1 //! Detecting diagnostic items.
3 //! Diagnostic items are items that are not language-inherent, but can reasonably be expected to
4 //! exist for diagnostic purposes. This allows diagnostic authors to refer to specific items
5 //! directly, without having to guess module paths and crates.
8 //! * Traits like `Debug`, that have no bearing on language semantics
10 //! * Compiler internal types like `Ty` and `TyCtxt`
14 use rustc_hir::diagnostic_items::DiagnosticItems;
15 use rustc_hir::itemlikevisit::ItemLikeVisitor;
16 use rustc_middle::ty::query::Providers;
17 use rustc_middle::ty::TyCtxt;
18 use rustc_span::def_id::{CrateNum, DefId, LocalDefId, LOCAL_CRATE};
19 use rustc_span::symbol::{sym, Symbol};
21 struct DiagnosticItemCollector<'tcx> {
23 diagnostic_items: DiagnosticItems,
26 impl<'v, 'tcx> ItemLikeVisitor<'v> for DiagnosticItemCollector<'tcx> {
27 fn visit_item(&mut self, item: &hir::Item<'_>) {
28 self.observe_item(item.def_id);
31 fn visit_trait_item(&mut self, trait_item: &hir::TraitItem<'_>) {
32 self.observe_item(trait_item.def_id);
35 fn visit_impl_item(&mut self, impl_item: &hir::ImplItem<'_>) {
36 self.observe_item(impl_item.def_id);
39 fn visit_foreign_item(&mut self, foreign_item: &hir::ForeignItem<'_>) {
40 self.observe_item(foreign_item.def_id);
44 impl<'tcx> DiagnosticItemCollector<'tcx> {
45 fn new(tcx: TyCtxt<'tcx>) -> DiagnosticItemCollector<'tcx> {
46 DiagnosticItemCollector { tcx, diagnostic_items: DiagnosticItems::default() }
49 fn observe_item(&mut self, def_id: LocalDefId) {
50 let hir_id = self.tcx.hir().local_def_id_to_hir_id(def_id);
51 let attrs = self.tcx.hir().attrs(hir_id);
52 if let Some(name) = extract(attrs) {
53 // insert into our table
54 collect_item(self.tcx, &mut self.diagnostic_items, name, def_id.to_def_id());
59 fn collect_item(tcx: TyCtxt<'_>, items: &mut DiagnosticItems, name: Symbol, item_def_id: DefId) {
60 items.id_to_name.insert(item_def_id, name);
61 if let Some(original_def_id) = items.name_to_id.insert(name, item_def_id) {
62 if original_def_id != item_def_id {
63 let mut err = match tcx.hir().span_if_local(item_def_id) {
66 .struct_span_err(span, &format!("duplicate diagnostic item found: `{name}`.")),
67 None => tcx.sess.struct_err(&format!(
68 "duplicate diagnostic item in crate `{}`: `{}`.",
69 tcx.crate_name(item_def_id.krate),
73 if let Some(span) = tcx.hir().span_if_local(original_def_id) {
74 err.span_note(span, "the diagnostic item is first defined here");
77 "the diagnostic item is first defined in crate `{}`.",
78 tcx.crate_name(original_def_id.krate)
86 /// Extract the first `rustc_diagnostic_item = "$name"` out of a list of attributes.p
87 fn extract(attrs: &[ast::Attribute]) -> Option<Symbol> {
88 attrs.iter().find_map(|attr| {
89 if attr.has_name(sym::rustc_diagnostic_item) { attr.value_str() } else { None }
93 /// Traverse and collect the diagnostic items in the current
94 fn diagnostic_items<'tcx>(tcx: TyCtxt<'tcx>, cnum: CrateNum) -> DiagnosticItems {
95 assert_eq!(cnum, LOCAL_CRATE);
97 // Initialize the collector.
98 let mut collector = DiagnosticItemCollector::new(tcx);
100 // Collect diagnostic items in this crate.
101 tcx.hir().visit_all_item_likes(&mut collector);
103 collector.diagnostic_items
106 /// Traverse and collect all the diagnostic items in all crates.
107 fn all_diagnostic_items<'tcx>(tcx: TyCtxt<'tcx>, (): ()) -> DiagnosticItems {
108 // Initialize the collector.
109 let mut items = DiagnosticItems::default();
111 // Collect diagnostic items in other crates.
112 for &cnum in tcx.crates(()).iter().chain(std::iter::once(&LOCAL_CRATE)) {
113 for (&name, &def_id) in &tcx.diagnostic_items(cnum).name_to_id {
114 collect_item(tcx, &mut items, name, def_id);
121 pub fn provide(providers: &mut Providers) {
122 providers.diagnostic_items = diagnostic_items;
123 providers.all_diagnostic_items = all_diagnostic_items;