rustc_attr_parsing/attributes/
link_attrs.rs

1use rustc_errors::msg;
2use rustc_feature::Features;
3use rustc_hir::attrs::AttributeKind::{LinkName, LinkOrdinal, LinkSection};
4use rustc_hir::attrs::*;
5use rustc_session::Session;
6use rustc_session::lint::builtin::ILL_FORMED_ATTRIBUTE_INPUT;
7use rustc_session::parse::feature_err;
8use rustc_span::kw;
9use rustc_target::spec::{Arch, BinaryFormat};
10
11use super::prelude::*;
12use super::util::parse_single_integer;
13use crate::attributes::cfg::parse_cfg_entry;
14use crate::session_diagnostics::{
15    AsNeededCompatibility, BundleNeedsStatic, EmptyLinkName, ExportSymbolsNeedsStatic,
16    ImportNameTypeRaw, ImportNameTypeX86, IncompatibleWasmLink, InvalidLinkModifier,
17    LinkFrameworkApple, LinkOrdinalOutOfRange, LinkRequiresName, MultipleModifiers,
18    NullOnLinkSection, RawDylibNoNul, RawDylibOnlyWindows, WholeArchiveNeedsStatic,
19};
20
21pub(crate) struct LinkNameParser;
22
23impl<S: Stage> SingleAttributeParser<S> for LinkNameParser {
24    const PATH: &[Symbol] = &[sym::link_name];
25    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepInnermost;
26    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::WarnButFutureError;
27    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowListWarnRest(&[
28        Allow(Target::ForeignFn),
29        Allow(Target::ForeignStatic),
30    ]);
31    const TEMPLATE: AttributeTemplate = ::rustc_feature::AttributeTemplate {
    word: false,
    list: None,
    one_of: &[],
    name_value_str: Some(&["name"]),
    docs: Some("https://doc.rust-lang.org/reference/items/external-blocks.html#the-link_name-attribute"),
}template!(
32        NameValueStr: "name",
33        "https://doc.rust-lang.org/reference/items/external-blocks.html#the-link_name-attribute"
34    );
35
36    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser) -> Option<AttributeKind> {
37        let Some(nv) = args.name_value() else {
38            cx.expected_name_value(cx.attr_span, None);
39            return None;
40        };
41        let Some(name) = nv.value_as_str() else {
42            cx.expected_string_literal(nv.value_span, Some(nv.value_as_lit()));
43            return None;
44        };
45
46        Some(LinkName { name, span: cx.attr_span })
47    }
48}
49
50pub(crate) struct LinkParser;
51
52impl<S: Stage> CombineAttributeParser<S> for LinkParser {
53    type Item = LinkEntry;
54    const PATH: &[Symbol] = &[sym::link];
55    const CONVERT: ConvertFn<Self::Item> = AttributeKind::Link;
56    const TEMPLATE: AttributeTemplate = ::rustc_feature::AttributeTemplate {
    word: false,
    list: Some(&[r#"name = "...""#,
                    r#"name = "...", kind = "dylib|static|...""#,
                    r#"name = "...", wasm_import_module = "...""#,
                    r#"name = "...", import_name_type = "decorated|noprefix|undecorated""#,
                    r#"name = "...", kind = "dylib|static|...", wasm_import_module = "...", import_name_type = "decorated|noprefix|undecorated""#]),
    one_of: &[],
    name_value_str: None,
    docs: Some("https://doc.rust-lang.org/reference/items/external-blocks.html#the-link-attribute"),
}template!(List: &[
57            r#"name = "...""#,
58            r#"name = "...", kind = "dylib|static|...""#,
59            r#"name = "...", wasm_import_module = "...""#,
60            r#"name = "...", import_name_type = "decorated|noprefix|undecorated""#,
61            r#"name = "...", kind = "dylib|static|...", wasm_import_module = "...", import_name_type = "decorated|noprefix|undecorated""#,
62        ], "https://doc.rust-lang.org/reference/items/external-blocks.html#the-link-attribute");
63    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(ALL_TARGETS); //FIXME Still checked fully in `check_attr.rs`
64
65    fn extend(
66        cx: &mut AcceptContext<'_, '_, S>,
67        args: &ArgParser,
68    ) -> impl IntoIterator<Item = Self::Item> {
69        let items = match args {
70            ArgParser::List(list) => list,
71            // This is an edgecase added because making this a hard error would break too many crates
72            // Specifically `#[link = "dl"]` is accepted with a FCW
73            // For more information, see https://github.com/rust-lang/rust/pull/143193
74            ArgParser::NameValue(nv) if nv.value_as_str().is_some_and(|v| v == sym::dl) => {
75                cx.warn_ill_formed_attribute_input(ILL_FORMED_ATTRIBUTE_INPUT);
76                return None;
77            }
78            _ => {
79                cx.expected_list(cx.attr_span, args);
80                return None;
81            }
82        };
83
84        let sess = cx.sess();
85        let features = cx.features();
86
87        let mut name = None;
88        let mut kind = None;
89        let mut modifiers = None;
90        let mut cfg = None;
91        let mut wasm_import_module = None;
92        let mut import_name_type = None;
93        for item in items.mixed() {
94            let Some(item) = item.meta_item() else {
95                cx.unexpected_literal(item.span());
96                continue;
97            };
98
99            let cont = match item.path().word().map(|ident| ident.name) {
100                Some(sym::name) => Self::parse_link_name(item, &mut name, cx),
101                Some(sym::kind) => Self::parse_link_kind(item, &mut kind, cx, sess, features),
102                Some(sym::modifiers) => Self::parse_link_modifiers(item, &mut modifiers, cx),
103                Some(sym::cfg) => Self::parse_link_cfg(item, &mut cfg, cx, sess, features),
104                Some(sym::wasm_import_module) => {
105                    Self::parse_link_wasm_import_module(item, &mut wasm_import_module, cx)
106                }
107                Some(sym::import_name_type) => {
108                    Self::parse_link_import_name_type(item, &mut import_name_type, cx)
109                }
110                _ => {
111                    cx.expected_specific_argument_strings(
112                        item.span(),
113                        &[
114                            sym::name,
115                            sym::kind,
116                            sym::modifiers,
117                            sym::cfg,
118                            sym::wasm_import_module,
119                            sym::import_name_type,
120                        ],
121                    );
122                    true
123                }
124            };
125            if !cont {
126                return None;
127            }
128        }
129
130        // Do this outside the above loop so we don't depend on modifiers coming after kinds
131        let mut verbatim = None;
132        if let Some((modifiers, span)) = modifiers {
133            for modifier in modifiers.as_str().split(',') {
134                let (modifier, value): (Symbol, bool) = match modifier.strip_prefix(&['+', '-']) {
135                    Some(m) => (Symbol::intern(m), modifier.starts_with('+')),
136                    None => {
137                        cx.emit_err(InvalidLinkModifier { span });
138                        continue;
139                    }
140                };
141
142                macro report_unstable_modifier($feature: ident) {
143                    if !features.$feature() {
144                        feature_err(
145                            sess,
146                            sym::$feature,
147                            span,
148                            format!("linking modifier `{modifier}` is unstable"),
149                        )
150                        .emit();
151                    }
152                }
153                let assign_modifier = |dst: &mut Option<bool>| {
154                    if dst.is_some() {
155                        cx.emit_err(MultipleModifiers { span, modifier });
156                    } else {
157                        *dst = Some(value);
158                    }
159                };
160                match (modifier, &mut kind) {
161                    (sym::bundle, Some(NativeLibKind::Static { bundle, .. })) => {
162                        assign_modifier(bundle)
163                    }
164                    (sym::bundle, _) => {
165                        cx.emit_err(BundleNeedsStatic { span });
166                    }
167
168                    (sym::export_symbols, Some(NativeLibKind::Static { export_symbols, .. })) => {
169                        assign_modifier(export_symbols)
170                    }
171
172                    (sym::export_symbols, _) => {
173                        cx.emit_err(ExportSymbolsNeedsStatic { span });
174                    }
175
176                    (sym::verbatim, _) => assign_modifier(&mut verbatim),
177
178                    (
179                        sym::whole_dash_archive,
180                        Some(NativeLibKind::Static { whole_archive, .. }),
181                    ) => assign_modifier(whole_archive),
182                    (sym::whole_dash_archive, _) => {
183                        cx.emit_err(WholeArchiveNeedsStatic { span });
184                    }
185
186                    (sym::as_dash_needed, Some(NativeLibKind::Dylib { as_needed }))
187                    | (sym::as_dash_needed, Some(NativeLibKind::Framework { as_needed }))
188                    | (sym::as_dash_needed, Some(NativeLibKind::RawDylib { as_needed })) => {
189                        if !features.native_link_modifiers_as_needed() {
    feature_err(sess, sym::native_link_modifiers_as_needed, span,
            ::alloc::__export::must_use({
                    ::alloc::fmt::format(format_args!("linking modifier `{0}` is unstable",
                            modifier))
                })).emit();
};report_unstable_modifier!(native_link_modifiers_as_needed);
190                        assign_modifier(as_needed)
191                    }
192                    (sym::as_dash_needed, _) => {
193                        cx.emit_err(AsNeededCompatibility { span });
194                    }
195
196                    _ => {
197                        cx.expected_specific_argument_strings(
198                            span,
199                            &[
200                                sym::bundle,
201                                sym::export_symbols,
202                                sym::verbatim,
203                                sym::whole_dash_archive,
204                                sym::as_dash_needed,
205                            ],
206                        );
207                    }
208                }
209            }
210        }
211
212        if let Some((_, span)) = wasm_import_module {
213            if name.is_some() || kind.is_some() || modifiers.is_some() || cfg.is_some() {
214                cx.emit_err(IncompatibleWasmLink { span });
215            }
216        }
217
218        if wasm_import_module.is_some() {
219            (name, kind) = (wasm_import_module, Some(NativeLibKind::WasmImportModule));
220        }
221        let Some((name, name_span)) = name else {
222            cx.emit_err(LinkRequiresName { span: cx.attr_span });
223            return None;
224        };
225
226        // Do this outside of the loop so that `import_name_type` can be specified before `kind`.
227        if let Some((_, span)) = import_name_type {
228            if !#[allow(non_exhaustive_omitted_patterns)] match kind {
    Some(NativeLibKind::RawDylib { .. }) => true,
    _ => false,
}matches!(kind, Some(NativeLibKind::RawDylib { .. })) {
229                cx.emit_err(ImportNameTypeRaw { span });
230            }
231        }
232
233        if let Some(NativeLibKind::RawDylib { .. }) = kind
234            && name.as_str().contains('\0')
235        {
236            cx.emit_err(RawDylibNoNul { span: name_span });
237        }
238
239        Some(LinkEntry {
240            span: cx.attr_span,
241            kind: kind.unwrap_or(NativeLibKind::Unspecified),
242            name,
243            cfg,
244            verbatim,
245            import_name_type,
246        })
247    }
248}
249
250impl LinkParser {
251    fn parse_link_name<S: Stage>(
252        item: &MetaItemParser,
253        name: &mut Option<(Symbol, Span)>,
254        cx: &mut AcceptContext<'_, '_, S>,
255    ) -> bool {
256        if name.is_some() {
257            cx.duplicate_key(item.span(), sym::name);
258            return true;
259        }
260        let Some(nv) = item.args().name_value() else {
261            cx.expected_name_value(item.span(), Some(sym::name));
262            return false;
263        };
264        let Some(link_name) = nv.value_as_str() else {
265            cx.expected_name_value(item.span(), Some(sym::name));
266            return false;
267        };
268
269        if link_name.is_empty() {
270            cx.emit_err(EmptyLinkName { span: nv.value_span });
271        }
272        *name = Some((link_name, nv.value_span));
273        true
274    }
275
276    fn parse_link_kind<S: Stage>(
277        item: &MetaItemParser,
278        kind: &mut Option<NativeLibKind>,
279        cx: &mut AcceptContext<'_, '_, S>,
280        sess: &Session,
281        features: &Features,
282    ) -> bool {
283        if kind.is_some() {
284            cx.duplicate_key(item.span(), sym::kind);
285            return true;
286        }
287        let Some(nv) = item.args().name_value() else {
288            cx.expected_name_value(item.span(), Some(sym::kind));
289            return true;
290        };
291        let Some(link_kind) = nv.value_as_str() else {
292            cx.expected_name_value(item.span(), Some(sym::kind));
293            return true;
294        };
295
296        let link_kind = match link_kind {
297            kw::Static => {
298                NativeLibKind::Static { bundle: None, whole_archive: None, export_symbols: None }
299            }
300            sym::dylib => NativeLibKind::Dylib { as_needed: None },
301            sym::framework => {
302                if !sess.target.is_like_darwin {
303                    cx.emit_err(LinkFrameworkApple { span: nv.value_span });
304                }
305                NativeLibKind::Framework { as_needed: None }
306            }
307            sym::raw_dash_dylib => {
308                if sess.target.is_like_windows {
309                    // raw-dylib is stable and working on Windows
310                } else if sess.target.binary_format == BinaryFormat::Elf && features.raw_dylib_elf()
311                {
312                    // raw-dylib is unstable on ELF, but the user opted in
313                } else if sess.target.binary_format == BinaryFormat::Elf && sess.is_nightly_build()
314                {
315                    feature_err(
316                        sess,
317                        sym::raw_dylib_elf,
318                        nv.value_span,
319                        rustc_errors::DiagMessage::Inline(std::borrow::Cow::Borrowed("link kind `raw-dylib` is unstable on ELF platforms"))msg!("link kind `raw-dylib` is unstable on ELF platforms"),
320                    )
321                    .emit();
322                } else {
323                    cx.emit_err(RawDylibOnlyWindows { span: nv.value_span });
324                }
325
326                NativeLibKind::RawDylib { as_needed: None }
327            }
328            sym::link_dash_arg => {
329                if !features.link_arg_attribute() {
330                    feature_err(
331                        sess,
332                        sym::link_arg_attribute,
333                        nv.value_span,
334                        rustc_errors::DiagMessage::Inline(std::borrow::Cow::Borrowed("link kind `link-arg` is unstable"))msg!("link kind `link-arg` is unstable"),
335                    )
336                    .emit();
337                }
338                NativeLibKind::LinkArg
339            }
340            _kind => {
341                cx.expected_specific_argument_strings(
342                    nv.value_span,
343                    &[
344                        kw::Static,
345                        sym::dylib,
346                        sym::framework,
347                        sym::raw_dash_dylib,
348                        sym::link_dash_arg,
349                    ],
350                );
351                return true;
352            }
353        };
354        *kind = Some(link_kind);
355        true
356    }
357
358    fn parse_link_modifiers<S: Stage>(
359        item: &MetaItemParser,
360        modifiers: &mut Option<(Symbol, Span)>,
361        cx: &mut AcceptContext<'_, '_, S>,
362    ) -> bool {
363        if modifiers.is_some() {
364            cx.duplicate_key(item.span(), sym::modifiers);
365            return true;
366        }
367        let Some(nv) = item.args().name_value() else {
368            cx.expected_name_value(item.span(), Some(sym::modifiers));
369            return true;
370        };
371        let Some(link_modifiers) = nv.value_as_str() else {
372            cx.expected_name_value(item.span(), Some(sym::modifiers));
373            return true;
374        };
375        *modifiers = Some((link_modifiers, nv.value_span));
376        true
377    }
378
379    fn parse_link_cfg<S: Stage>(
380        item: &MetaItemParser,
381        cfg: &mut Option<CfgEntry>,
382        cx: &mut AcceptContext<'_, '_, S>,
383        sess: &Session,
384        features: &Features,
385    ) -> bool {
386        if cfg.is_some() {
387            cx.duplicate_key(item.span(), sym::cfg);
388            return true;
389        }
390        let Some(link_cfg) = item.args().list() else {
391            cx.expected_list(item.span(), item.args());
392            return true;
393        };
394        let Some(link_cfg) = link_cfg.single() else {
395            cx.expected_single_argument(item.span());
396            return true;
397        };
398        if !features.link_cfg() {
399            feature_err(sess, sym::link_cfg, item.span(), rustc_errors::DiagMessage::Inline(std::borrow::Cow::Borrowed("link cfg is unstable"))msg!("link cfg is unstable")).emit();
400        }
401        *cfg = parse_cfg_entry(cx, link_cfg).ok();
402        true
403    }
404
405    fn parse_link_wasm_import_module<S: Stage>(
406        item: &MetaItemParser,
407        wasm_import_module: &mut Option<(Symbol, Span)>,
408        cx: &mut AcceptContext<'_, '_, S>,
409    ) -> bool {
410        if wasm_import_module.is_some() {
411            cx.duplicate_key(item.span(), sym::wasm_import_module);
412            return true;
413        }
414        let Some(nv) = item.args().name_value() else {
415            cx.expected_name_value(item.span(), Some(sym::wasm_import_module));
416            return true;
417        };
418        let Some(link_wasm_import_module) = nv.value_as_str() else {
419            cx.expected_name_value(item.span(), Some(sym::wasm_import_module));
420            return true;
421        };
422        *wasm_import_module = Some((link_wasm_import_module, item.span()));
423        true
424    }
425
426    fn parse_link_import_name_type<S: Stage>(
427        item: &MetaItemParser,
428        import_name_type: &mut Option<(PeImportNameType, Span)>,
429        cx: &mut AcceptContext<'_, '_, S>,
430    ) -> bool {
431        if import_name_type.is_some() {
432            cx.duplicate_key(item.span(), sym::import_name_type);
433            return true;
434        }
435        let Some(nv) = item.args().name_value() else {
436            cx.expected_name_value(item.span(), Some(sym::import_name_type));
437            return true;
438        };
439        let Some(link_import_name_type) = nv.value_as_str() else {
440            cx.expected_name_value(item.span(), Some(sym::import_name_type));
441            return true;
442        };
443        if cx.sess().target.arch != Arch::X86 {
444            cx.emit_err(ImportNameTypeX86 { span: item.span() });
445            return true;
446        }
447
448        let link_import_name_type = match link_import_name_type {
449            sym::decorated => PeImportNameType::Decorated,
450            sym::noprefix => PeImportNameType::NoPrefix,
451            sym::undecorated => PeImportNameType::Undecorated,
452            _ => {
453                cx.expected_specific_argument_strings(
454                    item.span(),
455                    &[sym::decorated, sym::noprefix, sym::undecorated],
456                );
457                return true;
458            }
459        };
460        *import_name_type = Some((link_import_name_type, item.span()));
461        true
462    }
463}
464
465pub(crate) struct LinkSectionParser;
466
467impl<S: Stage> SingleAttributeParser<S> for LinkSectionParser {
468    const PATH: &[Symbol] = &[sym::link_section];
469    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepInnermost;
470    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::WarnButFutureError;
471    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowListWarnRest(&[
472        Allow(Target::Static),
473        Allow(Target::Fn),
474        Allow(Target::Method(MethodKind::Inherent)),
475        Allow(Target::Method(MethodKind::Trait { body: true })),
476        Allow(Target::Method(MethodKind::TraitImpl)),
477    ]);
478    const TEMPLATE: AttributeTemplate = ::rustc_feature::AttributeTemplate {
    word: false,
    list: None,
    one_of: &[],
    name_value_str: Some(&["name"]),
    docs: Some("https://doc.rust-lang.org/reference/abi.html#the-link_section-attribute"),
}template!(
479        NameValueStr: "name",
480        "https://doc.rust-lang.org/reference/abi.html#the-link_section-attribute"
481    );
482
483    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser) -> Option<AttributeKind> {
484        let Some(nv) = args.name_value() else {
485            cx.expected_name_value(cx.attr_span, None);
486            return None;
487        };
488        let Some(name) = nv.value_as_str() else {
489            cx.expected_string_literal(nv.value_span, Some(nv.value_as_lit()));
490            return None;
491        };
492        if name.as_str().contains('\0') {
493            // `#[link_section = ...]` will be converted to a null-terminated string,
494            // so it may not contain any null characters.
495            cx.emit_err(NullOnLinkSection { span: cx.attr_span });
496            return None;
497        }
498
499        Some(LinkSection { name, span: cx.attr_span })
500    }
501}
502
503pub(crate) struct ExportStableParser;
504impl<S: Stage> NoArgsAttributeParser<S> for ExportStableParser {
505    const PATH: &[Symbol] = &[sym::export_stable];
506    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
507    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(ALL_TARGETS); //FIXME Still checked fully in `check_attr.rs`
508    const CREATE: fn(Span) -> AttributeKind = |_| AttributeKind::ExportStable;
509}
510
511pub(crate) struct FfiConstParser;
512impl<S: Stage> NoArgsAttributeParser<S> for FfiConstParser {
513    const PATH: &[Symbol] = &[sym::ffi_const];
514    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
515    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::ForeignFn)]);
516    const CREATE: fn(Span) -> AttributeKind = AttributeKind::FfiConst;
517}
518
519pub(crate) struct FfiPureParser;
520impl<S: Stage> NoArgsAttributeParser<S> for FfiPureParser {
521    const PATH: &[Symbol] = &[sym::ffi_pure];
522    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
523    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::ForeignFn)]);
524    const CREATE: fn(Span) -> AttributeKind = AttributeKind::FfiPure;
525}
526
527pub(crate) struct StdInternalSymbolParser;
528impl<S: Stage> NoArgsAttributeParser<S> for StdInternalSymbolParser {
529    const PATH: &[Symbol] = &[sym::rustc_std_internal_symbol];
530    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
531    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
532        Allow(Target::Fn),
533        Allow(Target::ForeignFn),
534        Allow(Target::Static),
535        Allow(Target::ForeignStatic),
536    ]);
537    const CREATE: fn(Span) -> AttributeKind = AttributeKind::RustcStdInternalSymbol;
538}
539
540pub(crate) struct LinkOrdinalParser;
541
542impl<S: Stage> SingleAttributeParser<S> for LinkOrdinalParser {
543    const PATH: &[Symbol] = &[sym::link_ordinal];
544    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
545    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
546    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
547        Allow(Target::ForeignFn),
548        Allow(Target::ForeignStatic),
549        Warn(Target::MacroCall),
550    ]);
551    const TEMPLATE: AttributeTemplate = ::rustc_feature::AttributeTemplate {
    word: false,
    list: Some(&["ordinal"]),
    one_of: &[],
    name_value_str: None,
    docs: Some("https://doc.rust-lang.org/reference/items/external-blocks.html#the-link_ordinal-attribute"),
}template!(
552        List: &["ordinal"],
553        "https://doc.rust-lang.org/reference/items/external-blocks.html#the-link_ordinal-attribute"
554    );
555
556    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser) -> Option<AttributeKind> {
557        let ordinal = parse_single_integer(cx, args)?;
558
559        // According to the table at
560        // https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#import-header, the
561        // ordinal must fit into 16 bits. Similarly, the Ordinal field in COFFShortExport (defined
562        // in llvm/include/llvm/Object/COFFImportFile.h), which we use to communicate import
563        // information to LLVM for `#[link(kind = "raw-dylib"_])`, is also defined to be uint16_t.
564        //
565        // FIXME: should we allow an ordinal of 0?  The MSVC toolchain has inconsistent support for
566        // this: both LINK.EXE and LIB.EXE signal errors and abort when given a .DEF file that
567        // specifies a zero ordinal. However, llvm-dlltool is perfectly happy to generate an import
568        // library for such a .DEF file, and MSVC's LINK.EXE is also perfectly happy to consume an
569        // import library produced by LLVM with an ordinal of 0, and it generates an .EXE.  (I
570        // don't know yet if the resulting EXE runs, as I haven't yet built the necessary DLL --
571        // see earlier comment about LINK.EXE failing.)
572        let Ok(ordinal) = ordinal.try_into() else {
573            cx.emit_err(LinkOrdinalOutOfRange { span: cx.attr_span, ordinal });
574            return None;
575        };
576
577        Some(LinkOrdinal { ordinal, span: cx.attr_span })
578    }
579}
580
581pub(crate) struct LinkageParser;
582
583impl<S: Stage> SingleAttributeParser<S> for LinkageParser {
584    const PATH: &[Symbol] = &[sym::linkage];
585
586    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
587
588    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
589    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
590        Allow(Target::Fn),
591        Allow(Target::Method(MethodKind::Inherent)),
592        Allow(Target::Method(MethodKind::Trait { body: true })),
593        Allow(Target::Method(MethodKind::TraitImpl)),
594        Allow(Target::Static),
595        Allow(Target::ForeignStatic),
596        Allow(Target::ForeignFn),
597        Warn(Target::Method(MethodKind::Trait { body: false })), // Not inherited
598    ]);
599
600    const TEMPLATE: AttributeTemplate = ::rustc_feature::AttributeTemplate {
    word: false,
    list: None,
    one_of: &[],
    name_value_str: Some(&["available_externally", "common", "extern_weak",
                    "external", "internal", "linkonce", "linkonce_odr", "weak",
                    "weak_odr"]),
    docs: None,
}template!(NameValueStr: [
601        "available_externally",
602        "common",
603        "extern_weak",
604        "external",
605        "internal",
606        "linkonce",
607        "linkonce_odr",
608        "weak",
609        "weak_odr",
610    ]);
611
612    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser) -> Option<AttributeKind> {
613        let Some(name_value) = args.name_value() else {
614            cx.expected_name_value(cx.attr_span, Some(sym::linkage));
615            return None;
616        };
617
618        let Some(value) = name_value.value_as_str() else {
619            cx.expected_string_literal(name_value.value_span, Some(name_value.value_as_lit()));
620            return None;
621        };
622
623        // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
624        // applicable to variable declarations and may not really make sense for
625        // Rust code in the first place but allow them anyway and trust that the
626        // user knows what they're doing. Who knows, unanticipated use cases may pop
627        // up in the future.
628        //
629        // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
630        // and don't have to be, LLVM treats them as no-ops.
631        let linkage = match value {
632            sym::available_externally => Linkage::AvailableExternally,
633            sym::common => Linkage::Common,
634            sym::extern_weak => Linkage::ExternalWeak,
635            sym::external => Linkage::External,
636            sym::internal => Linkage::Internal,
637            sym::linkonce => Linkage::LinkOnceAny,
638            sym::linkonce_odr => Linkage::LinkOnceODR,
639            sym::weak => Linkage::WeakAny,
640            sym::weak_odr => Linkage::WeakODR,
641
642            _ => {
643                cx.expected_specific_argument(
644                    name_value.value_span,
645                    &[
646                        sym::available_externally,
647                        sym::common,
648                        sym::extern_weak,
649                        sym::external,
650                        sym::internal,
651                        sym::linkonce,
652                        sym::linkonce_odr,
653                        sym::weak,
654                        sym::weak_odr,
655                    ],
656                );
657                return None;
658            }
659        };
660
661        Some(AttributeKind::Linkage(linkage, cx.attr_span))
662    }
663}
664
665pub(crate) struct NeedsAllocatorParser;
666
667impl<S: Stage> NoArgsAttributeParser<S> for NeedsAllocatorParser {
668    const PATH: &[Symbol] = &[sym::needs_allocator];
669    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
670    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Crate)]);
671    const CREATE: fn(Span) -> AttributeKind = |_| AttributeKind::NeedsAllocator;
672}
673
674pub(crate) struct CompilerBuiltinsParser;
675
676impl<S: Stage> NoArgsAttributeParser<S> for CompilerBuiltinsParser {
677    const PATH: &[Symbol] = &[sym::compiler_builtins];
678    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
679    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Crate)]);
680    const CREATE: fn(Span) -> AttributeKind = |_| AttributeKind::CompilerBuiltins;
681}
rustc_attr_parsing/attributes/link_attrs.rs

rustc_attr_parsing/attributes/
link_attrs.rs
