2da9accab9
Add an alternative to `tcx.all_traits()` that only shows traits that the user might be able to use, for diagnostic purposes. With this available, make use of it for diagnostics including associated type errors, which is part of the problem with [1]. Includes a few comment updates for related API. [1]: https://github.com/rust-lang/rust/issues/135232
101 lines
3.4 KiB
Rust
101 lines
3.4 KiB
Rust
//! Detecting diagnostic items.
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//!
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//! Diagnostic items are items that are not language-inherent, but can reasonably be expected to
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//! exist for diagnostic purposes. This allows diagnostic authors to refer to specific items
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//! directly, without having to guess module paths and crates.
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//! Examples are:
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//!
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//! * Traits like `Debug`, that have no bearing on language semantics
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//!
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//! * Compiler internal types like `Ty` and `TyCtxt`
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use rustc_hir::diagnostic_items::DiagnosticItems;
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use rustc_hir::{Attribute, OwnerId};
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use rustc_middle::query::{LocalCrate, Providers};
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use rustc_middle::ty::TyCtxt;
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use rustc_span::def_id::{DefId, LOCAL_CRATE};
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use rustc_span::{Symbol, sym};
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use crate::errors::DuplicateDiagnosticItemInCrate;
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fn observe_item<'tcx>(tcx: TyCtxt<'tcx>, diagnostic_items: &mut DiagnosticItems, owner: OwnerId) {
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let attrs = tcx.hir().attrs(owner.into());
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if let Some(name) = extract(attrs) {
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// insert into our table
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collect_item(tcx, diagnostic_items, name, owner.to_def_id());
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}
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}
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fn collect_item(tcx: TyCtxt<'_>, items: &mut DiagnosticItems, name: Symbol, item_def_id: DefId) {
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items.id_to_name.insert(item_def_id, name);
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if let Some(original_def_id) = items.name_to_id.insert(name, item_def_id) {
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if original_def_id != item_def_id {
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report_duplicate_item(tcx, name, original_def_id, item_def_id);
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}
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}
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}
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fn report_duplicate_item(
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tcx: TyCtxt<'_>,
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name: Symbol,
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original_def_id: DefId,
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item_def_id: DefId,
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) {
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let orig_span = tcx.hir().span_if_local(original_def_id);
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let duplicate_span = tcx.hir().span_if_local(item_def_id);
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tcx.dcx().emit_err(DuplicateDiagnosticItemInCrate {
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duplicate_span,
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orig_span,
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crate_name: tcx.crate_name(item_def_id.krate),
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orig_crate_name: tcx.crate_name(original_def_id.krate),
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different_crates: (item_def_id.krate != original_def_id.krate),
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name,
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});
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}
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/// Extract the first `rustc_diagnostic_item = "$name"` out of a list of attributes.
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fn extract(attrs: &[Attribute]) -> Option<Symbol> {
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attrs.iter().find_map(|attr| {
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if attr.has_name(sym::rustc_diagnostic_item) { attr.value_str() } else { None }
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})
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}
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/// Traverse and collect the diagnostic items in the current
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fn diagnostic_items(tcx: TyCtxt<'_>, _: LocalCrate) -> DiagnosticItems {
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// Initialize the collector.
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let mut diagnostic_items = DiagnosticItems::default();
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// Collect diagnostic items in this crate.
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let crate_items = tcx.hir_crate_items(());
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for id in crate_items.owners() {
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observe_item(tcx, &mut diagnostic_items, id);
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}
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diagnostic_items
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}
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/// Traverse and collect all the diagnostic items in all crates.
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fn all_diagnostic_items(tcx: TyCtxt<'_>, (): ()) -> DiagnosticItems {
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// Initialize the collector.
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let mut items = DiagnosticItems::default();
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// Collect diagnostic items in visible crates.
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for cnum in tcx
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.crates(())
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.iter()
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.copied()
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.filter(|cnum| tcx.is_user_visible_dep(*cnum))
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.chain(std::iter::once(LOCAL_CRATE))
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{
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for (&name, &def_id) in &tcx.diagnostic_items(cnum).name_to_id {
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collect_item(tcx, &mut items, name, def_id);
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}
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}
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items
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}
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pub(crate) fn provide(providers: &mut Providers) {
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providers.diagnostic_items = diagnostic_items;
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providers.all_diagnostic_items = all_diagnostic_items;
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}
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