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Avoid more MetaItem-to-Attribute conversions.

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There is code for converting `Attribute` (syntactic) to `MetaItem`
(semantic). There is also code for the reverse direction. The reverse
direction isn't really necessary; it's currently only used when
generating attributes, e.g. in `derive` code.

This commit adds some new functions for creating `Attributes`s directly,
without involving `MetaItem`s: `mk_attr_word`, `mk_attr_name_value_str`,
`mk_attr_nested_word`, and
`ExtCtxt::attr_{word,name_value_str,nested_word}`.

These new methods replace the old functions for creating `Attribute`s:
`mk_attr_inner`, `mk_attr_outer`, and `ExtCtxt::attribute`. Those
functions took `MetaItem`s as input, and relied on many other functions
that created `MetaItems`, which are also removed: `mk_name_value_item`,
`mk_list_item`, `mk_word_item`, `mk_nested_word_item`,
`{MetaItem,MetaItemKind,NestedMetaItem}::token_trees`,
`MetaItemKind::attr_args`, `MetaItemLit::{from_lit_kind,to_token}`,
`ExtCtxt::meta_word`.

Overall this cuts more than 100 lines of code and makes thing simpler.
This commit is contained in:
Nicholas Nethercote 2022-11-29 18:43:44 +11:00
parent d1b61a31c5
commit ba1751a201
20 changed files with 116 additions and 211 deletions
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17
compiler/rustc_ast_lowering/src/expr.rs
View file

@ -1606,16 +1606,13 @@ impl<'hir> LoweringContext<'_, 'hir> {
};
// `#[allow(unreachable_code)]`
let attr = {
// `allow(unreachable_code)`
let allow = {
let allow_ident = Ident::new(sym::allow, self.lower_span(span));
let uc_ident = Ident::new(sym::unreachable_code, self.lower_span(span));
let uc_nested = attr::mk_nested_word_item(uc_ident);
attr::mk_list_item(allow_ident, vec![uc_nested])
};
attr::mk_attr_outer(&self.tcx.sess.parse_sess.attr_id_generator, allow)
};
let attr = attr::mk_attr_nested_word(
&self.tcx.sess.parse_sess.attr_id_generator,
AttrStyle::Outer,
sym::allow,
sym::unreachable_code,
self.lower_span(span),
);
let attrs: AttrVec = thin_vec![attr];
// `ControlFlow::Continue(val) => #[allow(unreachable_code)] val,`