1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! A pass that annotates every item and method with its stability level,
12 //! propagating default levels lexically from parent to children ast nodes.
14 use util::nodemap::{NodeMap, DefIdMap};
15 use syntax::codemap::Span;
16 use syntax::{attr, visit};
18 use syntax::ast::{Attribute, Block, Crate, DefId, FnDecl, NodeId, Variant};
19 use syntax::ast::{Item, RequiredMethod, ProvidedMethod, TraitItem};
20 use syntax::ast::{TypeMethod, Method, Generics, StructField, TypeTraitItem};
21 use syntax::ast_util::is_local;
22 use syntax::attr::Stability;
23 use syntax::visit::{FnKind, FkMethod, Visitor};
25 use metadata::csearch;
27 use std::mem::replace;
29 /// A stability index, giving the stability level for items and methods.
31 // stability for crate-local items; unmarked stability == no entry
32 local: NodeMap<Stability>,
33 // cache for extern-crate items; unmarked stability == entry with None
34 extern_cache: DefIdMap<Option<Stability>>
37 // A private tree-walker for producing an Index.
40 parent: Option<Stability>
44 // Determine the stability for a node based on its attributes and inherited
45 // stability. The stability is recorded in the index and used as the parent.
46 fn annotate<F>(&mut self, id: NodeId, use_parent: bool,
47 attrs: &Vec<Attribute>, f: F) where
48 F: FnOnce(&mut Annotator),
50 match attr::find_stability(attrs.as_slice()) {
52 self.index.local.insert(id, stab.clone());
54 // Don't inherit #[stable]
55 if stab.level != attr::Stable {
56 let parent = replace(&mut self.parent, Some(stab));
65 self.parent.clone().map(|stab| self.index.local.insert(id, stab));
73 impl<'v> Visitor<'v> for Annotator {
74 fn visit_item(&mut self, i: &Item) {
75 // FIXME (#18969): the following is a hack around the fact
76 // that we cannot currently annotate the stability of
77 // `deriving`. Basically, we do *not* allow stability
78 // inheritance on trait implementations, so that derived
79 // implementations appear to be unannotated. This then allows
80 // derived implementations to be automatically tagged with the
81 // stability of the trait. This is WRONG, but expedient to get
82 // libstd stabilized for the 1.0 release.
83 let use_parent = match i.node {
84 ast::ItemImpl(_, _, Some(_), _, _) => false,
88 self.annotate(i.id, use_parent, &i.attrs, |v| visit::walk_item(v, i));
90 if let ast::ItemStruct(ref sd, _) = i.node {
92 self.annotate(id, true, &i.attrs, |_| {})
97 fn visit_fn(&mut self, fk: FnKind<'v>, _: &'v FnDecl,
98 _: &'v Block, _: Span, _: NodeId) {
99 if let FkMethod(_, _, meth) = fk {
100 // Methods are not already annotated, so we annotate it
101 self.annotate(meth.id, true, &meth.attrs, |_| {});
103 // Items defined in a function body have no reason to have
104 // a stability attribute, so we don't recurse.
107 fn visit_trait_item(&mut self, t: &TraitItem) {
108 let (id, attrs) = match *t {
109 RequiredMethod(TypeMethod {id, ref attrs, ..}) => (id, attrs),
111 // work around lack of pattern matching for @ types
112 ProvidedMethod(ref method) => {
114 Method {ref attrs, id, ..} => (id, attrs),
118 TypeTraitItem(ref typedef) => (typedef.ty_param.id, &typedef.attrs),
120 self.annotate(id, true, attrs, |v| visit::walk_trait_item(v, t));
123 fn visit_variant(&mut self, var: &Variant, g: &'v Generics) {
124 self.annotate(var.node.id, true, &var.node.attrs,
125 |v| visit::walk_variant(v, var, g))
128 fn visit_struct_field(&mut self, s: &StructField) {
129 self.annotate(s.node.id, true, &s.node.attrs,
130 |v| visit::walk_struct_field(v, s));
133 fn visit_foreign_item(&mut self, i: &ast::ForeignItem) {
134 self.annotate(i.id, &i.attrs, |_| {});
139 /// Construct the stability index for a crate being compiled.
140 pub fn build(krate: &Crate) -> Index {
141 let mut annotator = Annotator {
143 local: NodeMap::new(),
144 extern_cache: DefIdMap::new()
148 annotator.annotate(ast::CRATE_NODE_ID, true, &krate.attrs,
149 |v| visit::walk_crate(v, krate));
154 /// Lookup the stability for a node, loading external crate
155 /// metadata as necessary.
156 pub fn lookup(tcx: &ty::ctxt, id: DefId) -> Option<Stability> {
157 // is this definition the implementation of a trait method?
158 match ty::trait_item_of_item(tcx, id) {
159 Some(ty::MethodTraitItemId(trait_method_id))
160 if trait_method_id != id => {
161 return lookup(tcx, trait_method_id)
166 let item_stab = if is_local(id) {
167 tcx.stability.borrow().local.get(&id.node).cloned()
169 let stab = csearch::get_stability(&tcx.sess.cstore, id);
170 let mut index = tcx.stability.borrow_mut();
171 (*index).extern_cache.insert(id, stab.clone());
175 item_stab.or_else(|| {
176 if let Some(trait_id) = ty::trait_id_of_impl(tcx, id) {
177 // FIXME (#18969): for the time being, simply use the
178 // stability of the trait to determine the stability of any
179 // unmarked impls for it. See FIXME above for more details.
181 lookup(tcx, trait_id)