rustc_attr_parsing/attributes/
link_attrs.rs

1use rustc_feature::Features;
2use rustc_hir::attrs::AttributeKind::{LinkName, LinkOrdinal, LinkSection};
3use rustc_hir::attrs::*;
4use rustc_session::Session;
5use rustc_session::parse::feature_err;
6use rustc_span::kw;
7use rustc_target::spec::BinaryFormat;
8
9use super::prelude::*;
10use super::util::parse_single_integer;
11use crate::attributes::cfg::parse_cfg_entry;
12use crate::fluent_generated;
13use crate::session_diagnostics::{
14    AsNeededCompatibility, BundleNeedsStatic, EmptyLinkName, ImportNameTypeRaw, ImportNameTypeX86,
15    IncompatibleWasmLink, InvalidLinkModifier, LinkFrameworkApple, LinkOrdinalOutOfRange,
16    LinkRequiresName, MultipleModifiers, NullOnLinkSection, RawDylibNoNul, RawDylibOnlyWindows,
17    WholeArchiveNeedsStatic,
18};
19
20pub(crate) struct LinkNameParser;
21
22impl<S: Stage> SingleAttributeParser<S> for LinkNameParser {
23    const PATH: &[Symbol] = &[sym::link_name];
24    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepInnermost;
25    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::WarnButFutureError;
26    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowListWarnRest(&[
27        Allow(Target::ForeignFn),
28        Allow(Target::ForeignStatic),
29    ]);
30    const TEMPLATE: AttributeTemplate = template!(
31        NameValueStr: "name",
32        "https://doc.rust-lang.org/reference/items/external-blocks.html#the-link_name-attribute"
33    );
34
35    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
36        let Some(nv) = args.name_value() else {
37            cx.expected_name_value(cx.attr_span, None);
38            return None;
39        };
40        let Some(name) = nv.value_as_str() else {
41            cx.expected_string_literal(nv.value_span, Some(nv.value_as_lit()));
42            return None;
43        };
44
45        Some(LinkName { name, span: cx.attr_span })
46    }
47}
48
49pub(crate) struct LinkParser;
50
51impl<S: Stage> CombineAttributeParser<S> for LinkParser {
52    type Item = LinkEntry;
53    const PATH: &[Symbol] = &[sym::link];
54    const CONVERT: ConvertFn<Self::Item> = AttributeKind::Link;
55    const TEMPLATE: AttributeTemplate = template!(List: &[
56            r#"name = "...""#,
57            r#"name = "...", kind = "dylib|static|...""#,
58            r#"name = "...", wasm_import_module = "...""#,
59            r#"name = "...", import_name_type = "decorated|noprefix|undecorated""#,
60            r#"name = "...", kind = "dylib|static|...", wasm_import_module = "...", import_name_type = "decorated|noprefix|undecorated""#,
61        ], "https://doc.rust-lang.org/reference/items/external-blocks.html#the-link-attribute");
62    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(ALL_TARGETS); //FIXME Still checked fully in `check_attr.rs`
63
64    fn extend<'c>(
65        cx: &'c mut AcceptContext<'_, '_, S>,
66        args: &'c ArgParser<'_>,
67    ) -> impl IntoIterator<Item = Self::Item> + 'c {
68        let items = match args {
69            ArgParser::List(list) => list,
70            // This is an edgecase added because making this a hard error would break too many crates
71            // Specifically `#[link = "dl"]` is accepted with a FCW
72            // For more information, see https://github.com/rust-lang/rust/pull/143193
73            ArgParser::NameValue(nv) if nv.value_as_str().is_some_and(|v| v == sym::dl) => {
74                let suggestions = <Self as CombineAttributeParser<S>>::TEMPLATE
75                    .suggestions(cx.attr_style, "link");
76                let span = cx.attr_span;
77                cx.emit_lint(AttributeLintKind::IllFormedAttributeInput { suggestions }, span);
78                return None;
79            }
80            _ => {
81                cx.expected_list(cx.attr_span);
82                return None;
83            }
84        };
85
86        let sess = cx.sess();
87        let features = cx.features();
88
89        let mut name = None;
90        let mut kind = None;
91        let mut modifiers = None;
92        let mut cfg = None;
93        let mut wasm_import_module = None;
94        let mut import_name_type = None;
95        for item in items.mixed() {
96            let Some(item) = item.meta_item() else {
97                cx.unexpected_literal(item.span());
98                continue;
99            };
100
101            let cont = match item.path().word().map(|ident| ident.name) {
102                Some(sym::name) => Self::parse_link_name(item, &mut name, cx),
103                Some(sym::kind) => Self::parse_link_kind(item, &mut kind, cx, sess, features),
104                Some(sym::modifiers) => Self::parse_link_modifiers(item, &mut modifiers, cx),
105                Some(sym::cfg) => Self::parse_link_cfg(item, &mut cfg, cx, sess, features),
106                Some(sym::wasm_import_module) => {
107                    Self::parse_link_wasm_import_module(item, &mut wasm_import_module, cx)
108                }
109                Some(sym::import_name_type) => {
110                    Self::parse_link_import_name_type(item, &mut import_name_type, cx)
111                }
112                _ => {
113                    cx.expected_specific_argument_strings(
114                        item.span(),
115                        &[
116                            sym::name,
117                            sym::kind,
118                            sym::modifiers,
119                            sym::cfg,
120                            sym::wasm_import_module,
121                            sym::import_name_type,
122                        ],
123                    );
124                    true
125                }
126            };
127            if !cont {
128                return None;
129            }
130        }
131
132        // Do this outside the above loop so we don't depend on modifiers coming after kinds
133        let mut verbatim = None;
134        if let Some((modifiers, span)) = modifiers {
135            for modifier in modifiers.as_str().split(',') {
136                let (modifier, value): (Symbol, bool) = match modifier.strip_prefix(&['+', '-']) {
137                    Some(m) => (Symbol::intern(m), modifier.starts_with('+')),
138                    None => {
139                        cx.emit_err(InvalidLinkModifier { span });
140                        continue;
141                    }
142                };
143
144                macro report_unstable_modifier($feature: ident) {
145                    if !features.$feature() {
146                        // FIXME: make this translatable
147                        #[expect(rustc::untranslatable_diagnostic)]
148                        feature_err(
149                            sess,
150                            sym::$feature,
151                            span,
152                            format!("linking modifier `{modifier}` is unstable"),
153                        )
154                        .emit();
155                    }
156                }
157                let assign_modifier = |dst: &mut Option<bool>| {
158                    if dst.is_some() {
159                        cx.emit_err(MultipleModifiers { span, modifier });
160                    } else {
161                        *dst = Some(value);
162                    }
163                };
164                match (modifier, &mut kind) {
165                    (sym::bundle, Some(NativeLibKind::Static { bundle, .. })) => {
166                        assign_modifier(bundle)
167                    }
168                    (sym::bundle, _) => {
169                        cx.emit_err(BundleNeedsStatic { span });
170                    }
171
172                    (sym::verbatim, _) => assign_modifier(&mut verbatim),
173
174                    (
175                        sym::whole_dash_archive,
176                        Some(NativeLibKind::Static { whole_archive, .. }),
177                    ) => assign_modifier(whole_archive),
178                    (sym::whole_dash_archive, _) => {
179                        cx.emit_err(WholeArchiveNeedsStatic { span });
180                    }
181
182                    (sym::as_dash_needed, Some(NativeLibKind::Dylib { as_needed }))
183                    | (sym::as_dash_needed, Some(NativeLibKind::Framework { as_needed }))
184                    | (sym::as_dash_needed, Some(NativeLibKind::RawDylib { as_needed })) => {
185                        report_unstable_modifier!(native_link_modifiers_as_needed);
186                        assign_modifier(as_needed)
187                    }
188                    (sym::as_dash_needed, _) => {
189                        cx.emit_err(AsNeededCompatibility { span });
190                    }
191
192                    _ => {
193                        cx.expected_specific_argument_strings(
194                            span,
195                            &[
196                                sym::bundle,
197                                sym::verbatim,
198                                sym::whole_dash_archive,
199                                sym::as_dash_needed,
200                            ],
201                        );
202                    }
203                }
204            }
205        }
206
207        if let Some((_, span)) = wasm_import_module {
208            if name.is_some() || kind.is_some() || modifiers.is_some() || cfg.is_some() {
209                cx.emit_err(IncompatibleWasmLink { span });
210            }
211        }
212
213        if wasm_import_module.is_some() {
214            (name, kind) = (wasm_import_module, Some(NativeLibKind::WasmImportModule));
215        }
216        let Some((name, name_span)) = name else {
217            cx.emit_err(LinkRequiresName { span: cx.attr_span });
218            return None;
219        };
220
221        // Do this outside of the loop so that `import_name_type` can be specified before `kind`.
222        if let Some((_, span)) = import_name_type {
223            if !matches!(kind, Some(NativeLibKind::RawDylib { .. })) {
224                cx.emit_err(ImportNameTypeRaw { span });
225            }
226        }
227
228        if let Some(NativeLibKind::RawDylib { .. }) = kind
229            && name.as_str().contains('\0')
230        {
231            cx.emit_err(RawDylibNoNul { span: name_span });
232        }
233
234        Some(LinkEntry {
235            span: cx.attr_span,
236            kind: kind.unwrap_or(NativeLibKind::Unspecified),
237            name,
238            cfg,
239            verbatim,
240            import_name_type,
241        })
242    }
243}
244
245impl LinkParser {
246    fn parse_link_name<S: Stage>(
247        item: &MetaItemParser<'_>,
248        name: &mut Option<(Symbol, Span)>,
249        cx: &mut AcceptContext<'_, '_, S>,
250    ) -> bool {
251        if name.is_some() {
252            cx.duplicate_key(item.span(), sym::name);
253            return true;
254        }
255        let Some(nv) = item.args().name_value() else {
256            cx.expected_name_value(item.span(), Some(sym::name));
257            return false;
258        };
259        let Some(link_name) = nv.value_as_str() else {
260            cx.expected_name_value(item.span(), Some(sym::name));
261            return false;
262        };
263
264        if link_name.is_empty() {
265            cx.emit_err(EmptyLinkName { span: nv.value_span });
266        }
267        *name = Some((link_name, nv.value_span));
268        true
269    }
270
271    fn parse_link_kind<S: Stage>(
272        item: &MetaItemParser<'_>,
273        kind: &mut Option<NativeLibKind>,
274        cx: &mut AcceptContext<'_, '_, S>,
275        sess: &Session,
276        features: &Features,
277    ) -> bool {
278        if kind.is_some() {
279            cx.duplicate_key(item.span(), sym::kind);
280            return true;
281        }
282        let Some(nv) = item.args().name_value() else {
283            cx.expected_name_value(item.span(), Some(sym::kind));
284            return true;
285        };
286        let Some(link_kind) = nv.value_as_str() else {
287            cx.expected_name_value(item.span(), Some(sym::kind));
288            return true;
289        };
290
291        let link_kind = match link_kind {
292            kw::Static => NativeLibKind::Static { bundle: None, whole_archive: None },
293            sym::dylib => NativeLibKind::Dylib { as_needed: None },
294            sym::framework => {
295                if !sess.target.is_like_darwin {
296                    cx.emit_err(LinkFrameworkApple { span: nv.value_span });
297                }
298                NativeLibKind::Framework { as_needed: None }
299            }
300            sym::raw_dash_dylib => {
301                if sess.target.is_like_windows {
302                    // raw-dylib is stable and working on Windows
303                } else if sess.target.binary_format == BinaryFormat::Elf && features.raw_dylib_elf()
304                {
305                    // raw-dylib is unstable on ELF, but the user opted in
306                } else if sess.target.binary_format == BinaryFormat::Elf && sess.is_nightly_build()
307                {
308                    feature_err(
309                        sess,
310                        sym::raw_dylib_elf,
311                        nv.value_span,
312                        fluent_generated::attr_parsing_raw_dylib_elf_unstable,
313                    )
314                    .emit();
315                } else {
316                    cx.emit_err(RawDylibOnlyWindows { span: nv.value_span });
317                }
318
319                NativeLibKind::RawDylib { as_needed: None }
320            }
321            sym::link_dash_arg => {
322                if !features.link_arg_attribute() {
323                    feature_err(
324                        sess,
325                        sym::link_arg_attribute,
326                        nv.value_span,
327                        fluent_generated::attr_parsing_link_arg_unstable,
328                    )
329                    .emit();
330                }
331                NativeLibKind::LinkArg
332            }
333            _kind => {
334                cx.expected_specific_argument_strings(
335                    nv.value_span,
336                    &[
337                        kw::Static,
338                        sym::dylib,
339                        sym::framework,
340                        sym::raw_dash_dylib,
341                        sym::link_dash_arg,
342                    ],
343                );
344                return true;
345            }
346        };
347        *kind = Some(link_kind);
348        true
349    }
350
351    fn parse_link_modifiers<S: Stage>(
352        item: &MetaItemParser<'_>,
353        modifiers: &mut Option<(Symbol, Span)>,
354        cx: &mut AcceptContext<'_, '_, S>,
355    ) -> bool {
356        if modifiers.is_some() {
357            cx.duplicate_key(item.span(), sym::modifiers);
358            return true;
359        }
360        let Some(nv) = item.args().name_value() else {
361            cx.expected_name_value(item.span(), Some(sym::modifiers));
362            return true;
363        };
364        let Some(link_modifiers) = nv.value_as_str() else {
365            cx.expected_name_value(item.span(), Some(sym::modifiers));
366            return true;
367        };
368        *modifiers = Some((link_modifiers, nv.value_span));
369        true
370    }
371
372    fn parse_link_cfg<S: Stage>(
373        item: &MetaItemParser<'_>,
374        cfg: &mut Option<CfgEntry>,
375        cx: &mut AcceptContext<'_, '_, S>,
376        sess: &Session,
377        features: &Features,
378    ) -> bool {
379        if cfg.is_some() {
380            cx.duplicate_key(item.span(), sym::cfg);
381            return true;
382        }
383        let Some(link_cfg) = item.args().list() else {
384            cx.expected_list(item.span());
385            return true;
386        };
387        let Some(link_cfg) = link_cfg.single() else {
388            cx.expected_single_argument(item.span());
389            return true;
390        };
391        if !features.link_cfg() {
392            feature_err(
393                sess,
394                sym::link_cfg,
395                item.span(),
396                fluent_generated::attr_parsing_link_cfg_unstable,
397            )
398            .emit();
399        }
400        *cfg = parse_cfg_entry(cx, link_cfg);
401        true
402    }
403
404    fn parse_link_wasm_import_module<S: Stage>(
405        item: &MetaItemParser<'_>,
406        wasm_import_module: &mut Option<(Symbol, Span)>,
407        cx: &mut AcceptContext<'_, '_, S>,
408    ) -> bool {
409        if wasm_import_module.is_some() {
410            cx.duplicate_key(item.span(), sym::wasm_import_module);
411            return true;
412        }
413        let Some(nv) = item.args().name_value() else {
414            cx.expected_name_value(item.span(), Some(sym::wasm_import_module));
415            return true;
416        };
417        let Some(link_wasm_import_module) = nv.value_as_str() else {
418            cx.expected_name_value(item.span(), Some(sym::wasm_import_module));
419            return true;
420        };
421        *wasm_import_module = Some((link_wasm_import_module, item.span()));
422        true
423    }
424
425    fn parse_link_import_name_type<S: Stage>(
426        item: &MetaItemParser<'_>,
427        import_name_type: &mut Option<(PeImportNameType, Span)>,
428        cx: &mut AcceptContext<'_, '_, S>,
429    ) -> bool {
430        if import_name_type.is_some() {
431            cx.duplicate_key(item.span(), sym::import_name_type);
432            return true;
433        }
434        let Some(nv) = item.args().name_value() else {
435            cx.expected_name_value(item.span(), Some(sym::import_name_type));
436            return true;
437        };
438        let Some(link_import_name_type) = nv.value_as_str() else {
439            cx.expected_name_value(item.span(), Some(sym::import_name_type));
440            return true;
441        };
442        if cx.sess().target.arch != "x86" {
443            cx.emit_err(ImportNameTypeX86 { span: item.span() });
444            return true;
445        }
446
447        let link_import_name_type = match link_import_name_type {
448            sym::decorated => PeImportNameType::Decorated,
449            sym::noprefix => PeImportNameType::NoPrefix,
450            sym::undecorated => PeImportNameType::Undecorated,
451            _ => {
452                cx.expected_specific_argument_strings(
453                    item.span(),
454                    &[sym::decorated, sym::noprefix, sym::undecorated],
455                );
456                return true;
457            }
458        };
459        *import_name_type = Some((link_import_name_type, item.span()));
460        true
461    }
462}
463
464pub(crate) struct LinkSectionParser;
465
466impl<S: Stage> SingleAttributeParser<S> for LinkSectionParser {
467    const PATH: &[Symbol] = &[sym::link_section];
468    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepInnermost;
469    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::WarnButFutureError;
470    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowListWarnRest(&[
471        Allow(Target::Static),
472        Allow(Target::Fn),
473        Allow(Target::Method(MethodKind::Inherent)),
474        Allow(Target::Method(MethodKind::Trait { body: false })),
475        Allow(Target::Method(MethodKind::Trait { body: true })),
476        Allow(Target::Method(MethodKind::TraitImpl)),
477    ]);
478    const TEMPLATE: AttributeTemplate = 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::StdInternalSymbol;
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 = 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: false })),
593        Allow(Target::Method(MethodKind::Trait { body: true })),
594        Allow(Target::Method(MethodKind::TraitImpl)),
595        Allow(Target::Static),
596        Allow(Target::ForeignStatic),
597        Allow(Target::ForeignFn),
598    ]);
599
600    const TEMPLATE: AttributeTemplate = 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}
rustc_attr_parsing/attributes/link_attrs.rs

rustc_attr_parsing/attributes/
link_attrs.rs
