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Avoid uneccessary clone of Annotatable #91324

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merged 1 commit into from Dec 1, 2021
Merged

Avoid uneccessary clone of Annotatable #91324

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52 changes: 30 additions & 22 deletions compiler/rustc_builtin_macros/src/cfg_eval.rs
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Expand Up @@ -11,7 +11,7 @@ use rustc_expand::base::{Annotatable, ExtCtxt};
use rustc_expand::config::StripUnconfigured;
use rustc_expand::configure;
use rustc_feature::Features;
use rustc_parse::parser::ForceCollect;
use rustc_parse::parser::{ForceCollect, Parser};
use rustc_session::utils::FlattenNonterminals;
use rustc_session::Session;
use rustc_span::symbol::sym;
Expand Down Expand Up @@ -138,8 +138,34 @@ impl CfgEval<'_, '_> {
// the location of `#[cfg]` and `#[cfg_attr]` in the token stream. The tokenization
// process is lossless, so this process is invisible to proc-macros.

// FIXME - get rid of this clone
let nt = annotatable.clone().into_nonterminal();
let parse_annotatable_with: fn(&mut Parser<'_>) -> _ = match annotatable {
Annotatable::Item(_) => {
|parser| Annotatable::Item(parser.parse_item(ForceCollect::Yes).unwrap().unwrap())
}
Annotatable::TraitItem(_) => |parser| {
Annotatable::TraitItem(
parser.parse_trait_item(ForceCollect::Yes).unwrap().unwrap().unwrap(),
)
},
Annotatable::ImplItem(_) => |parser| {
Annotatable::ImplItem(
parser.parse_impl_item(ForceCollect::Yes).unwrap().unwrap().unwrap(),
)
},
Annotatable::ForeignItem(_) => |parser| {
Annotatable::ForeignItem(
parser.parse_foreign_item(ForceCollect::Yes).unwrap().unwrap().unwrap(),
)
},
Annotatable::Stmt(_) => |parser| {
Annotatable::Stmt(P(parser.parse_stmt(ForceCollect::Yes).unwrap().unwrap()))
},
Annotatable::Expr(_) => {
|parser| Annotatable::Expr(parser.parse_expr_force_collect().unwrap())
}
_ => unreachable!(),
};
let nt = annotatable.into_nonterminal();

let mut orig_tokens = rustc_parse::nt_to_tokenstream(
&nt,
Expand Down Expand Up @@ -173,25 +199,7 @@ impl CfgEval<'_, '_> {
let mut parser =
rustc_parse::stream_to_parser(&self.cfg.sess.parse_sess, orig_tokens, None);
parser.capture_cfg = true;
annotatable = match annotatable {
Annotatable::Item(_) => {
Annotatable::Item(parser.parse_item(ForceCollect::Yes).unwrap().unwrap())
}
Annotatable::TraitItem(_) => Annotatable::TraitItem(
parser.parse_trait_item(ForceCollect::Yes).unwrap().unwrap().unwrap(),
),
Annotatable::ImplItem(_) => Annotatable::ImplItem(
parser.parse_impl_item(ForceCollect::Yes).unwrap().unwrap().unwrap(),
),
Annotatable::ForeignItem(_) => Annotatable::ForeignItem(
parser.parse_foreign_item(ForceCollect::Yes).unwrap().unwrap().unwrap(),
),
Annotatable::Stmt(_) => {
Annotatable::Stmt(P(parser.parse_stmt(ForceCollect::Yes).unwrap().unwrap()))
}
Annotatable::Expr(_) => Annotatable::Expr(parser.parse_expr_force_collect().unwrap()),
_ => unreachable!(),
};
annotatable = parse_annotatable_with(&mut parser);

// Now that we have our re-parsed `AttrAnnotatedTokenStream`, recursively configuring
// our attribute target will correctly the tokens as well.
Expand Down