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::{Block, 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: &Vec<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                 } else if tag == "deprecated" {
 175                     if !self.tcx.sess.features.borrow().deprecated {
 176                         self.tcx.sess.span_err(attr.span(),
 177                                                "`#[deprecated]` attribute is unstable");
 178                         fileline_help!(self.tcx.sess, attr.span(), "add #![feature(deprecated)] to \
 179                                                                     the crate features to enable");
 180                     }
 181                 }
 182             }
 183
 184             if let Some(depr) = attr::find_deprecation(self.tcx.sess.diagnostic(), attrs, item_sp) {
 185                 if kind == AnnotationKind::Prohibited {
 186                     self.tcx.sess.span_err(item_sp, "This deprecation annotation is useless");
 187                 }
 188
 189                 // `Deprecation` is just two pointers, no need to intern it
 190                 let def_id = self.tcx.map.local_def_id(id);
 191                 self.index.depr_map.insert(def_id, Some(depr.clone()));
 192
 193                 let orig_parent_depr = replace(&mut self.parent_depr, Some(depr));
 194                 visit_children(self);
 195                 self.parent_depr = orig_parent_depr;
 196             } else if let Some(depr) = self.parent_depr.clone() {
 197                 let def_id = self.tcx.map.local_def_id(id);
 198                 self.index.depr_map.insert(def_id, Some(depr));
 199                 visit_children(self);
 200             } else {
 201                 visit_children(self);
 202             }
 203         }
 204     }
 205 }
 206
 207 impl<'a, 'tcx, 'v> Visitor<'v> for Annotator<'a, 'tcx> {
 208     /// Because stability levels are scoped lexically, we want to walk
 209     /// nested items in the context of the outer item, so enable
 210     /// deep-walking.
 211     fn visit_nested_item(&mut self, item: hir::ItemId) {
 212         self.visit_item(self.tcx.map.expect_item(item.id))
 213     }
 214
 215     fn visit_item(&mut self, i: &Item) {
 216         let orig_in_trait_impl = self.in_trait_impl;
 217         let orig_in_enum = self.in_enum;
 218         let mut kind = AnnotationKind::Required;
 219         match i.node {
 220             // Inherent impls and foreign modules serve only as containers for other items,
 221             // they don't have their own stability. They still can be annotated as unstable
 222             // and propagate this unstability to children, but this annotation is completely
 223             // optional. They inherit stability from their parents when unannotated.
 224             hir::ItemImpl(_, _, _, None, _, _) | hir::ItemForeignMod(..) => {
 225                 self.in_trait_impl = false;
 226                 kind = AnnotationKind::Container;
 227             }
 228             hir::ItemImpl(_, _, _, Some(_), _, _) => {
 229                 self.in_trait_impl = true;
 230             }
 231             hir::ItemStruct(ref sd, _) => {
 232                 self.in_enum = false;
 233                 if !sd.is_struct() {
 234                     self.annotate(sd.id(), &i.attrs, i.span, AnnotationKind::Required, |_| {})
 235                 }
 236             }
 237             hir::ItemEnum(..) => {
 238                 self.in_enum = true;
 239             }
 240             _ => {}
 241         }
 242
 243         self.annotate(i.id, &i.attrs, i.span, kind, |v| {
 244             intravisit::walk_item(v, i)
 245         });
 246         self.in_trait_impl = orig_in_trait_impl;
 247         self.in_enum = orig_in_enum;
 248     }
 249
 250     fn visit_trait_item(&mut self, ti: &hir::TraitItem) {
 251         self.annotate(ti.id, &ti.attrs, ti.span, AnnotationKind::Required, |v| {
 252             intravisit::walk_trait_item(v, ti);
 253         });
 254     }
 255
 256     fn visit_impl_item(&mut self, ii: &hir::ImplItem) {
 257         let kind = if self.in_trait_impl {
 258             AnnotationKind::Prohibited
 259         } else {
 260             AnnotationKind::Required
 261         };
 262         self.annotate(ii.id, &ii.attrs, ii.span, kind, |v| {
 263             intravisit::walk_impl_item(v, ii);
 264         });
 265     }
 266
 267     fn visit_variant(&mut self, var: &Variant, g: &'v Generics, item_id: NodeId) {
 268         self.annotate(var.node.data.id(), &var.node.attrs, var.span, AnnotationKind::Required, |v| {
 269             intravisit::walk_variant(v, var, g, item_id);
 270         })
 271     }
 272
 273     fn visit_struct_field(&mut self, s: &StructField) {
 274         // FIXME: This is temporary, can't use attributes with tuple variant fields until snapshot
 275         let kind = if self.in_enum && s.node.kind.is_unnamed() {
 276             AnnotationKind::Prohibited
 277         } else {
 278             AnnotationKind::Required
 279         };
 280         self.annotate(s.node.id, &s.node.attrs, s.span, kind, |v| {
 281             intravisit::walk_struct_field(v, s);
 282         });
 283     }
 284
 285     fn visit_foreign_item(&mut self, i: &hir::ForeignItem) {
 286         self.annotate(i.id, &i.attrs, i.span, AnnotationKind::Required, |v| {
 287             intravisit::walk_foreign_item(v, i);
 288         });
 289     }
 290
 291     fn visit_macro_def(&mut self, md: &'v hir::MacroDef) {
 292         if md.imported_from.is_none() {
 293             self.annotate(md.id, &md.attrs, md.span, AnnotationKind::Required, |_| {});
 294         }
 295     }
 296 }
 297
 298 impl<'tcx> Index<'tcx> {
 299     /// Construct the stability index for a crate being compiled.
 300     pub fn build(&mut self, tcx: &ty::ctxt<'tcx>, krate: &Crate, access_levels: &AccessLevels) {
 301         let mut annotator = Annotator {
 302             tcx: tcx,
 303             index: self,
 304             parent_stab: None,
 305             parent_depr: None,
 306             access_levels: access_levels,
 307             in_trait_impl: false,
 308             in_enum: false,
 309         };
 310         annotator.annotate(ast::CRATE_NODE_ID, &krate.attrs, krate.span, AnnotationKind::Required,
 311                            |v| intravisit::walk_crate(v, krate));
 312     }
 313
 314     pub fn new(krate: &Crate) -> Index<'tcx> {
 315         let mut is_staged_api = false;
 316         for attr in &krate.attrs {
 317             if attr.name() == "stable" || attr.name() == "unstable" {
 318                 is_staged_api = true;
 319                 break
 320             }
 321         }
 322
 323         let mut staged_api = FnvHashMap();
 324         staged_api.insert(LOCAL_CRATE, is_staged_api);
 325         Index {
 326             staged_api: staged_api,
 327             stab_map: DefIdMap(),
 328             depr_map: DefIdMap(),
 329         }
 330     }
 331 }
 332
 333 /// Cross-references the feature names of unstable APIs with enabled
 334 /// features and possibly prints errors. Returns a list of all
 335 /// features used.
 336 pub fn check_unstable_api_usage(tcx: &ty::ctxt)
 337                                 -> FnvHashMap<InternedString, StabilityLevel> {
 338     let ref active_lib_features = tcx.sess.features.borrow().declared_lib_features;
 339
 340     // Put the active features into a map for quick lookup
 341     let active_features = active_lib_features.iter().map(|&(ref s, _)| s.clone()).collect();
 342
 343     let mut checker = Checker {
 344         tcx: tcx,
 345         active_features: active_features,
 346         used_features: FnvHashMap(),
 347         in_skip_block: 0,
 348     };
 349     intravisit::walk_crate(&mut checker, tcx.map.krate());
 350
 351     let used_features = checker.used_features;
 352     return used_features;
 353 }
 354
 355 struct Checker<'a, 'tcx: 'a> {
 356     tcx: &'a ty::ctxt<'tcx>,
 357     active_features: FnvHashSet<InternedString>,
 358     used_features: FnvHashMap<InternedString, StabilityLevel>,
 359     // Within a block where feature gate checking can be skipped.
 360     in_skip_block: u32,
 361 }
 362
 363 impl<'a, 'tcx> Checker<'a, 'tcx> {
 364     fn check(&mut self, id: DefId, span: Span,
 365              stab: &Option<&Stability>, _depr: &Option<Deprecation>) {
 366         if !is_staged_api(self.tcx, id) {
 367             return;
 368         }
 369         // Only the cross-crate scenario matters when checking unstable APIs
 370         let cross_crate = !id.is_local();
 371         if !cross_crate {
 372             return
 373         }
 374
 375         // We don't need to check for stability - presumably compiler generated code.
 376         if self.in_skip_block > 0 {
 377             return;
 378         }
 379
 380         match *stab {
 381             Some(&Stability { level: attr::Unstable {ref reason, issue}, ref feature, .. }) => {
 382                 self.used_features.insert(feature.clone(), Unstable);
 383
 384                 if !self.active_features.contains(feature) {
 385                     let msg = match *reason {
 386                         Some(ref r) => format!("use of unstable library feature '{}': {}",
 387                                                &feature, &r),
 388                         None => format!("use of unstable library feature '{}'", &feature)
 389                     };
 390                     emit_feature_err(&self.tcx.sess.parse_sess.span_diagnostic,
 391                                       &feature, span, GateIssue::Library(Some(issue)), &msg);
 392                 }
 393             }
 394             Some(&Stability { ref level, ref feature, .. }) => {
 395                 self.used_features.insert(feature.clone(), StabilityLevel::from_attr_level(level));
 396
 397                 // Stable APIs are always ok to call and deprecated APIs are
 398                 // handled by a lint.
 399             }
 400             None => {
 401                 // This is an 'unmarked' API, which should not exist
 402                 // in the standard library.
 403                 if self.tcx.sess.features.borrow().unmarked_api {
 404                     self.tcx.sess.span_warn(span, "use of unmarked library feature");
 405                     self.tcx.sess.span_note(span, "this is either a bug in the library you are \
 406                                                    using or a bug in the compiler - please \
 407                                                    report it in both places");
 408                 } else {
 409                     self.tcx.sess.span_err(span, "use of unmarked library feature");
 410                     self.tcx.sess.span_note(span, "this is either a bug in the library you are \
 411                                                    using or a bug in the compiler - please \
 412                                                    report it in both places");
 413                     self.tcx.sess.span_note(span, "use #![feature(unmarked_api)] in the \
 414                                                    crate attributes to override this");
 415                 }
 416             }
 417         }
 418     }
 419 }
 420
 421 impl<'a, 'v, 'tcx> Visitor<'v> for Checker<'a, 'tcx> {
 422     /// Because stability levels are scoped lexically, we want to walk
 423     /// nested items in the context of the outer item, so enable
 424     /// deep-walking.
 425     fn visit_nested_item(&mut self, item: hir::ItemId) {
 426         self.visit_item(self.tcx.map.expect_item(item.id))
 427     }
 428
 429     fn visit_item(&mut self, item: &hir::Item) {
 430         // When compiling with --test we don't enforce stability on the
 431         // compiler-generated test module, demarcated with `DUMMY_SP` plus the
 432         // name `__test`
 433         if item.span == DUMMY_SP && item.name.as_str() == "__test" { return }
 434
 435         check_item(self.tcx, item, true,
 436                    &mut |id, sp, stab, depr| self.check(id, sp, stab, depr));
 437         intravisit::walk_item(self, item);
 438     }
 439
 440     fn visit_expr(&mut self, ex: &hir::Expr) {
 441         check_expr(self.tcx, ex,
 442                    &mut |id, sp, stab, depr| self.check(id, sp, stab, depr));
 443         intravisit::walk_expr(self, ex);
 444     }
 445
 446     fn visit_path(&mut self, path: &hir::Path, id: ast::NodeId) {
 447         check_path(self.tcx, path, id,
 448                    &mut |id, sp, stab, depr| self.check(id, sp, stab, depr));
 449         intravisit::walk_path(self, path)
 450     }
 451
 452     fn visit_path_list_item(&mut self, prefix: &hir::Path, item: &hir::PathListItem) {
 453         check_path_list_item(self.tcx, item,
 454                    &mut |id, sp, stab, depr| self.check(id, sp, stab, depr));
 455         intravisit::walk_path_list_item(self, prefix, item)
 456     }
 457
 458     fn visit_pat(&mut self, pat: &hir::Pat) {
 459         check_pat(self.tcx, pat,
 460                   &mut |id, sp, stab, depr| self.check(id, sp, stab, depr));
 461         intravisit::walk_pat(self, pat)
 462     }
 463
 464     fn visit_block(&mut self, b: &hir::Block) {
 465         let old_skip_count = self.in_skip_block;
 466         match b.rules {
 467             hir::BlockCheckMode::PushUnstableBlock => {
 468                 self.in_skip_block += 1;
 469             }
 470             hir::BlockCheckMode::PopUnstableBlock => {
 471                 self.in_skip_block = self.in_skip_block.checked_sub(1).unwrap();
 472             }
 473             _ => {}
 474         }
 475         intravisit::walk_block(self, b);
 476         self.in_skip_block = old_skip_count;
 477     }
 478 }
 479
 480 /// Helper for discovering nodes to check for stability
 481 pub fn check_item(tcx: &ty::ctxt, item: &hir::Item, warn_about_defns: bool,
 482                   cb: &mut FnMut(DefId, Span, &Option<&Stability>, &Option<Deprecation>)) {
 483     match item.node {
 484         hir::ItemExternCrate(_) => {
 485             // compiler-generated `extern crate` items have a dummy span.
 486             if item.span == DUMMY_SP { return }
 487
 488             let cnum = match tcx.sess.cstore.extern_mod_stmt_cnum(item.id) {
 489                 Some(cnum) => cnum,
 490                 None => return,
 491             };
 492             let id = DefId { krate: cnum, index: CRATE_DEF_INDEX };
 493             maybe_do_stability_check(tcx, id, item.span, cb);
 494         }
 495
 496         // For implementations of traits, check the stability of each item
 497         // individually as it's possible to have a stable trait with unstable
 498         // items.
 499         hir::ItemImpl(_, _, _, Some(ref t), _, ref impl_items) => {
 500             let trait_did = tcx.def_map.borrow().get(&t.ref_id).unwrap().def_id();
 501             let trait_items = tcx.trait_items(trait_did);
 502
 503             for impl_item in impl_items {
 504                 let item = trait_items.iter().find(|item| {
 505                     item.name() == impl_item.name
 506                 }).unwrap();
 507                 if warn_about_defns {
 508                     maybe_do_stability_check(tcx, item.def_id(), impl_item.span, cb);
 509                 }
 510             }
 511         }
 512
 513         _ => (/* pass */)
 514     }
 515 }
 516
 517 /// Helper for discovering nodes to check for stability
 518 pub fn check_expr(tcx: &ty::ctxt, e: &hir::Expr,
 519                   cb: &mut FnMut(DefId, Span, &Option<&Stability>, &Option<Deprecation>)) {
 520     let span;
 521     let id = match e.node {
 522         hir::ExprMethodCall(i, _, _) => {
 523             span = i.span;
 524             let method_call = ty::MethodCall::expr(e.id);
 525             tcx.tables.borrow().method_map[&method_call].def_id
 526         }
 527         hir::ExprField(ref base_e, ref field) => {
 528             span = field.span;
 529             match tcx.expr_ty_adjusted(base_e).sty {
 530                 ty::TyStruct(def, _) => def.struct_variant().field_named(field.node).did,
 531                 _ => tcx.sess.span_bug(e.span,
 532                                        "stability::check_expr: named field access on non-struct")
 533             }
 534         }
 535         hir::ExprTupField(ref base_e, ref field) => {
 536             span = field.span;
 537             match tcx.expr_ty_adjusted(base_e).sty {
 538                 ty::TyStruct(def, _) => def.struct_variant().fields[field.node].did,
 539                 ty::TyTuple(..) => return,
 540                 _ => tcx.sess.span_bug(e.span,
 541                                        "stability::check_expr: unnamed field access on \
 542                                         something other than a tuple or struct")
 543             }
 544         }
 545         hir::ExprStruct(_, ref expr_fields, _) => {
 546             let type_ = tcx.expr_ty(e);
 547             match type_.sty {
 548                 ty::TyStruct(def, _) => {
 549                     // check the stability of each field that appears
 550                     // in the construction expression.
 551                     for field in expr_fields {
 552                         let did = def.struct_variant()
 553                             .field_named(field.name.node)
 554                             .did;
 555                         maybe_do_stability_check(tcx, did, field.span, cb);
 556                     }
 557
 558                     // we're done.
 559                     return
 560                 }
 561                 // we don't look at stability attributes on
 562                 // struct-like enums (yet...), but it's definitely not
 563                 // a bug to have construct one.
 564                 ty::TyEnum(..) => return,
 565                 _ => {
 566                     tcx.sess.span_bug(e.span,
 567                                       &format!("stability::check_expr: struct construction \
 568                                                 of non-struct, type {:?}",
 569                                                type_));
 570                 }
 571             }
 572         }
 573         _ => return
 574     };
 575
 576     maybe_do_stability_check(tcx, id, span, cb);
 577 }
 578
 579 pub fn check_path(tcx: &ty::ctxt, path: &hir::Path, id: ast::NodeId,
 580                   cb: &mut FnMut(DefId, Span, &Option<&Stability>, &Option<Deprecation>)) {
 581     match tcx.def_map.borrow().get(&id).map(|d| d.full_def()) {
 582         Some(def::DefPrimTy(..)) => {}
 583         Some(def::DefSelfTy(..)) => {}
 584         Some(def) => {
 585             maybe_do_stability_check(tcx, def.def_id(), path.span, cb);
 586         }
 587         None => {}
 588     }
 589 }
 590
 591 pub fn check_path_list_item(tcx: &ty::ctxt, item: &hir::PathListItem,
 592                   cb: &mut FnMut(DefId, Span, &Option<&Stability>, &Option<Deprecation>)) {
 593     match tcx.def_map.borrow().get(&item.node.id()).map(|d| d.full_def()) {
 594         Some(def::DefPrimTy(..)) => {}
 595         Some(def) => {
 596             maybe_do_stability_check(tcx, def.def_id(), item.span, cb);
 597         }
 598         None => {}
 599     }
 600 }
 601
 602 pub fn check_pat(tcx: &ty::ctxt, pat: &hir::Pat,
 603                  cb: &mut FnMut(DefId, Span, &Option<&Stability>, &Option<Deprecation>)) {
 604     debug!("check_pat(pat = {:?})", pat);
 605     if is_internal(tcx, pat.span) { return; }
 606
 607     let v = match tcx.pat_ty_opt(pat) {
 608         Some(&ty::TyS { sty: ty::TyStruct(def, _), .. }) => def.struct_variant(),
 609         Some(_) | None => return,
 610     };
 611     match pat.node {
 612         // Foo(a, b, c)
 613         // A Variant(..) pattern `hir::PatEnum(_, None)` doesn't have to be recursed into.
 614         hir::PatEnum(_, Some(ref pat_fields)) => {
 615             for (field, struct_field) in pat_fields.iter().zip(&v.fields) {
 616                 maybe_do_stability_check(tcx, struct_field.did, field.span, cb)
 617             }
 618         }
 619         // Foo { a, b, c }
 620         hir::PatStruct(_, ref pat_fields, _) => {
 621             for field in pat_fields {
 622                 let did = v.field_named(field.node.name).did;
 623                 maybe_do_stability_check(tcx, did, field.span, cb);
 624             }
 625         }
 626         // everything else is fine.
 627         _ => {}
 628     }
 629 }
 630
 631 fn maybe_do_stability_check(tcx: &ty::ctxt, id: DefId, span: Span,
 632                             cb: &mut FnMut(DefId, Span,
 633                                            &Option<&Stability>, &Option<Deprecation>)) {
 634     if is_internal(tcx, span) {
 635         debug!("maybe_do_stability_check: \
 636                 skipping span={:?} since it is internal", span);
 637         return;
 638     }
 639     let (stability, deprecation) = if is_staged_api(tcx, id) {
 640         (lookup_stability(tcx, id), None)
 641     } else {
 642         (None, lookup_deprecation(tcx, id))
 643     };
 644     debug!("maybe_do_stability_check: \
 645             inspecting id={:?} span={:?} of stability={:?}", id, span, stability);
 646     cb(id, span, &stability, &deprecation);
 647 }
 648
 649 fn is_internal(tcx: &ty::ctxt, span: Span) -> bool {
 650     tcx.sess.codemap().span_allows_unstable(span)
 651 }
 652
 653 fn is_staged_api(tcx: &ty::ctxt, id: DefId) -> bool {
 654     match tcx.trait_item_of_item(id) {
 655         Some(ty::MethodTraitItemId(trait_method_id))
 656             if trait_method_id != id => {
 657                 is_staged_api(tcx, trait_method_id)
 658             }
 659         _ => {
 660             *tcx.stability.borrow_mut().staged_api.entry(id.krate).or_insert_with(
 661                 || tcx.sess.cstore.is_staged_api(id.krate))
 662         }
 663     }
 664 }
 665
 666 /// Lookup the stability for a node, loading external crate
 667 /// metadata as necessary.
 668 pub fn lookup_stability<'tcx>(tcx: &ty::ctxt<'tcx>, id: DefId) -> Option<&'tcx Stability> {
 669     if let Some(st) = tcx.stability.borrow().stab_map.get(&id) {
 670         return *st;
 671     }
 672
 673     let st = lookup_stability_uncached(tcx, id);
 674     tcx.stability.borrow_mut().stab_map.insert(id, st);
 675     st
 676 }
 677
 678 pub fn lookup_deprecation<'tcx>(tcx: &ty::ctxt<'tcx>, id: DefId) -> Option<Deprecation> {
 679     if let Some(depr) = tcx.stability.borrow().depr_map.get(&id) {
 680         return depr.clone();
 681     }
 682
 683     let depr = lookup_deprecation_uncached(tcx, id);
 684     tcx.stability.borrow_mut().depr_map.insert(id, depr.clone());
 685     depr
 686 }
 687
 688 fn lookup_stability_uncached<'tcx>(tcx: &ty::ctxt<'tcx>, id: DefId) -> Option<&'tcx Stability> {
 689     debug!("lookup(id={:?})", id);
 690
 691     // is this definition the implementation of a trait method?
 692     match tcx.trait_item_of_item(id) {
 693         Some(ty::MethodTraitItemId(trait_method_id)) if trait_method_id != id => {
 694             debug!("lookup: trait_method_id={:?}", trait_method_id);
 695             return lookup_stability(tcx, trait_method_id)
 696         }
 697         _ => {}
 698     }
 699
 700     let item_stab = if id.is_local() {
 701         None // The stability cache is filled partially lazily
 702     } else {
 703         tcx.sess.cstore.stability(id).map(|st| tcx.intern_stability(st))
 704     };
 705
 706     item_stab.or_else(|| {
 707         if tcx.is_impl(id) {
 708             if let Some(trait_id) = tcx.trait_id_of_impl(id) {
 709                 // FIXME (#18969): for the time being, simply use the
 710                 // stability of the trait to determine the stability of any
 711                 // unmarked impls for it. See FIXME above for more details.
 712
 713                 debug!("lookup: trait_id={:?}", trait_id);
 714                 return lookup_stability(tcx, trait_id);
 715             }
 716         }
 717         None
 718     })
 719 }
 720
 721 fn lookup_deprecation_uncached<'tcx>(tcx: &ty::ctxt<'tcx>, id: DefId) -> Option<Deprecation> {
 722     debug!("lookup(id={:?})", id);
 723
 724     // is this definition the implementation of a trait method?
 725     match tcx.trait_item_of_item(id) {
 726         Some(ty::MethodTraitItemId(trait_method_id)) if trait_method_id != id => {
 727             debug!("lookup: trait_method_id={:?}", trait_method_id);
 728             return lookup_deprecation(tcx, trait_method_id)
 729         }
 730         _ => {}
 731     }
 732
 733     let item_depr = if id.is_local() {
 734         None // The stability cache is filled partially lazily
 735     } else {
 736         tcx.sess.cstore.deprecation(id)
 737     };
 738
 739     item_depr.or_else(|| {
 740         if tcx.is_impl(id) {
 741             if let Some(trait_id) = tcx.trait_id_of_impl(id) {
 742                 // FIXME (#18969): for the time being, simply use the
 743                 // stability of the trait to determine the stability of any
 744                 // unmarked impls for it. See FIXME above for more details.
 745
 746                 debug!("lookup: trait_id={:?}", trait_id);
 747                 return lookup_deprecation(tcx, trait_id);
 748             }
 749         }
 750         None
 751     })
 752 }
 753
 754 /// Given the list of enabled features that were not language features (i.e. that
 755 /// were expected to be library features), and the list of features used from
 756 /// libraries, identify activated features that don't exist and error about them.
 757 pub fn check_unused_or_stable_features(sess: &Session,
 758                                        lib_features_used: &FnvHashMap<InternedString,
 759                                                                       StabilityLevel>) {
 760     let ref declared_lib_features = sess.features.borrow().declared_lib_features;
 761     let mut remaining_lib_features: FnvHashMap<InternedString, Span>
 762         = declared_lib_features.clone().into_iter().collect();
 763
 764     let stable_msg = "this feature is stable. attribute no longer needed";
 765
 766     for &span in &sess.features.borrow().declared_stable_lang_features {
 767         sess.add_lint(lint::builtin::STABLE_FEATURES,
 768                       ast::CRATE_NODE_ID,
 769                       span,
 770                       stable_msg.to_string());
 771     }
 772
 773     for (used_lib_feature, level) in lib_features_used {
 774         match remaining_lib_features.remove(used_lib_feature) {
 775             Some(span) => {
 776                 if *level == Stable {
 777                     sess.add_lint(lint::builtin::STABLE_FEATURES,
 778                                   ast::CRATE_NODE_ID,
 779                                   span,
 780                                   stable_msg.to_string());
 781                 }
 782             }
 783             None => ( /* used but undeclared, handled during the previous ast visit */ )
 784         }
 785     }
 786
 787     for &span in remaining_lib_features.values() {
 788         sess.add_lint(lint::builtin::UNUSED_FEATURES,
 789                       ast::CRATE_NODE_ID,
 790                       span,
 791                       "unused or unknown feature".to_string());
 792     }
 793 }