rustc_builtin_macros/
cfg_accessible.rs

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1//! Implementation of the `#[cfg_accessible(path)]` attribute macro.
2
3use rustc_ast as ast;
4use rustc_expand::base::{Annotatable, ExpandResult, ExtCtxt, Indeterminate, MultiItemModifier};
5use rustc_feature::AttributeTemplate;
6use rustc_parse::validate_attr;
7use rustc_span::{Span, sym};
8
9use crate::errors;
10
11pub(crate) struct Expander;
12
13fn validate_input<'a>(ecx: &ExtCtxt<'_>, mi: &'a ast::MetaItem) -> Option<&'a ast::Path> {
14    use errors::CfgAccessibleInvalid::*;
15    match mi.meta_item_list() {
16        None => {}
17        Some([]) => {
18            ecx.dcx().emit_err(UnspecifiedPath(mi.span));
19        }
20        Some([_, .., l]) => {
21            ecx.dcx().emit_err(MultiplePaths(l.span()));
22        }
23        Some([nmi]) => match nmi.meta_item() {
24            None => {
25                ecx.dcx().emit_err(LiteralPath(nmi.span()));
26            }
27            Some(mi) => {
28                if !mi.is_word() {
29                    ecx.dcx().emit_err(HasArguments(mi.span));
30                }
31                return Some(&mi.path);
32            }
33        },
34    }
35    None
36}
37
38impl MultiItemModifier for Expander {
39    fn expand(
40        &self,
41        ecx: &mut ExtCtxt<'_>,
42        span: Span,
43        meta_item: &ast::MetaItem,
44        item: Annotatable,
45        _is_derive_const: bool,
46    ) -> ExpandResult<Vec<Annotatable>, Annotatable> {
47        let template = AttributeTemplate { list: Some("path"), ..Default::default() };
48        validate_attr::check_builtin_meta_item(
49            &ecx.sess.psess,
50            meta_item,
51            ast::AttrStyle::Outer,
52            sym::cfg_accessible,
53            template,
54            true,
55        );
56
57        let Some(path) = validate_input(ecx, meta_item) else {
58            return ExpandResult::Ready(Vec::new());
59        };
60
61        match ecx.resolver.cfg_accessible(ecx.current_expansion.id, path) {
62            Ok(true) => ExpandResult::Ready(vec![item]),
63            Ok(false) => ExpandResult::Ready(Vec::new()),
64            Err(Indeterminate) if ecx.force_mode => {
65                ecx.dcx().emit_err(errors::CfgAccessibleIndeterminate { span });
66                ExpandResult::Ready(vec![item])
67            }
68            Err(Indeterminate) => ExpandResult::Retry(item),
69        }
70    }
71}
rustc_builtin_macros/cfg_accessible.rs

rustc_builtin_macros/
cfg_accessible.rs
