60 lines
2.1 KiB
Rust
60 lines
2.1 KiB
Rust
//! Implementation of the `#[cfg_accessible(path)]` attribute macro.
|
|
|
|
use rustc_ast as ast;
|
|
use rustc_expand::base::{Annotatable, ExpandResult, ExtCtxt, MultiItemModifier};
|
|
use rustc_feature::AttributeTemplate;
|
|
use rustc_parse::validate_attr;
|
|
use rustc_span::symbol::sym;
|
|
use rustc_span::Span;
|
|
|
|
crate struct Expander;
|
|
|
|
fn validate_input<'a>(ecx: &mut ExtCtxt<'_>, mi: &'a ast::MetaItem) -> Option<&'a ast::Path> {
|
|
match mi.meta_item_list() {
|
|
None => {}
|
|
Some([]) => ecx.span_err(mi.span, "`cfg_accessible` path is not specified"),
|
|
Some([_, .., l]) => ecx.span_err(l.span(), "multiple `cfg_accessible` paths are specified"),
|
|
Some([nmi]) => match nmi.meta_item() {
|
|
None => ecx.span_err(nmi.span(), "`cfg_accessible` path cannot be a literal"),
|
|
Some(mi) => {
|
|
if !mi.is_word() {
|
|
ecx.span_err(mi.span, "`cfg_accessible` path cannot accept arguments");
|
|
}
|
|
return Some(&mi.path);
|
|
}
|
|
},
|
|
}
|
|
None
|
|
}
|
|
|
|
impl MultiItemModifier for Expander {
|
|
fn expand(
|
|
&self,
|
|
ecx: &mut ExtCtxt<'_>,
|
|
_span: Span,
|
|
meta_item: &ast::MetaItem,
|
|
item: Annotatable,
|
|
) -> ExpandResult<Vec<Annotatable>, Annotatable> {
|
|
let template = AttributeTemplate { list: Some("path"), ..Default::default() };
|
|
let attr = &ecx.attribute(meta_item.clone());
|
|
validate_attr::check_builtin_attribute(
|
|
&ecx.sess.parse_sess,
|
|
attr,
|
|
sym::cfg_accessible,
|
|
template,
|
|
);
|
|
|
|
let path = match validate_input(ecx, meta_item) {
|
|
Some(path) => path,
|
|
None => return ExpandResult::Ready(Vec::new()),
|
|
};
|
|
|
|
let failure_msg = "cannot determine whether the path is accessible or not";
|
|
match ecx.resolver.cfg_accessible(ecx.current_expansion.id, path) {
|
|
Ok(true) => ExpandResult::Ready(vec![item]),
|
|
Ok(false) => ExpandResult::Ready(Vec::new()),
|
|
Err(_) => ExpandResult::Retry(item, failure_msg.into()),
|
|
}
|
|
}
|
|
}
|