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Expand #[derive] attribute macro invocations last.

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This commit is contained in:
Jeffrey Seyfried 2016-10-10 08:47:54 +00:00
parent a7bfb1aba9
commit 60a4b69ec0
1 changed files with 30 additions and 5 deletions
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35
src/libsyntax_ext/deriving/mod.rs
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@ -11,6 +11,7 @@
//! The compiler code necessary to implement the `#[derive]` extensions.
use syntax::ast::{self, MetaItem};
use syntax::attr::HasAttrs;
use syntax::ext::base::{Annotatable, ExtCtxt};
use syntax::ext::build::AstBuilder;
use syntax::feature_gate;
@ -104,13 +105,37 @@ pub fn expand_derive(cx: &mut ExtCtxt,
}
};
if mitem.value_str().is_some() {
cx.span_err(mitem.span, "unexpected value in `derive`");
let mut derive_attrs = Vec::new();
item = item.map_attrs(|attrs| {
let partition = attrs.into_iter().partition(|attr| &attr.name() == "derive");
derive_attrs = partition.0;
partition.1
});
// Expand `#[derive]`s after other attribute macro invocations.
if cx.resolver.find_attr_invoc(&mut item.attrs.clone()).is_some() {
return vec![Annotatable::Item(item.map_attrs(|mut attrs| {
attrs.push(cx.attribute(span, P(mitem.clone())));
attrs.extend(derive_attrs);
attrs
}))];
}
let mut traits = mitem.meta_item_list().unwrap_or(&[]).to_owned();
if traits.is_empty() {
cx.span_warn(mitem.span, "empty trait list in `derive`");
let get_traits = |mitem: &MetaItem, cx: &ExtCtxt| {
if mitem.value_str().is_some() {
cx.span_err(mitem.span, "unexpected value in `derive`");
}
let traits = mitem.meta_item_list().unwrap_or(&[]).to_owned();
if traits.is_empty() {
cx.span_warn(mitem.span, "empty trait list in `derive`");
}
traits
};
let mut traits = get_traits(mitem, cx);
for derive_attr in derive_attrs {
traits.extend(get_traits(&derive_attr.node.value, cx));
}
// First, weed out malformed #[derive]