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Auto merge of #53397 - varkor:feature-collector-expand-visitor, r=nikomatsakis

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Visit all attributes for feature collection

Previously feature attributes were just collected on item-like "things" as well as exported macros and crate attributes. This ignored some places feature attributes could be specified, such as on enum variants.

Fixes https://github.com/rust-lang/rust/issues/53391.
This commit is contained in:
bors 2018-08-16 22:11:58 +00:00
commit 81ba448f75
1 changed files with 39 additions and 55 deletions
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94
src/librustc/middle/lib_features.rs
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@ -18,8 +18,7 @@ use ty::TyCtxt;
use syntax::symbol::Symbol;
use syntax::ast::{Attribute, MetaItem, MetaItemKind};
use syntax_pos::{Span, DUMMY_SP};
use hir;
use hir::itemlikevisit::ItemLikeVisitor;
use hir::intravisit::{self, NestedVisitorMap, Visitor};
use rustc_data_structures::fx::{FxHashSet, FxHashMap};
use errors::DiagnosticId;
@ -59,47 +58,44 @@ impl<'a, 'tcx> LibFeatureCollector<'a, 'tcx> {
}
}
fn extract(&self, attrs: &[Attribute]) -> Vec<(Symbol, Option<Symbol>, Span)> {
fn extract(&self, attr: &Attribute) -> Option<(Symbol, Option<Symbol>, Span)> {
let stab_attrs = vec!["stable", "unstable", "rustc_const_unstable"];
let mut features = vec![];
for attr in attrs {
// Find a stability attribute (i.e. `#[stable (..)]`, `#[unstable (..)]`,
// `#[rustc_const_unstable (..)]`).
if let Some(stab_attr) = stab_attrs.iter().find(|stab_attr| {
attr.check_name(stab_attr)
}) {
let meta_item = attr.meta();
if let Some(MetaItem { node: MetaItemKind::List(ref metas), .. }) = meta_item {
let mut feature = None;
let mut since = None;
for meta in metas {
if let Some(mi) = meta.meta_item() {
// Find the `feature = ".."` meta-item.
match (&*mi.name().as_str(), mi.value_str()) {
("feature", val) => feature = val,
("since", val) => since = val,
_ => {}
}
// Find a stability attribute (i.e. `#[stable (..)]`, `#[unstable (..)]`,
// `#[rustc_const_unstable (..)]`).
if let Some(stab_attr) = stab_attrs.iter().find(|stab_attr| {
attr.check_name(stab_attr)
}) {
let meta_item = attr.meta();
if let Some(MetaItem { node: MetaItemKind::List(ref metas), .. }) = meta_item {
let mut feature = None;
let mut since = None;
for meta in metas {
if let Some(mi) = meta.meta_item() {
// Find the `feature = ".."` meta-item.
match (&*mi.name().as_str(), mi.value_str()) {
("feature", val) => feature = val,
("since", val) => since = val,
_ => {}
}
}
if let Some(feature) = feature {
// This additional check for stability is to make sure we
// don't emit additional, irrelevant errors for malformed
// attributes.
if *stab_attr != "stable" || since.is_some() {
features.push((feature, since, attr.span));
}
}
// We need to iterate over the other attributes, because
// `rustc_const_unstable` is not mutually exclusive with
// the other stability attributes, so we can't just `break`
// here.
}
if let Some(feature) = feature {
// This additional check for stability is to make sure we
// don't emit additional, irrelevant errors for malformed
// attributes.
if *stab_attr != "stable" || since.is_some() {
return Some((feature, since, attr.span));
}
}
// We need to iterate over the other attributes, because
// `rustc_const_unstable` is not mutually exclusive with
// the other stability attributes, so we can't just `break`
// here.
}
}
features
None
}
fn collect_feature(&mut self, feature: Symbol, since: Option<Symbol>, span: Span) {
@ -140,25 +136,17 @@ impl<'a, 'tcx> LibFeatureCollector<'a, 'tcx> {
}
}
}
fn collect_from_attrs(&mut self, attrs: &[Attribute]) {
for (feature, stable, span) in self.extract(attrs) {
self.collect_feature(feature, stable, span);
}
}
}
impl<'a, 'v, 'tcx> ItemLikeVisitor<'v> for LibFeatureCollector<'a, 'tcx> {
fn visit_item(&mut self, item: &hir::Item) {
self.collect_from_attrs(&item.attrs);
impl<'a, 'tcx> Visitor<'tcx> for LibFeatureCollector<'a, 'tcx> {
fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
NestedVisitorMap::All(&self.tcx.hir)
}
fn visit_trait_item(&mut self, trait_item: &hir::TraitItem) {
self.collect_from_attrs(&trait_item.attrs);
}
fn visit_impl_item(&mut self, impl_item: &hir::ImplItem) {
self.collect_from_attrs(&impl_item.attrs);
fn visit_attribute(&mut self, attr: &'tcx Attribute) {
if let Some((feature, stable, span)) = self.extract(attr) {
self.collect_feature(feature, stable, span);
}
}
}
@ -169,10 +157,6 @@ pub fn collect<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>) -> LibFeatures {
collector.collect_feature(feature, since, DUMMY_SP);
}
}
collector.collect_from_attrs(&tcx.hir.krate().attrs);
tcx.hir.krate().visit_all_item_likes(&mut collector);
for exported_macro in &tcx.hir.krate().exported_macros {
collector.collect_from_attrs(&exported_macro.attrs);
}
intravisit::walk_crate(&mut collector, tcx.hir.krate());
collector.lib_features
}