path: root/compiler/rustc_attr_parsing/src/attributes/codegen_attrs.rs

use rustc_attr_data_structures::{AttributeKind, OptimizeAttr, UsedBy};
use rustc_feature::{AttributeTemplate, template};
use rustc_session::parse::feature_err;
use rustc_span::{Span, Symbol, sym};

use super::{
    AcceptMapping, AttributeOrder, AttributeParser, NoArgsAttributeParser, OnDuplicate,
    SingleAttributeParser,
};
use crate::context::{AcceptContext, FinalizeContext, Stage};
use crate::parser::ArgParser;
use crate::session_diagnostics::{NakedFunctionIncompatibleAttribute, NullOnExport};

pub(crate) struct OptimizeParser;

impl<S: Stage> SingleAttributeParser<S> for OptimizeParser {
    const PATH: &[Symbol] = &[sym::optimize];
    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepLast;
    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::WarnButFutureError;
    const TEMPLATE: AttributeTemplate = template!(List: "size|speed|none");

    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
        let Some(list) = args.list() else {
            cx.expected_list(cx.attr_span);
            return None;
        };

        let Some(single) = list.single() else {
            cx.expected_single_argument(list.span);
            return None;
        };

        let res = match single.meta_item().and_then(|i| i.path().word().map(|i| i.name)) {
            Some(sym::size) => OptimizeAttr::Size,
            Some(sym::speed) => OptimizeAttr::Speed,
            Some(sym::none) => OptimizeAttr::DoNotOptimize,
            _ => {
                cx.expected_specific_argument(single.span(), vec!["size", "speed", "none"]);
                OptimizeAttr::Default
            }
        };

        Some(AttributeKind::Optimize(res, cx.attr_span))
    }
}

pub(crate) struct ColdParser;

impl<S: Stage> NoArgsAttributeParser<S> for ColdParser {
    const PATH: &[Symbol] = &[sym::cold];
    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
    const CREATE: fn(Span) -> AttributeKind = AttributeKind::Cold;
}

pub(crate) struct ExportNameParser;

impl<S: Stage> SingleAttributeParser<S> for ExportNameParser {
    const PATH: &[rustc_span::Symbol] = &[sym::export_name];
    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepFirst;
    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::WarnButFutureError;
    const TEMPLATE: AttributeTemplate = template!(NameValueStr: "name");

    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
        let Some(nv) = args.name_value() else {
            cx.expected_name_value(cx.attr_span, None);
            return None;
        };
        let Some(name) = nv.value_as_str() else {
            cx.expected_string_literal(nv.value_span, Some(nv.value_as_lit()));
            return None;
        };
        if name.as_str().contains('\0') {
            // `#[export_name = ...]` will be converted to a null-terminated string,
            // so it may not contain any null characters.
            cx.emit_err(NullOnExport { span: cx.attr_span });
            return None;
        }
        Some(AttributeKind::ExportName { name, span: cx.attr_span })
    }
}

#[derive(Default)]
pub(crate) struct NakedParser {
    span: Option<Span>,
}

impl<S: Stage> AttributeParser<S> for NakedParser {
    const ATTRIBUTES: AcceptMapping<Self, S> =
        &[(&[sym::naked], template!(Word), |this, cx, args| {
            if let Err(span) = args.no_args() {
                cx.expected_no_args(span);
                return;
            }

            if let Some(earlier) = this.span {
                let span = cx.attr_span;
                cx.warn_unused_duplicate(earlier, span);
            } else {
                this.span = Some(cx.attr_span);
            }
        })];

    fn finalize(self, cx: &FinalizeContext<'_, '_, S>) -> Option<AttributeKind> {
        // FIXME(jdonszelmann): upgrade this list to *parsed* attributes
        // once all of these have parsed forms. That'd make the check much nicer...
        //
        // many attributes don't make sense in combination with #[naked].
        // Notable attributes that are incompatible with `#[naked]` are:
        //
        // * `#[inline]`
        // * `#[track_caller]`
        // * `#[test]`, `#[ignore]`, `#[should_panic]`
        //
        // NOTE: when making changes to this list, check that `error_codes/E0736.md` remains
        // accurate.
        const ALLOW_LIST: &[rustc_span::Symbol] = &[
            // conditional compilation
            sym::cfg_trace,
            sym::cfg_attr_trace,
            // testing (allowed here so better errors can be generated in `rustc_builtin_macros::test`)
            sym::test,
            sym::ignore,
            sym::should_panic,
            sym::bench,
            // diagnostics
            sym::allow,
            sym::warn,
            sym::deny,
            sym::forbid,
            sym::deprecated,
            sym::must_use,
            // abi, linking and FFI
            sym::cold,
            sym::export_name,
            sym::link_section,
            sym::linkage,
            sym::no_mangle,
            sym::instruction_set,
            sym::repr,
            sym::rustc_std_internal_symbol,
            sym::align,
            // obviously compatible with self
            sym::naked,
            // documentation
            sym::doc,
        ];

        let span = self.span?;

        // only if we found a naked attribute do we do the somewhat expensive check
        'outer: for other_attr in cx.all_attrs {
            for allowed_attr in ALLOW_LIST {
                if other_attr.segments().next().is_some_and(|i| cx.tools.contains(&i.name)) {
                    // effectively skips the error message  being emitted below
                    // if it's a tool attribute
                    continue 'outer;
                }
                if other_attr.word_is(*allowed_attr) {
                    // effectively skips the error message  being emitted below
                    // if its an allowed attribute
                    continue 'outer;
                }

                if other_attr.word_is(sym::target_feature) {
                    if !cx.features().naked_functions_target_feature() {
                        feature_err(
                            &cx.sess(),
                            sym::naked_functions_target_feature,
                            other_attr.span(),
                            "`#[target_feature(/* ... */)]` is currently unstable on `#[naked]` functions",
                        ).emit();
                    }

                    continue 'outer;
                }
            }

            cx.emit_err(NakedFunctionIncompatibleAttribute {
                span: other_attr.span(),
                naked_span: span,
                attr: other_attr.get_attribute_path().to_string(),
            });
        }

        Some(AttributeKind::Naked(span))
    }
}

pub(crate) struct TrackCallerParser;
impl<S: Stage> NoArgsAttributeParser<S> for TrackCallerParser {
    const PATH: &[Symbol] = &[sym::track_caller];
    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
    const CREATE: fn(Span) -> AttributeKind = AttributeKind::TrackCaller;
}

pub(crate) struct NoMangleParser;
impl<S: Stage> NoArgsAttributeParser<S> for NoMangleParser {
    const PATH: &[Symbol] = &[sym::no_mangle];
    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
    const CREATE: fn(Span) -> AttributeKind = AttributeKind::NoMangle;
}

#[derive(Default)]
pub(crate) struct UsedParser {
    first_compiler: Option<Span>,
    first_linker: Option<Span>,
}

// A custom `AttributeParser` is used rather than a Simple attribute parser because
// - Specifying two `#[used]` attributes is a warning (but will be an error in the future)
// - But specifying two conflicting attributes: `#[used(compiler)]` and `#[used(linker)]` is already an error today
// We can change this to a Simple parser once the warning becomes an error
impl<S: Stage> AttributeParser<S> for UsedParser {
    const ATTRIBUTES: AcceptMapping<Self, S> = &[(
        &[sym::used],
        template!(Word, List: "compiler|linker"),
        |group: &mut Self, cx, args| {
            let used_by = match args {
                ArgParser::NoArgs => UsedBy::Linker,
                ArgParser::List(list) => {
                    let Some(l) = list.single() else {
                        cx.expected_single_argument(list.span);
                        return;
                    };

                    match l.meta_item().and_then(|i| i.path().word_sym()) {
                        Some(sym::compiler) => {
                            if !cx.features().used_with_arg() {
                                feature_err(
                                    &cx.sess(),
                                    sym::used_with_arg,
                                    cx.attr_span,
                                    "`#[used(compiler)]` is currently unstable",
                                )
                                .emit();
                            }
                            UsedBy::Compiler
                        }
                        Some(sym::linker) => {
                            if !cx.features().used_with_arg() {
                                feature_err(
                                    &cx.sess(),
                                    sym::used_with_arg,
                                    cx.attr_span,
                                    "`#[used(linker)]` is currently unstable",
                                )
                                .emit();
                            }
                            UsedBy::Linker
                        }
                        _ => {
                            cx.expected_specific_argument(l.span(), vec!["compiler", "linker"]);
                            return;
                        }
                    }
                }
                ArgParser::NameValue(_) => return,
            };

            let target = match used_by {
                UsedBy::Compiler => &mut group.first_compiler,
                UsedBy::Linker => &mut group.first_linker,
            };

            let attr_span = cx.attr_span;
            if let Some(prev) = *target {
                cx.warn_unused_duplicate(prev, attr_span);
            } else {
                *target = Some(attr_span);
            }
        },
    )];

    fn finalize(self, _cx: &FinalizeContext<'_, '_, S>) -> Option<AttributeKind> {
        // Ratcheting behaviour, if both `linker` and `compiler` are specified, use `linker`
        Some(match (self.first_compiler, self.first_linker) {
            (_, Some(span)) => AttributeKind::Used { used_by: UsedBy::Linker, span },
            (Some(span), _) => AttributeKind::Used { used_by: UsedBy::Compiler, span },
            (None, None) => return None,
        })
    }
}