1 //! Implementation of the `#[cfg_accessible(path)]` attribute macro.
4 use rustc_expand::base::{Annotatable, ExpandResult, ExtCtxt, Indeterminate, MultiItemModifier};
5 use rustc_feature::AttributeTemplate;
6 use rustc_parse::validate_attr;
7 use rustc_span::symbol::sym;
10 pub(crate) struct Expander;
12 fn validate_input<'a>(ecx: &mut ExtCtxt<'_>, mi: &'a ast::MetaItem) -> Option<&'a ast::Path> {
13 match mi.meta_item_list() {
15 Some([]) => ecx.span_err(mi.span, "`cfg_accessible` path is not specified"),
16 Some([_, .., l]) => ecx.span_err(l.span(), "multiple `cfg_accessible` paths are specified"),
17 Some([nmi]) => match nmi.meta_item() {
18 None => ecx.span_err(nmi.span(), "`cfg_accessible` path cannot be a literal"),
21 ecx.span_err(mi.span, "`cfg_accessible` path cannot accept arguments");
23 return Some(&mi.path);
30 impl MultiItemModifier for Expander {
33 ecx: &mut ExtCtxt<'_>,
35 meta_item: &ast::MetaItem,
37 _is_derive_const: bool,
38 ) -> ExpandResult<Vec<Annotatable>, Annotatable> {
39 let template = AttributeTemplate { list: Some("path"), ..Default::default() };
40 let attr = &ecx.attribute(meta_item.clone());
41 validate_attr::check_builtin_attribute(
48 let Some(path) = validate_input(ecx, meta_item) else {
49 return ExpandResult::Ready(Vec::new());
52 match ecx.resolver.cfg_accessible(ecx.current_expansion.id, path) {
53 Ok(true) => ExpandResult::Ready(vec![item]),
54 Ok(false) => ExpandResult::Ready(Vec::new()),
55 Err(Indeterminate) if ecx.force_mode => {
56 ecx.span_err(span, "cannot determine whether the path is accessible or not");
57 ExpandResult::Ready(vec![item])
59 Err(Indeterminate) => ExpandResult::Retry(item),