| //! Detecting diagnostic items. |
| //! |
| //! Diagnostic items are items that are not language-inherent, but can reasonably be expected to |
| //! exist for diagnostic purposes. This allows diagnostic authors to refer to specific items |
| //! directly, without having to guess module paths and crates. |
| //! Examples are: |
| //! |
| //! * Traits like `Debug`, that have no bearing on language semantics |
| //! |
| //! * Compiler internal types like `Ty` and `TyCtxt` |
| |
| use rustc::ty::query::Providers; |
| use rustc::ty::TyCtxt; |
| use rustc_data_structures::fx::FxHashMap; |
| use rustc_hir as hir; |
| use rustc_hir::def_id::{DefId, LOCAL_CRATE}; |
| use rustc_hir::itemlikevisit::ItemLikeVisitor; |
| use rustc_span::symbol::{sym, Symbol}; |
| use syntax::ast; |
| |
| struct DiagnosticItemCollector<'tcx> { |
| // items from this crate |
| items: FxHashMap<Symbol, DefId>, |
| tcx: TyCtxt<'tcx>, |
| } |
| |
| impl<'v, 'tcx> ItemLikeVisitor<'v> for DiagnosticItemCollector<'tcx> { |
| fn visit_item(&mut self, item: &hir::Item<'_>) { |
| self.observe_item(&item.attrs, item.hir_id); |
| } |
| |
| fn visit_trait_item(&mut self, trait_item: &hir::TraitItem<'_>) { |
| self.observe_item(&trait_item.attrs, trait_item.hir_id); |
| } |
| |
| fn visit_impl_item(&mut self, impl_item: &hir::ImplItem<'_>) { |
| self.observe_item(&impl_item.attrs, impl_item.hir_id); |
| } |
| } |
| |
| impl<'tcx> DiagnosticItemCollector<'tcx> { |
| fn new(tcx: TyCtxt<'tcx>) -> DiagnosticItemCollector<'tcx> { |
| DiagnosticItemCollector { tcx, items: Default::default() } |
| } |
| |
| fn observe_item(&mut self, attrs: &[ast::Attribute], hir_id: hir::HirId) { |
| if let Some(name) = extract(attrs) { |
| let def_id = self.tcx.hir().local_def_id(hir_id); |
| // insert into our table |
| collect_item(self.tcx, &mut self.items, name, def_id); |
| } |
| } |
| } |
| |
| fn collect_item( |
| tcx: TyCtxt<'_>, |
| items: &mut FxHashMap<Symbol, DefId>, |
| name: Symbol, |
| item_def_id: DefId, |
| ) { |
| // Check for duplicates. |
| if let Some(original_def_id) = items.insert(name, item_def_id) { |
| if original_def_id != item_def_id { |
| let mut err = match tcx.hir().span_if_local(item_def_id) { |
| Some(span) => tcx.sess.struct_span_err( |
| span, |
| &format!("duplicate diagnostic item found: `{}`.", name), |
| ), |
| None => tcx.sess.struct_err(&format!( |
| "duplicate diagnostic item in crate `{}`: `{}`.", |
| tcx.crate_name(item_def_id.krate), |
| name |
| )), |
| }; |
| if let Some(span) = tcx.hir().span_if_local(original_def_id) { |
| err.span_note(span, "first defined here."); |
| } else { |
| err.note(&format!( |
| "first defined in crate `{}`.", |
| tcx.crate_name(original_def_id.krate) |
| )); |
| } |
| err.emit(); |
| } |
| } |
| } |
| |
| /// Extract the first `rustc_diagnostic_item = "$name"` out of a list of attributes. |
| fn extract(attrs: &[ast::Attribute]) -> Option<Symbol> { |
| attrs.iter().find_map(|attr| { |
| if attr.check_name(sym::rustc_diagnostic_item) { attr.value_str() } else { None } |
| }) |
| } |
| |
| /// Traverse and collect the diagnostic items in the current |
| fn collect<'tcx>(tcx: TyCtxt<'tcx>) -> &'tcx FxHashMap<Symbol, DefId> { |
| // Initialize the collector. |
| let mut collector = DiagnosticItemCollector::new(tcx); |
| |
| // Collect diagnostic items in this crate. |
| tcx.hir().krate().visit_all_item_likes(&mut collector); |
| |
| tcx.arena.alloc(collector.items) |
| } |
| |
| /// Traverse and collect all the diagnostic items in all crates. |
| fn collect_all<'tcx>(tcx: TyCtxt<'tcx>) -> &'tcx FxHashMap<Symbol, DefId> { |
| // Initialize the collector. |
| let mut collector = FxHashMap::default(); |
| |
| // Collect diagnostic items in other crates. |
| for &cnum in tcx.crates().iter().chain(std::iter::once(&LOCAL_CRATE)) { |
| for (&name, &def_id) in tcx.diagnostic_items(cnum).iter() { |
| collect_item(tcx, &mut collector, name, def_id); |
| } |
| } |
| |
| tcx.arena.alloc(collector) |
| } |
| |
| pub fn provide(providers: &mut Providers<'_>) { |
| providers.diagnostic_items = |tcx, id| { |
| assert_eq!(id, LOCAL_CRATE); |
| collect(tcx) |
| }; |
| providers.all_diagnostic_items = |tcx, id| { |
| assert_eq!(id, LOCAL_CRATE); |
| collect_all(tcx) |
| }; |
| } |