src/librustc/middle/stability.rs

   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.
   4 //
   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.
  10
  11 //! A pass that annotates every item and method with its stability level,
  12 //! propagating default levels lexically from parent to children ast nodes.
  13
  14 pub use self::StabilityLevel::*;
  15
  16 use session::Session;
  17 use lint;
  18 use middle::cstore::{CrateStore, LOCAL_CRATE};
  19 use middle::def;
  20 use middle::def_id::{CRATE_DEF_INDEX, DefId};
  21 use middle::ty;
  22 use middle::privacy::AccessLevels;
  23 use syntax::parse::token::InternedString;
  24 use syntax::codemap::{Span, DUMMY_SP};
  25 use syntax::ast;
  26 use syntax::ast::{NodeId, Attribute};
  27 use syntax::feature_gate::{GateIssue, emit_feature_err};
  28 use syntax::attr::{self, Stability, Deprecation, AttrMetaMethods};
  29 use util::nodemap::{DefIdMap, FnvHashSet, FnvHashMap};
  30
  31 use rustc_front::hir;
  32 use rustc_front::hir::{Crate, Item, Generics, StructField, Variant};
  33 use rustc_front::intravisit::{self, Visitor};
  34
  35 use std::mem::replace;
  36 use std::cmp::Ordering;
  37
  38 #[derive(RustcEncodable, RustcDecodable, PartialEq, PartialOrd, Clone, Copy, Debug, Eq, Hash)]
  39 pub enum StabilityLevel {
  40     Unstable,
  41     Stable,
  42 }
  43
  44 impl StabilityLevel {
  45     pub fn from_attr_level(level: &attr::StabilityLevel) -> Self {
  46         if level.is_stable() { Stable } else { Unstable }
  47     }
  48 }
  49
  50 #[derive(PartialEq)]
  51 enum AnnotationKind {
  52     // Annotation is required if not inherited from unstable parents
  53     Required,
  54     // Annotation is useless, reject it
  55     Prohibited,
  56     // Annotation itself is useless, but it can be propagated to children
  57     Container,
  58 }
  59
  60 /// A stability index, giving the stability level for items and methods.
  61 pub struct Index<'tcx> {
  62     /// This is mostly a cache, except the stabilities of local items
  63     /// are filled by the annotator.
  64     stab_map: DefIdMap<Option<&'tcx Stability>>,
  65     depr_map: DefIdMap<Option<Deprecation>>,
  66
  67     /// Maps for each crate whether it is part of the staged API.
  68     staged_api: FnvHashMap<ast::CrateNum, bool>
  69 }
  70
  71 // A private tree-walker for producing an Index.
  72 struct Annotator<'a, 'tcx: 'a> {
  73     tcx: &'a ty::ctxt<'tcx>,
  74     index: &'a mut Index<'tcx>,
  75     parent_stab: Option<&'tcx Stability>,
  76     parent_depr: Option<Deprecation>,
  77     access_levels: &'a AccessLevels,
  78     in_trait_impl: bool,
  79     in_enum: bool,
  80 }
  81
  82 impl<'a, 'tcx: 'a> Annotator<'a, 'tcx> {
  83     // Determine the stability for a node based on its attributes and inherited
  84     // stability. The stability is recorded in the index and used as the parent.
  85     fn annotate<F>(&mut self, id: NodeId, attrs: &[Attribute],
  86                    item_sp: Span, kind: AnnotationKind, visit_children: F)
  87         where F: FnOnce(&mut Annotator)
  88     {
  89         if self.index.staged_api[&LOCAL_CRATE] && self.tcx.sess.features.borrow().staged_api {
  90             debug!("annotate(id = {:?}, attrs = {:?})", id, attrs);
  91             if let Some(..) = attr::find_deprecation(self.tcx.sess.diagnostic(), attrs, item_sp) {
  92                 self.tcx.sess.span_err(item_sp, "`#[deprecated]` cannot be used in staged api, \
  93                                                  use `#[rustc_deprecated]` instead");
  94             }
  95             if let Some(mut stab) = attr::find_stability(self.tcx.sess.diagnostic(),
  96                                                          attrs, item_sp) {
  97                 // Error if prohibited, or can't inherit anything from a container
  98                 if kind == AnnotationKind::Prohibited ||
  99                    (kind == AnnotationKind::Container &&
 100                     stab.level.is_stable() &&
 101                     stab.rustc_depr.is_none()) {
 102                     self.tcx.sess.span_err(item_sp, "This stability annotation is useless");
 103                 }
 104
 105                 debug!("annotate: found {:?}", stab);
 106                 // If parent is deprecated and we're not, inherit this by merging
 107                 // deprecated_since and its reason.
 108                 if let Some(parent_stab) = self.parent_stab {
 109                     if parent_stab.rustc_depr.is_some() && stab.rustc_depr.is_none() {
 110                         stab.rustc_depr = parent_stab.rustc_depr.clone()
 111                     }
 112                 }
 113
 114                 let stab = self.tcx.intern_stability(stab);
 115
 116                 // Check if deprecated_since < stable_since. If it is,
 117                 // this is *almost surely* an accident.
 118                 if let (&Some(attr::RustcDeprecation {since: ref dep_since, ..}),
 119                         &attr::Stable {since: ref stab_since}) = (&stab.rustc_depr, &stab.level) {
 120                     // Explicit version of iter::order::lt to handle parse errors properly
 121                     for (dep_v, stab_v) in dep_since.split(".").zip(stab_since.split(".")) {
 122                         if let (Ok(dep_v), Ok(stab_v)) = (dep_v.parse::<u64>(), stab_v.parse()) {
 123                             match dep_v.cmp(&stab_v) {
 124                                 Ordering::Less => {
 125                                     self.tcx.sess.span_err(item_sp, "An API can't be stabilized \
 126                                                                      after it is deprecated");
 127                                     break
 128                                 }
 129                                 Ordering::Equal => continue,
 130                                 Ordering::Greater => break,
 131                             }
 132                         } else {
 133                             // Act like it isn't less because the question is now nonsensical,
 134                             // and this makes us not do anything else interesting.
 135                             self.tcx.sess.span_err(item_sp, "Invalid stability or deprecation \
 136                                                              version found");
 137                             break
 138                         }
 139                     }
 140                 }
 141
 142                 let def_id = self.tcx.map.local_def_id(id);
 143                 self.index.stab_map.insert(def_id, Some(stab));
 144
 145                 let orig_parent_stab = replace(&mut self.parent_stab, Some(stab));
 146                 visit_children(self);
 147                 self.parent_stab = orig_parent_stab;
 148             } else {
 149                 debug!("annotate: not found, parent = {:?}", self.parent_stab);
 150                 let mut is_error = kind == AnnotationKind::Required &&
 151                                    self.access_levels.is_reachable(id) &&
 152                                    !self.tcx.sess.opts.test;
 153                 if let Some(stab) = self.parent_stab {
 154                     if stab.level.is_unstable() {
 155                         let def_id = self.tcx.map.local_def_id(id);
 156                         self.index.stab_map.insert(def_id, Some(stab));
 157                         is_error = false;
 158                     }
 159                 }
 160                 if is_error {
 161                     self.tcx.sess.span_err(item_sp, "This node does not have \
 162                                                      a stability attribute");
 163                 }
 164                 visit_children(self);
 165             }
 166         } else {
 167             // Emit errors for non-staged-api crates.
 168             for attr in attrs {
 169                 let tag = attr.name();
 170                 if tag == "unstable" || tag == "stable" || tag == "rustc_deprecated" {
 171                     attr::mark_used(attr);
 172                     self.tcx.sess.span_err(attr.span(), "stability attributes may not be used \
 173                                                          outside of the standard library");
 174                 }
 175             }
 176
 177             if let Some(depr) = attr::find_deprecation(self.tcx.sess.diagnostic(), attrs, item_sp) {
 178                 if kind == AnnotationKind::Prohibited {
 179                     self.tcx.sess.span_err(item_sp, "This deprecation annotation is useless");
 180                 }
 181
 182                 // `Deprecation` is just two pointers, no need to intern it
 183                 let def_id = self.tcx.map.local_def_id(id);
 184                 self.index.depr_map.insert(def_id, Some(depr.clone()));
 185
 186                 let orig_parent_depr = replace(&mut self.parent_depr, Some(depr));
 187                 visit_children(self);
 188                 self.parent_depr = orig_parent_depr;
 189             } else if let Some(depr) = self.parent_depr.clone() {
 190                 let def_id = self.tcx.map.local_def_id(id);
 191                 self.index.depr_map.insert(def_id, Some(depr));
 192                 visit_children(self);
 193             } else {
 194                 visit_children(self);
 195             }
 196         }
 197     }
 198 }
 199
 200 impl<'a, 'tcx, 'v> Visitor<'v> for Annotator<'a, 'tcx> {
 201     /// Because stability levels are scoped lexically, we want to walk
 202     /// nested items in the context of the outer item, so enable
 203     /// deep-walking.
 204     fn visit_nested_item(&mut self, item: hir::ItemId) {
 205         self.visit_item(self.tcx.map.expect_item(item.id))
 206     }
 207
 208     fn visit_item(&mut self, i: &Item) {
 209         let orig_in_trait_impl = self.in_trait_impl;
 210         let orig_in_enum = self.in_enum;
 211         let mut kind = AnnotationKind::Required;
 212         match i.node {
 213             // Inherent impls and foreign modules serve only as containers for other items,
 214             // they don't have their own stability. They still can be annotated as unstable
 215             // and propagate this unstability to children, but this annotation is completely
 216             // optional. They inherit stability from their parents when unannotated.
 217             hir::ItemImpl(_, _, _, None, _, _) | hir::ItemForeignMod(..) => {
 218                 self.in_trait_impl = false;
 219                 kind = AnnotationKind::Container;
 220             }
 221             hir::ItemImpl(_, _, _, Some(_), _, _) => {
 222                 self.in_trait_impl = true;
 223             }
 224             hir::ItemStruct(ref sd, _) => {
 225                 self.in_enum = false;
 226                 if !sd.is_struct() {
 227                     self.annotate(sd.id(), &i.attrs, i.span, AnnotationKind::Required, |_| {})
 228                 }
 229             }
 230             hir::ItemEnum(..) => {
 231                 self.in_enum = true;
 232             }
 233             _ => {}
 234         }
 235
 236         self.annotate(i.id, &i.attrs, i.span, kind, |v| {
 237             intravisit::walk_item(v, i)
 238         });
 239         self.in_trait_impl = orig_in_trait_impl;
 240         self.in_enum = orig_in_enum;
 241     }
 242
 243     fn visit_trait_item(&mut self, ti: &hir::TraitItem) {
 244         self.annotate(ti.id, &ti.attrs, ti.span, AnnotationKind::Required, |v| {
 245             intravisit::walk_trait_item(v, ti);
 246         });
 247     }
 248
 249     fn visit_impl_item(&mut self, ii: &hir::ImplItem) {
 250         let kind = if self.in_trait_impl {
 251             AnnotationKind::Prohibited
 252         } else {
 253             AnnotationKind::Required
 254         };
 255         self.annotate(ii.id, &ii.attrs, ii.span, kind, |v| {
 256             intravisit::walk_impl_item(v, ii);
 257         });
 258     }
 259
 260     fn visit_variant(&mut self, var: &Variant, g: &'v Generics, item_id: NodeId) {
 261         self.annotate(var.node.data.id(), &var.node.attrs, var.span, AnnotationKind::Required, |v| {
 262             intravisit::walk_variant(v, var, g, item_id);
 263         })
 264     }
 265
 266     fn visit_struct_field(&mut self, s: &StructField) {
 267         // FIXME: This is temporary, can't use attributes with tuple variant fields until snapshot
 268         let kind = if self.in_enum && s.node.kind.is_unnamed() {
 269             AnnotationKind::Prohibited
 270         } else {
 271             AnnotationKind::Required
 272         };
 273         self.annotate(s.node.id, &s.node.attrs, s.span, kind, |v| {
 274             intravisit::walk_struct_field(v, s);
 275         });
 276     }
 277
 278     fn visit_foreign_item(&mut self, i: &hir::ForeignItem) {
 279         self.annotate(i.id, &i.attrs, i.span, AnnotationKind::Required, |v| {
 280             intravisit::walk_foreign_item(v, i);
 281         });
 282     }
 283
 284     fn visit_macro_def(&mut self, md: &'v hir::MacroDef) {
 285         if md.imported_from.is_none() {
 286             self.annotate(md.id, &md.attrs, md.span, AnnotationKind::Required, |_| {});
 287         }
 288     }
 289 }
 290
 291 impl<'tcx> Index<'tcx> {
 292     /// Construct the stability index for a crate being compiled.
 293     pub fn build(&mut self, tcx: &ty::ctxt<'tcx>, krate: &Crate, access_levels: &AccessLevels) {
 294         let mut annotator = Annotator {
 295             tcx: tcx,
 296             index: self,
 297             parent_stab: None,
 298             parent_depr: None,
 299             access_levels: access_levels,
 300             in_trait_impl: false,
 301             in_enum: false,
 302         };
 303         annotator.annotate(ast::CRATE_NODE_ID, &krate.attrs, krate.span, AnnotationKind::Required,
 304                            |v| intravisit::walk_crate(v, krate));
 305     }
 306
 307     pub fn new(krate: &Crate) -> Index<'tcx> {
 308         let mut is_staged_api = false;
 309         for attr in &krate.attrs {
 310             if attr.name() == "stable" || attr.name() == "unstable" {
 311                 is_staged_api = true;
 312                 break
 313             }
 314         }
 315
 316         let mut staged_api = FnvHashMap();
 317         staged_api.insert(LOCAL_CRATE, is_staged_api);
 318         Index {
 319             staged_api: staged_api,
 320             stab_map: DefIdMap(),
 321             depr_map: DefIdMap(),
 322         }
 323     }
 324 }
 325
 326 /// Cross-references the feature names of unstable APIs with enabled
 327 /// features and possibly prints errors. Returns a list of all
 328 /// features used.
 329 pub fn check_unstable_api_usage(tcx: &ty::ctxt)
 330                                 -> FnvHashMap<InternedString, StabilityLevel> {
 331     let ref active_lib_features = tcx.sess.features.borrow().declared_lib_features;
 332
 333     // Put the active features into a map for quick lookup
 334     let active_features = active_lib_features.iter().map(|&(ref s, _)| s.clone()).collect();
 335
 336     let mut checker = Checker {
 337         tcx: tcx,
 338         active_features: active_features,
 339         used_features: FnvHashMap(),
 340         in_skip_block: 0,
 341     };
 342     intravisit::walk_crate(&mut checker, tcx.map.krate());
 343
 344     let used_features = checker.used_features;
 345     return used_features;
 346 }
 347
 348 struct Checker<'a, 'tcx: 'a> {
 349     tcx: &'a ty::ctxt<'tcx>,
 350     active_features: FnvHashSet<InternedString>,
 351     used_features: FnvHashMap<InternedString, StabilityLevel>,
 352     // Within a block where feature gate checking can be skipped.
 353     in_skip_block: u32,
 354 }
 355
 356 impl<'a, 'tcx> Checker<'a, 'tcx> {
 357     fn check(&mut self, id: DefId, span: Span,
 358              stab: &Option<&Stability>, _depr: &Option<Deprecation>) {
 359         if !is_staged_api(self.tcx, id) {
 360             return;
 361         }
 362         // Only the cross-crate scenario matters when checking unstable APIs
 363         let cross_crate = !id.is_local();
 364         if !cross_crate {
 365             return
 366         }
 367
 368         // We don't need to check for stability - presumably compiler generated code.
 369         if self.in_skip_block > 0 {
 370             return;
 371         }
 372
 373         match *stab {
 374             Some(&Stability { level: attr::Unstable {ref reason, issue}, ref feature, .. }) => {
 375                 self.used_features.insert(feature.clone(), Unstable);
 376
 377                 if !self.active_features.contains(feature) {
 378                     let msg = match *reason {
 379                         Some(ref r) => format!("use of unstable library feature '{}': {}",
 380                                                &feature, &r),
 381                         None => format!("use of unstable library feature '{}'", &feature)
 382                     };
 383                     emit_feature_err(&self.tcx.sess.parse_sess.span_diagnostic,
 384                                       &feature, span, GateIssue::Library(Some(issue)), &msg);
 385                 }
 386             }
 387             Some(&Stability { ref level, ref feature, .. }) => {
 388                 self.used_features.insert(feature.clone(), StabilityLevel::from_attr_level(level));
 389
 390                 // Stable APIs are always ok to call and deprecated APIs are
 391                 // handled by a lint.
 392             }
 393             None => {
 394                 // This is an 'unmarked' API, which should not exist
 395                 // in the standard library.
 396                 if self.tcx.sess.features.borrow().unmarked_api {
 397                     self.tcx.sess.struct_span_warn(span, "use of unmarked library feature")
 398                                  .span_note(span, "this is either a bug in the library you are \
 399                                                    using or a bug in the compiler - please \
 400                                                    report it in both places")
 401                                  .emit()
 402                 } else {
 403                     self.tcx.sess.struct_span_err(span, "use of unmarked library feature")
 404                                  .span_note(span, "this is either a bug in the library you are \
 405                                                    using or a bug in the compiler - please \
 406                                                    report it in both places")
 407                                  .span_note(span, "use #![feature(unmarked_api)] in the \
 408                                                    crate attributes to override this")
 409                                  .emit()
 410                 }
 411             }
 412         }
 413     }
 414 }
 415
 416 impl<'a, 'v, 'tcx> Visitor<'v> for Checker<'a, 'tcx> {
 417     /// Because stability levels are scoped lexically, we want to walk
 418     /// nested items in the context of the outer item, so enable
 419     /// deep-walking.
 420     fn visit_nested_item(&mut self, item: hir::ItemId) {
 421         self.visit_item(self.tcx.map.expect_item(item.id))
 422     }
 423
 424     fn visit_item(&mut self, item: &hir::Item) {
 425         // When compiling with --test we don't enforce stability on the
 426         // compiler-generated test module, demarcated with `DUMMY_SP` plus the
 427         // name `__test`
 428         if item.span == DUMMY_SP && item.name.as_str() == "__test" { return }
 429
 430         check_item(self.tcx, item, true,
 431                    &mut |id, sp, stab, depr| self.check(id, sp, stab, depr));
 432         intravisit::walk_item(self, item);
 433     }
 434
 435     fn visit_expr(&mut self, ex: &hir::Expr) {
 436         check_expr(self.tcx, ex,
 437                    &mut |id, sp, stab, depr| self.check(id, sp, stab, depr));
 438         intravisit::walk_expr(self, ex);
 439     }
 440
 441     fn visit_path(&mut self, path: &hir::Path, id: ast::NodeId) {
 442         check_path(self.tcx, path, id,
 443                    &mut |id, sp, stab, depr| self.check(id, sp, stab, depr));
 444         intravisit::walk_path(self, path)
 445     }
 446
 447     fn visit_path_list_item(&mut self, prefix: &hir::Path, item: &hir::PathListItem) {
 448         check_path_list_item(self.tcx, item,
 449                    &mut |id, sp, stab, depr| self.check(id, sp, stab, depr));
 450         intravisit::walk_path_list_item(self, prefix, item)
 451     }
 452
 453     fn visit_pat(&mut self, pat: &hir::Pat) {
 454         check_pat(self.tcx, pat,
 455                   &mut |id, sp, stab, depr| self.check(id, sp, stab, depr));
 456         intravisit::walk_pat(self, pat)
 457     }
 458
 459     fn visit_block(&mut self, b: &hir::Block) {
 460         let old_skip_count = self.in_skip_block;
 461         match b.rules {
 462             hir::BlockCheckMode::PushUnstableBlock => {
 463                 self.in_skip_block += 1;
 464             }
 465             hir::BlockCheckMode::PopUnstableBlock => {
 466                 self.in_skip_block = self.in_skip_block.checked_sub(1).unwrap();
 467             }
 468             _ => {}
 469         }
 470         intravisit::walk_block(self, b);
 471         self.in_skip_block = old_skip_count;
 472     }
 473 }
 474
 475 /// Helper for discovering nodes to check for stability
 476 pub fn check_item(tcx: &ty::ctxt, item: &hir::Item, warn_about_defns: bool,
 477                   cb: &mut FnMut(DefId, Span, &Option<&Stability>, &Option<Deprecation>)) {
 478     match item.node {
 479         hir::ItemExternCrate(_) => {
 480             // compiler-generated `extern crate` items have a dummy span.
 481             if item.span == DUMMY_SP { return }
 482
 483             let cnum = match tcx.sess.cstore.extern_mod_stmt_cnum(item.id) {
 484                 Some(cnum) => cnum,
 485                 None => return,
 486             };
 487             let id = DefId { krate: cnum, index: CRATE_DEF_INDEX };
 488             maybe_do_stability_check(tcx, id, item.span, cb);
 489         }
 490
 491         // For implementations of traits, check the stability of each item
 492         // individually as it's possible to have a stable trait with unstable
 493         // items.
 494         hir::ItemImpl(_, _, _, Some(ref t), _, ref impl_items) => {
 495             let trait_did = tcx.def_map.borrow().get(&t.ref_id).unwrap().def_id();
 496             let trait_items = tcx.trait_items(trait_did);
 497
 498             for impl_item in impl_items {
 499                 let item = trait_items.iter().find(|item| {
 500                     item.name() == impl_item.name
 501                 }).unwrap();
 502                 if warn_about_defns {
 503                     maybe_do_stability_check(tcx, item.def_id(), impl_item.span, cb);
 504                 }
 505             }
 506         }
 507
 508         _ => (/* pass */)
 509     }
 510 }
 511
 512 /// Helper for discovering nodes to check for stability
 513 pub fn check_expr(tcx: &ty::ctxt, e: &hir::Expr,
 514                   cb: &mut FnMut(DefId, Span, &Option<&Stability>, &Option<Deprecation>)) {
 515     let span;
 516     let id = match e.node {
 517         hir::ExprMethodCall(i, _, _) => {
 518             span = i.span;
 519             let method_call = ty::MethodCall::expr(e.id);
 520             tcx.tables.borrow().method_map[&method_call].def_id
 521         }
 522         hir::ExprField(ref base_e, ref field) => {
 523             span = field.span;
 524             match tcx.expr_ty_adjusted(base_e).sty {
 525                 ty::TyStruct(def, _) => def.struct_variant().field_named(field.node).did,
 526                 _ => tcx.sess.span_bug(e.span,
 527                                        "stability::check_expr: named field access on non-struct")
 528             }
 529         }
 530         hir::ExprTupField(ref base_e, ref field) => {
 531             span = field.span;
 532             match tcx.expr_ty_adjusted(base_e).sty {
 533                 ty::TyStruct(def, _) => def.struct_variant().fields[field.node].did,
 534                 ty::TyTuple(..) => return,
 535                 _ => tcx.sess.span_bug(e.span,
 536                                        "stability::check_expr: unnamed field access on \
 537                                         something other than a tuple or struct")
 538             }
 539         }
 540         hir::ExprStruct(_, ref expr_fields, _) => {
 541             let type_ = tcx.expr_ty(e);
 542             match type_.sty {
 543                 ty::TyStruct(def, _) => {
 544                     // check the stability of each field that appears
 545                     // in the construction expression.
 546                     for field in expr_fields {
 547                         let did = def.struct_variant()
 548                             .field_named(field.name.node)
 549                             .did;
 550                         maybe_do_stability_check(tcx, did, field.span, cb);
 551                     }
 552
 553                     // we're done.
 554                     return
 555                 }
 556                 // we don't look at stability attributes on
 557                 // struct-like enums (yet...), but it's definitely not
 558                 // a bug to have construct one.
 559                 ty::TyEnum(..) => return,
 560                 _ => {
 561                     tcx.sess.span_bug(e.span,
 562                                       &format!("stability::check_expr: struct construction \
 563                                                 of non-struct, type {:?}",
 564                                                type_));
 565                 }
 566             }
 567         }
 568         _ => return
 569     };
 570
 571     maybe_do_stability_check(tcx, id, span, cb);
 572 }
 573
 574 pub fn check_path(tcx: &ty::ctxt, path: &hir::Path, id: ast::NodeId,
 575                   cb: &mut FnMut(DefId, Span, &Option<&Stability>, &Option<Deprecation>)) {
 576     match tcx.def_map.borrow().get(&id).map(|d| d.full_def()) {
 577         Some(def::DefPrimTy(..)) => {}
 578         Some(def::DefSelfTy(..)) => {}
 579         Some(def) => {
 580             maybe_do_stability_check(tcx, def.def_id(), path.span, cb);
 581         }
 582         None => {}
 583     }
 584 }
 585
 586 pub fn check_path_list_item(tcx: &ty::ctxt, item: &hir::PathListItem,
 587                   cb: &mut FnMut(DefId, Span, &Option<&Stability>, &Option<Deprecation>)) {
 588     match tcx.def_map.borrow().get(&item.node.id()).map(|d| d.full_def()) {
 589         Some(def::DefPrimTy(..)) => {}
 590         Some(def) => {
 591             maybe_do_stability_check(tcx, def.def_id(), item.span, cb);
 592         }
 593         None => {}
 594     }
 595 }
 596
 597 pub fn check_pat(tcx: &ty::ctxt, pat: &hir::Pat,
 598                  cb: &mut FnMut(DefId, Span, &Option<&Stability>, &Option<Deprecation>)) {
 599     debug!("check_pat(pat = {:?})", pat);
 600     if is_internal(tcx, pat.span) { return; }
 601
 602     let v = match tcx.pat_ty_opt(pat) {
 603         Some(&ty::TyS { sty: ty::TyStruct(def, _), .. }) => def.struct_variant(),
 604         Some(_) | None => return,
 605     };
 606     match pat.node {
 607         // Foo(a, b, c)
 608         // A Variant(..) pattern `hir::PatEnum(_, None)` doesn't have to be recursed into.
 609         hir::PatEnum(_, Some(ref pat_fields)) => {
 610             for (field, struct_field) in pat_fields.iter().zip(&v.fields) {
 611                 maybe_do_stability_check(tcx, struct_field.did, field.span, cb)
 612             }
 613         }
 614         // Foo { a, b, c }
 615         hir::PatStruct(_, ref pat_fields, _) => {
 616             for field in pat_fields {
 617                 let did = v.field_named(field.node.name).did;
 618                 maybe_do_stability_check(tcx, did, field.span, cb);
 619             }
 620         }
 621         // everything else is fine.
 622         _ => {}
 623     }
 624 }
 625
 626 fn maybe_do_stability_check(tcx: &ty::ctxt, id: DefId, span: Span,
 627                             cb: &mut FnMut(DefId, Span,
 628                                            &Option<&Stability>, &Option<Deprecation>)) {
 629     if is_internal(tcx, span) {
 630         debug!("maybe_do_stability_check: \
 631                 skipping span={:?} since it is internal", span);
 632         return;
 633     }
 634     let (stability, deprecation) = if is_staged_api(tcx, id) {
 635         (lookup_stability(tcx, id), None)
 636     } else {
 637         (None, lookup_deprecation(tcx, id))
 638     };
 639     debug!("maybe_do_stability_check: \
 640             inspecting id={:?} span={:?} of stability={:?}", id, span, stability);
 641     cb(id, span, &stability, &deprecation);
 642 }
 643
 644 fn is_internal(tcx: &ty::ctxt, span: Span) -> bool {
 645     tcx.sess.codemap().span_allows_unstable(span)
 646 }
 647
 648 fn is_staged_api(tcx: &ty::ctxt, id: DefId) -> bool {
 649     match tcx.trait_item_of_item(id) {
 650         Some(ty::MethodTraitItemId(trait_method_id))
 651             if trait_method_id != id => {
 652                 is_staged_api(tcx, trait_method_id)
 653             }
 654         _ => {
 655             *tcx.stability.borrow_mut().staged_api.entry(id.krate).or_insert_with(
 656                 || tcx.sess.cstore.is_staged_api(id.krate))
 657         }
 658     }
 659 }
 660
 661 /// Lookup the stability for a node, loading external crate
 662 /// metadata as necessary.
 663 pub fn lookup_stability<'tcx>(tcx: &ty::ctxt<'tcx>, id: DefId) -> Option<&'tcx Stability> {
 664     if let Some(st) = tcx.stability.borrow().stab_map.get(&id) {
 665         return *st;
 666     }
 667
 668     let st = lookup_stability_uncached(tcx, id);
 669     tcx.stability.borrow_mut().stab_map.insert(id, st);
 670     st
 671 }
 672
 673 pub fn lookup_deprecation<'tcx>(tcx: &ty::ctxt<'tcx>, id: DefId) -> Option<Deprecation> {
 674     if let Some(depr) = tcx.stability.borrow().depr_map.get(&id) {
 675         return depr.clone();
 676     }
 677
 678     let depr = lookup_deprecation_uncached(tcx, id);
 679     tcx.stability.borrow_mut().depr_map.insert(id, depr.clone());
 680     depr
 681 }
 682
 683 fn lookup_stability_uncached<'tcx>(tcx: &ty::ctxt<'tcx>, id: DefId) -> Option<&'tcx Stability> {
 684     debug!("lookup(id={:?})", id);
 685     if id.is_local() {
 686         None // The stability cache is filled partially lazily
 687     } else {
 688         tcx.sess.cstore.stability(id).map(|st| tcx.intern_stability(st))
 689     }
 690 }
 691
 692 fn lookup_deprecation_uncached<'tcx>(tcx: &ty::ctxt<'tcx>, id: DefId) -> Option<Deprecation> {
 693     debug!("lookup(id={:?})", id);
 694     if id.is_local() {
 695         None // The stability cache is filled partially lazily
 696     } else {
 697         tcx.sess.cstore.deprecation(id)
 698     }
 699 }
 700
 701 /// Given the list of enabled features that were not language features (i.e. that
 702 /// were expected to be library features), and the list of features used from
 703 /// libraries, identify activated features that don't exist and error about them.
 704 pub fn check_unused_or_stable_features(sess: &Session,
 705                                        lib_features_used: &FnvHashMap<InternedString,
 706                                                                       StabilityLevel>) {
 707     let ref declared_lib_features = sess.features.borrow().declared_lib_features;
 708     let mut remaining_lib_features: FnvHashMap<InternedString, Span>
 709         = declared_lib_features.clone().into_iter().collect();
 710
 711     let stable_msg = "this feature is stable. attribute no longer needed";
 712
 713     for &span in &sess.features.borrow().declared_stable_lang_features {
 714         sess.add_lint(lint::builtin::STABLE_FEATURES,
 715                       ast::CRATE_NODE_ID,
 716                       span,
 717                       stable_msg.to_string());
 718     }
 719
 720     for (used_lib_feature, level) in lib_features_used {
 721         match remaining_lib_features.remove(used_lib_feature) {
 722             Some(span) => {
 723                 if *level == Stable {
 724                     sess.add_lint(lint::builtin::STABLE_FEATURES,
 725                                   ast::CRATE_NODE_ID,
 726                                   span,
 727                                   stable_msg.to_string());
 728                 }
 729             }
 730             None => ( /* used but undeclared, handled during the previous ast visit */ )
 731         }
 732     }
 733
 734     for &span in remaining_lib_features.values() {
 735         sess.add_lint(lint::builtin::UNUSED_FEATURES,
 736                       ast::CRATE_NODE_ID,
 737                       span,
 738                       "unused or unknown feature".to_string());
 739     }
 740 }