_feature) attribute.

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This uses the feature gate for
https://github.com/rust-lang/rust/issues/143352, but is described in
https://github.com/rust-lang/rfcs/pull/3820 which is strongly tied to
the experiment.
This commit is contained in:
Luca Versari
2025-08-18 15:09:45 +02:00
parent 6ba0ce4094
commit 291da71b2a
21 changed files with 262 additions and 61 deletions
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118
compiler/rustc_attr_parsing/src/attributes/codegen_attrs.rs
View File

@@ -385,57 +385,68 @@ impl<S: Stage> AttributeParser<S> for UsedParser {
}
}
fn parse_tf_attribute<'c, S: Stage>(
cx: &'c mut AcceptContext<'_, '_, S>,
args: &'c ArgParser<'_>,
) -> impl IntoIterator<Item = (Symbol, Span)> + 'c {
let mut features = Vec::new();
let ArgParser::List(list) = args else {
cx.expected_list(cx.attr_span);
return features;
};
if list.is_empty() {
cx.warn_empty_attribute(cx.attr_span);
return features;
}
for item in list.mixed() {
let Some(name_value) = item.meta_item() else {
cx.expected_name_value(item.span(), Some(sym::enable));
return features;
};
// Validate name
let Some(name) = name_value.path().word_sym() else {
cx.expected_name_value(name_value.path().span(), Some(sym::enable));
return features;
};
if name != sym::enable {
cx.expected_name_value(name_value.path().span(), Some(sym::enable));
return features;
}
// Use value
let Some(name_value) = name_value.args().name_value() else {
cx.expected_name_value(item.span(), Some(sym::enable));
return features;
};
let Some(value_str) = name_value.value_as_str() else {
cx.expected_string_literal(name_value.value_span, Some(name_value.value_as_lit()));
return features;
};
for feature in value_str.as_str().split(",") {
features.push((Symbol::intern(feature), item.span()));
}
}
features
}
pub(crate) struct TargetFeatureParser;
impl<S: Stage> CombineAttributeParser<S> for TargetFeatureParser {
type Item = (Symbol, Span);
const PATH: &[Symbol] = &[sym::target_feature];
const CONVERT: ConvertFn<Self::Item> = |items, span| AttributeKind::TargetFeature(items, span);
const CONVERT: ConvertFn<Self::Item> = |items, span| AttributeKind::TargetFeature {
features: items,
attr_span: span,
was_forced: false,
};
const TEMPLATE: AttributeTemplate = template!(List: &["enable = \"feat1, feat2\""]);
fn extend<'c>(
cx: &'c mut AcceptContext<'_, '_, S>,
args: &'c ArgParser<'_>,
) -> impl IntoIterator<Item = Self::Item> + 'c {
let mut features = Vec::new();
let ArgParser::List(list) = args else {
cx.expected_list(cx.attr_span);
return features;
};
if list.is_empty() {
cx.warn_empty_attribute(cx.attr_span);
return features;
}
for item in list.mixed() {
let Some(name_value) = item.meta_item() else {
cx.expected_name_value(item.span(), Some(sym::enable));
return features;
};
// Validate name
let Some(name) = name_value.path().word_sym() else {
cx.expected_name_value(name_value.path().span(), Some(sym::enable));
return features;
};
if name != sym::enable {
cx.expected_name_value(name_value.path().span(), Some(sym::enable));
return features;
}
// Use value
let Some(name_value) = name_value.args().name_value() else {
cx.expected_name_value(item.span(), Some(sym::enable));
return features;
};
let Some(value_str) = name_value.value_as_str() else {
cx.expected_string_literal(name_value.value_span, Some(name_value.value_as_lit()));
return features;
};
for feature in value_str.as_str().split(",") {
features.push((Symbol::intern(feature), item.span()));
}
}
features
parse_tf_attribute(cx, args)
}
const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
@@ -449,3 +460,30 @@ impl<S: Stage> CombineAttributeParser<S> for TargetFeatureParser {
Warn(Target::MacroDef),
]);
}
pub(crate) struct ForceTargetFeatureParser;
impl<S: Stage> CombineAttributeParser<S> for ForceTargetFeatureParser {
type Item = (Symbol, Span);
const PATH: &[Symbol] = &[sym::force_target_feature];
const CONVERT: ConvertFn<Self::Item> = |items, span| AttributeKind::TargetFeature {
features: items,
attr_span: span,
was_forced: true,
};
const TEMPLATE: AttributeTemplate = template!(List: &["enable = \"feat1, feat2\""]);
fn extend<'c>(
cx: &'c mut AcceptContext<'_, '_, S>,
args: &'c ArgParser<'_>,
) -> impl IntoIterator<Item = Self::Item> + 'c {
parse_tf_attribute(cx, args)
}
const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
Allow(Target::Fn),
Allow(Target::Method(MethodKind::Inherent)),
Allow(Target::Method(MethodKind::Trait { body: true })),
Allow(Target::Method(MethodKind::TraitImpl)),
]);
}