bjoernager/rust
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derive: Do not configure or clone items unless necessary

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This commit is contained in:
Vadim Petrochenkov 2021-07-17 17:28:43 +03:00
parent c993984e4d
commit 92804cd490
2 changed files with 47 additions and 22 deletions
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40
compiler/rustc_builtin_macros/src/derive.rs
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@ -1,12 +1,13 @@
use crate::cfg_eval::cfg_eval;
use rustc_ast::{self as ast, attr, token, ItemKind, MetaItemKind, NestedMetaItem, StmtKind};
use rustc_ast as ast;
use rustc_ast::{attr, token, GenericParamKind, ItemKind, MetaItemKind, NestedMetaItem, StmtKind};
use rustc_errors::{struct_span_err, Applicability};
use rustc_expand::base::{Annotatable, ExpandResult, ExtCtxt, Indeterminate, MultiItemModifier};
use rustc_feature::AttributeTemplate;
use rustc_parse::validate_attr;
use rustc_session::Session;
use rustc_span::symbol::sym;
use rustc_span::symbol::{sym, Ident};
use rustc_span::Span;
crate struct Expander;
@ -26,8 +27,7 @@ impl MultiItemModifier for Expander {
return ExpandResult::Ready(vec![item]);
}
let configured_item = cfg_eval(ecx, item.clone());
let (sess, features) = (ecx.sess, ecx.ecfg.features);
let result =
ecx.resolver.resolve_derives(ecx.current_expansion.id, ecx.force_mode, &|| {
let template =
@ -40,7 +40,8 @@ impl MultiItemModifier for Expander {
template,
);
attr.meta_item_list()
let mut resolutions: Vec<_> = attr
.meta_item_list()
.unwrap_or_default()
.into_iter()
.filter_map(|nested_meta| match nested_meta {
@ -56,8 +57,21 @@ impl MultiItemModifier for Expander {
report_path_args(sess, &meta);
meta.path
})
.map(|path| (path, configured_item.clone(), None))
.collect()
.map(|path| (path, dummy_annotatable(), None))
.collect();
// Do not configure or clone items unless necessary.
match &mut resolutions[..] {
[] => {}
[(_, first_item, _), others @ ..] => {
*first_item = cfg_eval(sess, features, item.clone());
for (_, item, _) in others {
*item = first_item.clone();
}
}
}
resolutions
});
match result {
@ -67,6 +81,18 @@ impl MultiItemModifier for Expander {
}
}
// The cheapest `Annotatable` to construct.
fn dummy_annotatable() -> Annotatable {
Annotatable::GenericParam(ast::GenericParam {
id: ast::DUMMY_NODE_ID,
ident: Ident::invalid(),
attrs: Default::default(),
bounds: Default::default(),
is_placeholder: false,
kind: GenericParamKind::Lifetime,
})
}
fn report_bad_target(sess: &Session, item: &Annotatable, span: Span) -> bool {
let item_kind = match item {
Annotatable::Item(item) => Some(&item.kind),