rustc_passes/
diagnostic_items.rs

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1//! Detecting diagnostic items.
2//!
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.
6//! Examples are:
7//!
8//! * Traits like `Debug`, that have no bearing on language semantics
9//!
10//! * Compiler internal types like `Ty` and `TyCtxt`
11
12use rustc_hir::diagnostic_items::DiagnosticItems;
13use rustc_hir::{Attribute, OwnerId};
14use rustc_middle::query::{LocalCrate, Providers};
15use rustc_middle::ty::TyCtxt;
16use rustc_span::def_id::{DefId, LOCAL_CRATE};
17use rustc_span::{Symbol, sym};
18
19use crate::errors::DuplicateDiagnosticItemInCrate;
20
21fn observe_item<'tcx>(tcx: TyCtxt<'tcx>, diagnostic_items: &mut DiagnosticItems, owner: OwnerId) {
22    let attrs = tcx.hir().attrs(owner.into());
23    if let Some(name) = extract(attrs) {
24        // insert into our table
25        collect_item(tcx, diagnostic_items, name, owner.to_def_id());
26    }
27}
28
29fn collect_item(tcx: TyCtxt<'_>, items: &mut DiagnosticItems, name: Symbol, item_def_id: DefId) {
30    items.id_to_name.insert(item_def_id, name);
31    if let Some(original_def_id) = items.name_to_id.insert(name, item_def_id) {
32        if original_def_id != item_def_id {
33            report_duplicate_item(tcx, name, original_def_id, item_def_id);
34        }
35    }
36}
37
38fn report_duplicate_item(
39    tcx: TyCtxt<'_>,
40    name: Symbol,
41    original_def_id: DefId,
42    item_def_id: DefId,
43) {
44    let orig_span = tcx.hir().span_if_local(original_def_id);
45    let duplicate_span = tcx.hir().span_if_local(item_def_id);
46    tcx.dcx().emit_err(DuplicateDiagnosticItemInCrate {
47        duplicate_span,
48        orig_span,
49        crate_name: tcx.crate_name(item_def_id.krate),
50        orig_crate_name: tcx.crate_name(original_def_id.krate),
51        different_crates: (item_def_id.krate != original_def_id.krate),
52        name,
53    });
54}
55
56/// Extract the first `rustc_diagnostic_item = "$name"` out of a list of attributes.
57fn extract(attrs: &[Attribute]) -> Option<Symbol> {
58    attrs.iter().find_map(|attr| {
59        if attr.has_name(sym::rustc_diagnostic_item) { attr.value_str() } else { None }
60    })
61}
62
63/// Traverse and collect the diagnostic items in the current
64fn diagnostic_items(tcx: TyCtxt<'_>, _: LocalCrate) -> DiagnosticItems {
65    // Initialize the collector.
66    let mut diagnostic_items = DiagnosticItems::default();
67
68    // Collect diagnostic items in this crate.
69    let crate_items = tcx.hir_crate_items(());
70    for id in crate_items.owners() {
71        observe_item(tcx, &mut diagnostic_items, id);
72    }
73
74    diagnostic_items
75}
76
77/// Traverse and collect all the diagnostic items in all crates.
78fn all_diagnostic_items(tcx: TyCtxt<'_>, (): ()) -> DiagnosticItems {
79    // Initialize the collector.
80    let mut items = DiagnosticItems::default();
81
82    // Collect diagnostic items in visible crates.
83    for cnum in tcx
84        .crates(())
85        .iter()
86        .copied()
87        .filter(|cnum| tcx.is_user_visible_dep(*cnum))
88        .chain(std::iter::once(LOCAL_CRATE))
89    {
90        for (&name, &def_id) in &tcx.diagnostic_items(cnum).name_to_id {
91            collect_item(tcx, &mut items, name, def_id);
92        }
93    }
94
95    items
96}
97
98pub(crate) fn provide(providers: &mut Providers) {
99    providers.diagnostic_items = diagnostic_items;
100    providers.all_diagnostic_items = all_diagnostic_items;
101}
rustc_passes/diagnostic_items.rs

rustc_passes/
diagnostic_items.rs
