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`
13 use rustc_hir::diagnostic_items::DiagnosticItems;
14 use rustc_middle::ty::query::Providers;
15 use rustc_middle::ty::TyCtxt;
16 use rustc_span::def_id::{CrateNum, DefId, LocalDefId, LOCAL_CRATE};
17 use rustc_span::symbol::{sym, Symbol};
19 fn observe_item<'tcx>(
21 diagnostic_items: &mut DiagnosticItems,
24 let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
25 let attrs = tcx.hir().attrs(hir_id);
26 if let Some(name) = extract(attrs) {
27 // insert into our table
28 collect_item(tcx, diagnostic_items, name, def_id.to_def_id());
32 fn collect_item(tcx: TyCtxt<'_>, items: &mut DiagnosticItems, name: Symbol, item_def_id: DefId) {
33 items.id_to_name.insert(item_def_id, name);
34 if let Some(original_def_id) = items.name_to_id.insert(name, item_def_id) {
35 if original_def_id != item_def_id {
36 let mut err = match tcx.hir().span_if_local(item_def_id) {
39 .struct_span_err(span, &format!("duplicate diagnostic item found: `{name}`.")),
40 None => tcx.sess.struct_err(&format!(
41 "duplicate diagnostic item in crate `{}`: `{}`.",
42 tcx.crate_name(item_def_id.krate),
46 if let Some(span) = tcx.hir().span_if_local(original_def_id) {
47 err.span_note(span, "the diagnostic item is first defined here");
50 "the diagnostic item is first defined in crate `{}`.",
51 tcx.crate_name(original_def_id.krate)
59 /// Extract the first `rustc_diagnostic_item = "$name"` out of a list of attributes.
60 fn extract(attrs: &[ast::Attribute]) -> Option<Symbol> {
61 attrs.iter().find_map(|attr| {
62 if attr.has_name(sym::rustc_diagnostic_item) { attr.value_str() } else { None }
66 /// Traverse and collect the diagnostic items in the current
67 fn diagnostic_items<'tcx>(tcx: TyCtxt<'tcx>, cnum: CrateNum) -> DiagnosticItems {
68 assert_eq!(cnum, LOCAL_CRATE);
70 // Initialize the collector.
71 let mut diagnostic_items = DiagnosticItems::default();
73 // Collect diagnostic items in this crate.
74 let crate_items = tcx.hir_crate_items(());
76 for id in crate_items.items() {
77 observe_item(tcx, &mut diagnostic_items, id.def_id);
80 for id in crate_items.trait_items() {
81 observe_item(tcx, &mut diagnostic_items, id.def_id);
84 for id in crate_items.impl_items() {
85 observe_item(tcx, &mut diagnostic_items, id.def_id);
88 for id in crate_items.foreign_items() {
89 observe_item(tcx, &mut diagnostic_items, id.def_id);
95 /// Traverse and collect all the diagnostic items in all crates.
96 fn all_diagnostic_items<'tcx>(tcx: TyCtxt<'tcx>, (): ()) -> DiagnosticItems {
97 // Initialize the collector.
98 let mut items = DiagnosticItems::default();
100 // Collect diagnostic items in other crates.
101 for &cnum in tcx.crates(()).iter().chain(std::iter::once(&LOCAL_CRATE)) {
102 for (&name, &def_id) in &tcx.diagnostic_items(cnum).name_to_id {
103 collect_item(tcx, &mut items, name, def_id);
110 pub fn provide(providers: &mut Providers) {
111 providers.diagnostic_items = diagnostic_items;
112 providers.all_diagnostic_items = all_diagnostic_items;