rustc_attr_parsing/attributes/diagnostic/
on_unknown.rs

1use rustc_errors::Diagnostic;
2use rustc_hir::attrs::diagnostic::Directive;
3use rustc_session::lint::builtin::MISPLACED_DIAGNOSTIC_ATTRIBUTES;
4
5use crate::ShouldEmit;
6use crate::attributes::diagnostic::*;
7use crate::attributes::prelude::*;
8use crate::errors::DiagnosticOnUnknownOnlyForImports;
9
10#[derive(#[automatically_derived]
impl ::core::default::Default for OnUnknownParser {
    #[inline]
    fn default() -> OnUnknownParser {
        OnUnknownParser {
            span: ::core::default::Default::default(),
            directive: ::core::default::Default::default(),
        }
    }
}Default)]
11pub(crate) struct OnUnknownParser {
12    span: Option<Span>,
13    directive: Option<(Span, Directive)>,
14}
15
16impl OnUnknownParser {
17    fn parse<'sess, S: Stage>(
18        &mut self,
19        cx: &mut AcceptContext<'_, 'sess, S>,
20        args: &ArgParser,
21        mode: Mode,
22    ) {
23        if let Some(features) = cx.features
24            && !features.diagnostic_on_unknown()
25        {
26            // `UnknownDiagnosticAttribute` is emitted in rustc_resolve/macros.rs
27            return;
28        }
29        let span = cx.attr_span;
30        self.span = Some(span);
31
32        // At early parsing we get passed `Target::Crate` regardless of the item we're on.
33        // Only do target checking if we're late.
34        let early = #[allow(non_exhaustive_omitted_patterns)] match cx.stage.should_emit() {
    ShouldEmit::Nothing => true,
    _ => false,
}matches!(cx.stage.should_emit(), ShouldEmit::Nothing);
35
36        if !early && !#[allow(non_exhaustive_omitted_patterns)] match cx.target {
    Target::Use => true,
    _ => false,
}matches!(cx.target, Target::Use) {
37            let target_span = cx.target_span;
38            cx.emit_lint(
39                MISPLACED_DIAGNOSTIC_ATTRIBUTES,
40                move |dcx, level| {
41                    DiagnosticOnUnknownOnlyForImports { target_span }.into_diag(dcx, level)
42                },
43                span,
44            );
45            return;
46        }
47
48        let Some(items) = parse_list(cx, args, mode) else { return };
49
50        if let Some(directive) = parse_directive_items(cx, mode, items.mixed(), true) {
51            merge_directives(cx, &mut self.directive, (span, directive));
52        };
53    }
54}
55
56impl<S: Stage> AttributeParser<S> for OnUnknownParser {
57    const ATTRIBUTES: AcceptMapping<Self, S> = &[(
58        &[sym::diagnostic, sym::on_unknown],
59        ::rustc_feature::AttributeTemplate {
    word: false,
    list: Some(&[r#"/*opt*/ message = "...", /*opt*/ label = "...", /*opt*/ note = "...""#]),
    one_of: &[],
    name_value_str: None,
    docs: None,
}template!(List: &[r#"/*opt*/ message = "...", /*opt*/ label = "...", /*opt*/ note = "...""#]),
60        |this, cx, args| {
61            this.parse(cx, args, Mode::DiagnosticOnUnknown);
62        },
63    )];
64    // "Allowed" for all targets, but noop for all but use statements.
65    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(ALL_TARGETS);
66
67    fn finalize(self, _cx: &FinalizeContext<'_, '_, S>) -> Option<AttributeKind> {
68        if let Some(span) = self.span {
69            Some(AttributeKind::OnUnknown {
70                span,
71                directive: self.directive.map(|d| Box::new(d.1)),
72            })
73        } else {
74            None
75        }
76    }
77}
rustc_attr_parsing/attributes/diagnostic/on_unknown.rs

rustc_attr_parsing/attributes/diagnostic/
on_unknown.rs
