rustc_passes/
diagnostic_items.rs

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::attrs::diagnostic_items::DiagnosticItems;
13use rustc_hir::{CRATE_OWNER_ID, OwnerId, find_attr};
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::diagnostics::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) = {
    'done:
        {
        for i in attrs {
            #[allow(unused_imports)]
            use ::rustc_attr_ir::AttributeKind::*;
            let i: &::rustc_attr_ir::Attribute = i;
            match i {
                ::rustc_attr_ir::Attribute::Parsed(RustcDiagnosticItem(name))
                    => {
                    break 'done Some(name);
                }
                ::rustc_attr_ir::Attribute::Unparsed(..) =>
                    {}
                    #[deny(unreachable_patterns)]
                    _ => {}
            }
        }
        None
    }
}find_attr!(attrs, RustcDiagnosticItem(name) => name) {
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/// Traverse and collect the diagnostic items in the current crate
57fn diagnostic_items(tcx: TyCtxt<'_>, _: LocalCrate) -> DiagnosticItems {
58    // Initialize the collector.
59    let mut diagnostic_items = DiagnosticItems::default();
60
61    // Optimization: can this crate even define diagnostic items?
62    // (But do not mark `rustc_attrs` as used while doing so)
63    if tcx.features().enabled_features().contains(&sym::rustc_attrs) {
64        // Collect diagnostic items in this crate.
65        let crate_items = tcx.hir_crate_items(());
66        for id in crate_items.owners().chain(std::iter::once(CRATE_OWNER_ID)) {
67            observe_item(tcx, &mut diagnostic_items, id);
68        }
69    }
70
71    diagnostic_items
72}
73
74/// Traverse and collect all the diagnostic items in all crates.
75fn all_diagnostic_items(tcx: TyCtxt<'_>, (): ()) -> DiagnosticItems {
76    // Initialize the collector.
77    let mut items = DiagnosticItems::default();
78
79    // Collect diagnostic items in visible crates.
80    for cnum in tcx
81        .crates(())
82        .iter()
83        .copied()
84        .filter(|cnum| tcx.is_user_visible_dep(*cnum))
85        .chain(std::iter::once(LOCAL_CRATE))
86    {
87        for (&name, &def_id) in &tcx.diagnostic_items(cnum).name_to_id {
88            collect_item(tcx, &mut items, name, def_id);
89        }
90    }
91
92    items
93}
94
95pub(crate) fn provide(providers: &mut Providers) {
96    providers.diagnostic_items = diagnostic_items;
97    providers.all_diagnostic_items = all_diagnostic_items;
98}
rustc_passes/diagnostic_items.rs

rustc_passes/
diagnostic_items.rs
