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.
15 use metadata::csearch;
16 use syntax::codemap::Span;
17 use syntax::{attr, visit};
19 use syntax::ast::{Attribute, Block, Crate, DefId, FnDecl, NodeId, Variant};
20 use syntax::ast::{Item, RequiredMethod, ProvidedMethod, TraitItem};
21 use syntax::ast::{TypeMethod, Method, Generics, StructField, TypeTraitItem};
22 use syntax::ast_util::is_local;
23 use syntax::attr::Stability;
24 use syntax::visit::{FnKind, FkMethod, Visitor};
25 use util::nodemap::{NodeMap, DefIdMap};
26 use util::ppaux::Repr;
28 use std::mem::replace;
30 /// A stability index, giving the stability level for items and methods.
32 // stability for crate-local items; unmarked stability == no entry
33 local: NodeMap<Stability>,
34 // cache for extern-crate items; unmarked stability == entry with None
35 extern_cache: DefIdMap<Option<Stability>>
38 // A private tree-walker for producing an Index.
41 parent: Option<Stability>
45 // Determine the stability for a node based on its attributes and inherited
46 // stability. The stability is recorded in the index and used as the parent.
47 fn annotate<F>(&mut self, id: NodeId, use_parent: bool,
48 attrs: &Vec<Attribute>, f: F) where
49 F: FnOnce(&mut Annotator),
51 match attr::find_stability(attrs.as_slice()) {
53 self.index.local.insert(id, stab.clone());
55 // Don't inherit #[stable]
56 if stab.level != attr::Stable {
57 let parent = replace(&mut self.parent, Some(stab));
66 self.parent.clone().map(|stab| self.index.local.insert(id, stab));
74 impl<'v> Visitor<'v> for Annotator {
75 fn visit_item(&mut self, i: &Item) {
76 // FIXME (#18969): the following is a hack around the fact
77 // that we cannot currently annotate the stability of
78 // `deriving`. Basically, we do *not* allow stability
79 // inheritance on trait implementations, so that derived
80 // implementations appear to be unannotated. This then allows
81 // derived implementations to be automatically tagged with the
82 // stability of the trait. This is WRONG, but expedient to get
83 // libstd stabilized for the 1.0 release.
84 let use_parent = match i.node {
85 ast::ItemImpl(_, _, _, Some(_), _, _) => false,
89 self.annotate(i.id, use_parent, &i.attrs, |v| visit::walk_item(v, i));
91 if let ast::ItemStruct(ref sd, _) = i.node {
93 self.annotate(id, true, &i.attrs, |_| {})
98 fn visit_fn(&mut self, fk: FnKind<'v>, _: &'v FnDecl,
99 _: &'v Block, _: Span, _: NodeId) {
100 if let FkMethod(_, _, meth) = fk {
101 // Methods are not already annotated, so we annotate it
102 self.annotate(meth.id, true, &meth.attrs, |_| {});
104 // Items defined in a function body have no reason to have
105 // a stability attribute, so we don't recurse.
108 fn visit_trait_item(&mut self, t: &TraitItem) {
109 let (id, attrs) = match *t {
110 RequiredMethod(TypeMethod {id, ref attrs, ..}) => (id, attrs),
112 // work around lack of pattern matching for @ types
113 ProvidedMethod(ref method) => {
115 Method {ref attrs, id, ..} => (id, attrs),
119 TypeTraitItem(ref typedef) => (typedef.ty_param.id, &typedef.attrs),
121 self.annotate(id, true, attrs, |v| visit::walk_trait_item(v, t));
124 fn visit_variant(&mut self, var: &Variant, g: &'v Generics) {
125 self.annotate(var.node.id, true, &var.node.attrs,
126 |v| visit::walk_variant(v, var, g))
129 fn visit_struct_field(&mut self, s: &StructField) {
130 self.annotate(s.node.id, true, &s.node.attrs,
131 |v| visit::walk_struct_field(v, s));
134 fn visit_foreign_item(&mut self, i: &ast::ForeignItem) {
135 self.annotate(i.id, true, &i.attrs, |_| {});
140 /// Construct the stability index for a crate being compiled.
141 pub fn build(krate: &Crate) -> Index {
142 let mut annotator = Annotator {
144 local: NodeMap::new(),
145 extern_cache: DefIdMap::new()
149 annotator.annotate(ast::CRATE_NODE_ID, true, &krate.attrs,
150 |v| visit::walk_crate(v, krate));
155 /// Lookup the stability for a node, loading external crate
156 /// metadata as necessary.
157 pub fn lookup(tcx: &ty::ctxt, id: DefId) -> Option<Stability> {
158 debug!("lookup(id={})",
161 // is this definition the implementation of a trait method?
162 match ty::trait_item_of_item(tcx, id) {
163 Some(ty::MethodTraitItemId(trait_method_id)) if trait_method_id != id => {
164 debug!("lookup: trait_method_id={}", trait_method_id);
165 return lookup(tcx, trait_method_id)
170 let item_stab = if is_local(id) {
171 tcx.stability.borrow().local.get(&id.node).cloned()
173 let stab = csearch::get_stability(&tcx.sess.cstore, id);
174 let mut index = tcx.stability.borrow_mut();
175 (*index).extern_cache.insert(id, stab.clone());
179 item_stab.or_else(|| {
180 if let Some(trait_id) = ty::trait_id_of_impl(tcx, id) {
181 // FIXME (#18969): for the time being, simply use the
182 // stability of the trait to determine the stability of any
183 // unmarked impls for it. See FIXME above for more details.
185 debug!("lookup: trait_id={}", trait_id);
186 lookup(tcx, trait_id)